Those little 12V ones are good for small volumes like bike tires (although for a road bike, you need 120 psi) and for topping up/checking pressure on car tires. If you are actually putting in a lot of air, you would be better served to get something with a tank on it. No need to go overboard and get a refigerator-sized tank, just a reservoir so that you're not working directly from the pump.