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Old 01-20-2023, 08:49 PM   #1
Jeff F
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City: Guelph
Vessel Name: Escapade
Vessel Model: 50` US Navy Utility trawler conversion
Join Date: Nov 2015
Posts: 2,432
Alternators - leave them alone and forget about them

I've been following the challenges that come with adopting lithium for a long time. By far the most intractable challenge has been hooking them up to the alternator.

I have a solution. Don't. Leave the OEM alternator charging the start battery and look elsewhere for charging sources for the house bank.

Let's assume you have a lithium house bank sized to accomodate 24 hours typical use.

I can think of three viable ways to charge the house bank away from the dock. Alternator, genset through AC charger, and solar.

None of these are any better or worse for the battery. The charge cycle doesn't have to match the discharge cycle. There is no necessity in achieving or maintaining full charge, and no practical constraint on charge rate. Lithium is liberating that way.

It seems to me you can pick any two out of three charging sources and get on with life. If you're optimizing for liveaboard at anchor you've learned to do without alternator input. Why not give it up completely?

Go ahead. Shoot me down. But honestly I'm tired of the alternator angst when maybe we can just not go there. Not going there might be easy.

Tell me again why charging from the engine is a good idea. We needed it way back when, but now? Why do we treat it as a necessity? My Prius had a 12v start battery but no alternator. Let's be a little creative.
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