Li-Ion protection technology and possible dangers

[yifu]

Re: Newbie question

Yes that behaviour is very normal. Once a PCB kicks in due to overdischarge (usually around 2.6V for non-18650 AW cells but this isn't always 100% reliable as some members have reported it not cutting off in the older cells so it shouldn't be relied on to tell you when to stop using the light), overcharge, overcurrent etc, the circuit is cut and a cold start voltage must be given to the PCB to reactivate it again.
I have a Zebralight SC600 and it does cut off reliably at around 2.8V, at that point only the low modes work.

 

[SilverFox]

Re: Newbie question

Hello Dbare,

Welcome to CPF.

First of all understand that the only stupid question is the one that is not asked...

What you are seeing is the result of the protection circuit kicking in. When the cells voltage drops to the point where the protection circuit kicks in, it will often read 0 volts. To figure out what the cell voltage really is, you need to reset the protection circuit. You can do this by putting the cell in the charger for a second or two and then removing it and measuring the voltage.

Depending on where the protection circuit is set, completely draining a cell to where the protection circuit kicks in every time may reduce the cycle life of the cell. It is probably better to use the light a little less before charging the cell back up. Fortunately charging a Li-Ion cell before it is completely empty does not damage it.

Many of us look at the protection circuit as a last line of defense. If we totally loose track of the time we have been using the light, the protection circuit will kick in to protect the cell from extreme over discharge. It is nice to have the safety in place, but in normal use you would be better off charging more often and using the safety of the protection circuit less often.

Tom

 

[dbare]

Re: Newbie question

Thanks, yifu. g'day to ya

And also to you, SilverFox

best regards,

dbare

ps: A little lcd volt meter window somewhere in the body of the flashlight would be very convenient - yes? (with a .0000005ma draw)

 

[Burgess]

Re: Newbie question

No need for an LCD volt meter *window*.


Simply have it " flash " out the voltage, in Morse Code !

 

[Empath]

Re: Newbie question

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