John61CT wrote:Can you change the definition of 100% SoC?
Hitting any setpoint over 13.8V is fine especially if it is holding CV / Absorption stage.
Not saying 14.1V is "overcharging" per se but really anything higher than the minimum required to get to 3.33-3.35Vpc is just unnecessary stress, does not significantly add to actual usable capacity, aka "surface charge"
That is for normal usage cycling
maintenance protocols for occasional balancing, SoH benchmarking can go higher, even to max spec voltage if desired
The battery monitor automatically synchronizes the charge level to 100% on its own. I can synchronize it manually back to 90% yes, but don't really mind, since 90% is for my purposes, "full."
I hear what you're saying about 13.8 volts being sufficient to charge the battery without undue stress. I think that's what Andy from the Off Grid Garage has his absorption charge set to. I may play around with it and move the number back to 13.8 to see how it goes. Andy also uses 15 minutes for absorption time rather than the default 2 hours. I am not sure what the difference would really be in regards to charging, but the voltage would not be held at the max for as long every day, possibly leading to less degradation. On the other hand, since cell balancing at the BMS is most effective when the voltage is higher, I would guess it is good to have at least some time during the day with the battery up at absorption voltage.
^^^ Here is the record of amp hour status of the battery over the last 24 hours. You can see the steady drain by the Venus GX (Raspberry Pi's) during the night, the chasm of battery heating in the morning, and the steady rise during morning charging. At about 12:00 PM you can see the vertical up, which is when the battery monitor resynchronized itself to 100%.
^^^ John, looking at the difference in 13.8 vs. 14.2 volts-- The difference today was literally only a difference of 9 minutes of charging (11:51 am for 13.8 volts, 12:00 pm for 14.2 volts). During those 9 minutes the battery only added 0.4 amp hours, using data from the previous graph. Seems like you and Andy are probably right. Those 0.4 amp hours are not worth the extra degradation that would occur over a lifetime of use at a set point of 14.2 volts vs. 13.8 volts. I'll set my absorption voltage to 13.8 and see how it goes tomorrow.