Fitting an electric boat with solar

[shebainu]

Total "amateur" on solar, but learning. I have an older ELDEBO Electric deck boat, of which I want to install solar. It has 4 - 12Volt deep cycle batteries DC F27.
My trolling motor is 24 volts. My charger operates on 110/120 Volt AC current converts this energy to 20 AMPS of 12V DC current. Is this enough info to get some help in determining what size solar panels are needed and controller, to charge these batteries? The boat is not used much right now as charging with electricity is not an option right now, but need solar to not only charge boat but also to maintain battery.

 

[SolarRat]

That's a small boat, so space and weight is going to decide how big or how many panels you can (or want to) fit. If you make a hardtop the full size of the boat you could probably fit close to 1500w or so, but that would be huge and probably too top heavy.

I'm guessing you are currently running the batteries in 2p2s for about a 24v 200ah bank. A single 350w panel going through a solar charge controller (no need for your 120v charger) can give you about 14 amps at 24v. That should be enough to charge the batteries over two sunny days (if down to a 50% DOD), and will extend the range some too. The max you'd want to charge a LA 200ah battery is 30amps, so 2 350w panels, if you could fit them, would be the most I'd go.

If you are still using the stock 70lb motor, it will probably draw a max of about 30-35 amps (~750amps) at 24v at full speed. One thing I learned with these motors is backing it down a bit from full speed uses much less power with very little speed loss (400w might be 3.5 mph vs 4mph @ 750w).

If it were me, I'd stick to one large 300+ panel on that size boat. Or 3-4 100w panels.

 

[shebainu]

Thanks for the help....
"Im guessing you are currently running the batteries in 2p2s for about a 24v 200ah bank" Tell me what this means and I will be a happy camper

"A solar charge controller (no need for your 120v charger) can give you about 14 amps at 24v." Suggest a charger of Watt, etc?

This boat might get used 2-3 times a month, it has no bells or whistles i.e. stereo, running lights or other. Do I need the 4 batteries to run this motor or is there a better battery to run this motor?

Thanks so much for your help

 

[SolarRat]

2p2s means you have two sets of batteries connected in parallel (2 x 12v 100ah batteries in parallel = 12v 200ah), then those are connected in series for 24v and 200ah.

Any 20 amp or higher charge controller that can do 24v will do. For a boat I'd recommend a Victron or Midnite.

You could run only two batteries in series (24v 100ah) but your run-time will be cut in half. If you want to spend some money, lithium (LiFepo) batteries will save space and a lot of weight and will increase your runtime. 2 Battleborns in series would be the easiest, but also close to $2k. It doesn't sound like you are ready for the cheaper DIY batteries...

 

[shebainu]

Awesome, Thanks for your help