Batteries - When to discard

OK so I found a box of old cells ranging in size from 10440 to 26650..... Probably about 40 cells all up.

i thought I would discharge each cell with a hobby charger down to 3.0v then charge up to see the capacity.

i always thought that when the cell gets to 70% or less of its stated mah that it was close to dead.

is this the case?

These cells had not been cycled for over a year......

one 26650 cell said 4000 mah ... The first Cycled it got to only 661mah.... Pretty bad I thought...

so so I cycled it again and to my surprise it is still charging up at over 1000mah ? Weird ?

should I cycle all these cells a few times to see what they get up to?

Any battery experts out there?

stoli67

Hello Stoli67,

I recycle Li-Ion cells when they drop below 80% of their initial discharge capacity. They still have some life left, but I feel that the change in electrolyte chemistry effects the safety of the cell and I would rather move on than continue to play with it.

Tom

Can you tell by max charged voltage? All I have is voltage meter.

Even some of the cells with quite low charge capacities still seem to have reasonable voltage 4.17 to 4.19 ...... I just dont think they supply it for long

Hello recDNA,

The second part of the criteria is resting voltage. If the cell has around 80% (or more) of its original discharge capacity you then let the cell rest overnight and then measure its voltage. If the voltage is over 4.0 volts I continue to use the cell. If the voltage drops to under 4.0 volts the cell goes to the recycle bin.

Tom

Thanks Tom! I have 5 year old aw that charge to 4.15v

So the consensus is two criteria...

1, the cell should have a capacity of over 70% of its stated mah.

2. The cell should maintain over 4.0 volts overnight after a charge.

stoli67

Where do you discard batteries?

Battery shops like Battery world etc accept cells to dispose of properly

Hello Stoli67,

stoli67 said:

So the consensus is two criteria...

1, the cell should have a capacity of over 70% of its stated mah.

2. The cell should maintain over 4.0 volts overnight after a charge.

stoli67

Click to expand...

Actually I am picky and conservative so I go for 80%.

If a cell drops below 80% of its initial discharge capacity and/or drops below 4.00 volts overnight, I recycle it.

Tom