Adding an Additional Battery

[us2anddollar]

Hi all, we are thinking about adding an additional battery to our van, currently have a 110ah AGM battery, do we have to get an exact replica of the battery?

 

[Jimbohorlicks]

No you don't, but best to get one thats also close or at 110ah .they need wiring up in parallel don't forget. And beefy cables.
Some folks will say you shouldn't mix but I have had mixed batteries for years without any issues.

 

[Guigsy]

Ideally they should be matched. As a minimum, they should be of the same chemistry.

If you mix gel, lead acid and AGM, then you'll find one battery takes the majority of the load and one battery won't get fully charged. Do you'll get slightly faster degradation and a bit less capacity than you expected.

The only mildly dangerous situation is when you're pulling a lot of current assuming it's being supplied evenly, but much of the work is being done by one of the pair.

 

[treblid]

I would match the battery as closely as possible. You certainly need the same chemistry if they share the same charger as the charging profile
needs to match the battery type\chemistry.