T-Pain Is On A Boat: Re: [Electric Boats] Repowering 40' 1975 20,000 lb sailboat

Wednesday, September 30, 2009

Re: [Electric Boats] Repowering 40' 1975 20,000 lb sailboat

I am finding that charge acceptance is an issue with my wet lead-acid though a quality AGM should be better.

You ideally want to be able to put the full output of the generator into the batteries. With my setup it looks like I can only put 7-8amps in once the bulk phase is done. My genny/charger is ~22amp @48V and I could do 75amps if I had the juice.

The TPPL (AGM) batteries Nigel Calder is pushing might be the best choice when extended cruising - with those you could put..say..30-40 amps in and reasonably expect to charge the batteries off the genset in 2-3 hours of running. Otherwise you'll be basically cruising with the genset running full time (or worse sleeping with it running) - some of the juice going into the batteries, but the rest you have to burn off by running the motor (or just waste)

Otherwise, you'd have a fair chance of having to dock just so you could have quiet charging and a chance at sleep.

I think lithium is ~price competitive with TPPL if you factor in dollars/lifetime-KWH -- that's *if* the 2000-3000 cycle claims hold up.

My $0.02

-Keith

-----Denny Wrote---

"Still hard to beat AGM lead acid batteries for a sail boat - especially if you
can remove some of the lead you already have in the basement. A lithium bank
will increase initial cost 5x and its benefits of light weight and rapid charge
-discharge tolerance are not that important in your application."