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Continental Supplying Maxwell Ultracapacitor Booster Modules to PSA for Second-Generation Start-Stop Systems

Supercapacitor energy storage unit for the E-Booster Click to enlarge.

Continental AG is supplying Maxwell Technologies ultracapacitor-based booster systems to PSA Peugeot Citroën for its second-generation e-HDi Start-Stop Systems. PSA plans to sell around one million vehicles equipped with the new E-Booster micro-hybrid technology e-HDi over the next three years.

The system takes advantage of even the slightest opportunity to turn off the engine, thus noticeably reducing fuel consumption. A vehicle equipped with standard transmission will even shut off its engine when rolling at speeds below 20 km/h (12 mph). Under normal driving conditions, such a system can increase mileage by about 5%. That figure jumps to 15% if a lot of city driving is involved, with CO2 emissions also dropping by 15%.

Power electronics unit. Click to enlarge.

The micro-hybrid e-HDi technology uses a new 2.2 kW starter-generator, a 70% increase over first-generation systems.

A powerful booster module was required to deliver the power surge needed to assure easy diesel engine starts even at below-freezing temperatures. The module needed to get the engine to idling speed quickly so as to make vibrations and engine noises practically unnoticeable in 400 milliseconds—twice as fast as a normal starter motor.

Based on a concept by PSA Peugeot Citroën, Continental designed and built a booster module to meet those requirements, plus guarantee that restarting the engine wouldn’t drain power away from other devices such as the radio, headlights, or windshield wipers. The power electronics in the E-booster control recharging the ultracapacitors during the recuperative phase.

Maxwell Technologies says it has begun production-level deliveries of the BOOSTCAP ultracapacitors to Continental AG. PSA Peugeot Citroën plans to equip about 30% of its diesel automobiles with the new start-stop system by 2012.



Good to see progress here, Maxwell have consistently shown confidence and foresight with productive outcomes in this area.
It would seem that while larger integrated capacitors are more application specific as opposed to a generic 'starter only' approach, there would be weight and cost savings if these 'endlessly rechargeable' capacitors were seen as a part of a larger storage opportunity.

Obviously there is merit in reserving this capacity for starter only.

The market may not be ready for a larger integrated system and the knowledge acquired from this dedicated unit will assist the design of future capacitor banks.


One wonders how easily this system could be extended into e.g. launch-assist. The capacitor would have to be bigger and the electronics would need to be able to operate at a greater duty cycle... what else? The more energy that can be recuperated and re-used, the better it all works.


Wonder what percentage of braking/deceleration energy can be captured with such a small super capacitor bank?

To capture more wasted energy, larger electric drive motors/generators and capacitor banks would be required. It will probably come soon if and when it can be made light and cheap enough.


I guess you could combine several together to get a larger pack. I'd like to see the next generation of hybrids using supercaps and li-ion combo's instead of the NiMH


This system uses a 2.2 kW (roughly 3 HP) starter-generator. Adding 3 HP to the engine output right off the line would make the car feel zippier without burning more fuel, and recuperation would also reduce wear on brakes.

It still doesn't get close to Prius specs, but it wouldn't hurt. On the other hand, it would require several seconds of power storage, not just 400 msec. That means a much more expensive capacitor.


A mini ESStor ESSU would do it.

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