MF01s battery cells different voltages when stored in light. 2.53v, 2.64v, 3.43v, 3.69v

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Leyline
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MF01s battery cells different voltages when stored in light. 2.53v, 2.64v, 3.43v, 3.69v

So I pulled out my MF01 that has been stored for 7 months (with the head loosened for no drain / saftey)
The light had been used a bit and I think I put it away with the 3 click reporting 3.6-3.7v

Last night when I got it out 3 clicks said 3.3v
I used it for a bit to do some night time yard things, about an hour maybe, on a low-mid setting.

This morning I took the cells out to charge, and when I put them in the charger my LII-500s showed the cells at shockingly low, and pretty high values.

2.5v to 3.7v

Does this light drain the batteries that unevenly?

I am using Samsung 30q flat tops, unprotected, 3000mAh x4

Thanks!

nick779
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That seems extreme, but it is possible as it uses a 2S2P battery configuration (2 in series x 2 in parallel)

I thought that light required button tops?

Henk4U2
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If it’s only the voltage you’re interested in, try to measure that in the same slot.
I’m using “married cells” in my multi-cell lights, but every slot shows a differente value.
Though that difference is not as big as what you wrote.

You are a flashaholic if you are forced to come out of the closet, to make room for more flashlights.

thefreeman
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I’ve seen several reports from li ion batteries pack makers on EV forums of 30q’s being inconsistant with some cells having higher self discharge and developping some more as they age, thus disbalancing the pack. This could explain your voltage differences.

gravelmonkey
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Where were the cells purchased?

I’ve had 30Qs from banggood which showed wildly different internal resistances.

One other potential cause- I’ve had issues with cells not making good contact- can’t recall if it was my MF02, I used a set with bigger nipples to solve the problem.

Leyline
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I bought the cells from illumn.
Stupid me I didn’t just pull out my volt meter before I started charging.
I think I will run the light down and check them, and then also next time I let it sit a long time I will also check my cells with the multi meter before I move to charging.

Thanks for the note about the 30q’s having differing Self discharge. Seems extreme for them to loose so much, but I will monitor things more closely next time

Thanks all!