I only rated it 4 stars because I've only had it for 2 weeks and cannot yet comment on its longevity. It jump started a 710CCA battery and 5.6L V8 Nissan Armada, so it definitely packs a punch. I also charged it to 100% before using it. After jump starting the Armada, I used it to top off the air in all four tires in my 2008 Toyota Camry, and it was very quick and easy. The jump box still had over 80% battery remaining after the jump start and airing up the tires 2 weeks ago. I immediately charged it to 100% after, and, 2 weeks later it's still reading a 100% charge level. Yes, it was disconnected the morning after the charge 2 weeks ago. Time will tell how many uses I get out of it. I'm super impressed for now!