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One of the sources of increased fuel consumption in modern cars is the parasitic loss caused by the drag of having to turn ever larger alternators to provide electrical power to all the assorted accessories and features. The alternator is typically belt driven by the engine and runs continuously, providing juice to charge the battery and drive radios, lights, computers, etc.

For 2008 BMW is introducing what they call Brake Energy Regeneration on the 5-Series. The new system uses a larger than normal battery, and an electronically controlled alternator. The alternator is disengaged from the engine during normal cruise and acceleration and activates during vehicle deceleration. This adds to the engine drag braking, and the car's kinetic energy is effectively transformed into electrical energy which replenishes the battery, which now provides the accessory power.

When the battery level gets too low, the system reverts to normal charging mode. Until BMW introduces some hybrids in the next couple of years this provides a stop gap that gives an extra efficiency boost. WorldCarFans has an animated video that shows the flow of energy around the car in various operational modes.

[Source: WorldCarFans]


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    • 1 Second Ago
  • 10 Comments
      JOHN
      • 3 Years Ago
      Battery type hybrids are poor at saving energy; and, advancements in battery technology are most likely terminally limited. Flywheel technology is here now and power-flow is shock free and as smooth as though from an electric motor; see below. Here-to-fore the problem with flywheels has been complex and inefficient power management to and from the flywheel. This patent eliminates the above friction drive CVT with a IVT and completely solves this problem with maximum possible efficiency (85 -95%). PRESS RELEASE January 3, 2012 Reference: US Patent 7,931,107 B2 VEHICLE KINETIC ENERGY UTILIZATION TRANSMISSION SYSTEM. (KERS) This recent patent enables the reduction of fuel consumption in motor vehicles by the storage of kinetic energy for reuse. This technology incorporates an infinitely variable transmission (IVT) in the form of an eddy current induction device (called a Modulator) coupled to a gear system to conquer the torque flow management problem caused by infinitely varying bi-directional energy flow between a moving vehicle mass and an associated rotating flywheel mass created by the fact that the respective mass velocities move in an inverse acceleration relationship. To illustrate this phenomenon, observe that as kinetic energy passes from the moving vehicle to, and is captured by, the flywheel it is caused to accelerate, however the vehicle is consequently caused to slow; but to function efficiently, the flywheel requires an ever increasing input-speed factor from a source which is ever slowing. This always changing speed dichotomy can only be effectively managed by an infinitely variable transmission, and, other than that offered by the above patent, none have been successful for the subject purpose. The technology reflected in this patent involves very few parts, and is therefore economical to manufacture. It is in addition, long lived, requires little maintenance, and is very durable. Importantly, this system is suitable not only for passenger car use, but also for delivery vans, trucks, and buses. The conservation of kinetic energy through the use of battery energy-storage technology is exceedingly inefficient while such a mechanical approach is well known to be very high in efficiency. As may be realized, existing battery hybrid technology was developed because it was a way around this, now solved, torque-management problem. As these complicated and costly battery-related electric energy arrangements only avoid, and do not solve this problem, the penalty for this has been the great loss of efficiency as compared to a mechanical storage system such as that proposed by the subject patent. Thank you, South Essex Engineering
      • 8 Years Ago
      Actually the new 5 series is around 15% more efficient than the old ones. The regenerative braking is not the only change - they also introduced direc injection for the gas engines, electric steering instead of hydraulic, active aerodynamic tweaks (such as flaps behind the radiator grille!), coolant pumps that only run when needed...

      All that is standard, in every model across the line. Not in a fancy "green" model. The 520d gets 40 mpg now.
      • 8 Years Ago
      That was a very annoying video. First half made me dizzy and contained very little info. Did the video mean to suggest that at a stop light, the car turns off the engine and restarts it when you press the gas?
      • 8 Years Ago
      If it's being introduced on the 5-series, why does the video show a 3-series?
      trnichols17
      • 2 Years Ago
      Not being an auto engineer all I wanted to do was find out how the system works.The video needed someone to explain what was happening.Johns explaination was wonderful,if you knew what he was saying.I think this technology needs a explanation in laymans language!
      • 8 Years Ago
      Worse. Video. Ever.
      • 8 Years Ago
      I'm kind of confused. Is red energy "bad" and green energy "good" in this video?

      I understand that theoretically the load of the alternator on a car is a drain on energy, but how much in terms of real miles-per-gallon will be gained by this system? Seems overly-complex to me and as you know as a machine's complexity increases its potential for failure does too.
      JOHN
      • 3 Years Ago
      Battery type hybrids are poor at saving energy; and, advancements in battery technology are most likely terminally limited. Flywheel technology is here now and power-flow is shock free and as smooth as though from an electric motor; see below. Here-to-fore the problem with flywheels has been complex and inefficient power management to and from the flywheel. This patent eliminates the above friction drive CVT with a IVT and completely solves this problem with maximum possible efficiency (85 -95%). PRESS RELEASE January 3, 2012 Reference: US Patent 7,931,107 B2 VEHICLE KINETIC ENERGY UTILIZATION TRANSMISSION SYSTEM. (KERS) This recent patent enables the reduction of fuel consumption in motor vehicles by the storage of kinetic energy for reuse. This technology incorporates an infinitely variable transmission (IVT) in the form of an eddy current induction device (called a Modulator) coupled to a gear system to conquer the torque flow management problem caused by infinitely varying bi-directional energy flow between a moving vehicle mass and an associated rotating flywheel mass created by the fact that the respective mass velocities move in an inverse acceleration relationship. To illustrate this phenomenon, observe that as kinetic energy passes from the moving vehicle to, and is captured by, the flywheel it is caused to accelerate, however the vehicle is consequently caused to slow; but to function efficiently, the flywheel requires an ever increasing input-speed factor from a source which is ever slowing. This always changing speed dichotomy can only be effectively managed by an infinitely variable transmission, and, other than that offered by the above patent, none have been successful for the subject purpose. The technology reflected in this patent involves very few parts, and is therefore economical to manufacture. It is in addition, long lived, requires little maintenance, and is very durable. Importantly, this system is suitable not only for passenger car use, but also for delivery vans, trucks, and buses. The conservation of kinetic energy through the use of battery energy-storage technology is exceedingly inefficient while such a mechanical approach is well known to be very high in efficiency. As may be realized, existing battery hybrid technology was developed because it was a way around this, now solved, torque-management problem. As these complicated and costly battery-related electric energy arrangements only avoid, and do not solve this problem, the penalty for this has been the great loss of efficiency as compared to a mechanical storage system such as that proposed by the subject patent. Thank you, South Essex Engineering
      • 6 Years Ago
      this is nice video..
      also good effort to reduce the power consumption..& increase the efficiency...
      • 8 Years Ago
      It's BMWs version of a "belt alternator starter", but unlike the GM 36 volt version, runs on a standard large 12 volt battery.
      Not gonna be much benefit, but at least they are trying.