I have aWagan Power Dome EX 400-Watt Jump Starter with Built-In Air Compressorthat is a permanent tool in one of our family car. That unit's quality was highly questionable. Finally on the third replacement I had a good one. It had the features I wanted: compressor (for kids bikes, balls), inverter, USB power, and jumper. It was a worthy compromise of battery power and features.But I want a second unit, with focus on a battery that can power my electronics longer and jump a car. This model seems to allow longest running of electronics out of all battery-based units with inverter/jumper.When this unit arrive, I expected to charge for 48 hours per instruction. But seems like the unit was already fully charged before shipping out. Within minutes, the charging status showed solid green and battery status reported 100%. That's nice when they can charge it (Amazon warehouse?) before shipping it out.First test powering my more power-hungry laptops (80 watts), LCD monitors, portable fans, etc. I'm happy to report the expected duration is quite accurate. For example, one of my appliance that averages 75 watt runs for about 2 hours and 20 minutes. 100 watt electronics ran for 2 hours.*SIDE NOTE* One of my favorite thing is to power my PS3 console in this marvelous gaming case:GAEMS Halo UNSC Vanguard Personal Gaming Environment (Xbox NOT Included)As for starting a car with dead battery, I had the opportunity to tested just 2 days after receiving it. I had left my car's lights on in the morning, and by start of evening the battery was not strong enough to start the car. After connecting the jumpers, the first two cranks resulted in no go. After waited for 5 minutes, I started the car again and the car started without any hesitation.What this means to me that the rated crank amp of 350CA is not strong enough to jump start most cars with a "dead" battery. (I think AAA guy once told me average cars need 600 - 700 crank amps).  Even my Wagan 400 watt inverter (with 600 crank amps) couldn't get car started on first try many times.  If it cannot start immediately, don't panic! Wait a few minutes!  A car battery is technically dead at 12V, and fully charged at 12.6 - 12.8V. So by letting the powerpack to charge the car battery for 5 - minutes, it frequently is enough to raise the voltage close to 12.6 to start the car.Anyway, it's a good start for me on this battery. But time will tell if the battery can retain charge to be useful for at least two years. Will update here in a few months.