Hi, I am working in a project.
I have a solar panel (9 Voc) connected to a battery (AGM, 6V) and then to my arduino (Working with a LDO 3.3V).
I want to control my battery charge and discharge cycles so:
with a TL431 and a second mosfet I can make a circuit to disconnect my load (LDO IC and arduino) from battery when the voltage is low, and reconnect it when voltage has rise a little bit (my schema has a bit of hysteresis for doing this. If you want it, please, ask me).
with controlling my battery voltage, measuring it by AnalogRead from arduino, I want to disconnect my solar panel from the battery when it's more than 7V. ( my battery is a 6V system and solar panel is 9Voc)
I want to use a mosfet (for me is the same P or N channel): let's call it "solar-mosfet"
Arduino will control solar panel connection with my battery by putting ON or OFF the solar-mosfet. NO PROBLEM HERE. analogread--> digital write to control solar-mosfet
But If my arduino is disconnected from the battery (low voltage) so my arduino is NOT alive, may be for few days, how can I ensure that the solar-mosfet is ON so the solar panel is charging the battery?
NOTE: may be you have other options, but I want to keep it simply and I have already broke a battery because of it is going up to 8 or 9Volts, low current yes, but high voltage).
Thanks a lot.