Whether you build or maintain buses or heavy equipment that utilize 24-volt starting systems, you’ll want to seriously consider the Maxwell 24-Volt Engine Start Module. It provides up to 1100 CCA* at 24 volts in a single BCI Group 31 enclosure. The ESM takes over the starting function completely – leaving batteries free to power energy-intensive, parasitic loads. Batteries frequently do not have the power needed to start your engine – particularly if it’s been a while since the engine was last started.

Don’t leave starting to batteries. The Engine Start Module from Maxwell Technologies will provide the power to start your bus or heavy equipment consistently, most likely for the life of the vehicle.

Add the Engine Start Module to a 24-volt starting system for reliable starting from -40°F to 149°F (-40°C to +65°C).

Engine Starting
– Bus, school & public transportation
– Heavy equipment: construction, agriculture, off-road, mining, forestry & military

Features and Benefits

  • 900 or 1100 CCA* provides engine start reliability
  • 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
  • Faster cranking
  • Industry standard BCI Group 31 form factor
  • Recharges fully in less than 15 minutes
  • Long-life - limited 4 year non-prorated warranty**
ULTRA 31/900/24V
ULTRA 31/1100/24V
Vehicle Type
Medium – Heavy Duty
Heavy Duty
Diesel Engine Size
4L – 12.5L
10L – 15L
Cold Cranking Amps (CCA)*
Peak Power
45 kW
50 kW
Input Voltage
10V – 32V
10V – 32V
Output Voltage
25V – 27V
26.5V – 28.5V
Operating Temperature
-40°C to +65°C (-40°F to +149°F)
Current Draw
25A (max. during charging), < 10 mA when charged (sleep mode)
Recharge Time
12 minutes
15 minutes
7.7 kg (17 lbs)
8.2 kg (18 lbs)
BCI Group 31
13”L x 6 13/16” W x 9 7/16” H
(330mm L x 173mm W x 240mm H)

* Ultracapacitor CCA is calculated differently than for a battery using a different interval. Consult footnotes section of product datasheet for details.

** Lead acid batteries still power ESM/ECU. Results may vary. Additional terms and conditions, including the limited warranty apply at the time of purchase. See the warranty details for applicable operating and use requirements.