24Volt solar chargers

[Capt-Rum]

OK I just bought a hydraulic boat lift with a 24V DV motor. The batteries are 2 12volt deep cycle wired in series. I know you can buy solar panels to charge them from the Mfgr but don't what to pay those prices. Is there a way to use a standard 12v solar charger to do this?

[electricjohn]

It seems to me that you would need a pretty big array of panels to keep up with the demands of a lift. Typical solar panels give you about a watt and a half per square foot and your lift would pull many watts each time you use it (volt times amps). If you know the numbers (watts) of both the charger and the lift, you can do the math to figure out the recharge time for each use of the lift. Keep in mind you only get about 8 "good" charging hours each sunny day.

[Capt-Rum]

As I was informed from the salesman, typically the 12v systems will usually lift 5-6 times a day with no charge. The 24v systems will lift about 8-9 times with no charge. Now this may be a line of bull ****. We typically only lift the boat 3 times. Any other thoughts? The panel I was looking at was 5watt.

[electricjohn]

I do not doubt what the saleman is telling you. But the batteries will eventually need to be recharged. For compaison, a 10 amp battery charger puts out 120 watts and takes about 8 hours to recharge each spent deep cycle battery. A 5 watt solar panel would take 192 hours to put the same charge on each battery. If left connected all the time, it might be able to keep up, but with heavy use of the lift it might need to be supplemented with a charger.

[radioman]

use two 12v panels one on each battery.

[DizzyG]

I have friends who have done this for entire seasons and it works perfectly. They use the boat on weekends, both days and a couple times per week. Never had an issue with it not being charged up. I know he used a standard panel with cigarette lighter end, then just cut and rewired it to the batteries, worked great.

[Capt-Rum]

use two 12v panels one on each battery.

So one 12v to each battery? the common wire making the 24v system won't affect it?

[electricjohn]

It will sort of make the two 12v panels a 24v panel just like it makes the two 12v batteries a 24 volt battery. Just make sure you hook up one panel to one battery.

EDIT<> Give us a progress report during the summer if you go a head with your plans.

Edited March 21, 2008 by electricjohn

[Capt-Rum]

Thanks all, I'll post later once we get the boat in the water. They keep calling for the damn snow!!!!