Grading batteries?

[MarrtyG-H]

Morning all.

I'm wanting to grade some batteries, I'm using an Xtar VC4SL.

I started grading one of the batteries yesterday but after 14 hours it still hadn't finished the cycle and I needed to go to bed. Is it safe to leave batteries to grade over night? I wouldn't ever leave them to charge over night but I'm not sure how I can grade the batteries without leaving them over night when the cycle seems to take so long.

 

[stuartd]

I wouldn't leave any battery's charging overnight just a safety thing for me and it looks like the battery could be a dud if it's still charging after 14 hrs

 

[Razuddin]

I use a smart plug for this reason, dont like charging my batteries for long. I've worked out that my charge takes about 3.5 hours to charge my batteries to full, so each time my batteries need charging i turn it on for 3.5 hours and it auto turns off. You can grab cheapo smart plugs from poundland, the last ones i got cost me £3 (ultrabrite brand)

 

[Crispycritters]

I may be misunderstanding what you mean by 'grading' your batteries - but if you're doing a discharge and recharge cycle to check capacity it is normally the discharge part of the cycle that takes a long time. Discharging them at a very low rate (like 200mah per hour) can take ages with 18650s, and almost a full day with 21700s.

Although slow discharge will give a higher capacity result because there is less battery sag, in real life vaping use you will be discharging them at a much faster rate and low battery cut-off could be 3.2 (or 2.7 with DNA) instead of 2.5V of the charger so the higher capacity results are pretty meaningless. I don't have that charger, but if it can be set to discharge faster, then recharge - the figures will be lower, but more realistic and will still highlight which batteries have higher capacity - and it won't take an entire day to complete a cycle.

Although it is nice to have a charger with lots of features - bear in mind that they are not up to lab standards and different bays will give different results (something as simple as a bit of tarnishing on a contact will make a marked difference to the results. It is useful to have a comparative number for reach battery as you can quickly discover which are tired - but ensure everything is clean before attempting it.

I had a Miboxer charger that could do full discharge/recharge cycles and measure internal resistance - however I found that the internal resistance reading could vary for the same battery from slot to slot in the charger (if there was even a hint of dirt juice, sweat from my hands or a dull contact the resulting resistance had massive differences in readings, at first I was alarmed about how many newish batteries I had were showing up as way past their best until I scotchbrited the terminals - and the discharge/recharge numbers also varied because of this (although not with such a noticeable variation).

Personally I would fully charge your batteries, vape them until cutoff of the mod - then see how many mah they need to recharge which is the only realistic real life comparative capacity figure.

If you aren't doing capacity or internal resistance checks then please ignore me - as I'm not 100% sure of what you mean by 'grading' lol.

 

[MarrtyG-H]

I wouldn't leave any battery's charging overnight just a safety thing for me and it looks like the battery could be a dud if it's still charging after 14 hrs

They charge fine when in charge mode, their internal resistance reads fine etc. Its only when I put them on grading mode that it takes forever. They're Molicel P42A 4200mah cells, I put them on grading again at 10:00 today and they're still only at 2500-3000mah depending on which cell it reads. I've got 3 in there.

 

[MarrtyG-H]

I may be misunderstanding what you mean by 'grading' your batteries - but if you're doing a discharge and recharge cycle to check capacity it is normally the discharge part of the cycle that takes a long time. Discharging them at a very low rate (like 200mah per hour) can take ages with 18650s, and almost a full day with 21700s.

Although slow discharge will give a higher capacity result because there is less battery sag, in real life vaping use you will be discharging them at a much faster rate and low battery cut-off could be 3.2 (or 2.7 with DNA) instead of 2.5V of the charger so the higher capacity results are pretty meaningless. I don't have that charger, but if it can be set to discharge faster, then recharge - the figures will be lower, but more realistic and will still highlight which batteries have higher capacity - and it won't take an entire day to complete a cycle.

Although it is nice to have a charger with lots of features - bear in mind that they are not up to lab standards and different bays will give different results (something as simple as a bit of tarnishing on a contact will make a marked difference to the results. It is useful to have a comparative number for reach battery as you can quickly discover which are tired - but ensure everything is clean before attempting it.

I had a Miboxer charger that could do full discharge/recharge cycles and measure internal resistance - however I found that the internal resistance reading could vary for the same battery from slot to slot in the charger (if there was even a hint of dirt juice, sweat from my hands or a dull contact the resulting resistance had massive differences in readings, at first I was alarmed about how many newish batteries I had were showing up as way past their best until I scotchbrited the terminals - and the discharge/recharge numbers also varied because of this (although not with such a noticeable variation).

Personally I would fully charge your batteries, vape them until cutoff of the mod - then see how many mah they need to recharge which is the only realistic real life comparative capacity figure.

If you aren't doing capacity or internal resistance checks then please ignore me - as I'm not 100% sure of what you mean by 'grading' lol.

Yes, it is a charge, discharge and then recharge cycle to test capacity. I only want to do it because I've been changing to a new cell once the battery needs recharging at 20-25% and upon recharging the battery I get less than 2000mah on the capacity reading. I wanted to run a grading cycle to see how much capacity the cells actually have.