The Maxwell Technologies Engine Start Module (ESM) Ultra 31/900 assumes the starting responsibility for the truck and effectively eliminates cranking problems that come from weak or discharged batteries. The ESM ULTRA 31/900 delivers the quick-burst power trucks need to crank their engines in extreme cold, down to -40 degrees F. The 31/900 is lightweight (16 lbs.) and allows extensive use of lift-gates and buckets while the engine is off without fear of the truck not starting. The ESM ULTRA 31/900 is a no-acid, lead-free energy storage solution that weighs less than 1/4 of the Group 31 lead-acid battery it replaces. It stays fully charged even when the truck’s lead-acid battery is as low as 9.5V.