Battery/power issues

[Daymak duds]

Just bought a 2017 72v emmo monster, 155kms on it , batteries a yr old, charged it and red light didnt go green for full charge. led displays full bars and 74.5 volts . I drive 4 km s and its flashing no power. I tested batteries they re good, I the series and batteries read 74 .5 In total ,6x12 batteries. Charger reading 1. 45 output so half what it should be. I added extra battery simply for charging purposes as I have a 84v charger and red light still didn't go off

 

[indianajo]

the proper forum for this is maintenance & repairs.
Used batteries are often a problem. I won't buy them.
Lead acid batteries sulphate up pretty easily when not used weekly. Bikes don't get used much in the winter. I suggest you load test the batteries. Build a 15 ohm >500 watt resistor stack and see if the batteries will produce 5 amps. I use 5 ohm 225 watt resistors from apexsurplus soldered with 12 ga wire. If disassembly is possible, you could test batteries individually with 2.5 ohm >75 watt resistors. This could be a headlight or something.
An individual 12 v lead acid battery should produce about 13.5 v charged up, and should be charged individually with 14.4 v. If only one battery is low voltage after charging, maybe you could replace just that one with a sealed battery from newark or digikey.

 

[Off road all day]

Love your pic daymak, she's cute
As far as batteries go of any type, especially lith-ion, leave them on the charger! sometimes drained it will take up to a day for the light to come on
The battery is taking a trickle charge at this time until it is ready to take a full charge, then the light comes on.