For starting heavy duty diesel engines.

Ultracapacitor technology provides high amounts of burst power that is ideally suited for cranking and starting large diesel engines. Additionally, ultracapacitors have a long service life and perform well at cold temperatures. In comparison, lead-acid battery technology has not been able to keep up with the growing energy demands of the trucking industry, with particular difficulty in starting the engine after periods of powering energy-hungry accessories such as sleeper loads and lift-gates.

In December 2011, Maxwell recognized the need for a source of power dedicated to starting diesel truck engines and introduced the ultracapacitor-based Engine Start Module (ESM). Success soon followed. Presently, there are over 2,000 ESMs installed in medium and heavy duty trucks in North America, eliminating jump-starts and reducing idling, resulting in lower total cost of operation. Trucks are on the road and on schedule.


  • Ultra 31/900/24V (For heavy duty vehicles and equipment with maximum engine size 12.5 liters)
  • Ultra 31/1100/24V (For heavy duty vehicles and equipment with maximum engine size 15.0 liters)


  • No lead. No acid.
  • Improves overall system power performance
  • Shock & vibration resistant
  • Built-in overcharge protection
  • Low total cost of ownership
  • Cold weather reliability down to -40 °F (-40 °C)
  • Faster cranking
  • Industry standard BCI Group 31 form factor
  • Recharges fully in less than 15 minutes (Initial charge is 30 minutes or less)
  • Provides 900-1100 CCA
  • 4-year non pro-rated warranty
  • Assembled in the USA