12v or switch to 6v? Still not sure

[DRiveWell]

A few factors to consider in designing a solar charging system: 1) co-locate batteries as close as possible to each other to minimize voltage difference across/between the batteries, 2) locate charge controller as close as possible to the batteries as this connection carries a higher current than the connection to the panels, 3) portable panels provide more flexibility to you in your campsite selection (especially beneficial if you remain in place more than you are on the road), 4) consider sealed AGM batteries if they cannot be properly ventilated, and 5) you must determine your required 12 volt current draw before you can properly size your battery bank and panel capacity.

[Comanchecreek]

I run four 6V golf cart batteries in my 5th wheel. You hook 2 up in series and then hook each set up in parallel. Can run for better than five days at a time although don't have 12 volt fridge. I've had 4 rigs over 30 years and have always run down the road with fridge on propane. Not even sure why they make a three way as 12v fridge is so inefficient. You're probably not getting your batteries charged while driving because of the fridge current draw. You can buy Interstate Batteries at Costco.

[Bluepill]

Discussion of series and parallel wiring:

The 12volt Side of Life (Part 1)

[pmsherman]

Originally Posted by glarior

.....
What do you mean wired properly in parallel?

If you connect two 12V batteries in parallel and hook up the charging circuit and load to the + and - terminals of one of the batteries, you end up placing a larger load on the battery that those wires are hooked up to. The second battery has additional wire resistance between it and the load/charging circuitry which causes this. I doubt that you'd see much difference with a 1-3A load but when you start drawing 20, 50, or 100A then the resistance of the wires between the batteries starts making a lot more difference.

The correct way to wire two batteries in parallel is to attach the load + to one battery and the load - to the other battery. This equalizes the wire lengths to each battery and better balances the load on each. A similar approach needs to be done when using more batteries which can quickly lead to complicated wiring structures. Of course, with the load balanced, charging using the same terminals will also be balanced.

I have an interior 12V outlet in my Georgetown, wired with #10 wire. I also have a portable 80AH 12V deep cycle battery I can plug into it to add a third battery to the two that came with the rig. With less than a 10A load on the battery system, the inside battery will show over 3/4 volt higher voltage than the manufacturer installed house batteries. This difference is caused by the resistance of the 10' of #10 wire between the spare battery and the house batteries.



Question about replacing one of a pair of 6V batteries:

If one cell of a pair of 6V batteries fails, I'd replace both batteries. Batteries have a service life which should be the same for two identical batteries. Random differences in the batteries will always make one fail first and when this happens, you have no idea low long it'll be until the other one fails.

Phil

[Skyliner]

I have 3 pairs of 6 volt battery packs in my fifth wheel. I am 100% happy with the 132 amp hour Sams Club golf cart batteries; they are worth every penny. Sams Club sells two types of golf cart batteries. Don't settle for the cheaper low capacity ones. The plates on those are thinner and they won't last as long. Costco only sells the thinner plate golf cart batteries and doesn't over a premium golf cart battery. Interstate makes both the thin plated GC batteries and the thicker ones.

Each pair of my battery packs are switchable and usually use two at a time with one as a backup but occasionally use all three when I'm going bonkers with the microwave or other high power items in the camper.

[glarior]

Worked on other projects this weekend but thought about all the posts. I have more details on the current setup.

Batteries x 2 - Ever Start Deep Cycle 29DC and I will be replacing them lol. I missed that it says 122ah at 1amp. So... these batteries I will use for something else.

Solar panels - Voc 22.4; Isc 8.39; Vmp 18.5; Imp 7.84; Pmax 140. I been using one panel for the setup but have 3 of them. Also have a 100w panel.

Controller - Sunsaver 6. #10 wire used. Looking to upgrade to MPPT that can have multiple panels hooked up. Already have #4 wire ran to where the controller will be.

Do I go buy 2 T145 batteries? Or other brands that are just as good?

Controller recommendations?

Did I miss a reply to any of the other posts asking me a question?

[boondocking]

Originally Posted by glarior

Controller recommendations?

EPsolar makes an excellent controller that will not break the bank. I have been using that brand for 8 years now and have been very pleased.

[glarior]

FYI I bought 6v battery setup this afternoon and plan to install this weekend. I also bought a better MPPT solar controller. See how this setup install will go

[mikakuja]

Originally Posted by boondocking

EPsolar makes an excellent controller that will not break the bank. I have been using that brand for 8 years now and have been very pleased.

We installed a EPsolar Tracer BN2215 and MT50 controller in our previous trailer and were extremely happy with it.. Well made products IMO.

Our new system is a Go Power with a GP-PWM-30 (newest gen) which also gets good reviews. Will post my opinion on it once it is installed and I have some time to test it out.