What is supplement charge?
A. Charge between master charge and trickle charge. Your batteries are still not fully charged after first step high current fast charging. Compensation charge can fill the batteries up to their full capacity. It will take too long to fill the batteries up if only using trickle charge. Typical current at this stage is 250 mA for AA or 180 ma for AAA. It takes about 90 minutes before going to trickle charge. The LED is red at this stage.