My university's student electric racing team has to test a large number (250) of lipo cells before using them in our electric car. Our testing methodology will be approximately like this:
- Charge at 1C
- Let cells rest for a specific period.
- Discharge at constant current and measure capacity.
I've heard that some bad cells may charge and discharge to the nominal capacity if they are charged immediately, but do not hold up after time. Is this correct?
I've been unable to find any hard data on the interval between charging and discharging required to differentiate good cells from bad ones -- how long do we need to wait to know if the cell is good?
Sources of empirical data would be especially appreciated.