I have this project where I have connected a 3020 LED module which I ripped off from an IKEA JANSJÖ to a tp4056 v2 module which is connected to an old samsung 800mAh phone battery.
I had fully charged the phone battery using the tp4056 module and then started to power the LED to find out how long does it keep powering. I measured the battery voltage at the battery terminals regularly to keep track of the voltage. For the first 10 to 11 hours the battery voltage dropped from 4.18 volts to 3.57 volts. Then I simply tried to test how many amperes does it draw using the 200m function of the multimeter and got a value of 47.2. Suddenly just after I checked the ampere the battery voltage dropped to 2.8volts and the light would no longer turn on.????
I plugged in the USB charger to the tp4056 module and immediately unplugged it and suddenly the battery voltage jumped back to 3.5volts and the LED started to light up.?? 2 hours after that it still keeps o powering and voltage is at 3.5volts.
what the hell is happening? what did I do wrong here? :o
Note: With a USB power doctor the LED module draws 0.06 amps at 5 volts. The LED module seems to have current limiting with two J3 smd transistors and 2 smd resitors of value 100 and 682.