Serenco Mega Boost MB510

Punching out 510 cold cranking amps, this power pack spun our test car's engine significantly quicker than any other product in the group. But then this is a serious piece of kit, really aimed at professional users and large-engined vehicles. Apart from a solitary cigarette lighter socket, all other features are safety related. A key-operated isolator provides arcing protection and a buzzer prevents wrong connection. Very pricey in this company.