Bought this to try hoping it would be a cheap emergency jump box for my small car. I opened the box and my first impression was that the unit was way too small to perform as advertised. I fully charged it and decided to go test it out in case I was wrong. Short story: I wasn't wrong. All tests were done from a fully charged state. First test: 1.2L diesel 3 cylinder engine (small tractor engine). Unit failed to provide enough power to turn engine over 1 full revolution. Unit was low on battery power after only a single attempt (25% or less remaining). Test %232: 4.0L gas V6 engine (1990s era Ford Explorer). Unit had enough power and reserve to allow the engine to complete about 3 revolutions, but not enough power to allow the vehicle to start. Unit stopped functioning (low power needing full recharge) and the cables between the battery unit and clamps were too hot to safely touch (wire used is too thin). Test %233: 2.3L gas 4 cylinder (1970s era small pickup). Unit had enough power to allow the engine to turn several revolutions, but not sufficient voltage to allow ignition (system voltage was just over 10 volts). After only a few seconds, the unit shut itself off (low power needing recharge). Test %234: 1.4L gas 4 cylinder (Chevrolet Spark). This should have been the easiest engine to start. Unit failed to provide sufficient power to complete the starting cycle while maintaining correct voltage levels to allow the car to start. All 4 tests pieces were able to be started with another brand's similar style jump pack successfully despite the other pack being rated significantly lower (1000 amp peak vs. this unit's advertised 1500 amp peak draw). I would return this unit, but I waited too long and I'm outside of the return window, so I guess I'm just stuck with it. Maybe I can find some use for it jump starting my riding mower, because that's about all that it seems to be capable of.