Re: What to do with LiFePO4 batteries when the boat is layed up?
Scott SV Tengah
I would be surprised if the MV software doesn't allow you to stop charging at a certain SOC vs having to guess with voltage. I can implement that on my less well integrated Victron system. Again, ask Garulfo as I believe they said it was simple to do so.
With respect to ideal SOC for storage, Victron delivers their batteries around 50% SOC, so that might suggest something. There's literature out there on how to prolong lithium batteries, but it's generally for more sensitive / explosive cobalt based batteries, but the consensus is 50-60%, matching Victron's SOC at delivery.
And correct, I don't leave the boat on shore power, even when it's available. The solar is far more than enough during storage periods and I don't risk bad wiring at the marina eating up my zincs and then my through hulls. Note that I don't have an isolation transformer or even a galvanic isolator. Was considering installing it but I find we're rarely at marinas and even if we're at one and aboard, I often don't bother plugging in.
What I like about setting the inverter to run above 60% is that my solar is more than enough to put in more power than the dehumidifier can draw. That, in effect, causes the battery to fill to 100% every few days, at minimum, but even if it's taken to 100% by the time the sun sets, the dehumidifier will draw down the batteries overnight so they don't sit at full for very long. And even if it's drawn down to 60%, there's plenty of capacity remaining to run the bilge pump for a long time before the sun rises again.
2007 A54 #69