Ah, I have a jump box that is heavy duty for tow truck driver service. The small packs may be able to lay down some amps to turn over a car but check its specs to make sure it can run the ~12V for a decent time.. certain battery design is geared towards quick discharge vs steady consumption. Maybe better would be a simple UPS battery... online for cheap.. I use them for my kid's powerwheels, commonly used for wheelchairs, too.