Basic battery capacity question

JlightT

Newly Enlightened
Joined
Dec 29, 2023
Messages
3
Location
San Jose CA
I have some 16340s, some of which are a bit old. When I charge them to full capacity and put them on a voltmeter (tested across 2-3 voltmeters), I'll get readings like 4.1, 4.13, etc

When I put them on my new Mini MBT, these same batteries read as 80% or even 60%. Is there something wrong with my MBT? Or is it because the pulse load the MBT puts across the batteries can make old batteries sag? IOW, do I believe the voltmeter or MBT?

This does not seem to happen with some of my 16340s that I believe are a bit newer (but still probably 3-4 years old), the MBT considers those batteries 100% when they come off the charger. Leading me to believe I might have very old 16340s that are sagging under even a small load. Does this explanation make sense?
 

JlightT

Newly Enlightened
Joined
Dec 29, 2023
Messages
3
Location
San Jose CA
Thanks for the reply! Yep I should do a better job of writing down when I get batteries... some of these batteries might be 5-10 years old, I just don't k now which. Or maybe now I do, the ones that the MBT thinks are only partially charged even fresh off the charger
 

aznsx

Flashlight Enthusiast
Joined
Apr 24, 2015
Messages
1,693
Location
Phoenix, AZ USA
Thanks for the reply! Yep I should do a better job of writing down when I get batteries... some of these batteries might be 5-10 years old, I just don't k now which. Or maybe now I do, the ones that the MBT thinks are only partially charged even fresh off the charger
I just mark mine with a Sharpie - mmyy. That can rub off, but mine don't seem to get handled enough that it's proven to be a problem. If it did, I'd just mark over them again when they got faint, but don't recall having to do that. Might not work well with all-black cells, but practically none of mine are all-black.
 
Joined
Sep 30, 2020
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Caught in an air duct
I just mark mine with a Sharpie - mmyy. That can rub off, but mine don't seem to get handled enough that it's proven to be a problem. If it did, I'd just mark over them again when they got faint, but don't recall having to do that. Might not work well with all-black cells, but practically none of mine are all-black.
They also make silver Sharpies that I use on black surfaces. It seems more paint-like than black Sharpies.
 
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