18650 charge/discharge parameters?

[sp5it]

Hi. I have a lot of used 18650 cells.
I have iCharger 106b+.
I want to test them how they are performing, which to throw away, which are good to use.
What charging and discharging current should I use?
Mike

 

[VidPro]

1-2 amp
then remember the higher the amperage of the charge , the more likly that a Really Bad one can overheat, and start your house on fire.
so i would push them at 2 because i would want to make sure they could do that , and i would want to get it done. but i would Know that if they wont budge that could finish them, a poorly made one could even completly explode on a rare occurance.
really low rates when they are bad and not accepting charge the heat is much lower and the chances of a thermal issue are far less.

i discharge at the same rate usually as the charge, dont really understand discharging at 1/2 rate, other than you have to dissapate the power , and many chargers cant dump the power as well as they can put it in. so i say pump it up and draw it down at the same rate and get it done.

 

[sp5it]

Thanks for reply.
Should I use balancer and charge/discharge 4-6 cels in series or should I test only one cell at the time.
Michał

 

[VidPro]

certannly, set up for a balance charging and save a lot of time
just recognising that there:

1) isnt balance discharging on most of those things, so you might want to write down your final in series numbers , then continue the discharge singuarly to see where each cell really stands.

1b) or might want to singularly discharge anyways to save the hassle.

2) some of these thing have reported charging a cell a BIT too high when Badly out of balance, in series, then "post" balancing, meaning they get Close with the main charging, and that might not be close enough WHEN the cells are all different acting and wackey in capacity. Is completly fine when they are a good working team.

yes ok come to think of it because you dont KNOW nothing about the state of them, and one could be WAY different than the other, and they arent Teams, mabey staying single UNTIL you have some close matching cell items would be better.

me thinks you will know.

 

[HKJ]

Thanks for reply.
Should I use balancer and charge/discharge 4-6 cels in series or should I test only one cell at the time.
Michał

If the batteries has different capacities due to age, it is not a good idea to use a balancer, because the charge/discharge rate would then be controlled by the balancer.

 

[jh333233]

The charging current should not be over 1C in order to be safe
Where C is the current which the cell can discharge in 1 hour
i.e. the C value of a 2500mah cell is 2500mA

Measuring the intenal resistance of the cell can know how the cell doing.
As i know theres some device which can test the internal resistance
get some brand new cell which is identical to yours for control set-up

 

[sp5it]

Thanks for replys.
I tested a few used cells charged with 2A current, discharging with 2A load takes between 25-30 minutes to cutoff at 2.5V.
Mike

 

[pae77]

Hi. I have a lot of used 18650 cells.
I have iCharger 106b+.
I want to test them how they are performing, which to throw away, which are good to use.
What charging and discharging current should I use?
Mike

Here's some good general background info on charging Li-ion cells.

 

[jh333233]

Thanks for replys.
I tested a few used cells charged with 2A current, discharging with 2A load takes between 25-30 minutes to cutoff at 2.5V.
Mike

2.5 is too deep alrdy
to maintain it, u should NEVER get over 2.75-2.8
3.0-3.2v cut off is the best

For 3.7v rated LiCoO2 cell
(not for LiMn and LiFePO4)

Update: or just leave it to the protective circuit if exists

 

[sp5it]

Ok, I set 2.8V cutoff.
Mike