This battery charger, according to the instructions, should charge a low battery 40 amps and at the same time show 40 amps on the ammeter on the front of the charger. My first attempt at charging 40 amps just shows 10 amps on the gauge. With the 200 amp switch on, the gauge shows that it's charging 20 amps. This should be over in the "Start" side of the gauge.