Should I bin it.

chip100t

Newly Enlightened
Joined
Apr 1, 2021
Messages
86
Today I charged a few batteries and did capacity tests also. On my charger (vapcell s4 plus) one of the read outs is an m and an omega sign. All of my batteries bar one read between m omega 45-55, but one was in the 200s (please see pics) what does this read out measure? And is the fact one of the batteries being in the 200s a problem with this cell?

Seems a big difference.
A2B3BF08-6BD0-4330-BE74-2242EBD1F3D8.jpeg 9D655943-5E1B-4817-93DC-A341A09D7BD0.jpeg
 

sbj

Newly Enlightened
Joined
Feb 19, 2017
Messages
120
The internal resistance of the battery is displayed with the unit milliohm. 200mOhm versus 50mOhm would be a bad sign for the battery. This means that this battery is no longer so well suited for lamps with high current requirements.

However, for reasons of principle (high contact resistances), all slot chargers with spring-loaded minus sliding contacts are not well suited for an accurate internal resistance measurement. To keep this fundamental error as small as possible, you could do the following:

When inserting the battery, you should immediately press the negative contact against the battery with one hand and turn the battery back and forth with the other hand. This should at least ensure that the contact resistance at the battery terminals remains as low as possible and that no incorrect value that is too high is displayed.

A further contact resistance between the negative pole sliding contact and the device-internal negative - rail contact connection you can probably little influence.

With several measurements in a row, I use the lowest displayed value.

When measuring internal resistance, the battery should not be empty and should have normal room temperature.

In HKJ's charger test of this charger, he noticed that the displayed internal resistance values were displayed approx. 50% too low. That was then relatively constant, so that a comparison between different batteries is possible.

 

chip100t

Newly Enlightened
Joined
Apr 1, 2021
Messages
86
Thanks, as you can see the battery with the high resistance also charged at a quarter of the mA rate (240 mA compared to 1030 mA). And took much longer (hours and hours) to discharge and then fully charge.

I am not having much luck with olight batteries, I had another new and unused (but bought a few months ago and put by in my spares box) battery get very hot after only being on the charger a few minutes. So that one is going to the council tip when I pass by tomorrow.
 

sbj

Newly Enlightened
Joined
Feb 19, 2017
Messages
120
Before you dispose the battery right now, make another attempt to charge it, e.g. once in a different slot.

As I have already explained, the automatic internal resistance measurement is not very reliable with these chargers. This means that the automatic charging current adjustment does not work as expected.

If the charger has determined an internal resistance of more than 200mOhm for this battery, then of course it must not charge it with a high charging current. It could be a very small 10440 battery for which 1A would be too much!

So after a (partial) discharge, insert it again as I have described and see whether the internal resistance is then perhaps below 80mOhm.
 

chip100t

Newly Enlightened
Joined
Apr 1, 2021
Messages
86
Will do tomorrow,
Thank you for your help. If I could pick your brain once more. I managed to drop two batteries from kitchen counter height on to a wooden floor.

One has no visible damage and the other has a very small dink in the top (see pic).

Are these safe to use?

Once again thank you for your help as I know nothing about lithium ion batteries. C6FC808A-1C0D-4957-91AB-B1CEBB6BFEF4.jpeg 897232A7-3A1F-43DE-8F36-C6502E0FFA04.jpeg
 

sbj

Newly Enlightened
Joined
Feb 19, 2017
Messages
120
Something like that is always difficult to judge from the outside despite the relatively good pictures.
For safety reasons, I would dispose of the one with the dent.
I would mark the one without visible damage, but continue to use it.
 

chip100t

Newly Enlightened
Joined
Apr 1, 2021
Messages
86
Thanks, I googled should I use a dropped battery and found answers from “bin it if you value your face” to “I have dropped my batteries many times and they are held together with string and masking tape and never had a problem”

Thanks again.
 

sbj

Newly Enlightened
Joined
Feb 19, 2017
Messages
120
Yes - it is really difficult to give the right advice if it is only slightly damaged.

First I wanted to write that in such a case I would also observe the battery with the slight dent more intensively, but then probably continue to use it for myself.
The pressure point is really only small and therefore no impairment is to be expected. There is a 99.9% probability that this battery will also work perfectly.
However it makes a difference whether someone is ready for themselves to accept a minimal residual risk, or wants to advise someone else to do so.
Because of this responsibility I advised to dispose of it.

So in the end you have to decide that for yourself.
 
Top