I am toying around with the idea of using the arduino to control the charging of 4(maybe 6) NiMh AA batteries using a solar panel rated at 6V 400 mA.
First thing I would like to do is figure out exactly how the current varies throughout the day from my window.
Any advice on how to do this? I was thinking of using a voltage divider (I have read that higher resistance the better so as to not dissipate as much energy) and then measuring the voltage before and after an additional resistor to calculate current.
Will this work?
What's the best way to log this?
Once I get the logging figure out, any recommendations as to the best way to charge the NiMh batteries with solar panels? I was going to use an LM317 to provide a constant current to the NiMh batteries. However, I am also considering just wiring the panels directly to the batteries (with the appropriate diode). Will the NiMh batteries have a problem with the fluctuating current? If I go without the LM317, how will I know when they are fully charged? With the LM317, I was going to use the "negative delta v" cutoff method which relies on the fact that battery voltage peaks and drops about 20mV per cell when fully charged. Without regulating current, any ideas on when to cut off charging (perhaps a temperature sensor?).