I made a constant current charger for a NIMH AA battery. When I tested it out by powering it with 9 volts, it charged the AA from about 0.65 volts to just under 1.4 volts in a matter of minutes. I'm no expert, but I have charged many batteries, and this seems too fast to charge a battery. I'm worried that the circuit may damage NIMH batteries because it's charging them so quickly. The circuit uses an LM317 to provide a constant current of about 10.4 ma and the batteries are 1.2 volt 2000 mah batteries made in 2014 (not sure if manufacture date is important, but I wanted to provide it in case it is). The battery has writing on it that says its standard charge is 200 ma over 15 hours.
91 KB Views: 19