yopappamon
10 kW
My solar panel has an open circuit voltage of over 20v, too much for 4 cell lifepo4. My 40 watt panel came with a cheapy sla charge controller. The charge controller has an upper cut off voltage of 14v, that's 3.5v per cell, measured ended up around 3.45v per cell. Too low on the charge curve. Looking at the circuitry it looks like an op amp comparator turning off the charge transistor when the battery voltage gets high enough.
Simple hack, isolate the output leg of the charge transistor from the op amp circuit. Add a diode in series between the battery and the op amp to drop what the monitor sees by 0.7v. Now the charger chargers up to 14.7v about 3.68 per cell, measure at 3.6 v per cell. Perfect.
Simple hack, isolate the output leg of the charge transistor from the op amp circuit. Add a diode in series between the battery and the op amp to drop what the monitor sees by 0.7v. Now the charger chargers up to 14.7v about 3.68 per cell, measure at 3.6 v per cell. Perfect.
