Image to right show if charger has open ground fault. The red arrow on left show proper grounding. Red arrow on right show open ground that needs to be fixed. Why Adjustable? Set to 16 amps @ 240 volts, 24 amps @ 240 volts, or 32 amp @ 240 volt. The more time you have to charge your car, it's best set to the lowest setting. Example: if I have the entire night and can leave the car on charge for 6 hours, set to 16 amps. If traveling and using the optional Reverse14-50R box below, set to 16 amps. If stopping at home for lunch and only have an hour before I leave again, set to 32 amps. If I only have about 4 hours to charge my car, set to 24 amps. 1. 32 Amp @ 240 volt is super fast charging when you need fast charging. 2. The longer and slower you take to charge your batteries, the longer the batteries will last in both years as well as per charge. (Changing all the car batteries is expensive and this charger will maximize their lifespan!) Your batteries will last longer in both years before they will no longer hold a charge was well as each charge is more complete (each individual charge last longer.) 3. Take with you on the go. See below. Set to 16 amp and use the optional converter box below.