I realized my old camcorder battery is the perfect size for RCR123's. I pull it apart and it holds a pair of them. The problem is they show a meager ~1.7 volts. I'm charging it now. Can I expect disaster? Fwiw, I might not have ever used this battery since I bought an extended battery with the camcorder and preferred to use that the few times I had the camcorder because it was stolen.
I'll update this thread later...if I can. ;)
i would not recommend charging a cell that low
I was wrong. It's a 17360, not a 16340. Panasonic CGR17360. It fits in my oLight S10. :)
Neither would I. I'm doing it out of morbid curiosity. It's barely been on the charger, but it's already up to just under 3.2 volts.
If you haven't ever charged it, 1.7V might be its initial state, straight from the factory.
That's what I'm hoping. It's just under 3.5V now. It'll probably be another 3 hours before it's fully charged, or disaster.
Where are you charging it and at what rate?
Try mesuring the internal resistance after it’s fully charged (or after a couple cycles if you dare) using the instructions below: (The resistor should be about 2-5 ohms.)
I'm not sure on the charging current. It's either ~100mA or ~300mA. Based on charging times, I think it's the latter. It's charging in the bathroom in a steel can.
The battery and charger have remained cool to the touch.
Thanks for the internal resistance tip.
Correction, charging current was with this 450mA charger. I think this charger might be a LOT slower though. I switched to the charger I thought was 300mA. It was only at 3.82V. I expected more, but at least everything is staying cool.
It was at 3.87V, and then I let it charge again until a short while ago. It's taking a lot longer to charge than I thought it would. I really should test the current my chargers put out. I think it might be too long for my oLight S10 because it wouldn't turn on. It's my only RCR123 light. It might remain my only one too now that Fasttech has raised their Sunwayman prices.
I also charged the second cell for a short while, and it quickly bounced up to around 3.2V.
I'll finish charging (or destroying) these later.
First cell is 4.24V.
Low V cells can sometimes be recovered. Just last week I pulled two 14500 cells from a small Sony camcorder pack. I had bought the pack in 1999 but it saw little use because I had larger ones. When extracted from the pack one cell was at 1.66v and was at 2.54v. My hobby charger accepted the 2.54v cell and I charged it up at 100mA. The charger rejected the 1.66v cell and would not charge it, so I put it in my 47's charger and charged it at ~500mA for five minutes on, five minutes off, on, off ... until it was at a resting voltage of 2.3v. At that point I started charging it with the hobby charger at 100mA until full. After several cycles these two 14500s are now used in my SK68s which both draw better than 1A.
More sophisticated chargers often (and rightly, for safety reasons) reject cells that are below a set voltage. But low V cells can sometimes be rejuvenated if they are charged in a less intelligent charger until they reach a more normal voltage. I'm careful to watch them and monitor their temperature when doing this. The trick is to charge them very gently at low currents, especially with smaller cells.
But it doesn't always work. Two 17500's from a larger pack of similar age: One cell was 2.x volts and the other was at .9x volts. Guess which one didn't make it.
A cell resting at that low of voltage would have normal been considered by most junk. But that is apparently not the case. They were several people including me, that got in on some cheap laptop packs with Panasonic 2900mah cells inside that where never used. They were 3 1/2 years old and had never been charged but maybe by the manufacture. Once charged up they seemed perfectly fine in all our test. They where resting around 1.9v for most that received them. I have one that’s been setting charged since the day I charged it. The voltages after a month of setting where exactly as expected. The cells act as if the just rolled off the assembly line. So I don’t tell someone a cell should be tossed anymore from just the measured cell voltage. It must have more to do with the life of the cell and how its been treated. Even heat a little above room temperature can effect cell degradation.
This is the thread with the low voltage laptop pulls.
I forgot to update this thread. The second cell charged up fine and came off the charger at 4.21V. The cells sat in a drawer for four days. I measured them lastnight and got 4.21V & 4.23V, almost exactly the same as when they came off the charger.