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XBimmers | BMW X3 Forum > BMW X3 Forums | F25 (2011 - Current) > Second Generation BMW X3 General Forum » KERS failure warning?

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      04-10-2011, 04:47 AM   #1
X3buyerScotland
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KERS failure warning?

Just a thought after watching the F1 energy regeneration system failures. If you don't have Pro Nav (so no energy gauge), how can you tell if the system fails? Presume there must be a warning system Lotus or any other gurus?
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      04-10-2011, 05:06 AM   #2
X3buyerScotland
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Sorry for iPhone error folks. Could not find thread delete!
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      04-10-2011, 05:57 AM   #3
acey81
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I think you will get another warning in-dash if that is the case. The "kers" in this case doesn't give you any power anyway, simply charging the batter and therefor saving you some (very marginal) fuel.
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      04-10-2011, 06:18 AM   #4
roders
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Yeh, no button on the steering wheel for extra power :P
But would be nice
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      04-10-2011, 07:18 AM   #5
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Hmm! Having ordered the 3.0d power should not be a problem but a heavy right foot might be. I guess tho it would show as a battery fault were it not working as all the stop start will drain the juice I guess. Shame the Regen gauge is not standard on all cars (noting the brochure error that says it is!)
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      04-10-2011, 08:13 AM   #6
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Don't know for sure, but suspect it will show up on the display screen as a battery or alternator fault. The X3 does not have a dedicated battery or alternator dash fault light. The BMW BER (Brake Energy regeneration) system is programmed to consider the state of the battery and only works when the battery is fairly well charged. On my car, the BER will start working when the battery reaches about 80% charge and will stop working when the battery drops to around 55-60%.

How do I know since I don't have the display meter? I drove around for a month with a plug-in digital voltmeter connected to the 12v. outlet.

http://www.amazon.com/Vector-VEC008-...2438843&sr=8-3

It took about a week after the car was delivered to accumulate enough charge for the BER to begin working. When the battery is partially charged, the voltage will run around 14.1 or so all the time (alternator charging normally - light charging). Once the BER is activated, the charging voltage will drop to around 12.9 to 13.2 volts during steady speed driving, but will shoot up to 14.6-14-8 volts (very heavy charging) under moderate braking.

Without the BER gauge or a voltmeter, the BER function is transparent to the driver. The only possible indication of a very low battery charge is a loss of the highest blower fan speeds when using the automatic mode of the climate control. (X3 manual pp. 104).

The X3 has a "monster" alternator capable of generating up to 3kW for short periods. If they did use a "motor/generator" like a real F1 (electronic) KERS, it could add about 4hp for a long period of time (not the 8 sec F1 limit). About as much as a low restriction exhaust system.
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      04-10-2011, 08:23 AM   #7
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Knew you would know Lotus. Truely a guru.
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      04-10-2011, 10:12 AM   #8
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More than you every wanted to know about BERs

Hopefully, you'll not think this is too tedious, but even though I'm usually a staunch advocate of new technology, I'm beginning to wonder if the net gain of the "simple" BMW BER system isn't more marketing hype than a cheap source of "something for nothing" as BMW states in their literature.

BMW has publicly stated that the BER can improve fuel efficiency by "up to" 3% on the European Urban Driving Cycle (ECE-15). I've also read reports that state that no statistically valid gains were observed on the US EPA cycle (which is only slightly more “aggressive” than ECE-15. There are obviously no gains whatsoever in longer, highway driving situations.

Because of the low charging rate during steady state driving, a BMW with BERs will likely have a battery that normally averages a charge level of 60 to 70% most of the time. A conventional, standard “wet” battery will have significantly reduced life under that condition, and will also not like the periodic high charge rate of the BER. BMW has anticipated this condition and has specified and supplied new X3s with AGM (Absorbed Glass Mat) batteries. The AGM battery is also somewhat larger than needed to allow enough charge to be able to start the vehicle in cold climates when the battery is only partially charged. However, AGM batteries currently cost about 2 times more than standard “wet” batteries. The “larger” battery size required also adds to the cost, and adds a little extra weight to the vehicle (which hurts fuel consumption a tiny amount).

The bottom line: You might save a few pennies a week on fuel if you do mostly “urban” driving, but if you keep the car more than 4 or 5 years and need to replace the AGM battery, it will cost several hundred dollars more.

Last edited by Lotus7; 04-10-2011 at 10:18 AM.
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