BarryG
New member
- Joined
- Feb 15, 2019
- Messages
- 18
Hi,
Sorry if this is a much-asked question, but I can't find a definitive answer:
Like most of you guys on here, I guess, I am processing 18650 cells recovered from laptop batteries (and also some from e-Bike batteries). After checking for obvious visible faults, near-zero volt cells, etc, I start the processing by charging the cells. I label each cell with the "fully-charged" voltage (which, by the way, seems to vary quite a bit - I am using a "home-grown" set-up for charging multiple cells at the same time using TP4056's). I then letthem sit for 3 or 4 weeks and then measure thevoltage of each cellagain.
SO - Here's my question......obviously if the cell voltage is still the same as what it was when "fully charged", then this particular cell 'passes' this test. However, if the cell voltage is far lower than the "fully charged" voltage, then I discard that cell. BUT.....how close do the two measurements have to be, in order for it to be classed as a "good" cell?
I'd be very interested in what others use as a "rule-of-thumb" to determine if a cell discharges too much - and over what time period. For example, I am currently measuring roughly 4 weeks after charging and discard cells if they measuremore than 200 millivolts less than their "fully charged" value. So for example a cell that was originally measured as being 4.10v and is then measured as being only 4.00v after 4 weeks, would be within my limits currently, and would be kept.
Should I be more aggressive with my discarding and only keep cells that have lost less than, say,20 mV over 4 weeks?
Thanks for any and all responses. If I get a lot of answers, I'm happy to compile a bar-chart showing what 'the community' use as their test thresholds.....and report back......
Sorry if this is a much-asked question, but I can't find a definitive answer:
Like most of you guys on here, I guess, I am processing 18650 cells recovered from laptop batteries (and also some from e-Bike batteries). After checking for obvious visible faults, near-zero volt cells, etc, I start the processing by charging the cells. I label each cell with the "fully-charged" voltage (which, by the way, seems to vary quite a bit - I am using a "home-grown" set-up for charging multiple cells at the same time using TP4056's). I then letthem sit for 3 or 4 weeks and then measure thevoltage of each cellagain.
SO - Here's my question......obviously if the cell voltage is still the same as what it was when "fully charged", then this particular cell 'passes' this test. However, if the cell voltage is far lower than the "fully charged" voltage, then I discard that cell. BUT.....how close do the two measurements have to be, in order for it to be classed as a "good" cell?
I'd be very interested in what others use as a "rule-of-thumb" to determine if a cell discharges too much - and over what time period. For example, I am currently measuring roughly 4 weeks after charging and discard cells if they measuremore than 200 millivolts less than their "fully charged" value. So for example a cell that was originally measured as being 4.10v and is then measured as being only 4.00v after 4 weeks, would be within my limits currently, and would be kept.
Should I be more aggressive with my discarding and only keep cells that have lost less than, say,20 mV over 4 weeks?
Thanks for any and all responses. If I get a lot of answers, I'm happy to compile a bar-chart showing what 'the community' use as their test thresholds.....and report back......