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The CRMT range extender


The CRMT (Research Center for Thermal Machines) has developed a range extender which primary purpose is to extend the range of electric vehicles and extend their use. Electric traction can thus draw the energy needed to move the vehicle from the battery and / or motor generator. The CRMT offers a complete solution including:

  • The range extender:  Generator + thermal engine
  • The controller: range extender controller + complete vehicle management
Energy management of CRMT Range Extender

The CRMT controller manages power based on requests from the driver, the remaining battery power and the road profile. Energy management strategy implemented by CRMT is divided into three modes depending on the SOC (State of Charge: Remaining battery power) following two road profiles: a profile of urban road and a binding road profile (mountain …). In case the battery is charged above 75%, the motor generator will provide power only extra energy to the battery, for example on a steep road. In contrast, in the nominal mode, the motor generator provides the average energy consumption and the battery provides energy in transitional phases. When the battery passes the threshold of 25% state of charge, the motor generator produces its maximum power and the surplus is used to recharge the battery on the less demanding parts of the road.

Battery management of the CRMT range extender

CRMT management strategy has several benefits beyond increasing the range of the vehicle:

  • The battery capacity can be reduced as the maximum power can be obtained by adding the energy provided by the range extender. The cost of the battery can thus be reduced,
  • The battery is operating at maximum in its ​​”comfort” zone between 20% and 80% in order have a longer life,
  • The engine works on points of maximum efficiency
  • The flexibility of power management can be adapted to each road profile without degrading the performance of the vehicle

The driver with the push of a button can switch from hybrid mode to electric mode and vice versa, to adapt the fuel and electricity consumption to its needs. The electric mode is the best compromise for a short ride.

Range extender modes management

The CRMT Range extender has passed the NEDC homologation tests for Euro6 at UTAC homologation center:




Euro6 Norm

68 mg/km

37.5 mg/km

1000 mg/km

Range Extender

35.16 mg/km

12.45 mg/km

404.6 mg/km

Range Extender compared to Euro 6 norm

52% of max allowed

33% of max allowed

40% of max allowed

CRMT Range Extender technical data

  • Displacement: 688 cc
  • Bi-cylinder in V: 90°
  • Max power: 11.5 kW electric @ 3000 rpm continuously
  • Fuel: gasoline (CNG variant to come)
  • Injection system: indirect multi-point phased injection
  • After-treatment: Closed loop lambda control, 1 sensor per cylinder, 3 way catalyst.
  • Mass: 45 kg
Source: CRMT
Romain’s opinion:

The Range Extender for urban vehicles is a particularly advantageous solution to provide sufficient autonomy to the vehicle while containing battery cost. Do you think this type of technology will emerge on mass production vehicle (Smart, Twingo, Up …)?

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