jm1 said:
DCkiwi said:
I'd also like to know with what hardware you are [pre-]charging them .. better not be an Opus ... *ugh* ... (they pulse charge at INSANE high current -- do NOT use as chargers!).
So are you stating that the Opus would damage or kill the Sony cell but not degrade the LG's and Samsungs for example?
I have a few different hobby chargers and I can set the voltage and amps to the exact level I want. I also have an Opus farm so I use those to charge when I have more cells then places to charge them.
An Opus 'charger' may damage any cell ... will it? not entirely sure.
But
I AM sure that an Opus can't be turned right down to 100mA like a hobby charger. (which I then split four ways in the 6s4p yoke)
I pre/charge so slow and so many cells .... it works out to be roughly an 8-10 to 1 ratio of charging slots I have to have, to testing slots. things got much easier once I added a 6s12p yoke to my 6s4p ones. (pictures coming today in another thread, will link from here). there is simply no way my Opus's could come close to coping with volume of charge I do.
and yeah, it would totally WRECK all the <0.5V recovered cells. they would all end up testing great once, then rapidly losing all capacity. sound familiar?
jm1 said:
BlueSwordM said:
@jm1, at what voltage are you recovering the cells, and at what current level?
I don't recover any cells that start off lower then 2V, if I open a pack and its <2V I put them right into the recycling bin. I just took 100's of green Sonys that tested above 2000 to the recyclers and I no longer process them since the pattern is the same. I have enough of the better more stable name brand cells that I don't have to waste the time with the questionable ones.
If people think these work then I will have a bunch of green sony packs (not processed) that I will sell for barely more than the price of shipping.
I would have to add: I see in another thread you use very low mA charge rates off less than 500 mA. Once my cells are into the standard voltage range as specified by the manufacturer, I charge and discharge at nothing less than 1A because thats how I intend to use my packs in the real world so if they fail at 1A they are not suitable for my project.
anything under 3.3V is pretty damaged, IMHO. I dont see ANYTHING special about your 2V cutoff point.
this damage can be remedied. it needs a SLOW precharge, VERY LOW mA charge rates. 20-50mA per cell is lots. and let them 'breathe' after a few hours too. give them an hour or three break before resuming slow charge. you are rebuilding the internal chemistry at this stage, and it simply cant be rushed (AFAIK).
I understand your desire to test them at full speed. However,
recovering cells from this low a voltage is going to take a full cycle (or three!) to settle back into productive life. I used to do same as you ... and now regret killing and disposing of so many 'heaters' or 'failures' as I thought. Nowadays I still get failures, but not for this reason.
Your method of putting these 'high maintenance' cells aside until you run out of easier cells to process is a winner, I reckon.