I have made a DIY off-grid solar generator that utilizes an Arduino to determine when to dump excess energy to a water heating load.
I have programmed the Arduino to activate the load circuit when the cells reach 3.5 V.
My concern is that due to voltage sag of the battery, the instant the load is applied the Arduino will sense a lower voltage and disconnect the load.
This will cause the load to be turned on and off rapidly as the voltage sags below 3.5 V and then bounces back up to 3.5 V, putting the LiFePO4 cells through rapid cycles of charging then discharging. I am going to test this to determine at which frequency the cycling takes place, although I am sure this will be dependent on the power being provided by the solar array.
- Will this rapid switching between charging the batteries and discharging the batteries cause any sort of degradation?
- Is it possible that this could cause waste heat generation and side chain reactions that accelerate the aging of the battery?
I am considering adding a bank of capacitors and using a PWM output to smooth out the alternating current. I am still uncertain if any of that is necessary as I do no know the extent to which this is a concern for my battery. I did check the setup and determined that the load is switching at around 0.4 Hz.