pharding

What is it and how much does it cost?

UUronL

As far as I know, it's standard on the 2008 model. I think there are details on the BMW's various sites.

aybeesea

Otherwise spent energy from braking is intelligently used to charge the battery/power the car electrics. The alternator is used less frequently for this function, putting less load on the engine, thereby improving fuel economy and emissions.

ABC

hinckley

Is it included in all LCI models (starting with March production) or is there a delayed introduction as stated in another thread?

aybeesea

Not seen anything about a delay.

It would be catastrophic to BMWs reputation if such a central plank to their LCI marketing were unavailable at SOP.

Can you imagine the shouts for compensation etc...

ABC

Ray Hull

It's what all Priuses do: energy generated during braking is used to generate electricity, which charges batteries, which feed electric motors at X wheels to assist in takeoff and around town. Conversions are very expensive because the chassis has to modified. Also, batteries are all different. Also different brands use different driveline designs (different-size motors at more or fewer wheels).

Right now, at work, (NYSERDA) we are working on Plug-In Hybrids. They have larger LiIon battery capacity and can be supplementally charged on household current over night, thus providing more electric miles (about 100 mpg and generally peppier starts). Our black Pirus was finally delivered last week, after making the rounds to the White House etc. http://www.a123systems.com/html/news...022607_pr.html Haven't driven it yet, but I did do an event with the Governor in it.

Conversion to Plug-In hybrid status cost around $45,000, but is coming down rapidly as major maufacturers are investing in the technology. Check out our contractor's website A123systems.com .

Have not seen specific BMW info on it; to date, they have been working on hydrogen powered 7s.
Ray Hull

aybeesea

I believe this is a technique common to many hybrids.

BMW is using it to improve fuel economy and lower emissions.

ABC

timewa

It's standard on all E60 LCIs except for the 520d, who should get it in September with the new 177hp engine.

This is how it works as I understood it:
With "brake energy regeneration", the car is able to use a part of the brake energy to charge a special capacitor. That capacitor electrically supplies parts that were previously mechanically connected to the crank shaft like in traditional cars like the water pump.

In this way energy is saved that would otherwise be dissipated in your brakes. And, by controlling the water pump electronically with a DC motor, you are no longer engine RPM dependant, and you have much greater control over the flow. This makes the entire system more efficient, even if you take the inefficiency of the alternator into account.

You may wonder why they use a special capacitor: I think this is done because with the standard lead acid battery (which is still present) you're limited when it comes to storing a lot of energy in a short time (braking period only). It's a relatively light capacitor compared to Hybrid cars (e.g. the Prius' NiMH packs) and I think it could even be used to recharge the traditional battery (not sure if they do that though).

I believe that the alternator can also be decoupled from the crank shaft, just like the compressor of your A/C. The E60 LCI decouples it when you want to accelerate or if enough energy is present in the capacitor. In this way, a substantial amount of energy is saved (maybe the car can even accelerate faster!)

I think this is one of the reasons why the new E60 has improved so much on fuel consumption. I have read a German test where they actually saw an improvement of ~10% with the LCI 530d versus an "old" 530d that was tested earlier. BMW claims up to 20% depending on model, caused by Brake Energy Regeneration + newer generation high pressure direct injection + some small things.

Great development, credits for BMW. I hope other OEMs will follow as this is really bringing us something, without making the car significantly heavier.
I believe that technically it is very well possible to reduce fuel consumption even much further, if only the automotive industry would not be so extremely conservative... fortunately the first steps are now being taken.

Please correct my story above if anything's wrong, this is how I understood it from reading bits & pieces here and there.

P.S. I'm very sorry that my car will not have BER: I ordered a 520d LCI, will get it end of May... Hopefully my next E60 has it. On the other hand, the 520d is already very efficient with its 5.9l/100km (on paper at least)

Ray Hull

If this is all this system does, it is truly STUPID and another example of BMW over-engineering in order to APPEAR to be doing something green.

I have no idea what this setup costs, but anything over $20 is way too much; its beneifts can be measured in less than TENTHS of a PERCENT of overall efficiency. I checked with our engineers at work (see my post above) and relayed these tentative descrpitions to them. One, a German, who drives both BMW and Porsche was incredulous at this proposal. All of us dismissed this as a PR or advertising ploy to sound like they are becoming efficient. (Right along with that dopey hydrogen-powered 7 series. Talk about no-cost concern engineering!)

As for me? Well, I still have the US Gas Guzzler Tax receipts for all my 5 sport series cars since 1987....
Ray

aybeesea

a contribution of about 3 percent to overall fuel efficiency.

Not that stupid where fuel costs $140 per tankful, especially when contributing to a 15% overall fuel saving on some models between LCI and legacy.

As for the "setup cost", the US has the cheapest e60 prices anywhere AFAIK.

ABC