How do I hookup 1 solar panel to trickle charge my 2 connected RV batteries?

I want to trickle charge my RV batteries (which are connected to each other) using one solar panel. If I hook it up to one of the batteries will that cause an imbalance in the charge between them? Or since they are connected, will it even out? Or do I need to connect it to both of them individually? Do I need to connect a charge controller between the battery/batteries and solar panel or will the built-in charge controller in the RV suffice? The solar panel does have a built-in blocking diode. I'm trying to learn all I can about solar power -- hope you can help me.

sort by: active | newest | oldest

Consider buying 6v golf cart batteries (buy in sets of two) wire them in series parallel "12v" you get more Amp hours then with marine batteries and golf cart batteries are more efficient for solar purposes then marine batteries.

arnold54 (author)  matt.carrasquillo9 months ago

Thank you for your info.

mhkabir8 years ago
In what way are they connected, series or paralell?No, both batteries will equal out once power starts coming from the solar panel.You do not have to charge each seperately. In the RV,Does the charge controller have leads for inputs?If not, and you are DIRECTLY connecting the panel to the battery leads, you will have to install an additional caharge controller.If so, just connect the panel + and - leads to the RV controller, which I assume is connected to the batteries.

In the first picture,It is an series connection of the batteries.
In the second picture,It is an paralell connection of the batteries.
Both will work for your RV. I suggest series for a 12volt system. For 24 volt system, parallel is the way to go.I assume that each of your batteries is an deep-cycle, 12v battery?

A good website for battery wiring for solar is this:
radarmd mhkabir4 years ago
I came across this site and noticed this answer is wrong pertaining to the hookup and outputs....Regarding the first explanation of "How do I hookup 1 solar panel to trickle charge my 2 connected RV batteries?"

The top (first) picture is wired in parallel and it would produce 12 volts with a greater current (amps) output.

The bottom (second) picture is wired in series and would produce 24 volts with the same current (amps) output.

Just wanted to point that out since Karlie wanted to use the picture which I'm sure she would've caught being an electrical engineer student.
Karlie mhkabir6 years ago
My name is Karlie. i am an electrical engineering student at and i would like to request a permission to use the picture illustrating the panel, the charge controller and the batteries in // for my senior design project. in advance thanks.
Always use a charge controller no matter what. If you dont use one you risk overcharging your batteries
Be aware that your batteries should be identical for best results and lifetime - that means physically identical and identical age. Otherwise, you will find one battery hogging the charge curretn, unless you use a charge controller.
Steve, thanks for mentioning, I forgot to mention that. Also, they need NOT be identical, oly AmpHours capacity, voltage and age have to be same.Even the age need not be smae, it may differ a bit.