Lowest Voltage for 18650?

Batteries and Chargers Rechargeable Batteries
1

A week or two ago I ran one down to 2.78V, should I toss it? I think it was off a couple minutes before I got to the multimeter, so it may have been lower and “bounced” a bit. Cheapie cell.

I’ve heard if it goes under 2.9V, toss it, but I think some may go lower? Thinking cut off is lower on some drivers.

A bit later, maybe a couple hours or so, it was up over 3.10V, and I checked it this morning and it had “bounced” back up over 3.20V.

2

Huh? We would be buying batteries every week if that were so.

He is what I go by...

  • 2.5VDC lowest desirable but not a guarantee battery is toast if below that
  • For personal safety you do not want to try and drain below 2.5VDC
  • The higher the remaining capacity when placed on charger the more charge cycles you get
  • A good reliable charger is a must to avoid mishaps.

If your light does not have low voltage protection then use protected batteries. As for this battery....I would not be tossing it. I would be charging it and putting it back to work.

3

Thanks, that’s what I was thinking. Especially since it bounced back above 3.2V.

I think I read to toss it under 2.9V on candlepower forum.

4

How far it bounces back up can be an indication of how bad the cell is. The further back it bounces, the worse the cell.
For the fun of it, I charged some NOS cells that I found in a never used laptop pack I found in the recycle bin. They were sitting at 1.4v each. I put them in my OPUS and charged them up. (I did this outside, in the driveway) They charged up to 4.20v and quickly settled to 4.16v. I then discharged them through the OPUS at a 1A rate. The OPUS drew about 1400mAh from each one and shut down. When in perfect condition those cells should have been 2000mAh (Panasonic NCR18650A). They bounced back up to about 3.70v, that is a very large bounce back indicating a high internal resistance. Those cells proved to be no good (but we already knew that) and I will toss them.