With a 27,800-mAh capacity and a 4,000-amp peak, this Avapow portable jump-starter packs some serious power. It can start any vehicle with a gas engine, or any diesel engine up to 10 liters.

We only noted 51A during the test, but the pack still showed fully charged at the end. This is easily the best-looking device ... unit has a cover on its jump-start socket, but not USBs.

Ability of the Jump Pack to start a weak and dead battery at warmer ... Reserve capacity estimates how long the Jump Pack can be used to power other electrical equipment such as charging ...