Re: Converting my Amel 54 to lithium batteries: what I did, what I like and what I don't like (after one year of full time live aboard use)
Scott SV Tengah
I generally try to keep it between 40-80% but yes, the Victron literature tells you to charge to 100% every month or two to allow the BMV-712 battery monitor to re-calibrate. I believe it also allows your cells to balance out. We do this but only once every month or two.
My understanding is that if you don't do super heavy draws (eg - 1C or 450 amps in my case) or charge to the absolute highest voltage recommended, the batteries will tend to stay in balance. That has been our experience over the last year.
To be safe, once a year, I will charge up the bank completely using the Quattro then disconnecting all the batteries and charging them individually with a 12.8v 1.5amp charger until completely full. That's to maintain balance - most likely major overkill, but the cost of the system is quite high, so I'm ok overdoing it. :)
I think you will still need to run the genset now and then. If we have excess energy (eg - over 80% SOC), we will run the water maker to burn off energy. But often, we just do it while motoring. I considered adding another 220 watts (Sunpower flexible panels) on the Bimini. That would put me close to 1200 watts. But the cost and complication of that was too much for me right now (plenty of other higher priority items!) and I resigned to using the genset twice a week. At the end of the day, we should probably use the genset a bit, otherwise my understanding is that non-use can damage it also.
2007 A54 #69