I succesfully build an Arduino Uno which measures a lithium battery array which has 28.7V which gets charged with an 7A 24V (4 x 30W solar panels) and a P-mosfet controls the charging from solar panel to the battery array.
BUT when battery is charged , the mosfet stops the charge, the SOLAR PANEL positive gets disconnected. It gets to 44V in open circuit.
So is there a brake, stop, ceiling to test to get to safe voltage value before turning on the charging-P-Mosfet?
Just tried a load (100 ohms 40w resistor) and only get from 44 to 40V ... so I don't want to fry my P_MOSFET GATE
I guess you need to tell us the maximum voltage the MOSFET can handle.
Solar panels are rated in interesting specifications. The current produced is with the leads shorted together. The peak voltage is with the leads connected only to a volt meter. Your panels should have been rated at 44 volts and 7 Amps. Where did the 24 volt rating come from?
Paul
At least in the U.S., solar panels are often specified by the voltage output when charging a lead acid battery.
A "12V" solar panel is intended for charging a 12V lead acid battery and the open circuit voltage will typically be 21 - 22V. That voltage will drop substantially when the panel is loaded.
Exactly!!! commercial charge controller are expensive and could not find a charge controller for 7 x 3,7V ( 7 x 18650 in series) voltage with balancing capabilities
so I was planing on building and control it with Arduino