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?
Unfortunately, welcome to marketing tricks of the Chinese vendor (others too for sure).
Although it probably states such in very tiny print in the documentation.
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.