Regenerative Braking in the USA?

[rvacha]

Originally Posted by T Bone

If I can get power for free, I will take it but I think we are a decade away from seeing a 3000 pound Hybrid performance car.

I think you are probably correct. In the meantime however, what we will get are cars that weigh a couple hundred pounds more than a traditional car, but because of the electronics and technology, they will perform better and feel lighter than the traditional car.

We definitely need to get to the 3000lb performance hybrid. Without getting too political, our energy policy should deal mostly with funding basic technologies such as batteries (and other forms of energy storage) and deal less with how much ethanol we produce. It’s not all boring stuff. For example laminated flywheels may surface in F1 cars very soon. If we spent half as much on energy storage as we did getting to the moon I think that everyone - including us enthusiasts - would be thrilled with the end results

[T Bone]

Originally Posted by rvacha

I think you are probably correct. In the meantime however, what we will get are cars that weigh a couple hundred pounds more than a traditional car, but because of the electronics and technology, they will perform better and feel lighter than the traditional car.

We definitely need to get to the 3000lb performance hybrid. Without getting too political, our energy policy should deal mostly with funding basic technologies such as batteries (and other forms of energy storage) and deal less with how much ethanol we produce. It’s not all boring stuff. For example laminated flywheels may surface in F1 cars very soon. If we spent half as much on energy storage as we did getting to the moon I think that everyone - including us enthusiasts - would be thrilled with the end results

I will be a happy fast follower for Hybrid and other fuel smart technologies for performance cars when they get exciting. I can't get excited over regenerative braking, in fact, I feel marketing slime on me

[southlight]

Originally Posted by Epacy

I would have to further research the weight difference between the two. Do you have figures?
Also, how do you know the gain is only minimal by disconnecting the alternator. Do you have data?

Take a look at this: http://bmwfans.info/original/E92/Cou...1/ill-61_2091/

Difference is about 2kg for the battery itself.


Best regards, south

[M2381]

This is just what I read on this website and I dont know how true it is but I thought I might bring it up.

http://www.automobilemag.com/auto_sh...onclusion.html

"We won't be getting it in the U.S., but elsewhere, the M3 will have BMW's new brake energy regeneration system, which sounds more complex and hybrid-y than it actually is."

[badfish]

I don't see why this is even necessary. I know about high tech alternator that will shut off to create more power, but it's not as if the M3 were a hybrid and needs to be super energy efficient. If they leave it off, I'll be glad because I think it will become a maintenance item we don't need in the future.

[swamp2]

Originally Posted by rvacha

I'll answer it - there's very little difference, although AGMs are definitely a little heavier. However, they are virtually guaranteed not to outgas, rupture or explode and as a result there are gains in other areas of the vehicle such as trays, vent tubes, alternator size and weight, etc. AGMs are essentially the same as “maintenance-free” batteries but instead of letting the acid just slop around it is held in place between the plates with glass mats, i.e. fiberglass. The fiberglass weighs next to nothing, but the plates are sometimes packed closer together leading to more weight.

Batteries in BMWs are simply big and heavy no matter what kind they are. This is driven by the cold crank current required of the starter and the plethora of electrical gadgets (navi, heated seats, defrosters, high speed injectors, high compute power DMEs, etc). A modern car can easily top 3KW if all the stuff is turned on.

There's also more power being used for performance too. Now we have to have somebody operate our clutches for us. Other applications begging for more power are individual solenoid driven engine valves (instead of cam shafts and VANOS), pre-heated cats, electronic braking, per-wheel controllable torque, direct injection, blah blah blah. Like it or not big-ass batteries are here to stay.

The S65B40 outputs 313KW. If we assume the electrical stuff is pulling 1KW this means that the alternator steals about 0.3% of the available WOT engine power. If the AGM battery were to add 10lbs (and it doesn't) then the car would be 0.27% heavier than it would otherwise be. If you disconnect the alternator you are ahead of the game at WOT. However, most people will not drive WOT all the time and engine output will be lower, let's say 50KW, and a 1KW load would steal 2% of the available power. Here disconnecting the alternator yields even better returns

Nice post but isn't it a bit simpler than this? I could not find the current rating on the M3 alternator but the current M6 is 170 amps. I bet the M3 is very close to this if not identical.

P = V * I = 12.5 x 170 = 2.1kW ~ 3 hp

If the battery difference is 2 kg as south posted then the power (gain) to weight of this BER system is

~ 4.5 lb / 3 hp = 1.5 lb/hp

When the car is about 8.8 lb/hp this is an awfully impressive ration. Sure it is only 3 hp but the weight "penalty" is absolutely meaningless. Even if the alternator is drawing 50% of its rated load it still offers a phenomenal power to weight ratio.

Technically there may be other weight penalties other than just the batter but I doubt they are significant enough to change this argument.

Finally can anyone say what TIS says?? It seems there still is not certainty about this system in the US.