I have a bunch of batteries laying around, some with VERY little run-time on them. They are all Surefire brand. Is it safe for me to take a volt-meter to them and pair them according to voltage as long as the voltage is no more than 0.1 VDC off? Or is this not good?
Is this safe? Pairing up slightly used batteries
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Moonshadow
Enlightened
Re: Is this safe?
Just using an ordinary voltmeter won't tell you very much about how the batteries will behave when a current is being drawn. They could have different internal resistances for example.
You really need a dedicated battery tester that checks the voltage under load.
Just using an ordinary voltmeter won't tell you very much about how the batteries will behave when a current is being drawn. They could have different internal resistances for example.
You really need a dedicated battery tester that checks the voltage under load.
Size15's
Flashaholic
I suggest you don't take the risk and use up these 'slightly' used batteries in a single-battery light.
I wouldn't put them in my favorite light. Chances are it might work, but there is also a risk. Let me explain: as mentioned by moonshadow, a voltmeter doesn't tell you how much charge there is left in a battery. Whenever a batery has more charge than another one in contact, it will discharge itself slowly into the other battery. This might have multiple outcomes:
they might equalize their charge (best-case scenario)
one battery could discharge until the charges are equal
one battery could discharge completely and this could lead to a leak (rare, but it happens, especially if left in that state for a certain period of time)
one battery could actually discharge in a manner that will unbalance the other battery (like charging it backwards) and cause a major leak (very rare and usually happens with batteries of different brands, but I've seen it) and this could lead to battery explosion or fire (haven't seen that happen, as I took out the batteries out at the first sign of trouble)
In short, It's seriously not recommended, especially with CR123 and family. I have done it with AA's and AAA's of the same brand in a cheapo light and it did work, but the first thing to look for is a sign of heat (not very risky with AAA's, but I've seen it happen too and took them out immediately to throw them out.)
they might equalize their charge (best-case scenario)
one battery could discharge until the charges are equal
one battery could discharge completely and this could lead to a leak (rare, but it happens, especially if left in that state for a certain period of time)
one battery could actually discharge in a manner that will unbalance the other battery (like charging it backwards) and cause a major leak (very rare and usually happens with batteries of different brands, but I've seen it) and this could lead to battery explosion or fire (haven't seen that happen, as I took out the batteries out at the first sign of trouble)
In short, It's seriously not recommended, especially with CR123 and family. I have done it with AA's and AAA's of the same brand in a cheapo light and it did work, but the first thing to look for is a sign of heat (not very risky with AAA's, but I've seen it happen too and took them out immediately to throw them out.)
Well crap. Now I have a bunch of 5-20 minute used CR123A SF batteries laying around.
I would love to argue in some way that it is safe, but too many smart people have told me it's not, lol. I will probably gift these to someone or wait until I buy a cheap 3P imitation from SOlarforce or something. Maybe a good gift for the next girlfriend. WHo knows.
I would love to argue in some way that it is safe, but too many smart people have told me it's not, lol. I will probably gift these to someone or wait until I buy a cheap 3P imitation from SOlarforce or something. Maybe a good gift for the next girlfriend. WHo knows.
Black Rose
Flashlight Enthusiast
If you are in the US, you could always get a cheap battery vampire light like the Dorcy Super 1 watt. About $20 at Target and will happily use the left over energy in your CR123A primary cells.
The 3P clone from Solarforce requires a 16340 to run, unless you buy a different drop-in.
The 3P clone from Solarforce requires a 16340 to run, unless you buy a different drop-in.
VidPro
Flashlight Enthusiast
dude :thinking: ya aint even supposed to mix brands and stuff because of capacity/resistance differences, series batts need to be a team, specially with volitile chemistries.
need to go BACK where this started , and have kept them as a team discharge, so even if you were using them for just a bit here and there, they would be used AS that same TEAM in the next thing.
so you could'a got away with all this kinda thing easily, if when you pulled a team you were intending on re-using, you marked it as a team.
see i would hate to see you Waste anything, and you should be able to have nice new batts for going out on longer treks and all, and you gotta be able to test your different lights and all, so that would be a longer term solution. Pair them up, or right before you unload them out of a part used light, put a quick mark on them, or keep them in a holder/spot together
makes me wonder if they shouldnt be selling them wrapped as a stick even, when used in pairs/trios, but that is the idea. if you HAD (as in hindsight) kept them teamed up, then you would just toss them in anything as that same team.
the rest was already said, you can tell a LITTLE bit from the voltage, specially if they are the same age/time/batch/brand/storage, but more extensive testing would tell better if they are similar, but even say 300ma offset could cause issues WHEN the lower cell becomes completly drained.
need to go BACK where this started , and have kept them as a team discharge, so even if you were using them for just a bit here and there, they would be used AS that same TEAM in the next thing.
so you could'a got away with all this kinda thing easily, if when you pulled a team you were intending on re-using, you marked it as a team.
see i would hate to see you Waste anything, and you should be able to have nice new batts for going out on longer treks and all, and you gotta be able to test your different lights and all, so that would be a longer term solution. Pair them up, or right before you unload them out of a part used light, put a quick mark on them, or keep them in a holder/spot together
makes me wonder if they shouldnt be selling them wrapped as a stick even, when used in pairs/trios, but that is the idea. if you HAD (as in hindsight) kept them teamed up, then you would just toss them in anything as that same team.
the rest was already said, you can tell a LITTLE bit from the voltage, specially if they are the same age/time/batch/brand/storage, but more extensive testing would tell better if they are similar, but even say 300ma offset could cause issues WHEN the lower cell becomes completly drained.
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Tony Hanna
Newly Enlightened
I'd like to preface this by saying that I have no idea what I'm talking about and that my first ever cr123 light is still on it's first set of cells (the first lithium primaries that I've ever purchased). I'm typing this more to see if my instinct in this situation would be right or wrong, not as advice...
That said, I'd be tempted to build a little rig to put a load on each cell individually. Ideally it would be something like a 3v incan bulb (or bulbs wired parallel) that pulls around the same current as the light I wanted to use the cells in. I'd use that with a digital volt meter to see what the voltage looked like for each cell under a load similar to what they'll see in use and then pair them up accordingly.
Would that be a reasonable strategy for a DIY load tester or still asking for trouble?
Thanks,
Tony
That said, I'd be tempted to build a little rig to put a load on each cell individually. Ideally it would be something like a 3v incan bulb (or bulbs wired parallel) that pulls around the same current as the light I wanted to use the cells in. I'd use that with a digital volt meter to see what the voltage looked like for each cell under a load similar to what they'll see in use and then pair them up accordingly.
Would that be a reasonable strategy for a DIY load tester or still asking for trouble?
Thanks,
Tony
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VidPro
Flashlight Enthusiast
yes tony they put a "load" on and test the voltage under load to have a "better" idea of the "capacity" , there are also very extensive resistance formulas and multi load tests, but what you propose would give you a BETTER idea than a 5 item display,as having a full display of the actual voltage underload would be better than that showing as 5-7 leds of range.
eng_driver
Newly Enlightened
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Using a series of cells, you should always use the exact same cells. Basically, in electronics there is no good exception to this rule.
Tony Hanna
Newly Enlightened
Thanks. I guess if I ever end up with a bunch of lithium primaries in unknown condition I'll match them up that way then.
N162E
Enlightened
As long as they are the same make and close voltage wise they will work fine in a series configuration. If you measure a box of new ones they will vary from cell to cell. The rules for Lithium are different than NIMH.
N162E
Enlightened
Issues? Like what, the light goes out?
jp2515
Flashlight Enthusiast
Black Rose is this the Dorcy light you speak of?
http://www.dorcydirect.com/p-15-41-4262-45-lumens-1-watt-led-flashlight-with-cr123-battery.aspx
Black Rose
Flashlight Enthusiast
Yes, that's the one.
CanadianGuy
Newly Enlightened
I'm no expert here, but that is very little runtime. IMO, if it's not a high draw light, they're still pretty much new. I'm not discounting what everyone here says, because it's all valid and best to err on the side of caution, but in this case I think that is such little use that they might not have drained at all.
VidPro
Flashlight Enthusiast
dead batteries are more likly to leak (for what reason i dont know) so when teamed up poorly one cell end up in there dead, ready to cause problems.
and (more important and probably related)
Series discharges (depending entirly on the curcuit or in most incans) can cause reverse charge situations, which can leak or explode the discharged Cell being reverse charged.
if the light goes out (cut-off) that would be a good thing
The problem occurs when the light doesnt go out, when the voltage on one cell is 0v in series configuration.
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VidPro
Flashlight Enthusiast
not my box
i can measure multiples of energypster lithium cells and they are all so close , you would think they were making batteries for a living or something
N162E
Enlightened
Try it with any brand Cr123 and tell me how it works out for you.not my box
