Re: What to do with LiFePO4 batteries when the boat is layed up?

Joerg Esdorn

I have discussed the issue with a senior technician at MV support.  His explanation for the recommendation to keep the batteries at 100% with a float voltage of 27.0V was that their batteries are different in design from other manufacturers' batteries.  They are made for being kept at full charge over long periods.  I further asked him if I wanted to keep them at a lower SOC, how to achieve that.  His response was to change the float voltage to 26.5 from 27.0V rather than program an event that turns the charger off at 80% SOC.  The event will result in a lot of switching which would be avoided with the adjustment of the float voltage.   I've tried to do this and the SOC essentially goes to about 78% with the charger connected.  So presumably you could set the float voltage to even less than 26.5V and end up with a SOC lower than 78%.  

I would be very interested in seeing the research paper(s) showing what the best SOC for long term storage is.  I am very hesitant setting the SOC for the winter at lower than 80% because of the risk that something will go wrong with the charger and the battery will go to the 20% cutoff point.   I also wonder whether it's worth avoiding charging the batteries to 100%.  I bought these batteries among other things to have much more capacity available than before.  I really don't want to restrict the range of SOC I can use to get some uncertain benefit on longevity.  MV says the batteries are good for 2000 cycles.  My Easyview monitor tells me I've used up 23 of those over the last 3 months on the boat.   At that rate, I will kick the bucket before the batteries!  

Joerg Esdorn
A55 Kincsem
Currently cruising Brittany


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