So I've tried a computer power supply and a car battery and the power is not the issue. When I set the charger to 6 amps it will only charge at 4 to 4.2 amps. Why is this happening? Has anybody else had this problem?
Nope- it's not broken.
This is normal operation for this charger.
If you need more amps you need a bigger charger.
I have the AC6 and an ECO 6 (The Accuel claims it's a 6 amp, the ECO (HK) claims it's a 5 amp) the most either one will do is about 4.5 amps. No way to "fix" it.