The MidNite battery capacity meter will watch for a set voltage and requires it to stay there for 2 hours the following is the voltage it must see to turn the green light on:
Jumper = On / Off
12 volt battery = 13.65 / 14.25
24 volt battery = 27.30 / 28.50
36 volt battery = 40.95 / 42.75
48 volt battery = 54.60 / 57.00
The most common reason for the red light to stay on is an absorb time that is shorter than 2 hours.