caravan, two battery system. ideas please!

[(RIP) PLANK]

having spent the last week sitting in the dark due to to an unfortunate combination of electrical gremlins, i am planning a two battery system. your thoughts on cable for running between batteries, position of second battery etc. will be gratefully received :thumb2

[zippy656]

In a caravan you need to have a proper battery box

Sealed so no battery gas enters the van

[(RIP) PLANK]

thanks, but i have that bit covered :thumb2

[zippy656]

So a wiring question


Split chager as you would for a second car battery relay and the like

[solarman216]

both batteries close together is best, unless it makes a big difference to balance, for two reasons, one only one compartment needs ventilating, two short cables are better, but will depend on the load amps, but I guess only lights tv etc in which case link the two bats with 6mm cable and a fuse of a rating a little greater than the max amps to be drawn, if charging from the aux car plug then I regard that as not good, as the bats will only ever be charged to around 75% of their capacity, Rick

[zippy656]

Both need to be vented
as both will be charged, from car or internal charger

[(RIP) PLANK]

that was pretty much what i had in mind, Rick, Thanks. But i may have to mount them about 6ft apart, which would mean around 8ft of cable, will this make much difference?

zippy, i think Rick meant having them both in one compartment, :-)

[zippy656]

Why so far apart

[Lazy-Ferret]

Location is really down to where you have space, then you have to work from there...

How do you charge the batteries currently?

If you charge from the mains, then maybe go for 2 separate chargers, one for each battery, and a change over switch, so you can run from one, then when it is low, switch over to the other... that way you know how much time you have left before you have to worry about charging again

Another option is to put the second battery in the car, and then use that to power the van when you need it, that way it gets charged each time you go out.

[solarman216]

Both need to be vented
as both will be charged, from car or internal charger

That's what I said Zips, one compartment two bats, but now you mention split charging that assumes he wants to keep them as separate batteries? I assumed he just wanted to up the capacity, Rick

[solarman216]

that was pretty much what i had in mind, Rick, Thanks. But i may have to mount them about 6ft apart, which would mean around 8ft of cable, will this make much difference?

zippy, i think Rick meant having them both in one compartment, :-)

6ft apart is not bad just upgrade the linking cables to 10 or 16 mm, fuse stays the same, Rick

[(RIP) PLANK]

l there is another locker the same size as the battery one on the opposite side that doesn't really get used, i can replace this with a locker designed to hold a battery and make a tidy job. I would prefer to put them both in the caravan a i use different towing vehicles, an with both together i can make the most of the solar panels on bright days :thumb2

[zippy656]

Iz never seen a compatment that takes two

Yep. Up cable size have fuse maybe a kill switch too


No cable through gas compartment, unless in conduit

[(RIP) PLANK]

thanks everyone :thumb2 Rick, do you mean fuse betwen the batteries?

[zippy656]

Yes between would be good

[solarman216]

thanks everyone :thumb2 Rick, do you mean fuse betwen the batteries?

Yes cos if one battery goes down (internal short) the fuse will blow rather than melt the cables, Rick

[solarman216]

Iz never seen a compatment that takes two

Yep. Up cable size have fuse maybe a kill switch too


No cable through gas compartment, unless in conduit

I guessed he would make his own like I would, Kill switch is good, as would swap over switches so you can run on one bat and keep the other for reserve/emergency etc, and be able to cycle them to keep usage even, likewise conduit if going through gas compartment, Rick

[Thomas-the-Terrano2]

both batteries want to be same size and age, then connected in parallel, not in switch over,
as better to nibble little power from both, thus keeping them as full equally as they do drain
as for many items you need near on full voltage and much less than 12.5V is as good as flat.

a decent solar panel will keep both charged, indeed the built in mains charger will work too.

as for inter connect cable want something of the gauge used in jump leads, have a pal who
has 3 110Ahs so linked.

[(RIP) PLANK]

thinking of two brand new 110ah, i have decent solar system. one issues, when fusing heavy cables like 10mm, what sort of fuse holder and fuse? as they allways look like they are a bit flimsy and high resistance compared to the cable (in my opninion)

[Lazy-Ferret]

thinking of two brand new 110ah, i have decent solar system. one issues, when fusing heavy cables like 10mm, what sort of fuse holder and fuse? as they allways look like they are a bit flimsy and high resistance compared to the cable (in my opninion)

I used these on the car... with 150 amp fuses in, but IIRC you can go up to 300amp if you need.

http://www.ebay.co.uk/itm/MEGA-FUSE-HOLDER-INLINE-FUSES-CAR-AUTO-ELECTRIC-FU28-/280728157103?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item415cb3bbaf

Also have a look at the ones the nutters who do serious ICE use.

[(RIP) PLANK]

thanks LF ! :thumb2