Jules_Theone
Member
I've recently bought a two cell 600mA battery charger from China for £3.49 to charge some cells I've got from dismantling laptop batteries. I've removed the protection circuits from the packs because I want different voltage / currents. Anyway, I've figured out the schematic for it to understand it more - can anyone see any obvious errors with it or suggest the value for two resistors with "?" marks next to them or the zener diode ZD1 voltage as it doesn't say explicitly what they are.
Also, it doesn't seem complicated enough. I was under the impression it needed three different stages for charging - constant charge current until the cell reaches 4.2V then constant voltage until the current drops to 10% of the capacity, then boost when the voltage drops to 4.0V. I understand this is cheap charger and probably only performs the first stage, am I correct to assume that?
It came with two AA size cells (900mA each) which it appears to charge in parallel, but I plan to charge 2200mA cells. Is there any problems with charging larger cells and is there a limit to how many i can charge at once? Is it a bad idea to charge two cells which are at different voltage levels with this charge - could the higher charged cell discharge into the less charged one at high amps (blowing internal fuse(s)?)
Thanks,
Jules
Also, it doesn't seem complicated enough. I was under the impression it needed three different stages for charging - constant charge current until the cell reaches 4.2V then constant voltage until the current drops to 10% of the capacity, then boost when the voltage drops to 4.0V. I understand this is cheap charger and probably only performs the first stage, am I correct to assume that?
It came with two AA size cells (900mA each) which it appears to charge in parallel, but I plan to charge 2200mA cells. Is there any problems with charging larger cells and is there a limit to how many i can charge at once? Is it a bad idea to charge two cells which are at different voltage levels with this charge - could the higher charged cell discharge into the less charged one at high amps (blowing internal fuse(s)?)
Thanks,
Jules