LX2 uneven discharge on cr123 batteries

I recently bought a LX2 and went thru my first set of batteries. The light was strobing and the light would dim when turned on. I used Surefire brand batteries to replace the original ones. I don't have a battery tester yet, but I recently put the used batteries in a single cr123 light to see how much power was left. One of the batteries would barely light up and the other was as bright as a new battery. Without knowing the remaining power in both batteries using a tester, is this normal or do batteries discharge equal when used in pairs? I will test the next set of batteries that come out of my LX2 with a meter to see how much power remains.

What kind of runtime did you get out of the batteries?

One of the batteries may have just had some extra juice in it to start. Or one of the cells could have had a slightly higher internal resistance due to manufacturing tolerances causing them to become unevenly charged with use.

The LX2 doesn't really enter into the equation as there isn't really much it could do to cause an uneven discharge with two series cells. However, I'd expect there to be more unevenness due to differences in internal resistance if the batteries were discharged faster versus slower. i.e. I'd expect more of an uneven discharge using high mode all the time. (Because the power wasted due to internal resistance should equal the current squared times the resistance)

Of course, one of the batteries could have even been defective initially, although that seems unlikely.

husky said:

I recently bought a LX2 and went thru my first set of batteries. The light was strobing and the light would dim when turned on. I used Surefire brand batteries to replace the original ones. I don't have a battery tester yet, but I recently put the used batteries in a single cr123 light to see how much power was left. One of the batteries would barely light up and the other was as bright as a new battery. Without knowing the remaining power in both batteries using a tester, is this normal or do batteries discharge equal when used in pairs? I will test the next set of batteries that come out of my LX2 with a meter to see how much power remains.

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I had the exact same thing happen to me from batteries out of my brand new G2 LED. I decided to check them on a 1.5 volt cheap battery checker for 1.5 volt batteries just for kicks and giggles. One of the spent batteries flung the pointer to the good side at 100 miles per hour, and when I tested the second battery it stayed on the bad side. (this battery tester doesn't tell actual voltage, just if its "good" or "bad".) Anyone have any idea whats going on?

As I understand it, batteries in combination can not discharge beyond the discharge capability of the weakest battery of the set. It is very difficult to ensure that a set of batteries will be perfectly matched in use so it is normal for there to be difference. This has all been discussed before on CPF although I don't have threads to hand sorry.

Consequently, CPFers often have a single-battery light capable of sucking every last drop of unused juice from 'used' batteries. A so-called battery vampire.
It is important to never mix old and new batteries, or attempt to match up partially used batteries, and to store used batteries in cool dry conditions such that they can't be short-circuited prior to feeding them to your single-celled battery vampire of choice.

So it is safe to assume that when your 2 cell cr123 light goes dim, the batteries may not be discharged to the same level and may still have use in another 1 cell light. That may or may not be the case when the batteries are closely matched. Always good to check batteries before disposal! :thumbsup: