I am using the cleaner in normal mode. Turbo mode runs for a few seconds, then cuts out.
Another day.
Hello, it seems that keeping the cells not used and fully charged increases the internal resistance of the cells.
Because they evolved differently, their self discharge rate was not equal and got unbalanced.
You need to exercise the cells, full discharge, close to 3V, let them rest and recover, keep draining again until 3V, until they cannot recover anymore.
To do this, you can drain the pack externally until 3.0V with a load connected directly on the cells or the whole pack, similar with what I did, like a car lamp bulb or something similar.
Do not worry to trigger any fault since you can reset again. After discharge you can plug the charger.
Doing this charge - discharge cycle you will notice if any cell got weaker and it might trigger the red flashing light lock later.
I am experimenting now with some cells ( taken out of what it was a Ryobi 40V pack) that were completely dead ( not leaked ) and to my surprise, they take and hold a charge and the tested capacity it's actual around 1900mAh.
These cells were in pairs of 2, like the one in the pictures. I will try to test them all to have a conclusion. As you can see they are 0.02V initial voltage..
Pre-charging them from 0 to 2.5 V has to be done in very low, like 100mA max current, that charger does this based on the internal resistance measured and not chemistry.
I know this is not exactly safe but I keep an eye on them to check the temperature while charging, at any warm sign I stop charging. I will report back in couple of day, if nothing happens...
Interesting relevant info about maximum discharge voltage here:
https://lygte-info.dk/info/BatteryLowVoltage%20UK.htmlConclusion from that site is that under 3.0V might not be much energy left anyway, so no need to go further discharged. Below 2.0V is not recommended to go as capacity is affected.
So there is hope your cells will improve after couple of charge to full discharge ( 3.0V) cycles. Try that.