That big 12v battery will outlast any batts you'd hook up to the SB. My 12v can last me a week of bump starting. How you ask? Well for one I always make sure the motors and in the box is clean. The rubber wheel only comes in contact with the flywheel. Also, my engines are quite reliable so a bump or to then the car is up and running.
Trying to live every day like its the last....