Major battery upgrade

It was a mistake to put 160 kilos of batteries in the boot of my S700, and then add a 130kg scooter! The van never complained, but there was a gradual awareness that it was too light at the front. We all make mistakes!

So how do I get powerful batteries in the front of my Hymer, when there is no obvious place to put them? Easy says Peter Curry, take the gas bottles out of the gas locker, install an underslung gas tank, then install anOdyssey PC1800 200 amp hour battery, which only weighs 60kilos, in the now empty gas locker.

So that's what we did! I did the electrics, while Peter did the gas tank. And then when we had finished all that Peter installed a new dash board in 12mm ply which has stiffened up the front end a treat - in addition to being almost a work of art!

The costs have been reasonable, especially after the sale of the old batteries, which Justin snapped up for the Linnebago 900 - which being a 7 and a half tonner doesn't even notice the weight. And the old refillable gas bottles went to a guy for his newly imported 670.

Everybody happy, and the van handles a lot better - I can feel the difference just by walking around inside. And I still have more power than I can shake a stick at - I am greedy when it comes to power.

Tech specs - 

Out - 4 x 100ah Yuasa professional sealed lead acid batteries.
In - 1 x Odyssey PC 1800 AGM 200ah marine battery.

Inverter - Victron 12/1600/70 inverter charger with auto changeover.

Solar - 3 x 120w Kyocera panels + 30amp MPPT controller

Nasa BM1 - compact battery management computer with 100amp shunt.

Gas 

Out - 2 x Gas-it 11kg refillable bottles

In - Gas-it 30kg (60 litre) underslung gas tank with external fill point and LED level meter inside van.

For lovers of tech trivia when I press the lever on my toaster, the battery delivers 105 amps to the inverter for the 4 minutes it takes to make toast. On a sunny day the solar will put that back in under an hour! But some days I have Muesli ...

Finished locker - gas now underslung, and a free shoe shelf with every pack!

Battery in red, Victron in blue, all sitting nicely on a plywood floor in the ex gas locker. Cables enter bottom left corner - 2 x 240v along chassis to consumer unit, very thick 12v cable across van chassis to original battery box, earth direct to chassis, solar cables along chassis and up through floor and wardrobe to roof. At bottom of picture is grey solar controller, which normally sits on top of Victron.

Closeup of 100amp shunt as supplied with Nasa BM1 battery monitor. Note thickness of cables - but also note that I used what was available and my cables are probably a bit over the top. There are online calculators for 12v cable size - but use the thickest you can.

And here is a follow up I wrote about the BM1 ...

The final piece of the jigsaw! Today I finally finished what I consider to be the ultimate energy system (for me anyway!), with the installation of abattery management monitor. 

I can now track and measure every amp in and out, which now enables me to calculate with good accuracy exactly how much longer my batteries will last, and how long it will take to fully recharge them, by any means.

This is only achievable if everything goes through a single shunt installed on the negative side of the battery - the original Hymer system and meters are untouched and fully functional.

The top display is the battery management monitor, and the lower display is the solar controller display, which isn't strictly necessary now that I have the new monitor display, but I had it already and it looks pretty.

What I have already learned, is that I am using a significant amount of power just doing nothing, as much as 4 amps if I am careless, but usually more like 2. I have a lot of gear in the van, and I am amazed at how much power is consumed when it's all switched off! This can be as much as 20amps wasted overnight, or the difference between getting a full charge and a partial charge from the solar panels on a cloudy day, while out shopping. So I am now going to install isolation switches so that no power is consumed while sleeping, or when not in the van so that the maximum charge goes into the batteries from the panels. I can also now see exactly what consumes what - the TV, the music system, the computer, the lights ... it is really informative and interesting - well it is to an anorak like me anyway!

Not every van needs such a system, but we live in our van for half the year, and we like to have pretty much as much power and convenience as we would have in a house, which isn't possible with just a single leisure battery.

Now we have bigger batteries, solar panels and an inverter/charger, and a system that tells us exactly how much power we have left, which means we can plan our movements much more accurately.

When the sun starts shining again, I am looking forward to seeing just how much sun is needed for daily self sufficiency.

Display of BM1 - top and Solar controller - bottom. Once you have a shunt which measures every amp in and out, then the BM1 can calculate the exact state of charge of your battery - you programme in the a/h capacity into the BM1 on installation. The top left photo shows 105% and 199 hours - which means it is fully charged.

And finally a quick and dirty schematic of the whole thing