Synon
10 W
Just a little background, I'm using a Thunder 1220 charger and I'm working with used 18650 laptop cells (in this example, working with a single cell), I'm also using a Fluke 117 multimeter to monitor the cell.
When I first turn the charger on the voltage read by the charger is 3.71v and the fluke reads 3.745v. Once I begin charging at .2C the charger now shows 4.05v and the fluke shows 3.790v, when the charger goes through its 5 second "rest" period the charger reads 3.72v and the fluke 3.75v.
Why is there such a large difference in voltage reading while actively charging? I figured if the voltage reading was off I could adjust a pot like I do to calibrate my other cheap multimeter, but if I adjust it then the resting voltage will be off. This doesn't seem like normal behavior, am I missing something? My cells all end up at lower voltages than what the charger is told to charge them to.
When I first turn the charger on the voltage read by the charger is 3.71v and the fluke reads 3.745v. Once I begin charging at .2C the charger now shows 4.05v and the fluke shows 3.790v, when the charger goes through its 5 second "rest" period the charger reads 3.72v and the fluke 3.75v.
Why is there such a large difference in voltage reading while actively charging? I figured if the voltage reading was off I could adjust a pot like I do to calibrate my other cheap multimeter, but if I adjust it then the resting voltage will be off. This doesn't seem like normal behavior, am I missing something? My cells all end up at lower voltages than what the charger is told to charge them to.