New LiFePO4, all else same?

schrater said:

Lots of good advice and perspective here. The one part I’m not following is the assertion that the AGM and LiFePO4 must be on separate chargers due to needing different charging profiles, when other people say it’s fine to use the AGM setting for charging LiFePO4. I wonder if we’re splitting hairs here?

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Five years into Lithium, the idea that there is a need for separate chargers for my LA starter bank and my LFP bank makes little sense. The manufacturer of my LFP recommends charging to 3.65v per cell - 29.2 @24vdc or 14.6v @ 12vdc with very short to non existent absorption. The net effect of this is that when charging the LA starter bank, the batteries reach a high, but not damaging voltage, then go almost immediately to float. So, hard to see what the point would be for a separate charger. My average lifespan for the LA starter bank is around 8 years.

Greg QS said:

I have had a boat in registered in my name since 14. 56 as of the 30th. Never gotten more than 3 yars out of a house battery . Even the boat I purchased in 22 , all batteries dead in capacity were from 2018 , 4 YEAEAS old . I cycle too much power through them. Starting up to 10 years. Its how much power you cycle through a led acid. Its simple chemistry. the more power you cycle through the led the more degradation of the led. Resulting in battery failure.

Regardless of Weather or not you accept my documenting. Just look at spec of lead acid. 500 cycles at 50% .

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We see Lifeline AGMs (lead acid) spec'd at 1000 cycles to 50%. And I think most of the flooded lead acid and AGM 6V "deep cycle" batteries (Trojan, Lifeline, etc.) are spec'd to 1000 cycles... On our previous boat, we got 11 and 12 seasons, respectively, from two different banks of Odyssey AGMs. (Our "cycling" is pretty lightweight, though.)

I wonder if your house banks have been minimally sized? So you've maybe been cycling at 80% or more? Or using starting batteries to service house loads? Or really cheapo batteries? Or...?

Not meaning to sound like I'm questioning your facts, just wondering how you got there from here. Lots of folks seem to get batter results even from crap batteries...

Near as I can tell, the middle-of-the-road lead-acid batteries we're just now replacing lasted probably 5 seasons...

-Chris