Second Carvan battery

Hi,

The 2nd battery should be mounted next to, or as close as possible to the 1st battery. This will eliminate uneven charging and discharging.

Cheers

Racey

Hello mhquay,

if your charger has a battery temperature sensor, the limiting factor is the length of its cable, obviously.

Other than that there are no practical limits in terms of distance or charging efficiency. Just ensure the cable is rated higher than the max charging current, select the next bigger gauge, and you'll be fine.

Some might argue there's going to be voltage drop.

So what.
This only will prolong the bulk charging and absorption stages for a few minutes, as the cable loss will heat up the wires by a few degrees, instead of contributing to the chemical reactions inside the battery.
In the end, before the charger switches over to the lower float charging voltage, the current is small, thus voltage drop won't be a factor affecting the voltage set points for boost and float.

Different story though if you had loads like fridge etc connected to the battery, while the charger is some metres away.
Then of course the voltage set points will be off due to the additional load current.
In this case, select thicker wire again.
There is simple maths involved if you want to find out the exact wire dimensions (given the voltage set point limits), depending on distance and load current.

I'll juggle this for you if you tell me the distance battery/charger, and type of load and/or max load current during charging.

cheers, Peter

so if the two batteries will never be connected at the same time for either use or when being charged, so the battery can be placed in the van anywhere, but the battery charging cable has to be thick.

I assume it's being charged independently by 240v charging system ?

Maîneÿ . . .

As Peter has said, though there may be considerations regarding usage. For a discussion of lots of the factors involved, see our blog Electricity for Camping. Links to wire sizing are towards the end of the blog.

Cheers

John

Thanks to everybody who has replied. I am think I have enough info to proceed.

If you are placing it inside the van it needs to be an AGM or if not must be sealed from the inside and vented to the outside.

Thanks Graham. Its 112 AH AGM.