What is an EBL? All about the Elektroblock - in detail. Updated 2026 with notes for lithium batteries.

If you just want the very basics of what the EBL is, then all you need is this first section in bold.

The EBL is a box fitted to later post 95 (approx) classic Hymers which handles all of the habitation electrics.

Earlier pre 95 vans have separate components - ie fuse box, relays and mains charger, but the later vans have all this incorporated into one box - the EBL.

So an EBL contains a 230v charger, split charge relays and 12v habitation distribution and fusing. It is connected to both the engine battery (EB) and the leisure battery (LB), to the alternator D+ signal cable, to the fridge for 12v fridge operation and to the various habitation circuits - lights, pumps etc. The EBL is also responsible for driving the control panel, where the meters are etc.

It also has a socket into which a solar controller can be connected - but there are limits to what can be connected to this - see below.

At first glance it looks a complicated beast, with a whole plate of spaghetti on the front of it. But you only have to study it for a while and you will discover that it has typically efficient German design and common sense going on. All you have to do is learn a few new words - "block" and "pin".

All the cables are connected to the EBL via multi connectors - these are called "mate n lok"  - it's a brand name. These are good connectors, but the downside for the amateur is that you need special tools to attach the pins to the cable ends, and then the pins push into the holes and have a tang which locks them into place. This means they can't easily be taken out - you need a special tool. However the good news is that the average owner rarely needs to do this - modifications and repairs can usually be made without special tools or pin removal.

The sockets on the EBL are called "blocks", and they are lettered - A B C etc. And within each block, the pins are numbered. if you look closely you will see that the pins are numbered in such a way as you can work out which pin is what. So for example Block A may be a 3 x 5 block - the lower left hand pin will be numbered 1, the end of the row will be numbered 3, and the top right is 15. So that is telling you the numbering scheme - start at one and count across in rows. So if you want pin 7, that will be third row up, first pin .... all very logical.

So when you are talking technical with EBLs, you will often see - Block A pin 7.

All the EBL models are made by a company in Germany called Schaudt, and they are used in many other vans - not just Hymers - and all the technical manuals and diagrams are available online. The diagrams show the function of each pin.

So looking at this diag you can see that Battery 2 positive - the leisure battery - is connected to Block C pin 2 .... and if you look closely, you can see that pin 2 is also paralleled with pin 5 - this is common in EBLs to allow more current carrying capacity. Note this is an example and does not mean that all EBLs have the LB connected to these pins.

So now you know how to identify the connections on your EBL - but remember that there are several models of EBL - EBL99, EBL104 and EBL105 are common ones, but there are others - but the principles are the same for all.

So now let's look at some of the functions of the EBL.

230v Charging.

All EBLs have a 230v connection. This is to power the internal charger. There is usually a switch on the EBL marked on/off and this switches on and off the 230v supply to the charger. usually it is left on, and so when the van is plugged in to EHU, the charger is live and delivering 12v charge to the battery.

It is important to remember that the EBL has nothing to do with 230v distribution to the 230v sockets around the van. The sockets are fed directly from the EHU connection, via the breaker box (consumer unit), and the EBL also takes its 230v power from here also. The switch on the EBL only affects the charger.

Most classic EBLs only charge the leisure battery, but some also charge the engine battery as well. You have to consult the documentation to see if your EBL has this function.

The other thing you have to remember is that even when you are plugged in to EHU, everything in the van, except the 230v sockets, is still powered from the LB. All the lights and pumps etc are powered from the LB, and the EBL charger replaces the battery power used as you go. This means that if the EBL charger fails, or is switched off, you can still end up in a situation where the LB goes flat and the lights go out even if you are plugged in - although this is a rare situation, it can cause confusion. The EBL does not provide 12v power directly to the van - it just replaces the battery power used in real time, and any left over goes to top up the LB.

Engine charging

The EBL is also connected to the engine battery (EB). And of course the EB is connected to the alternator - and the alternator charges the EB. But of course when you are driving you want the LB to be charged as well. This is achieved by relays inside the EBL. Relays are the same as switches. 

All alternators have a signal line called the D+. This is the same signal line that operates the red battery light on the dashboard instruments of your van. When the engine is on, the alternator is spinning, and the D+ line goes to +12v. This D+ 12v is used to switch on the relays inside the EBL. So when the engine is on, the relays are operated and the two batteries - EB and LB are connected together - in parallel - and this allows alternator power to flow to both batteries while engine is on. As soon as the engine is switched off, the relays switch off, and the LB is no longer connected to the EB. This arrangement is traditionally called a split charge relay system and is common to all motorhomes and caravans. The reason it is done this way, with relays, is so that the LB can go flat while the van is parked, but the EB always stays fully charged so that the van engine will always start.

You can see this in action by looking at the meters - the voltage on both batteries will rise to the same level - above 13v, with the engine on, and the relays are working properly. Conversely if you do not see this then that indicates a problem either with the relays (rare) or the D+ line (common). At the factory Hymer had to add an extension to the D+ wire, and the connector they used to achieve this can get corroded after 30 years, leading to failure of the D+ voltage getting to the EBL.

Fridge on 12v

The same system is used to power the fridge on 12v while driving - assuming you have switched the fridge to this mode. A typical fridge takes 10 amps on 12v, which would soon flatten a leisure battery, but is no problem to an alternator, so the fridge is only allowed to run on 12v while the engine is running.

Fusing

There is a big row of fuses on all EBLs - and the function of each fuse is written on the EBL next to each fuse. They vary from van to van, but basically all the habitation circuits - ie everything in the living side of the van is fed from the cables on the EBL, and all are fused. So if something stops working, these fuses are the first place to look. You can use google translate in camera mode to decipher the fuse labels. The main ones are "KREIS" which means circuit. Just like the pre 95 non EBL vans, there are 2 or 3 main habitation circuits that feed the lights and stuff around the van, usually in zones. The EBL often takes this a step further and has separate fused circuits for the water pump and heating - all marked in German.

Metering

Because both batteries and all the hab circuits are connected to the EBL, it is logical for the control panel to also be connected to the EBL. The voltage and power meters are fed by a multi core cable from the EBL to the panel. On some vans there is a master 12v on/off switch on the panel - this operates another relay switch inside the EBL which switches on or off main 12v power to the van hab circuits.

Solar

Solar and the EBL confuses a lot of people. There is a socket (block) on the EBL marked "solar". This is to connect solar controllers into the EBL, but the only solar controllers that plug straight into this socket are those made by Schaudt, and another German company Votronic. These are PWM controllers - which are now regarded as old technology - don't forget that the basic design of everything electrical in a classic Hymer is 1980s and 90s technology. Back then solar was expensive, and much less powerful than today. Most EBL manuals state that the maximum solar power that can be plugged into the EBL is around 10 amps - roughly equivalent to a 100 or 150w solar panel. 

But these days solar panels are much more powerful - 200w and above, and more efficient MPPT controllers have replaced the older PWM controllers, so if modern or upgraded solar is fitted to a van with an EBL it is normal to not use the solar input on the EBL and to connect solar controllers directly to the battery.

Upgrades and bigger batteries - including lithium.

So what does a modern classic owner do when they want to install bigger batteries, bigger solar panels or bigger chargers to a van that has an EBL?

There is a limit to how much power input an EBL can handle - after all it was designed over 30 years ago. So if you want more, then it has to be thought about. The simple answer is to connect all of these more powerful components directly to the leisure batteries and to disable all functions of the EBL except for 12v power distribution and fusing. So lets look at all these functions in turn.

230v charger upgrade

Most EBLs have a charger of around 10amps. The basic configuration of a van 30 years ago was a 100ah LB. So if you fit a bigger battery, then it makes sense to fit a bigger charger, especially if you plug in a lot, or if you want to spend as much time off grid as possible, and then get a rapid overnight charge from EHU ready for going off grid again. If fitting a newer bigger charger, then all you have to do is unplug the 230v plug from the EBL - this will disable the internal charger. Then connect the new charger directly to the LB.

Notes for Lithium - if you are fitting a smaller lithium battery, say 100ah to replace the original, then you may wonder if you can use the original charger. There are plenty of armchair pundits who will scream NO at you online, and the more loony of them will offer doom and gloom explosion and fire. I have written about this at length in another blog, but te bottom line is that using the EBL to charge lithium is not dangerous, but it is not optimum. If your EBL has an AGM selection switch, and you had AGM batteries previously, then deselect AGM, this reduces charging voltage slightly. An original EBL charger will happily charge a lithium battery, but it may not charge it fully - it may stop just short - around 90%, which to be honest is no big deal. And most vans with lithium will also have modern solar, which will have a lithium profile, and as solar is connected all the time, it will happily work with the old charger and top off the battery.

The other issue is that a lithium battery will work the charger harder - it won't abuse it, but it will be asking it to work hrder than it has in the past. Plus the van is 30 or more years old, so a sudden change to  harder work may well see off a charger that was getting old anyway. This has given rise to memes that "lithium killed my charger" or "the charger sacrificed itself to save my family" and over the years this has morphed into "you must not use a non lithium charger". However, if you are spending money on a major upgrade, a charger upgrade is a good investment anyway.

And if you are fitting big lithium - ie 200ah and more, then a charger upgrade is a no brainer. My favourite is the Victron Blue Smart IP22 30a charger. Beware of cheaper dedicated lithium chargers - these can have noisy fans on all the time you are on EHU which can be a pain if the charger is near where you sleep.

But if you are experimenting, or upgrading a bit at a time, you can use the EBL charger on lithium.

Solar upgrade

The same goes for solar - ignore the solar input on the EBL and connect your new panels and MPPT controllers directly to the LB. Modern MPPT solar controllers have lithium (Lifepo4) profiles. Victron, Epever and Renogy make good controllers for lithium.

Engine charging upgrade - this is the hardest one! And how it affects the fridge on 12v.

If you are fitting bigger leisure batteries and need more charge from your alternator, then things start to get a bit more complicated.  A lead acid battery will take charge at roughly 20% of its rated capacity - so a 100ah battery will take 20a - a 200ah battery will take 40a, and so on. But most EBLs were only designed for 100ah batteries (occasionally 200ah) so the relays and cable sizes are too small to handle more alternator power.

Notes for lithium. Like the 230v charger, the EBL relays maybe asked to work a bit harder, but internet memes about ruined alternators are to be safely ignored.

So to bypass the relays inside the EBL so that more power can be delivered from the alternator, the split charge relay system inside the EBL has to be disabled and new bigger cabling and more powerful external split charge relays have to be fitted externally. Or in some cases a relay is not used, and a b2b - battery to battery charger - may also be installed. A b2b is the better choice for lithium, but a good voltage controlled relay such as the Victron Cyrix will also work well.

The easiest way to disable the split charge relays in the EBL is to simply cut the D+ alternator line to the EBL - usually a yellow wire. This will then stop the internal relays from operating. However this will also stop the fridge relay from operating, so just cutting the D+ line also disable the 12v supply to the fridge while driving. 

If it is important to preserve this function then there are several ways - either the internal split charge relays can be disabled - this means opening the EBL and going inside, so is only for owners with this competence. Or, an external fridge relay can be fitted. This external relay would be operated by an extension to the D+ line, and the new relay would be connected to the branch from the incoming EB line to the EBL, and the 12v feed to the fridge from the EBL would be removed from its plug, and connected to the output of the new relay, via an inline fuse. This sounds more complicated than it is but is achievable with basic 12v wiring skills.

Other possibilities are to run the fridge on gas while driving, or even run the fridge on 230v via an inverter - this might sound daft, but with a bigger battery system and more power from the alternator, then diverting 10amps to the fridge to power it on 230v from an inverter is no different to the original 12v arrangement. And of course 12v only compressor fridges are becoming more and more popular, because these big power upgrades have the ability to power them. A 12v only compressor fridge needs nothing more than a connection direct to the LB - this can even be done via the EBL - and many EBLs have a dedicated fused connection specifically for a comp fridge, so all you have to do

Once you have decided which method you are using, then you should run a thicker cable via an inline fuse from the engine battery to either your new b2b or relay, and from there direct to the LB.

EDIT I now have more information on how to deal with the EBL104 and EBL99 (the 2 most common ones in classic Hymers) when fitting lithium. Contact me directly via Classic Hymers Technical FB group.

So a typical big lithium (or lead acid) battery upgrade will result in the following.

• EBL unplugged from 230v - disables the internal charger.
• Solar connected directly to LB.
• Internal relays disabled by several methods as discussed and external relay or b2b fitted.
• Alternative arrangements made for powering fridge on 12v if desired.

This will result in the EBL being only used for 12v fused distribution. The panel meters will still work for voltage, but will no longer be accurate for power "STROM", because previously all power in and out went through the EBL, which measured it and sent it to the meter but this is now disabled because power is flowing externally. But this is now no problem as you will have chosen (didn't you!?) a lithium battery that has bluetooth and an app, and the app will give you all the information and more than the panel meters ever did. If you have fitted "dumb" lithium, or lead acid, and you want accurate metering info, then you can fit a battery monitor such as a smart shunt and app, which I have written about elsewhere. 




So that covers most aspects of EBL modification. There are now many vans with EBLs on the road sporting big solar and chargers and lithium batteries where the EBL is only used for 12v fusing and distribution, and all other functions have been bypassed.

Differences between pre 95 and post 95 classics.

Or to put it another way - differences between EBL vans and non EBL vans. Non EBL vans have basically the same functionality, but it is in separate components, not just in one box. So the early vans have a separate fuse panel, and the relays are in a box behind that panel. They also have a separate 230v charger. If an early van has solar, then it is always connected directly to the LB.

More info

There are 2 firms in the UK that specialise in EBL repair

They are Apuljack Engineering and A & N Caravan Services

Both come up on google first page.

The A & N web site is a mine of information on EBLs, but is not for the faint hearted - the author uses technical language and assumes that the reader has the same ability.

For more info and discussion, join and ask on the Classic Hymers Technical Facebook group.

https://www.facebook.com/groups/297054424534823

Lithium in the Classic Hymer (pre 95 non EBL)

Too busy for a long article? Can you just “drop in” a lithium battery into an unmodified classic Hymer? Basically yes you can, as long as you keep an eye on it, and the best way to do this is to choose a "smart" lithium battery that comes with a bluetooth app for your phone or tablet that shows you exactly what is happening to the battery in real time. Then you are in control. There is really no point in installing a "dumb" lithium battery - unless you are quite technical and have other means of monitoring and testing.

For the technical discussion .... read on.

Can you just “drop in” a lithium battery into an unmodified classic Hymer? I am afraid that there is no definitive black and white answer. I asked 3 leading lithium leisure battery manufacturers this question. One said yes, the other said their advice was to always fit a battery to battery charger, and the other didn’t reply!
So lets take each of these charging sources in turn, and try and assess their suitability for charging lithium.

The main issue is that lithium has different charging parameters to normal batteries, and the implied danger is that charging devices might get overworked, because a lithium battery can usually take all the charge presented to it. This could result, for example, in components only originally designed for charging a standard 100ah leisure battery with around 20a of charge, to deliver much more than that when a lithium battery is installed.

Alternator charging

The standard pre 95 classic, Fiat or Merc has an alternator of around 50 to 70a, and cabling between the engine battery and the leisure battery, via the split charge relay behind the fuse panel, of around 10mm2 copper, and intended to handle around 20a. Hymer fitted a 70a relay, but it is important to remember that this was over specification by Hymer so that the relay would last for ever - not to actually handle 70a.  But the bottom line here is that you are starting with a charging circuit with a design capacity of around 20a. But this isn’t self regulating - it doesn’t limit itself automatically - if asked to do more, it will, but then every component in the chain of the circuit will be working harder than before and problems can occur. In practice, if an original charging circuit is used, then it needs to be monitored for the first few weeks and months. The limiting factor is usually cable thickness, but connections can also be a problem, especially old ones that may be corroded or tired.

But some owners can and do charge lithium directly from the alternator - by upgrading cables and relays. Bt these owners are usually technically minded, and have metering and monitoring in place to ensure that every component in the chain is solid, and that the alternator isn’t being asked to work too hard. You have to keep and eye on it, and have the metering in place to monitor it.

The other worry that you read about online is that a charging system designed for lead acid batts is not suitable for lithium. This is actually not really a problem. A lead acid charging circuit will deliver around 13.8v maybe a bit more. But the limit for lithium is 14.6v, and even if this voltage was reached for some reason, the lithium bat's BMS would kick in and disconnect the charge. And if you look at the cgarge vs voltage chart for lithium batts you will see that even a charge that goes no higher than 13.8v will still result in a 95% charge. And in practice, with most vans that have lithium will also have solar, with a solar controller that has a lithium profile, solar will take care of the remaining 5%.

What many forget is that lithium batts are not dumb like lead acid, they have brains - the BMS, Battery Management System, and the job of the BMS is to prevent abuse. So the BMS will simply switch off the battery if the voltage or current falls outside of preset safety values. So in reality it is actually almost impossible to damage a lithium batt by giving it wrong voltages - it will just shut down.

But when it comes to alternator charging the simple solution for most owners is to fit a battery to battery charger - a b2b. This is a device that sits between the engine battery and the leisure battery. It has two main functions - to limit the amount of strain put on the alternator, and to present the leisure battery with a near perfect charging profile. A b2b is easy to fit - it has just 3 connections - to the engine battery, to the leisure battery, and the D+ alternator control line. (some b2bs don’t even need D+ - they are auto sensing). The only other issue for classic Hymer owners when fitting a b2b is that the original Hymer split charge relay (discussed above) needs disabling. This is easily done by removing the original relay from the fuse box. All other original cabling is left intact, which preserves the original function of 12v fridge operation while driving. Then a new cable has to be installed from the engine battery to the b2b, and from the b2b to the new lithium battery. The size of this cable is dictated by the size of the chosen b2b. And the size of the b2b is dictated not by the size of the new battery, but by the max rating of the alternator. The general sensible rule is 50% of the alternator rating - for te vast majority this will be 30a.

If fitting a b2b which needs D+ switching, then the original D+ line to the original relays in the fuse box has to be identified and tapped into, and a new wire run to the b2b.

In the case of classic Fiat vans, where the engine battery is under the front bonnet, a longer cable to the b2b is usually needed, and the D+ line can be run alongside it - the original D+ wire is usually able to be found in the area of the engine battery.

In the case of classic Mercedes, with the double battery box next to the drivers seat access is easier - the b2b can be easily connected to the engine battery and from there to wherever the new lithium battery is located. An easy way to obtain a D+ signal in the Mercedes battery box is to open the trunking that leads across the bottom edge of the door (if fitted) and locate the 12v power feed to the fridge, and carefully split the cable and tap into the fridge feed. The 12v fridge feed is relay switched by the D+ in the fuse box, so is in itself a D+ proxy - this method just makes it easier. Please note this is a tip for certain types of install, not a mandatory requirement. Most modern b2b chargers, such as Victron orion, have voltage sensing and don't need D+. 

The other factor that needs thinking about when considering alternator charging, is just how much you want. There is a trend with lithium batteries to “go large” and fit batteries of 200ah or more. So you have to think about just how much driving time you will need the next day, in addition to whatever you get from solar, to replace the power you have recently used. With most classics having around 60 to 80 amp alternators, and a sensible limit of around 50% of this, then that means no more than about 30 to 40 amps per hour of driving will be available. This is usually enough for most owners, but if you want more, then the only alternative is to fit a bigger alternator. But before you do, consider this ...

Solar keeps working all the time, and many vans with lithium also have solar, and those that don't should have! And modern solar panels are big, and cheap. In 2025 you can get a 425w black panel that is 1700 x 1100mm and will fit perfectly on the front of most Hymer roofs. And if you have such a panel, or even 2 or 300 watts of other panels further back - these panels don't stop working while you are driving. On a sunny day in summer I have regularly seen 70a of charge while driving - 40a from the alternator and another 30 from the solar! So factor in your solar ad your driving habits (winter/summer) before you go to the expense and hassle of a bigger alternator. In my experience a bigger alternator is rarely justified if thought out properly. It depends on your lifestyle and intended power use.

EHU (230v) charging

Pre 95 vans have a separate 230v charger. Most owners have replaced the original separate charger, so what charger you now have dictates what mods if any are needed. The original factory charger, if you still have it, will work with lithium, but will not be optimum. But if you do need to use it, you can.

But most owners fitting lithium will opt for a new charger. The Victron Blue Smart IP22 30a is ideal. 

When fitting a new more powerful charger for lithium, the next question will be whether to use the original Hymer cabling or not. This is particularly relevant on vans that have the charger in the back and the battery in the front, it is tempting to use the old cable because running a new one is a big job.

You can use the old cable - it will handle 30a, but you have to take into account that the original charger was only 10a, and the 12v cable from the old charger to the front of the van goes to the fuse box, and then via a 16a fuse, and then to the battery. Not only will the fuse blow if you fit a 30a charger in the back, but the length of cable, with old and possibly corroded connections along the way, will lead to an unacceptable voltage drop - ie won't charge the battery optimally.

So what do you do in this situation? And remember we are only talking about vans with the charger in the back and battery in the front. You have 2 options. The first is to move the charger to the front and connect directly to the battery. This means you will have to supply the charger with a new 230v supply. How easy this is depends on your van layout and your DIY skills. The second is to use the original cable, but disconnect it from the fuse box and run it directly to the battery. This takes out the problem of the original fuse and the old connections in the fuse box, and it also shortens the cable run considerably. I have performed this mod on many vans and it works well. But there are different tricks to identify the cable and do this, depending on the van. Anybody wanting more info on this can contact me direct.

On vans with the charger already in the front, things are much simpler, but you still have the problem of the original charger cable going via the fuse box. So in these cases it is usually best to simply run a new cable, and leave the old charger cable unused and safely insulated and tucked away. But it can be used if you are willing to put a bit of extra work in - it can be disconnected from the fuse box and re-routed directly to the battery. Again I have hints on this if needed.

Solar charging

This is probably the easiest of all. Solar power is free from the sun, and is the only charge source that is available “off grid”, so is ideal for wild camping. Solar panels and MPPT charging are now so cheap, and powerful, that if you are fitting lithium batteries it makes sense to fit as much solar power as your roof will easily take. On most vans this will be between 200 and 400w. This means that on a summers day, you can reasonably expect to replace between 80 amp hours (200w panel) and 160 amp hours (400w panel) on a sunny summer day, based on 6 hours of sunshine. But in winter the figures can be as low as 20% of this because the sun is much lower and the days shorter in winter. This is no problem if you don’t use your van in winter, but for full timers it is a major factor in your off grid capability. Full timers who want to be off grid as much as possible need to fit as much solar as they can. This goes for any battery system, not just lithium. A common misconception is that a 200w solar panel is a constant - it is not! In December it is a 40w panel! And that is assuming that the sun shines in December.

Technically, modern solar MPPT controllers usually have a lithium profile, but you can still use those that do not. If the controller has user definable settings, just set everything to 14.2v. If this isn’t possible, then just leave it set to the lead acid profile, it won’t do any harm.

So those are the main points to consider about charging lithium.

The result of all or some of this work is that the new lithium battery will have some or all charge sources (EHU, engine, solar) connected directly to it. But power still needs to get from the battery to the habitation circuits - so the original Hymer cables are left in place - black positive and brown negative. These feed direct to the fuse box, and then to the van.

If you are fitting high power devices such as an inverter, then this should be connected directly to the battery via suitable fusing. More complex installations may use busbars or connection posts.

Types of lithium battery - what to buy.

The next subject to discuss is "what type of lithium battery"? All lithium batteries for the leisure vehicle industry are lithium iron phosphate - known as lifepo4. These are the safest type.

Prices are now so low that lithium batteries are hardly more expensive than lead acid. The choice nowadays is do you opt for "dumb" lithium or "smart" lithium. Smart means the battery has a bluetooth BMS that talks to an app or display. In the motorhome context, the choice is a no brainer - always buy smart. Having an app in your hand which tells you exactly what is going on in real time (see screen grab below) is the killer app of modern battery technology. It is daft to fit a dumb lithium battery to a motorhome. But for those that have fitted dumb lithium, all is not lost, because you can make a dumb system smart by adding a Victron Smart Shunt (or cheaper chinese version) which will then offer you the same valuable info as a smart system. But note that if you shop around, you can now buy smart lithium 12v batteries for roughly the same price as dumb ones - Epever and Fogstar from Bimble are 2 solid recommendations. Note that when browsing 12v lithium leisure batteries online, if it doesn't specifically say "Bluetooth BMS", then it will be dumb. There is a huge amount of old stock flying around, and also a lot of cheap chinese lithium leisure batteries. Chinese batteries from either AliExpress, or UK/EU suppliers and importers are everywhere now. There is great debate about quality. There are Youtubers who cut open cheap chinese batteries and dissect them and analyse at length. I have even done it myself. My conclusion - and I am by no means the last word on this - it is just based on experience, is that there is nothing wrong with cheap no name chinese lifepo4 batteries - as long as they are smart bluetooth, and you have to be careful with the ad small print. There are lots of dumb batteries around - used in golf carts and fishing boats (trolling motors) and many other applications that don't need smart - but for a motorhome owner, smart is essential, because having all that info in your hand is a game changer for van life - it puts you in control - no more unwelcome surprises of the lights going dim half way through the weekend.

To my mind, the choice comes down to whether you want UK support and warranty - if you do, you have Bimble, Fogstar and several others, and you will pay a bit extra. Renogy and Ecoworthy also deserve a mention - their support is not quite as good, but it does exist if you push. But the unknown suppliers on AliExpress, you will get little or no support.

But little or no support isn't as bad as it sounds because these batteries are pretty reliable. The reason for this is that unlike lead acid batteries, which are easy to abuse, and fail as a result, it is actually very difficult to damage a lithium battery because they have a computer brain - the BMS - protecting it. If you abuse it, it just shuts down. 

So basically cheap lithium smart batteries are fine for motorhome use. By all means pay a bit extra, but if budget is tight, you are usually OK.

But there is one area where it pays to go big on quality and that is high power. Big lithium at a reasonable price means that things that were only dreamed about in the past are now possible - I am talking about high power - microwaves, airfryers, hair dryers, coffee machines, toasters, even kettles, these can all be powered with a big lithium battery through an inverter. Putting aside that the installation has to be solid and well installed, and that any power you use for these luxuries has to be replaced somehow .... but just concentrating on the battery .... if you power a 1500w device that will be drawing over 100amps from the battery. That is a lot of power, so now quality does become a factor. Big power needs lots of copper, and generates heat, so build quality is important. So if you are planning big power then probably best to buy a battery at the top end of the scale. Reputable suppliers will publish detailed specs, and 200amp continuous discharge is easy to find.

But having said all that, as long as you have done things right in terms of cable spec, there is nothing wrong with a 20 minute airfryer session from a cheaper battery. Even the no name suppliers don't want warranty returns and bad online reviews.

many owners have no idea about power  - they are used to just plugging anything in at home and it works - for all intents and purposes power at home is limitless. But it is completely different in a van. It takes a LOT of 12v power to convert to 230v.

So here is a list of common appliances to guide you.

Low power, no problem under 50 watts- phones, pads, any small battery appliance -shavers tec.

Low-ish power - 50 to 200w - TVs, laptops, ebike chargers.

Medium power - 200w to 800w - small coffee machines, small kitchen appliances such as whisks.

High power - 800w to 1500w. Small airfryers, small kettles, microwaves, big coffee machines, hairdryers. Basically anything that generates heat - check the label for the watts, divide by 12, that is how many amps at 12v you need.

Air conditioning is a special case and a separate conversation.

Finally .... do you really need it?

There is also one more big thing to think about - and that is - “do you really need it”??!!

There is nothing special about lithium - it is exactly the same volts and amps as any other battery. So you have to really identify the need.

The three main advantages of lithium are power density, long life and better information. Power density means you can get more power out of the same size - so a rough example would be if you only have space for 1 traditional 100ah leisure battery, and you don't want or can't relocate the battery, then you would get roughly double the power from the same space.

Long life is exactly as it sounds - they last longer. In regular use a standard leisure battery is only good for a few hundred cycles of charge and discharge which in average use means they need replacing every 2, 3 or 4 years. Lithium batts are good for thousands of cycles. The jury is still out because it's new technology but it is generally accepted that a decent lithium battery setup should last decades. So if you use your van a lot and intend to carry on doing so for years, then the financial deal alone can justify it.

But the third reason, better information, is for me, the best reason by far - better monitoring and information. The latest lithium batts come with bluetooth monitoring, and a phone app that displays accurate battery information. This tells you exactly how much power is left in the battery, how much charge you are getting (from all sources), and how much power you are using. Basically it is an accurate battery fuel gauge. After a few days of use you soon get a feel for your battery system, and can plan your activities accordingly. This is particularly useful for those who like to be off-grid as much as possible, or for those who may need to run devices that potentially use a lot of power, such as coffee machines, ebike chargers etc. You soon get to know exactly how much power these devices use, and how much charge you need to replace that power used - from solar etc. It is incredibly useful and gives you complete control, with no nasty surprises. With a standard lead acid battery - it is quite difficult (but not impossible) to get this sort of accurate information. Having used these Bluetooth lithium battery systems for over a year now, for me, it is by far the best reason to do the upgrade.

But none of that is to say that lead acid batteries are old hat or obsolete - they are not. A lead acid battery with a good solar system can easily provide enough power for normal summer holiday use. One of the best reasons to upgrade is when your existing system simply isn't giving you the power you need.

But now that lithium is only slightly more expensive than lead acid, it should be considered. And for the hobbyist and technical enthusiast, a lithium upgrade is a fascinating project.

Lifepo4 charge discharge characteristics

Epever 100ah smart bluetooth Lifepo4 battery

A typical BMS phone app, showing exactly what is being used, being received and how much is left.

TESTING CONTINUITY WITH THE MULTIMETER

One of the most useful tools in the box for sorting out wiring and cabling problems  is the continuity feature of your multimeter. On most meters it is marked with a small arrow. When selected, if you touch the probes together, the meter should make a sound - usually a beep - this means "short circuit".

Not all meters have this beep function. Most modern ones do, and if you are going to buy a meter, make sure yours does. On meters without the beep, then you have to use the "Ohm" setting, or "Diode" setting which will display zero on the meter display when you touch the probes together. 

So to test a connection, you touch one end of the wire with one probe, and the other with the other probe, and if you get a beep, then that proves there is "continuity" along that wire.

So if you have a bunch of wires at 2 ends, and no idea which is which, you use this feature to identify which is which. Attach one probe to one wire at one end, and then touch the other probe to each of the others until you get a beep.

But you have to remember that one end of the wire being tested is free - ie open circuit. You can't use this technique on connected wires, because there may be a path through another part of the circuit that will give you a false reading.

If the meter leads are too short, then you simply extend them using a long piece of wire, suitably connected - can be as crude as wrapping and taping. You check that you have a good connection by simply touching the probes together.

This technique is also useful for identifying grounds. DC current flows from pos to neg, with neg being chassis ground. If the ground neg wire or connection is not a solid path, then the circuit will not complete. So when testing and troubleshooting, you have to be sure that the neg has a good path to ground. The way to do this with a meter (set to continuity) is to attach one probe of the meter to the negative terminal of the battery - because that is 100% guaranteed to be the neg ... and then the other probe to the neg wire in question. Again, it is usually necessary to extend the meter probes. A favourite tool of the auto electrician is a 20 foot long meter extension wire with a crocodile clip that connects to the battery negative. Then neg grounds can be tested anywhere in the vehicle - especially rear light clusters - which are just about as far away from the battery as can be.

This is hopefully a simple explanation for motorhome owners - there are lots of Youtubes that explain multimeter continuity testing in more detail.

Inherited a van with an old LPG tank?

This article was written in reply to a new owner who had bought a 1988 B544 Hymer with an big underslung LPG tank, and wanted info. Most tanks are 40m 50 or 60L, so if you have a smaller tank - adjust the estimates accordingly - and remember - they are just estimates.

If the van is LHD then is likely an import, and the tank could have been fitted any time since. They were never a factory option - always fitted by dealers or gas companies - here or in Germany (usually).

Now what you have to understand about gas is that the equipment doesn't last forever, and at the very least should be checked over every 10 years or so. That is not to say there will be any danger - lots of people love to shout doom and gloom whenever the word gas is mentioned - I am not one of them. I know of plenty of original gas tank systems that are over 30 years old and still going strong. If you have reasonable common sense you can inspect the system visually and assess it yourself. If it fills with gas at the pump, and then after standing still on level ground with no wind, you can't detect the slightest whiff of gas from anywhere, and the appliances appear to work fine, then you have taken reasonable precautions and are most of the way there. But the general common sense attitude is that you should have any gas system checked over properly at least every 10 years. if you have children, it's more or less a duty!

The most important component is the regulator. Regs do have a use by date - and should be replaced every 10 years. Old regs can and do fail, and it is a regular question on this technical group. An LPG tank reg is the same as a bottle reg, but is usually bulkhead mounted, or mounted out of sight near the tank. Remember that old german vans pre 95 almost always have 50mb gas systems - not the 30/37mb that is the modern standard. Don't let any gas guy tell you otherwise.

if you do feel it prudent to have it checked over, then this group does have a recommended gas guy - Charlie Lister at Autogas 2000 Ltd up in Yorkshire. He will fit a new reg and check things over, and is a mine of info on all things gas. There are other firms dotted around the country, but Charlie knows Hymers and motorhomes in general and has been an invaluable source of advice over the years - so worth the trip.

About the gauge - the glass ones fitted on the tank are hard to read, but generally reliable. Study it carefully so that you understand it - you really have to read the dial to get to know what is empty and full position. There are usually accessory LED level gauges available nowadays, and these are convenient.

Your tank looks quite big - around 60L. The normal 11kg German bottles that fit the gas locker are 11kg, and there is 2kg in a litre. So 2 bottles is around 44L. The germans fitted them for 2 main reasons - 1. Long periods between refills, minimum hassle, max time on site or off grid. 2. Crossing European borders. There are several different bottle systems in different countries, which makes gas bottles an expensive inconvenience for long euro road trips, especially in winter.

So LPG tanks are the system of choice for long termers and road trippers. If you are planning multi country Euro trips, then you have a good asset. A new LPG tank system is around £1000 these days. I swear by mine - had it for 8 years now, been all over Europe and it has paid for itself twice over. All you need is a set of LPG pump adaptors and you are good for any country - and LPG is much cheaper than bottle gas. There are a few idiosyncrasies - ie no LPG in Morocco, and different tax rates in Italy, but I've always managed. LPG availability is also a factor. There has been much discussion in recent years about LPG slowly disappearing from UK forecourts, and this is true, mainly because of the electric car boom, but LPG as a fuel will be around for decades yet, and the only inconvenience I have found is that you have to plan your fill ups - there are non forecourt sources in most big towns and cities, and there are apps that tell you where they are. On the continent there is no problem.

Consumption wise, in summer, fridge and cooking, a 60L tank will last you for months - at least 3 or 4. In winter, when you have the heating on, then a tank will last you at least a full month using the heating for 12 hours a day. I have a 40L tank and in cold weather with the heating on 24/7 - ie non stop, I get 1 to 2 weeks. In summer it's every few months. It is heating that uses gas - fridge and cooking are low consumption.

At the other end of the scale - if you had it checked over and a professional condemns it - corrosion perhaps - then you can have it removed and revert to gas bottles for not much money - the plumbing will still be there and the installer will remove the old tank and install new fittings in the gas locker. This would probably be the best option if you don't want to shell out for a new tank - ie if you only plan to stay in the UK and not use the van very often, and only in summer. But I only add this for info - it is highly likely that your system will check out OK - most do.

No need to spend big bucks to get wifi internet in the van with a router and why roof mounted antennas and MiFis are a waste of time

EDIT 2024. I have been getting some stick online from various "experts" who are adamant that the only method worth considering is to have a roof mounted antenna, and various other gizmos, usually costing £300 or more in total. As I explain below, you simply don't need to go to this expense. The number one technical requirement to get a decent mobile signal is the size of the antenna. Once you have a big antenna, as found in a full size router, as opposed to the tiny antennas built into the body of a MiFi unit or a normal phone, you get 90% of the advantage. It is antenna size that is the major factor. Phone antennas are small simply because they have to be. Mifis are the same - any Mifi is a complete waste of time in a motorhome because size and portability and battery power are not a factor - Mifis are for travellers who stay in hotels. I will go further .... the Netgear Mifis, Nighthawk etc, are ridiculously overpriced, and are all easily outperformed by a "normal" 12v full size router such as the B525, placed by a window.

The reasons for the arguments are purely commercial. There is no profit in a secondhand fifty quid Chinese router - it is as simple as that. So companies such as Solwise and Motorhome WiFi dress it up as a technical subject and sell it to you as a package. Nothing wrong with that, good luck to them. But I am not involved commercially, I don't sell anything, I am a motorhome blogger with no axe to grind, and I just happen to have an interest in radio technology, having held an amateur radio licence for 30 years - and to get one of those you have to pass an exam, and 30 years ago it was quite a tough one - I even had to learn morse code.

The title of this blog says it all - there is simply NO NEED to spend over £300 for a router based motorhome wifi system. or to put it another way, the £50 option performs as well as the £300 option.

I now have a standing bet - a bottle of champagne - the proper stuff - for the van that parks next to mine and shows a working internet connection from the same network that is only available to him and not to me.

Here is the original blog .....

You don't need anything fancy to get the best chance of internet in the van over 4G. It's the size of the antenna that counts, not the location. The antennas in a proper full size router are 10 times bigger than the tiny antennas in a phone - that's why a router will pull in a signal long after the phone (hotspot) says no service.

The advantage of paying extra for a roof mounted antenna, plus the cables and adapters is negligible, and I have proved this by experimentation, based on my training in antenna theory as a licensed radio amateur. Antenna performance is like earthquakes - the scale of power is logarithmic. This means that for noticeable gains the performance has to double each time.

So the biggest gains are made by having a much bigger antenna. But after that, the positioning of the big antenna is less important, so the difference between on the roof, and just a meter or so below, by a window, or on the dash, is hardly noticeable.

EDIT see below about the insides of a roof MIMO antenna.

So all I use now is a Huawei B525 12v mobile router, which can be had for around £50. It lives on the front dash, or inside a cupboard if it is too sunny. The only time I have to try and reposition it is on the rare occasions I get no signal, or just 1 bar - in these situations it rarely improves. There has to be a minimum signal strength to support a decent data rate - so if there is no signal at all, then that's that.

In my early days of experimenting I used to put the router on the roof temporarily, in a plastic box. But I soon learned that no signal in the van (by a window) was no different to being on the roof.

If you are slightly technically minded, here is the methodology - the B525 has a page which displays signal strength and quality of signal parameters - QOS.

This a screen shot of the numbers with the router on its internal antenna by a window. With my roof top antenna the numbers were barely changed. The reason I did the experiment was that my rooftop antenna terminated in the wardrobe, so the router had to be there. But then I couldn't see the lights on the router, which was a pain. So I relocated the router inside the van where I can see it, and for the last few years have monitored it quite carefully - hardly any difference. I have never had a situation where I had no signal, and reconnecting to the roof antenna gave a signal. If there is no signal, there is no signal. 

The Huawei has proved very reliable and easy to use - when I change country and get a new sim, in it goes and 9 times out of 10 it connects immediately.

The takeaway for full timers is that you don't need to spend more than the cost of a Huawei B525 - about £50. There is a whole family of 12v mobile routers - others are available, but I like Huawei - mainly because of the software and firmware.

There is no point at all for the average motorhome owner to pay silly money for any of these expensive "motorhome wifi" kits. All you need is a 12v router costing around £50. There is also no need for any sort of power conditioning, as often suggested. They work fine on any voltage that can happen in a van - from 11v to over 14v. Now that I am on lithium batteries my resting voltage is 14.4v for days at a time (when plugged in) and I have not had a single failure of anything 12v in the van.

With regard to SIM cards - that is a big subject, as is EU roaming. In the UK I have found the EE network to be best, but EE is expensive. Three are the cheapest - you can get unlimited data on a 1 mont contract for under £20 ... but Three is the worst network -they have too many customers on at the same time and sppeds go down in the evening - depending on where you are. I recommend 1pmobile - it is one of very few subnetworks of EE, and you can get PAYG data from them on the EE network, cheaper than EE. Their deal for 200gb for £20 is very good, and no contract. I have never used O2 or Voda, but they are average from what I read. 

MIFI - I am not a fan of the little mifi boxes - they do need external antennas - and expensive adapters for their tiny antenna sockets - so what's the point. I would go so far as to say that a mifi box is a waste of money in a motorhome - you might as well use a phone hotspot. The only practical use for a mifi is for  travellers who live from a suitcase in hotel rooms etc. Mifis are also battery powered from USB, and tey don't like being plugged in 24/7. But if you already have one, and you are happy enough, then it ain't broke so don't fix it - not everybody is a speed crazy internetaholic like me!

Update for 2023. I have been experimenting with 5G, and it has either been not available, or just as fast as 4G and only occasionally super high speed - ie over 100mbs. The bottom line is that 5G is mainly in cities and big towns, and while I am sure it will eventually replace 4G, just as 4G has replaced 3G, for now, I just can't see the point, and 5G 12v mobile routers are still expensive - well over £100. After 3 months I sold it for £20 less than I bought it for and went back to 4G. 5G is nothing special - 4G is and always has been fast enough to deliver an internet TV service - Netflix etc to a motorhome. Only working professionals in technical need of over 100mbs need to consider 5G in a van. Most new phones are now 5G - mine is, but unless I am in a town I never see it connected. But when I have been in a city I have noticed it can be amazingly fast - but in reality the extra speed makes no difference to daily use. All most van owners need is streaming TV netflix etc, and 4G is more than fast enough for that. I streamed Netflix and Iplayer for years on 3G before 4G arrived.

EDIT 2024/2. I have had a dome MIMO antenna on my roof since 2015, but I have not used it for many years since I bought a B525. Recently I was on the roof and noticed it was damaged, probably by a tree. This is what I found inside. I know it looks weird but I do have some training in antenna design, so the use of aluminium sheet is not unusual - the shape gives more bandwidth, but bandwidth does not equate to signal strength - only multiples of a wavelength can do that. But the build quality is awful, using foam and glue - totally unsuitable for the vibration experienced on a van roof. I bet that the internals collapsed long before the case was broken. Electrically - ie in terms of radio reception, the antennas inside this dome are no different to the same size antennas inside a B525 or similar sized router - which explans the very little difference in performance. But that is not to say all roof mounted antennas are bad - only this particular type. See photo below.

These are typical QOS numbers from the admin page of a B525.

Big antennas like these are the secret of of good mobile reception.

Inside an old broken MIMO roof antenna

How a 600ah lithium battery setup has changed my motorhome full-timing life.

But let me be honest from the beginning - very few people will actually need 600ah. I was actually planning 300ah, which was a meaningful upgrade from my original 200ah lead acid setup. But at the last minute a friend who was advising me said that for what it will cost - all other installation costs being the same, an extra £600 to double the capacity was, on paper, a bargain. Furthermore he said that he had found, with that much power on tap, that there were many more intangible benefits that would crawl out of the lithium woodwork. And he was right!

Background - my wife and I full time in our S700 in all seasons. We are also heavy power users. TV and laptop are on most days, most of the time. Our daily power use varies but averages about 75ah a day. Our original fully charged 220ah  lead acid battery, backed up with 500w of solar, would, in winter, just manage a full weekend off grid, with no engine charging or EHU. In summer we had power to spare, and could stay off grid almost indefinitely. But for full timers, it is winter performance that matters.

In winter, our routine was always different to our summer routine. In winter we needed to drive more, and plug in more, which meant using camp sites or visiting friends more often, or even occasionally running a generator. We never liked using it, but occasionally - maybe twice a year, it was a life saver.

Of course there is also the point to be made that you can always use less power - this is a valid point, and we can and do switch things off if we want to stay put for longer and eke out the battery, but it's no fun.

This last system, we ran for about 5 years, and it taught us a lot about energy use in a motorhome. We discovered 3 things. 1. accurate monitoring is essential - you need to know what you have and what you have left - same a the van fuel gauge. 2. No matter what, every amp you take out, has to be put back in. 3. Solar power is by far the most important part of any off-grid system.

1. Monitoring I have blogged about elesewhere. It's important. But I would add that in the context of lithium batteries, you usually get it for free - in an app, and this has proved to be a real benefit.

2. This sounds self evident, but is really important! In summer, a decent solar system will put in the next day all you took out the night before. But in winter, solar panels give a fraction of what they do in summer, so you have to monitor very carefully and plan your activities to put back in power from other sources.

3. Solar power is the only free source of power, and the only one you can be truly off-grid. So in a nutshell, you need to fit as much as your roof will hold.

The reason I make these 3 points is that having a huge battery is not the simple answer to all these problems. But what it does do, is give you options.

One example of this is that with 600ah on tap - whereas before we would have to move after 3 days - now we can stay for much longer. If we use 200ah over a weekend, we still have 400ah left. However we soon learned that if we do stay in one place and use say 90% of a 600ah capacity, then we really need a proper recharge. Winter sun would take weeks to recharge that much, so the reality has proved that if we do need 500ah of recharge, the only meaningful option is to plug in. So our EHU charger has to be capable of completely refilling a 600ah batter in an overnight charger - this basically means 10 to 12 hours at 50a. So another rule we have learned about big lithium, is that your EHU charge source needs to be big enough to recharge in less that 12 hours - ie overnight.

The same goes for alternator charging. A lithium battery will suck in every amp that you throw at it, so a 60a alternator will deliver exactly that, for long periods of time, and will eventually overheat. There are various ways to improve this - we chose to install a B2B - battery to battery charger. This is a unit that sits between the engine battery and the lithium battery, and limits the power that can be transferred. In our case this is 60a - half the capacity of our 120a upgraded alternator. A side effect of this is that with a 60a b2b, 2 hours of driving actually gives us 120a. This is quite different to our old lead acid battery, which would suck in high power for a short while, and then settle down to a fraction of that - so a 2 hour drive would give something like 30a of charge, even though 60a was theoretically available. This is quite technical, and down to the difference in charging characteristics of lead acid and lithium, but this is a noticeable example.

This also a good example of how fitting a lithium battery means that you also have to think about, and if necessary modify, your charging equipment. Lithium batts have different charging characteristics to lead acid batteries. In our case this proved to be a good thing, because as already mentioned in the past, especially in winter, we had to plan our movements carefully, especially with regard to the weather, and driving distance - now we have a decent B2B, we can drive less for the same power, or get more power from the same drive. So when we are just touring around, distance between stops can be less, saving diesel. It also means that with a 50a EHU charger, we can take advantage of even short stops where EHU is available - ie at friends etc.

But by far and away the biggest advantage for us has been simply the fact of having all that power on tap. We no longer have to move because we have to - we move because we want to. We can stay a week or more instead of just a weekend, and if we do, and use almost all of that 600ah - then we know that all we need is an overnight charge, and we are good to go again. In pure financial terms, with campsites and CLs costing around £15 these days, in winter we are saving around £60 a month. 

There have also been some minor advantages, but satisfying nevertheless. We now run our fridge on 220v while driving - this keeps it cooler. And in summer we run it on 220v quite often, even though it is a 3-way fridge and takes 10amps. This is saving us gas - LPG, and we have already noticed that we are using less gas. I have always defended 3-way fridges because they are the ultimate in versatility, and they are. Our 3-way is quite new, so no intentions of throwing it out for a compressor fridge, but if the situation arose, I would now have no problem handling a compressor fridge, even in winter.

Another advantage is the use of high power items. My old system was easily capable of delivering the 100a or so needed to run a toaster or coffee machine for a few minutes, and on paper, because they were only on for a few minutes - eg 100a for 5 mins = 8.3ah - not a lot. But over the months I soon noticed that regular high power use was changing the characteristics of my lead acid battery. I looked into the technicalities of this, and learned that the capacity (and long life) of a lead acid battery depends entirely on the type of discharge it is asked to perform. It will last longer with only light discharge, and shorter with heavy discharge. And because I have accurate monitoring, and am a bit of a geek, it didn't take me long to realise that these morning coffee and toaster sessions were affecting the battery noticeably. 10 minutes of breakfast use was taking much longer to recharge from solar than the numbers would suggest. So after a year or so, we stopped, and went back to gas for toast and coffee. No such problem with lithium - they are quite linear. Doesn't matter if you take out 100a in 1 hour or 1a in 100 hours - the result is the same. So although the basic rule of put back in what you take out still applies, there is no worry about affecting the life of the battery.

Don't forget what I said above - these are minor advantages, but I have enjoyed discovering them and experimenting. 

So do you need 600ah?? Probably not is the honest answer. But several of us full timers have, and nobody yet is regretting the extra cost. 300ah is probably a meaningful upgrade for most van livers upgrading from 100 or 200ah lead acid systems. My system is now 6 months old and I have yet to go below 300ah, but I know it's there, and I expect to be using it for the rest of my van life - 10 to 20 years - which is another good reason to go lithium - long life.

There are 2 ways to get lithium. DIY or ready made. I chose the DIY route. The DIY route involves buying the individual 3.2v Lifepo4 lithium battery cells, and connecting them together, in a case or frame of your own construction, to the power and voltage you want. So in my case I used 8 x 3.2v 300ah cells, in a 4 series 2 parallel configuration, giving 600ah at 13v. The mechanics and connections was a relatively easy DIY job. A lithium battery consisting of multiple cells needs a circuit board called a BMS - Battery Management System. This is a board that sits between the cells and the outside world. It has multiple functions - it balances the cells, and protects them from over and under discharge and voltage. It is an essential part of the system. Good BMS also have bluetooth built in and come with an app. That is all the technical detail I will go into at this point. But anybody with a multimeter, who knows how to use it, has hooked up batteries and stuff before, and is willing to read online from the many excellent DIY websites and forums - is capable.

The non DIY route is to buy from an established battery manufacturer. These companies do what I have just described above, but in a much more user friendly way - ie they put the 4 cells and the BMS inside a box that looks and feels like a traditional 12v battery. These can usually, but not always, be straight swap replacements for old 12v lead acid batteries - but you should check with the supplier. You also get UK based support backup and warranty. A typical example in the UK is Roamer batteries, who consistently get good reviews. But the cost difference is about 50 to 100% over DIY, because you have to pay their profit margin, which is well deserved!

Lastly - order cells directly from China at your peril. BMSs are usually OK, but ordering small quantities of lithium cells can be a nightmare from China, using Alibaba etc. Just take my word for it, and don't be tempted by what appear to be really cheap prices in dollars - that is only the beginning of it. Contact me more more details.

  

MERCEDES OM602 FAN BELT FIT

 This engine is found in most Merc S class classics - late 80s to 1995. I am not sure if the same arrangement is found on earlier or later engines.

I have now had to be recovered in my S700 4 times in 23 years, and 3 of those were for broken fanbelts. 1 was random, 2 a coincidence but 3 is definitely a pattern. It is probably a service item and should be changed every 50k or so - I don't know, I don't have that info. But the reason it rarely gets done is that it is an absolute pig of a job. I know this to be true because I have been witness to the grunting and swearing that has emanated from the garages I have used, plus the posts I have seen on other groups.

So if you have a Mercedes, take note of this post, which will be in the index, for future reference.

All the difficulty stems from releasing the tensioning roller in order to slip on the new belt - at first glance there seems to be no way of doing it.

The first thing I discovered is that most of the online information, and in particular the Russek manual, is either wrong, or at the best, ambiguous. The diagram in the Russek manual is accurate in the general layout, but lacking in detail. After the event, I managed to find much more accurate diags - see below.

The procedure is as follows. Identify where is the tensioning spring, which runs parallel with the hydraulic damping cylinder. Here you find a nut (3 - yellow arrow) which is located on a bolt, which appears to be attaching the top loop of the spring to the bracket. This nut has to be taken off - but if you try, the whole thing just spins. What you can't see, and what isn't explained clearly is that there is a hex bolt head at the other end of the bolt (6 - red arrow) - but where is it? It isn't obvious. The bolt is actually a 3 inch long bolt that goes into a hole in the top corner of the engine block - the hole is about 3 inches deep, and the head of the bolt is back there - you have to reach your fingers in to feel it, and you can just get a spanner on it. One you do, then the front nut removes easily.

Then you have to insert a bar/lever into the recess in the top of the spring bracket - this is depicted in the diag with arrows showing the direction to push. This bar has to be provided by you. By moving this bar to the left or right you can move the spring bracket, release the spring tension, and then using a drift (anything handy) you can then push the bolt back through the bracket and into its hole - you can also help it out with your fingers round the back - but don't take it out completely - just enough so that it no longer fixes the top spring bracket in place. Once this is released, the spring will lose tension, and the tension pulley will fall down a couple of inches, finally allowing enough slack to get the belt around all the various pulleys. It is still a tough job, but it will go on.

The blue arrow indicates the actual pivot point of the bracket - for info only, it has no function in the job.

It is also worth mentioning that there are 2 ways to approach the job - access is really tight, and that is half the problem - you need a good set of tools to get at that nut and bolt. But if you take the radiator off, the job is a whole lot easier. Taking the rad off is a 20 minute job. If you are doing this job yourself, and are not pushed for time, and maybe doing other work, consider removing the rad.

Once it is on, you have to re-tension the spring and then lock it back in place, under tension. To do this, you have to push your bar, which is still in its hole, well over to the left, which will pivot the top spring bracket anticlockwise, until the point where the holes in the bracket and the engine block align, and you can push the bolt forward, through the holes, and the spring is then tensioned and locked in place. Replace the nut, and that's it, job done. When you know what you are doing, and you have just the right sized bar, it's a 5 minute job. If you don't, then it's a frustrating episode with much swearing and skinned muscles.

The confusion arises from the fact that removing the nut is counter intuitive because you think that is what is holding the spring in place. It is and it isn't - the spring is held in place by a collar in the bracket, and the bolt slides through the middle to lock it in place. the actual pivot point of the racket is further down.

I just had to pay a French garage 2 hours labour because they had no clue, despite me presenting them with photos from my collection, and the Russek manual. In the end what saved us was a telephone call to my own mechanic friend in N Wales.

None of this will make the slightest sense to anybody! It doesn't apply to Fiat family owners, and it is of no interest to Merc owners, until it happens to you - at which point, this detailed description should be useful to you or your garage.

I am also now reasonably convinced that in motorhome use, Merc fanbelts have roughly a 5 to 8 year lifespan - probably nearer 5, especially if you have modified electrics, like I do - ie big batteries. In motorhome use, the alternator works harder and hotter and so does the belt. The belt can get damaged slightly if the engine is turned off when the alternator is hot, and the belt can get slightly "cooked" at that point. The alternator pulley is the smallest on the belt, and therefore is working hardest. My intention now is to make sure I have a new belt either every time other work is carried out at the front, or every 4 or 5 years.