250mA charge -> 250mA dischargehey @Oberfail @Wolf @floydR I just bought an used Liitokala Lii 500 from a guy. I want to ask what current rate should I use to test my 18650s in Normal testing mode? I used 700mA but they are getting pretty hot and the charger is also getting very hot, and after finishing discharging they arent charging up to 4.20 not even over 4.00v two of them got to 3.56v & 3.45v and the IR rating is changing every time. Am I doing something wrong or this charger is faulty?
Edit - The IR im getting from these cells are 27,43,52 and the cells are from 1680 to 2869 and one NCR18650A got 3045 but the cell is rated at 3000mAh.
500mA charge -> 250mA discharge
750mA charge -> 500mA discharge
1000mA charge -> 500mA discharge
The LiitoKala Lii-500 charges at set current till 1.5/4.2v and stops to charge, once the current going into the cell is less than 50mA. This results in the cells not having the full 4.20v when you take them out the charger. The lower the voltage after you take them out, the lower the capacity in general aswell. But it can also be, that the cell didnt sat in the charger correctly.
Personally, i go for 750mA charge if its cold and the cells are good, if its warm or the cells are just of average used quality, i go for 500mA charge.
Also go for Normal Test and not Fast Test.
You can ignore the mR value the charger gives you. Its highly inaccurate which has been proven many times. All consumer grade chargers have a unprecise mR meter.
All i did was to test them once with the LiitoKala-500 to know their capacity and let them sit 2 weeks on a full charge. Then I took out 2 cells that dropped their voltage below 4.1v. Now 448 of 512 cells sit in a 14s32p configuration in our garden, being discharged with a 20w bulb for 7 days (168hours) to test the capacity. After that i will charge the whole pack up to 4.2v again to test if sustains the high voltage. If it does, i'll apply my lower voltage limits to it, put the pack into a corner and let it stay there for months being connected to our DIY garden shed 12v grid with solar panels to test it trough the winter long-term.