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Author Topic:   Battery Charging Without 120-VAC
scalez posted 02-14-2007 12:58 AM ET (US)   Profile for scalez   Send Email to scalez  
WOW ! I'm amazed at the depth of experience concerning marine electronics displayed on this site!

I hope that someone here has addressed a problem similiar to the one I'm researching. My situation has no power to the dock but I need to recharge my AGM 24 trolling motor battery after each use. I try not to run it down below 50% but sometimes do. It is getting to be a real pain to pull it, haul it to the garage, recharge, rehaul and reinstall. I'd like to be able to mount a Photo-Voltaic panel or wind generator to do the job but my guess is this will take better than a week for 250 Ampere Hour (A-H). Most live aboard solutions appear to be maintainers only.

Any suggestions as to how to accomplish this with less effort and less time?

Does Yamaha have a larger stator that could be used for the bulk charge on the cruise back to the dock?

Chuck Tribolet posted 02-14-2007 07:14 AM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
24 = 24V? or #24 battery?

250 A-H is a LOT for a lead acid battery.


scalez posted 02-14-2007 10:11 AM ET (US)     Profile for scalez  Send Email to scalez     
OOPS !!! It was late! Lifeline AGM GPL 24 550CCA, 80 A-H so I guess 50% would be 40 A-H. Sorry!
Taylor posted 02-14-2007 08:01 PM ET (US)     Profile for Taylor  Send Email to Taylor     
I would think this is a natural for a solar panel. You may have only seen small float chargers, but you can get as many watts as you need. My sailboat has an 85 watt Kyrocera panel, about 2x3 feet. You probably don't need anything that big.

I found the forum at useful. The forum is run by

One thing I don't see on their website is a rollable panel. Flexible panels have gotten harder to find in the past year due to Unisolar not making them, but there was one at the GI Joes around the corner that was something like 30 watts, which strikes me as about what you need. 30 watts, that would be something like 2 amps full sun, over a week of mixed sun and shade.... check with the guys on the forum there and see what they would recommend.

One thing about charging a battery - nothing beats time for getting from 80% to 100% - you have to do it with a s;pw charge anyway, the bulk rate of high acceptance stops at 80% charge, and a solar panel works very well with long charge periods, such as weekend to weekend.

scalez posted 02-16-2007 02:51 PM ET (US)     Profile for scalez  Send Email to scalez     
It just keeps getting better! Thanks for the great link TAYLOR ! There are a number of threads there that address similiar situations.

One thing that is mentioned in those threads that gives me pause tho > several responders state that you should not expect any useable charging from the outboard stator. It is only intended for maintenance of the starting battery. If this is correct then the recharge of the trolling motor battery would need to begin from the 40ah draw down requiring 20 days at 2 amps from a 30w panel!
Is that the correct way of looking at it?

I'll post my question over there and see what they say.

jenkinsph posted 02-18-2007 11:34 AM ET (US)     Profile for jenkinsph  Send Email to jenkinsph     
I think you mean 20-hours at 2-amp rate, not 20 days. Next, are you able to mount a small to medium sized panel to the dock? Maybe adjacent a dock chest or locker this would keep
the boat tidy. Also the larger panels should be able to recharge a single battery in a days time with direct sunlight.
They are a little pricey though.


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