[quote=jon_slider
you sure?
that would make no sense to me. Best to use Lockout I suppose.
What Voltage did your battery go down to?
[/quote]
I think it was 3.25v
3.25v is well above the trigger for LVP
maybe someone else can inform whether the buttontop is in fact protected… (it should be)
a protected cell wont trip til gets down to 2.5v
and once protection trips, the cell will read 0 Volts…
protection is reset by placing the battery on a charger… at which point the voltage will be above 2.5v again
I don’t have it here but I’m pretty sure it isn’t. Mine was drained down to 2.3V or so when leaving it on to test runtime IIRC.
It was a 30Q in it. I think it may have come with a Sofirn cell or none at all. I have yet to see a protected Sofirn cell though.
ok, well… if the cell is unprotected AND the light has no built in LVP, thats obviously not a muggle safe combination… is the cell IMR then?
In any case, best not to rely on LVP, people should be charging their cells long before that
curiously enough I have a friend that has caused problems for a driver and a battery, in the past, by doing “runtime tests”, that imo ran Much too long, created too much heat, and in one case made the battery so hot it blew a vent…
be safe folks, dont rely on protection circuits to make up for LiIon safe use practices
in my experience lights with no lvp become dim when it gets to 2,5v. so you’ll know to turn it off and recharge the cell, however it only works when you know it, and when you actually using it, if you leave it on unattended, it will drain the cell too low, if you let someone borrow the light, and they wont know, or care, they will kill your cells.
LVP is like a gun, it is better to have it and not need it, than need it and not have it.
true for unregulated lights
I actually notice when my RRT-01 is about half as bright, which I take as a sign to recharge… at which point it tends to be around 3.2v
Thanks for this thread. I’d given my wife a Sofirn SP32AV2 a couple years ago. Upon reading some of the above accounts, it occurred to me that I hadn’t seen that light in quite awhile. I went up to her emergency basket beside the bed and found the light and tested the 30Q battery. Stone dead. Shame on me for not checking it regularly, doing a manual lock-out, etc. Thanks for the heads-up.
you did good to check
somebody with the skills should calculate the parasitic drain rate for that Sofirn
and load it with Protected cells in any case
what are you going to do now, with that overdischarged battery?
attempt a recharge in a fire safe area?
(feeling lucky?)
or
seek a place that accepts batteries for recycling?
(Prudence is the better part of Valor ;-))
I’ll take it to the recycling center. I’ve resuscitated a couple batteries over the years that got a bit too low but nothing like this. Pretty sure this one is a goner.
> Is Low Voltage Protection Necessary?
hope the OP also learned the answer to his question :student:
I’m not positive if a protected battery would be in any better shape, after sitting for a year or two. Protection circuits have a parasitic drain on the cell, in order to operate. Once the cell is down to 2.5v, and the protection kicks in, does the cell not continue to drain (albeit slowly)?
The danger is that you won’t know what the real voltage of the cell is. It reads 0v on your DMM, because the protection has tripped. But, does that mean the cell is 2.4v, and therefore safe to recharge? Or, does it mean the cell is 0.1v, and therefore unsafe to recharge? You won’t know. You could recharge a cell that has degraded, and has internal shorts. It could just catch fire at any time, and the protection circuit does nothing for internal shorts.
well
most chargers will not try to charge a cell under some minimum limit
the danger is that if they do, the cell may charge, but now it is a time bomb and may have internal shorts
or it may catch on fire while charging
it isn;t actually hazardous to overdischarge
just when you try to charge or use it later, do the problems occur
wle
Yeah, but a lot of chargers will try to charge a cell as low as 0v. Most good ones will at least do it slowly, which is better than just dumping 2 amps into it. Most of Xtar’s chargers do that. But, you really should measure a cell’s voltage yourself (with a DMM), if you’re at all unsure about its discharge state.
Or if you have a fancy charger that warns you about low voltage, that would be good too. Maybe something like the Skyray MC3000 does that? (I have no idea, since I don’t have one.)
i thought usually they would just sit there and not start a charge, if it is too low
may or may not read the volts for you
it just acts like ‘i do not see a cell here to charge’
wle
I can’t find an answer to whether or not protection circuits add parasitic drain after tripping. Sounds like the positive terminal is disconnected after tripping. The cell could still self discharge over time though.
Depends on the design, but the IC needs power if it’s still monitoring. They use very little, though, maybe less than self discharge. In any case, a cell that’s been drained for years below the trip… I’d want to know the real voltage.
Really?
That’s annoying. I hadn’t seen that mentioned in any reviews or anything… How long (roughly) do you think would it take to drain the 14500 below safe recharging levels?
it would be prudent to use Protected 14500 in the AA Tool, since the light itself has no built in LVP.
I would disable the tail LEDs.
or just use Eneloop
See post #12 for amp draw of tailcap;