BMW 5-series gets regenerative braking, but not why you think
by Dan Roth on Jan 13th 2007 at 11:57AM 
It would seem that BMW reads Autoblog. How else would you explain them, at least partially, answering our question about how a conventional automobile would utilize some of the hybrid demon-tweaks?
For the first time ever, BMW has equipped a non-hybrid car with a regenerative braking system. There's a new battery that uses fiberglass mats between the plates to keep the electrolytes put, and a corresponding "intelligent" alternator. The battery technology, known as Absorbtive Glass Mat construction is capable of being charged very quickly without boiling; and they stand up far better to the deep cycling that would be abusive to a traditional lead-acid battery. The ability to receive and deliver high amperages reliably makes the AGM batteries ideal for coupling with the rest of BMWs Efficient Dynamics program. The battery can be fully charged during braking, which reduces the load on the engine by making the alternator work less. The program's intent is to reduce weight and fuel consumption, ultimately keeping CO2 emissions down. BMWs efforts result in a vehicle that has the low-rolling-resistance tires, electrically operated AC and power steering and stop/start systems of a hybrid, without the electric motors.
[Source: Fifth Gear via Jalopnik]
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Reader Comments (Page 1 of 2)
olddavid 1:25PM (1/13/2007)
This is another question answered by BMW that no one is asking. Like I-Drive.
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sfast 1:25PM (1/13/2007)
It was about time for it. A car doesn't need to be a hybrid to be efficent.
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cmp 3:25PM (1/13/2007)
Hi,
Great blog and great idea by BMW.
My question might not have anything to do with anything though :)
I just want to use that pic as a wallpaper. Where could I find a hi-rez version?
thnks.
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Fairfield 3:31PM (1/13/2007)
Neat stuff - looks almost like a disassembled engine though. . .
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whoa 3:35PM (1/13/2007)
Yeah, cool - looks like it won't need spark plugs either - is it a diesel? I guess that's why it's filed under green. . .
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BMW M5 videos 4:01PM (1/13/2007)
From the picture first I thought it was M5 performance upgrade for the regular 5 series, but anyway this seems to be a great idea.
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Bob_Ericson 4:28PM (1/13/2007)
Ya'll gotta learn some English, kids...
The title should read:
"BMW 5-series gets regenerative braking, but not how you think"
Oh yeah, hire a proofreader.
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fyrewerx 5:29PM (1/13/2007)
AGM batteries by DELCO really sucked in the C5 Corvettes. Cells failed all the time. Conventional batteries were used in the 2004 models, and the C6 generation. Why would you want them in a hybrid???
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Trenton Lipscomb 5:47PM (1/13/2007)
the low-rolling-resistance tires
I don't know about you, but I want HIGH resistance tires on my Bimmer. Resistance is another word for friction, and friction is what keeps your car going in the direction you want.
While they're at it, salvage some 14" 185-series wheels of a 95 Civic and pick up a few more MPG?
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Michael Karesh 5:49PM (1/13/2007)
Maybe AGM technology has improved in the past decade? The post says they went that route to enable ultra-fast recharges.
BMW had another hybrid idea that was even niftier: using exhausts heat to generate steam to power a small steam engine hitched to the engine. Good for about ten horsepower, if memory serves. Which may not sound like much, but it's a significant chunk of what a car needs to just cruise down the road.
Great photo of the M5 engine bits, even if it is a bit OT.
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Goodday 5:50PM (1/13/2007)
So, how does an 'intelligent' alternator know anything about what's going on with the brakes.
A lot of 'useless' info about the battery and no info on how the system WORKS. Did I miss something?
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chuck 6:20PM (1/13/2007)
is this a similar battery to the mid 90's miata one.....i recall that being a matt battery as well
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Wiki 6:22PM (1/13/2007)
Hybrid != efficient
Battery will never provide so much power as bensine/diesel does!
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KazO 7:12PM (1/13/2007)
BMW's been shipping AGM batteries standard in a lot of models since MY02. I suppose they could be optimized for easier charging or something. But at least without more technical details, I don't see how this can be called regenerative _braking_. That implies that the regenerative process is like on hybrids and pure electrics, where the EM induction load (I think; I'm no electrical engineer) actually slows the vehicle.
In a normal IC engine car, it's engine compression (and in auto tranny cars, probably some from the torque converter) that provides 'non-frictional' braking. I suppose torque converter lockup can be modified, along with Valvetronic on BMWs, to 'transfer' the braking energy to the alternator.
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XGC75 7:27PM (1/13/2007)
The C5 is built from a GM parts bin. The alternator was never built for an engine nor a battery like those in the C5, which explains the fault. My neighbor blew the battery in his '01 C5, replaced both the battery and got a new alternator, and never had another problem of the such.
Regardless, I'm glad to see BMW continue to push the envelope on technology. Perhaps we can see other companies follow suit, or perhaps take other lessons from hybrids and apply those as well? I would very much like to see the industry change for the better due to radical moves like these.
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Guido 10:22PM (1/13/2007)
Very smart move from BMW. Gas/diesel savings without the batteri hassle. I think MB will follow with the new c series in the same way.
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Undercover Soul Brother 12:22AM (1/14/2007)
CMP- Here you go:
http://www.rsportscars.com/foto/01/bmwm506_engine5.jpg
I found it by google image search "m5 engine". I first saw this pic in the book: "The Complete Book of BMW" by Tony Lewin. A great book if you love the brand.
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Adrian 6:43AM (1/14/2007)
Here are some basics on the sistems in question here.
http://auto.howstuffworks.com/hybrid-car1.htm
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shrapnel 10:39AM (1/14/2007)
Some of you are missing part of the point on a grand scale (particularly the first poster, olddavid - odd that the first post is often the most ignorant).
BMW's mission is to make normal operating more efficient. For a long time, BMW drivetrains have been more efficient than comparable drivetrains, putting down more power with less parasitic loss. This is an attempt to reduce parasitic losses even further. The result will be the capability to run more efficiently - or put more power to the ground for any given engine.
Yeah olddavid - a problem no one had.
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Trenton Lipscomb 5:27PM (1/14/2007)
Copyright infringement and the S85 pic
You know, Autoblog, with all the random pictures you include on your site, deep linking, and lack of attributions, I wouldn't surprised if you and Weblogs Inc were gone one day due to using the wrong copyright holder's works.
Please be careful; I like coming here.
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