Adding 2nd battery to house battery

[BeeWatts]

I've added solar panel to my 2003 FS.

Now thinking about adding a 2nd house battery in the back under the sofa (just above the current house battery) to extend my capabilities.

Anybody done this and want to share insights?

I figure I'd use a battery case like this:
https://www.amazon.com/NOCO-HM300BK...4q32u3ds8e4ww_ttl?_encoding=UTF8&s=automotive

Then connect to current house battery.

Thanks in advance

 

[Sn0sk8er]

I too would like to add the 2nd battery under the sofa in the back, passenger side. I know there have been posts about it in the pass, but not much along the lines of "how to".

I think both of my batteries (under from seat and in back, divers side) are shot. Wont hold a charge. I tried to buy new batteries (Interstate) for both, but the dilemma is that every RV battery forum/site states that if you are buying one or more batteries (deep cycle) that they should both be the same. Being that the one under the seat is of such limited space, you cant find a deep cycle that fits size in height (sorry, can spring for AGM). The smaller "starter" battery (the only size that will fit under the seat) is more $ and half the amp power. So in my thinking, I get more bang for my buck with a 2nd deep cycle in the rear under on the passenger side.

Hope someone can chime in here. Layman's terms please. All this battery talk and wire schematics gives me a head ache. Its like going to the store to buy beer, don't want swill, but i don't need refined hops to make a good IPA.

Thanks, Sn0sk8.

 

[rimjaine]

I too would like to add the 2nd battery under the sofa in the back, passenger side. I know there have been posts about it in the pass, but not much along the lines of "how to".

I think both of my batteries (under from seat and in back, divers side) are shot. Wont hold a charge. I tried to buy new batteries (Interstate) for both, but the dilemma is that every RV battery forum/site states that if you are buying one or more batteries (deep cycle) that they should both be the same. Being that the one under the seat is of such limited space, you cant find a deep cycle that fits size in height (sorry, can spring for AGM). The smaller "starter" battery (the only size that will fit under the seat) is more $ and half the amp power. So in my thinking, I get more bang for my buck with a 2nd deep cycle in the rear under on the passenger side.

Hope someone can chime in here. Layman's terms please. All this battery talk and wire schematics gives me a head ache. Its like going to the store to buy beer, don't want swill, but i don't need refined hops to make a good IPA.

Thanks, Sn0sk8.

I have an AGM group 31 12v deep cycle battery under the front passenger seat, it is laying on it's side. It's a good idea to modify the the mounting area just a bit, cut the 2 corners furthest from the door and flatten them out to make the necessary room to put the battery in. An earlier post back in about 2008 or so showed this with pictures. Good luck, it works good.
Later, rimjaine

 

[tinman]

I'm running the chassis style battery, not deep cycle (doesn't appear to exist), under the passenger seat, and a group 34 (I think?) in the back driver side position. Replaced the rear battery recently, as it failed a load test, but the front unit passed the load test so I kept it. It's not an ideal setup, as I think the rear battery has a longer run for alternator charging (maybe not, if both go through the panel/ converter setup), but seems to work OK. I have installed a 150 watt solar panel, with the controller at the forward house battery site, again not optimal. Both batteries are rated at 100 amp/hour.

 

[nutterbutter]

In theory: If you do two batteries, they should match. The length and size of copper wire to each battery from the solar controller should be the same too, in order to balance the charging load.

In practice, unmatched batteries don't last as long. For an average RV user, you'll still get a few years from a set. I'd go flooded deep cycle for an unmatched set, due to the cheaper cost and inability to care for them perfectly. As long as they are both new, you don't discharge below 50%, and you do a monthly equalization charge you'll be fine.

The smart money is to make sure the under seat battery is a deep cycle (flooded or AGM). I did a slightly larger flooded, but had to modify the tray a little, and added a couple of washers to the seat rails to increase clearance. Wife has short legs, but didn't notice the height change because she already puts something under her feet on long drivers for comfort. Or you can use the highly referred to AGM on its side modification (more expensive, more capacity). Spending money on non-deep cycle, and using it for deep cycle is a waste of money.

For my use, a true deep cycle under the seat plus a roof solar is manageable. My largest use of higher amp power is showering. I make sure to run the generator or engine whenever we're pumping a large quantity of water (showering and rinsing dive gear). That one change has made a large difference in battery management.