Using Mismatched CR123A's

[Wassernaut]

I've read about the dangers of using mismatched RCR123A's - but how much can they be mismatched and be safe? I use a digital multimeter to check all my RCR123's when I am ready to use them. After they have come off the charger, and rested to stabilize, I use the multimeter to get an exact reading on them, and pair them up in the battery rack . . . but how much different can the readings be and still be safe?

For example I have a pair with readings of 3.76 and 3.74 - another pair reading 3.51 and 3.57. Some pairs have exactly the same readings.

I have about 26 rechargable RCR123's. I only use protected batteries. I never pair up different brands, and within the brands I keep them in pairs, with the closest readings paired up for use, and I always check them again just before use.

But I'd like to know how far apart can the readings be before they are unsafe to be used together.

As always, thanks to all you veterans for sharing your knowledge.

- Larry

 

[mdocod]

If they are all protected (low volt-cutoff) then it wouldn't be a huge deal, but you would want to try to recharge before bumping up against protection.

If they are NOT protected, then you will really want to be aware of how *out-a-wack* they are, because you don't want to over-discharge a li-ion, as that is really hard on them.

At the time of writing this, I have no personal information about any RCR123s ever "exploding" in any flashlight situation. (not saying it can't happen, just saying I've never heard of it happening)... It seems there is a much more significant problem with primary CR123s than their is with li-ion cells as far as flashlights are concerned.

A few hundredths difference isn't usually going to be a problem, you really want to make sure that you are careful not to run one of those cells below a "safe" level.... I think that's going to be around 3.0V for most li-ion cells.

When you charge, try to charge to a matched state of charge before putting them into a device, this will help reduce balance problems cropping up during the discharge to some extent.

 

[Illum]

I have no personal information about any RCR123s ever "exploding" in any flashlight situation. (not saying it can't happen, just saying I've never heard of it happening)... It seems there is a much more significant problem with primary CR123s than their is with li-ion cells as far as flashlights are concerned.

I dont know of any thread concern rcr123As exploding....I believe that they can explode...but the degree of venting is probably incomparable to that of a cr123a vent simply because different chemistry is used and [if I remember correctly, me if I'm wrong] smaller capacity than that of cr123As

 

[jrmcferren]

These readings seem to be within reasonable error ranges with contact resistance, meter error, and so on.

 

[DM51]

Maybe I'm getting the wrong end of the stick here, but how come these 2 pairs of cells are reading 3.51 - 3.57, and 3.74 - 3.76, if they have just come off the charger?

If these are the figures for 2 pairs of cells after discharge, they are perfectly OK, in fact pretty good IMO. You don't need to worry unless the difference is >0.1v, and all you have to do then is mark the cell and monitor it to see if it is consistently weaker than its pair. When this happens you can decide to use either (or both) separately, in single-cell lights, until the weak one deteriorates to an extent where it should be recycled.

One sign of a cell deteriorating is when it warms up more than it did previously during charging. If any cell becomes hot during charging, stop the charge at once. Recharging is the time when most accidents occur with Li-Ion cells.

When any Li-Ion cell can no longer hold 80% of its capacity, it is time to recycle it.