adding a 3rd battery

[dkupper]

I would like to add a third house battery to my 2003 Friendship. Has anyone done this successfully? If so, how?

[Dennis4809]

Assuming you have two 12 volt batteries, then they are connected in parallel, ie neg to neg and pos to pos. adding a third Identical battery is the same. Neg to neg and pos to pos. all batteries must be identical or one will carry the load.

IF you have 6 volt batteries, then you would have to add two. Two six v in series making 12 v then parallel the pair.

[Chuck v]

I agree with Dennis -- plus, lead acid batteries in parallel must be well matched to work correctly. Not only must they be the same brand and model, but they should be the same age and date of manufacture as well. Even then, the aging of the batteries usually results in a shortened life compared to a single battery or series connected application. This is of course even more difficult with THREE batteries in parallel, and why electric vehicles from golf carts to EVs have cells in series when charging and discharging -- and why use of two 6 volt cart batteries in series is a better solution than similarly physical sized 12 volt batteries in parallel for most RV uses.

If you have room -- choosing a larger pair of 12 volt batteries than you have now, or even better the largest 6 volt cart batteries in series could be a better approach than three nominally sized 12 volt batteries in parallel.

What problems are you trying to address by having added house battery capacity? Maybe a better understanding of the root issues you are attempting to address will let us make more specific suggestions. Some of the considerations and data that would be useful would include:

1. what group size or other information is on the existing batteries and what date code or other age related information do you have?
2. what size batteries can be accommodated? What are the dimensions of the battery compartment interior?
3. how much weight can you lift and position in the compartment, or will you have others do this work?
4. what is the budget for addressing this proposed increase in house battery capacity? How much of an increase is being sought?

I am sure there are other data that might be useful as well, so best to describe your needs and your particular use style for your coach.

Chuck