charging a 24 volt system with a solar panel

tektoneglm1

I have a fishing boat with a 24 volt trolling motor. (2 12 volt batteries in series). I have a solar panel mounted on the boat with two sets of leads going to the two 12 volt batteries. I know I can hook them up like normal as long as I disconnect the positive to negative link between the two batteries making them 2 separate 12 volt batteries, but that defeat my goal. I want to keep the trolling motor batteries charged while I am out on the lake. How can I do this because hooking them up pos to pos and neg to neg doesn't work?

Thanks

Gene

Cariboocoot

Re: charging a 24 volt system with a solar panel

Welcome to the forum Gene.

If I understand you correctly you have a Voltage difference problem: the batteries add up to 24 Volts but the panel is 12. Now whereas this problem can be overcome, the chances are the easiest way to do that is to buy another 12 Volt panel and put them in series like the batteries.

Another option would be to replace the 12 Volt panel with a 24 Volt one, but for best results make sure it is a "true 24 Volt" panel with a Vmp around 35. Since the wiring here is very short and I'm certain the goal is to extend run time rather than fully charge the batteries even one of the GT panels with a Vmp of 30 would help.

If you are intending to fully charge the batteries you may find you need more panel than will fit on the boat, depending on the capacity of the batteries.

The only other solution is a boost converter (doubles Voltage at the expense of current), and frankly that would not be worth looking into here.

tektoneglm1

Re: charging a 24 volt system with a solar panel

Thanks for the help

bill von novak

Re: charging a 24 volt system with a solar panel

tektoneglm1 wrote: »

I have a fishing boat with a 24 volt trolling motor. (2 12 volt batteries in series). I have a solar panel mounted on the boat with two sets of leads going to the two 12 volt batteries. I know I can hook them up like normal as long as I disconnect the positive to negative link between the two batteries making them 2 separate 12 volt batteries, but that defeat my goal. I want to keep the trolling motor batteries charged while I am out on the lake. How can I do this because hooking them up pos to pos and neg to neg doesn't work?

1) Replace with larger 24V panel
2) Get another identical 12V panel to make 24V
3) Use boost converter to boost 12V to 24V *
4) Use relay circuit to alternate panel between two batteries *

* (you'd probably have to build these yourself)