I am trying to maintain a 100Ah Lipo4 battery with 400W of solar panels (2x200w in series, 24v). I am getting the right voltage ca. 40 volts on sunny days (same voltage measured at panels and on the MPPT), but the system does not maintain battery even with low loads. I am running monitoring equipment that draws 5 watts or 120watts per day. The panels deliver approximately 120 watts but state of charge of batteries always declines by a couple of percent each day. Battery continues to discharge over time. The mppt gives an hour or so of bulk current first thing in morning, then goes to absorption then most of the day is in float mode. My system should be generating a max of about 1k but instead always generates a little less than the consumption each day. This does not change as the battery slowly discharges each day. I have checked all the connections, and have a good full day southern exposure. I am wondering if there is some setting I need to change to get it to maintain a consistent SOC.
I switched from old lead acid golf cart batteries to new lithium, but have same problem with batteries not maintaining a charge. I also tried using a new MPPT controller. This did not solve problem either. I also doubled size of PV array from 200watt to 400watt. This also did not change anything in terms of battery charging.
Here are my settings: Battery
Battery 100AH Li-time LIPO4 self heated
Settings
MPPT controller. 100/30
Battery voltage 12v
Max charge current 30a
Battery preset LIthium (LifePO4)
Absorption voltage 14.2A
Absorption duration Adaptive
Tail current 2.0A
Float voltage 13.5
temperature compensation disabled
automatic equalization disabled
Low temp cutoff 41 deg F
Battery shunt
battery capacity 100Ah
charged voltage 13.3V
discharge floor 10%
tail current 4.00%
charge detection time 3m
Peukert exponent. 1.05
charge efficiency 98%
current threshold 0.10a
time to go averaging period 3m
battery SOC on reset. keep SOC
