18650 voltage for charging/discharging

what numbers on my meter should i be looking for to determine when to charge and how much to stop charging?

Thanks

Any dedicated li-ion charger will do this for you. You can recharge whenever you want but don't let the cells go below 2.5V and don't leave them connected to a float charge forever either.

BillG said:

what numbers on my meter should i be looking for to determine when to charge and how much to stop charging?

Thanks

Click to expand...

4.20V +/- a couple hundredths of a volt is the fully charged voltage value. A charger will do constant current followed by constant voltage until the current drops to about 10% of the constant current charge value and call that a fully charged battery. You can also accomplish this with a power supply that has a current limit setting. You set the voltage to 4.20v and you set the current limit to whatever value you want to charge the battery at.......say 1.0 amps. Once the voltage reaches 4.20v, then the voltage won't climb anymore and the current begins to taper off.

To get a full charge you need to keep charging until the current drops to about 10% (ie: 100mA in this example or even lower if you have the patience to wait). Current only goes into the battery when the voltage of the charging source is higher than the battery. By limiting the voltage to 4.20v (which is the recommended limit for lithium ion), then the current decays in an exponential fashion once the voltage hits the 4.20v set point of the power supply.

After charging is over with, you usually end up with a battery that is around 4.18 to 4.19v or so.........depending on how long or low you allow the decaying current level to go. Sometimes when I want a more fully charged battery, I will charge at the 1 amp rate first (for speed) and then when that is done, charge at a 250mA rate. The C/10 (10% charge level) is 25mA at the 250mA charge rate so it charges longer...............but in reality its insignificant.