Originally Posted by lcv800
So Mike, how do they work if they are on a solar charger that continually charges daily (assuming it's sunny)? Would it be 365 charges or roughly a lifespan of 15 years?
If the battery is fully charged and the solar controller is merely on "Float", that doesn't count as a "Cycle". A cycle is when the battery is discharged and then fully charged.
FWIW, the LiFePo batteries I see commonly offered as "drop in's" for RV house batteries will go to zero charge current when fully charged, controlled by the internal BMS.
Some Solar Controllers also shut off charge after a specified period of time, depending on how you program.
It's recommended by Battleborn that charging be shut off when fully charged and only recharged when state of charge has been significantly reduced. I just ordered a $9 "Module for my PD9160L Converter that will allow my Victron Battery Monitor to turn the charger off when it reaches a set state of charge and turn it back on when SOC drops to whatever I program into the Victron monitor. This uses the relay that's part of the monitor.
My "parasitic" loads are less than 1 amp and I have 200 amp total capacity. If I shut down the converter at 80% or so, let the batteries just sit until they reach 50% SOC, the charger will kick on and bring back to 80% approximately once per week.
I could just go turn off the battery switch and let batteries sit with TT powered up by converter but I'd rather automate. The relay is there in the Victron and for $9 it's the kind of project I kind of enjoy. Hardest part will be running a pair of small wires from Converter to Victron and then just programming for On/Off settings. Also plan on adding a switch to the control wires so I can override the Victron relay. With the module, when control wires connected to each other it turns the Converter Off and when "open", the Converter is off. Progressive Dynamics started offering this feature at the request of "Smart" LiFePo batteries.
For those unfamiliar with LiFePo batteries, according to what I've found in research they last longer when kept between 50% and 80% state of charge when not being used. They do not "like" float charging as again, according to what I researched, the Li-Ions are then converted to Lithium which reduces capacity over time. The lithium is plated on internal elements by the constant charge.