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 con be connected here - 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.
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.
Fridge on 12v
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.
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.
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.
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?
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.
230v charger upgrade
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.
Solar upgrade
The same goes for solar - ignore the solar input on the EBL and connect your new panels and MPPT controllers dire tly to the LB.
Engine charging upgrade
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.
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?
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.
230v charger upgrade
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.
Solar upgrade
The same goes for solar - ignore the solar input on the EBL and connect your new panels and MPPT controllers dire tly to the LB.
Engine charging upgrade
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.
And if you are fitting lithium batteries this is even more important.
So 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.
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.
And finally ...
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.
Final notes
And if you are fitting lithium batteries this is even more important.
So 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.
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.
And finally ...
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.
Final notes
I have not mentioned shunts in this article - shunts are quite a technical subject, but for the sake of completeness, all EBLs contain a shunt, and it is the shunt that estimates current flow, and displays that info on the power meter on the panel - usually called the "STROM" meter - German for power.
More info
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.
For more info and discussion, join and ask on the Classic Hymers Technical Facebook group.
https://www.facebook.com/groups/297054424534823
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.
For more info and discussion, join and ask on the Classic Hymers Technical Facebook group.
https://www.facebook.com/groups/297054424534823
