14500 charging question

Eric_M

Enlightened
Joined
Aug 8, 2002
Messages
445
Hi,

How warm should a 14500 Lithium Ion battery get while charging? I converted a cell phone charger designed for Lithium Ion batteries to charge 1 14500 cell. The manufacturer information for the charger states that it is a "smart charger" and will not over charge the cells. After about 1 hour of charging the battery felt pretty warm. What should the voltage be during charging? I just started a cell and the charge voltage was 4.1 VDC. What should the final charged voltage of the cell be?

I'm sure these are beginner questions so sorry for that.

Thanks,

Eric Maier
 
Update, after a little over an hour on the charger the voltage is 4.71 VDC and the battery
is getting warm.

Should I be concerned?

Edit:


Battery was getting hot, I pulled the plug.

Battery voltage is 4.52.

Here is the charger I'm using:

http://www.wirelessground.com/lgvxlg12hotr.html

It's designed for a 3.7 V Lithium Ion battery
 
Hello Eric,

You have damaged your battery!

Li-Ion cells should not get hot during charging. I charge at about 72 degrees F room temperature. The cells will get up to around 74-76 degrees F. Warm to the touch but not hot. When you try to charge at too fast a rate (greater than 1C) or at too high a voltage (>4.2 volts) the battery will get hot. Left long enough at a high enough voltage and they will "rapidly vent with flame." I believe the flame temperature is quite high and will burn anything around it. The rapid venting can send hot burning shrapnel 5-10 feet endangering other combustible material in the area.

Your charger is designed to be used with a cell phone battery pack. The battery pack has a protection circuit in it to shut it off when the charge reaches 4.2 volts. When you removed the individual cells, you also removed the protection.

You can probably charge Pila cells in your charger (they have protection built into the cell) but it is not good for bare cells.

Li-Ion cells should be charged at a maximum rate of 1C to a maximum voltage of 4.2 volts and not be discharged below 2.5 volts under load or 3.0 volts resting.

Do you have your fire insurance paid up?

Tom
 
Top