locked Re: Batteries starting to get weak - MMM - What to do -


Thank you Scott for the additional information!!!!!

Going back to basics for this topic:

1. Building a bank out of cells - from what I can see the really good cells that can be bought and put together (Will Prowse website) costs are around 1k for a 24v 100ah battery. However not sure how things add up with other cells. Plus adding a good BMS and a separate Battery Conditioner to wire to the investor for higher amp loads etc... price seems to be about half of the BB 400ah 24v setup. 

Questions for that - is it worth doing all the setup yourself and not entirely having the warranty for 10yrs to save maybe half or less? I am all for DIY and can learn to do it but my goal would be to get much more amp hr's for less or similar money but have at least the same known reliability. 

2. I am understanding the LFEPO4 batts should be kept between 80% and 30%. so that turns a 400ah bank into a 200ah useful plus whatever solar you may have. From my calculations on a SM2k I would be using at anchor without using the AC around 200ah per day.  It seems with the electronics running for passage you would add another 150ah + to your daily use. (chart plotter is 5ah so 2x of them would be 100ah for the day). Also if you increase the bank size you then would be using less cycles than if you didn't increase it. 

The LFEPO4 batteries claim 80%SOC at the end of 3K cycles +.  From several YouTube boats showing a year on the LFEPO4 batts and having around 1k solar watts they showed using approximately 115 cycles for that year. That would mean 10yrs or so for 1k cycles. Batts mathematically should last at least 30yrs at the same rate. 

Ok we don't trust them that much and they haven't been around long enough but doing the math nothing even comes close to comparing. It seems a no brainer to go with them but now the choice for most of us is whether we DIY a bank or go the BB route. 

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