I have 300 watts of solar panels , 12 volt lithium battery, mppt and pwm controllers of which some are installed on my caravan.
I have the mppt controller set to control the lithium battery. Charging at 14.6 voltage and drops to 13.8 volts when charged. I have installed an on off switch to turn off the solar panels when in storage so as to stop charging the battery 100% all the time.
I have a battery monitor so I can keep an eye on the battery voltage and turn on the solar panels when the battery drops to 40% and off when it reaches 80%.
I have an idea to use a cheap pwm controller wired in parallel with the mppt controller and have it adjusted to charge at 13.2 volts and maintain about a 50% charge, that's only when the solar panels are disconnected form the mppt controller. When the switch is in the on position both controllers are connected in parallel.
Is this doable??
Submitted
1 year 6 months ago