Going Eco Pro - 2015 BMW M235i Convertible Long-Term Road Test

Edmunds.comEdmunds.com Member, Administrator, Moderator Posts: 10,316
edited November 2015 in BMW
imageGoing Eco Pro - 2015 BMW M235i Convertible Long-Term Road Test

Edmunds.com explores the Eco Pro drive mode setting in its long-term 2015 BMW M235i.

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  • daryleasondaryleason Member Posts: 501
    So the increased fuel economy, I get that. But what, exactly is the benefit of regenerative braking for a fossil fuel powered vehicle? So what if the brakes can recharge the 12 volt battery that's getting a constant feed of electricity from the alternator? Is it possible that BMW has some left-over programming from a hybrid setup? Or maybe they intend to offer a hybrid option on the 2 Series?
  • tsdriver27tsdriver27 Member Posts: 24
    The brakes do not charge the alternator directly. The alternator is activated to charge the battery during vehicle coasting or deceleration. This feature is NOT specific to eco-pro mode, it occurs in all modes. It just shows a power/charge gauge on this model when eco-pro mode is selected.
  • bnovidabnovida Member Posts: 12
    edited November 2015
    There is a BMW 225xe which is a PHEV in Europe.
  • daryleasondaryleason Member Posts: 501
    tsdriver27 said:

    The brakes do not charge the alternator directly. The alternator is activated to charge the battery during vehicle coasting or deceleration. This feature is NOT specific to eco-pro mode, it occurs in all modes. It just shows a power/charge gauge on this model when eco-pro mode is selected.

    @tsdriver 27 , I wasn't thinking that the brakes would charge the alternator. I just think that the regenerative brake feature on a solely gas or diesel powered vehicle is useless. The parasitic loss of the alternator under load while charging the battery can't be that great, compared to the offset cost of the additional weight for regenerative brake charging. As for the alternator being "activated" considering that a vehicle pulls ALL current through the battery, it'll continuously be in a charge/discharge state.
  • allthingshondaallthingshonda Member Posts: 878
    BMW loves computer controlled parts so their alternator may be capable of "turning off" when not needed unlike traditional alternators and use regenerative braking to keep the battery charged instead. They were one of the first manufacturers to use electronic water pumps and electrically heated thermostats, parts that traditionally are mechanical have no connection to the computer.

    Honda's trick to eek out a few more MPG's is a lot more simple. I've notice that they are moving all of their cars to automatic climate control systems, the new Civic has it standard on all models. Honda programs it to run in recirculate and lowest possible fan speed in most conditions when it's on full automatic. In my Acura the only time it turns off recirculate is at night after the car has reached set temperature or mild temperatures and cloudy conditions. This allows the compressor to cycle off more frequently reducing load on the engine. I notice if I override the system and manually select fresh air the compressor runs constantly without cycling off.
  • 5vzfe5vzfe Member Posts: 161
    daryleason said:

    tsdriver27 said:

    The brakes do not charge the alternator directly. The alternator is activated to charge the battery during vehicle coasting or deceleration. This feature is NOT specific to eco-pro mode, it occurs in all modes. It just shows a power/charge gauge on this model when eco-pro mode is selected.

    @tsdriver 27 , I wasn't thinking that the brakes would charge the alternator. I just think that the regenerative brake feature on a solely gas or diesel powered vehicle is useless. The parasitic loss of the alternator under load while charging the battery can't be that great, compared to the offset cost of the additional weight for regenerative brake charging. As for the alternator being "activated" considering that a vehicle pulls ALL current through the battery, it'll continuously be in a charge/discharge state.
    Mazda offers something similar, called i-Eloop, that supposedly helps to improve gas mileage by briefly powering certain functions like the AC with energy gained through regenerative braking. Models with it equipped are rated with higher epa estimates, but I haven't personally driven any new Mazdas so it's all marketing fluff for me at this point.
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