Measurements
With a 0 volt battery the charger is charging with about 2mA (This will reset a protection) while reporting standby mode.
The charger wakes at about 0.55 volt and starts testing with a low current (6mA).
Above 0.9 volt the charger will start charing with 0.5A.
Between 2.1 volt and 2.5 volt it will fail a battery after initial test.
Above 2.3 volt the charger will charge with 0.3A
The voltmeter is within about +/-0.1 volt when in range.
Power cycling and reinsertion of the battery will restart charging.
The charger remember LiIon/LiFePO4 selection, even when powered off.
LiIon batteries
When power is disconnected it discharges with 6mA from a LiIon battery
Above 3.1 volt the charger will switch to full LiIon charge current.
LiIon voltmeter can show 3.2 volt as lower value and 4.2 volt as maximum value.
If the voltage drops to 4.15, the charge will restart, but the display will still show "FULL".
To charger these batteries the button must be pressed until the display shows "Li-ion" and "Ion", before the battery is put into the charger.