my avapow 6000a wouldn't start my 3500 cummins at 8v or my lawn mower at (low volts not sure what) hooked up the gooloo gt4000 to the cummins and it started up like it had fresh batteries. used 20% charge. if it starts up the lawn mower too that would be nice. cummins alone it was worth it. good jump and doesn't seem to have the issues many of these do where the voltage needs to be close to 12v to jump it