Connecting Solar Charger to 2 Batteries

[ManWonder]

Does it matter which terminals I connect my solar charger to my 2 12v deep cycle coach batteries? I recall seeing a YouTube video saying I had to connect the positive from the charger to one battery's positive terminal and the negative lead from the charger to the other battery's negative terminal. Does this make sense?

[WJones]

Yes it does. It can make a small difference. By doing it that way, you end up with exactly the same wire lengths for both batteries. If you connect both positive and negative to one battery, the other battery will have the extra resistance of the interconnecting cables. The difference in resistance is small, but I saw a calculation somewhere and it can make a certain difference in how the batteries discharge.

[ManWonder]

Originally Posted by WJones

Yes it does. It can make a small difference. By doing it that way, you end up with exactly the same wire lengths for both batteries.

The thing is that in my RT 190P, my batteries are several feet apart, so it would be way more convenient if I could simply connect the charger to only one of them.

[avanti]

Originally Posted by ManWonder

The thing is that in my RT 190P, my batteries are several feet apart, so it would be way more convenient if I could simply connect the charger to only one of them.

One or the other of those batteries is presumably connected to the chassis ground. Simply connect the + side of the charger to the OTHER battery and the minus side to the chassis.

[ManWonder]

Originally Posted by avanti

One or the other of those batteries is presumably connected to the chassis ground. Simply connect the + side of the charger to the OTHER battery and the minus side to the chassis.

I like that -- thanks!

[WJones]

Well in fact, as far as connecting it to your batteries, your solar charge controller is no different than your converter/charger. If your system is well designed and installed, you should be able to connect it to the same places that your converter/charger is connected.

[booster]

On a Roadtrek 190 the batteries are a ways apart, and each likely have a long positive cable that goes nearly all the way across the van, under the body, where they will bolt to a binding post with another wire that goes up into the van.

Each battery normally has it's own negative cable to the frame, so with negative terminal on either battery, or the chassis, will work for the negative, and both positives are already tied together, so either battery is OK for that also. They are 12v batteries wired in parallel.