Reversed polarity charging, please help.

[KeyGrip]

Hey all. I accidentally hooked one of my Li-Ion C cells in to the charging rig backwards. Before I try to charge it again, I need to know if I did any damage to the cell. Is it toast, or did the protection circut keep it safe?

Thanks.

 

[KeyGrip]

Anybody? I'm not using these cells again until I get a solid answer.

 

[zipplet]

Hi,

If the cell was protected it should be safe. Do you have a DMM handy to measure the voltage? Put the cell on charge for a minute or so and then remove it from charge, let it rest for a minute and check the voltage.

If the cell was unprotected then I'm not sure... if the charger had reverse polarity protection then no harm would have been done.

Either way, measure the voltage!

 

[KeyGrip]

Thanks Zipplet. The cells are protected so they should be fine, but that's too much energy for me to be taking chances.

 

[HarryN]

Hi, I was just thinking through this so bear with me:

Imagine that instead of a "charger", you had "cell A" (mostly discharged) in series with "cell B" (mostly charged). I think this is close to your situation.

If the voltage in Cell A drops below the cut off voltage of the protection circuit (around 2.5 volts) it will stop current flow, and your cell should read more or less "0 volts" on the voltmeter.

Maybe check this aspect to see that the protection circuit really did shut it down.

 

[KeyGrip]

Okay, that makes sense. I'll get my hands on a multimeter. Thanks for the help everybody.

 

[KeyGrip]

Just to check in, I'm getting over 3v on both cells, so everything is fine. Thanks for the help.

 

[curry__muncha]

I have a story thats in a similar vein: Somehow the polarity of a AA Alkaline (energiser) reversed itself (while being used to power the doorbell) and i measured it, read 1.5V (but at opposite poles). So i shoved it in reverse in my ultrafire c3 with another semi-used energiser AA of correct polarity, it seemed to work perfectly for a while (30mins of on-off use) and then when it died, i went to open the tube to replace the battery, turns out the reverse polarity energiser blew up in side the tube!
Now hte tube is completely wrecked. Caked and hard-baked with alkaline >< lol!
Lucky i only decided to try my silly 'experiment' on a cheap flashlight. Good thing is the module is completely fine and has been put to good use elsewhere

[and yes i was completely aware of hte possiblities of every step when i did what i did =P]