4 Samsung 30Q's down to 1v

I've had 4 new n Astrolux MF01. It's been sitting for about 6 months, unused. When I went to use the light it wouldn't turn on, and when I went to charge the batteries it flashes red. Turns out they are each reading at only 1v in my multimeter.

Can anyone tell me what the heck happened? Does this light have a vampire effect perhaps? I'm assuming the cells are dead, right? No coming back from 1v if I understand correctly.

https://www.banggood.com/Astrolux-M...650-p-1165131.html?ID=529762&cur_warehouse=CN

Cells can come back from 1 V, it's just potentially dangerous. The longer they spent below 2-2.5 V, the more dangerous it is. The danger is that they have formed internal shorts that will lead to thermal runaway and the accompanying venting/burning/exploding the next time they're charged.

The least dangerous way to check is to charge them very slowly, like 100mA and constantly monitor the temperature. If they get warm, stop charging and take them in for recycling. If they won't charge all the way to 4.2V in the expected time, stop charging and take them in for recycling. If they charge fully, but end up below 4.1V after sitting on the shelf for a day, take them in for recycling.

Samsung says to discard cells below 1.0v. Between 1.0v and 2.5v, charge very slowly until above 2.5v, then charge normally. But Samsung doesn't say how long cells can sit at 1.0v and still be "okay".

I'd be cautious. The safest thing to do is get rid of those cells. But if you plan to use them, as mentioned charge very slowly. Measure their discharge capacity, if possible. Then charge normally, and make sure they don't get unusually warm (as mentioned above). When fully charged, leave them alone for a week. Make sure their voltage doesn't drop much during that time; they should stay above 4.15v.

BTW, do all the testing safely. Keep an eye on the charger and temperature of the cells when charging. And when leaving the cells to rest, stick them inside plastic holders and leave them contained in something fireproof like a metal can.

The cells are probably still okay, but it's up to you to determine your risk level.

Oh, and that light may have a fairly high parasitic drain on the cells. All lights with electronic switches have parasitic drain, but good designs keep that very small. I have some lights with unacceptably high drain (up to 10mA), and I make sure to disconnect the power on those (by removing the batteries or loosening the tailcap).

I bet it was parasitic drain then. It also had a breathing led effect on the switch which I couldn't disable.

Unfortunately my xtar sp2 won't charge them at all, it just flashes red. I guess I will throw them out they are cheap enough.

llmercll said:

I bet it was parasitic drain then. It also had a breathing led effect on the switch which I couldn't disable.

Click to expand...

While the flashlight is off, a long push will turn off the breather.