I have a 500mah 1S lipo battery. I wanted to charge it with my lab bench power supply.
Easy, I thought: I want to charge at 2C (which is 1A) so I simply set my power supply to 4.20V and 1A limit and done.
What actually happened is that the battery charged about 0.9C and it was slowing down the closer it got to 4.2V. This means that to charge at a constant 2C current the whole way I have to use voltage much higher than 4.2V, but a fully charged lipo cell must not be over 4.2V or it does the FLAME ON thing.
So my question is, how do normal chargers do it? Do they simply bump up the charging voltage until they reach the desired current (so they work in constant current mode) and they every couple of seconds the stop charging and measure the battery voltage to find out if it is 4.2V and if it is, then they stop charging, and if it is not they jump back into constant current mode?