Problem with Duracells and SF M6 MB20

[LED61]

I have been using my M6 with my rechargeable pack for the past few months, and at that time I loaded my MB 20 for emergency standby with 100% ZTS tested high quality duracells. The MB 20 saw absolutely no use in the M6 and has sat in a nice dry cool place all this time. Today I decided to take the cells out and measure them again, and to my surprise I am getting very erratic readings in the ZTS, same cell showing different states of charge, and all cells ranging in capacity from 20%-80%. A few read 100% in one of four tests.

So, WTH is happening here ? I remember CPF respected member BWaites posting some problem along these lines a while back and now it has happened to me. Could it be this MB20 "steals" current at idle from the cells ?

 

[Black Rose]

I was going to say to do multiple tests with the ZTS in case the cells decided to take a nap, but I see you did 4 tests.

 

[LED61]

Yeah, and usually the higher readings were obtained in the first test. I don´t know here there is something really goofy. Never had this erratic behavior on Duracells. One more thing, I have ruled out that the tester is at fault because I also tested some fresh cells of the same batch but that were not in the MB20 and they all tested consistently at 100%.

 

[mdocod]

Has anyone tried putting a pair of CR123s in parallel, just sitting around for a few weeks, to see what happens to them?

I have a hunch.

 

[LED61]

Has anyone tried putting a pair of CR123s in parallel, just sitting around for a few weeks, to see what happens to them?

I have a hunch.

What is on your mind mdocod ? I´d really appreciate your opinion or that of Silverfox or other informed fellows in this.

 

[Black Rose]

I just took a look at the MB20. What is the configuration of it?

 

[LED61]

I just took a look at the MB20. What is the configuration of it?

3S2P

 

[mdocod]

Well... I have noticed that the resting open circuit voltage of lithium primary cells seems to vary, even amongst cells of the same brand, in the same state of charge, usually not by much, like a couple hundredths of a volt, but electrical potential is electrical potential, and I wonder if those small imbalances to start with, are enough to trigger a slow but gradual exchange of electrical storage that teeter-totters back and forth. Most of the energy would end up slowly lost to heat in such a scenario.

That's my hunch/theory. It's nothing more. I've put my cards on the table, just not sure what anyone else is holding yet....

 

[Kiessling]

That would be a terrible scenario for all parallel configurations.

 

[KD5XB]

I'm guessing that parallel setups are fairly rare, at least in flashlights -- I was considering how that could be put together, and in a straight round tube, it would take insulators and wires and be an overall mess...

 

[DM51]

This sounds like passivation. Try using the M6 for a short period, and then test the cells again. You may find they have regained consistency.