Reduced power if use acceleration to much?

[sasman]

Just read this on a german webpage "After we completed several transactions acceleration from 0 to 100 km / h Here it was noted that the time needed by about seven seconds at the beginning gradually increased to eight, nine, ten, and finally eleven seconds."

Has anyone had this happen to them? ..How many times can you use full power before you start to have reduced power?

here is the link http://www.focus.de/auto/fahrberichte/bmw-i3-im-alltagstest-der-i3-vollgastest_id_3562891.html

 

[fdl1409]

Possible. Reason might be overheating of motor or power electronics. If that happens max. power may be reduced to protect the hardware. Unlikely to feel that in real life, because you just don`t drive that way.

BMW answered: "Die Spitzenleistung des Elektromotors von 125 kW kann über mehrere Minuten abgerufen werden. Wenn Sie immerzu ohne Unterbrechung von 0 auf 100 km/h beschleunigen, greift die Begrenzung auf Dauerleistungsniveau - das sind 75 kW und eine entsprechend längere Beschleunigungszeit.“
Translation: Peak power 125kW can be used for several minutes. If you accelerate permanently from 0-100 km/h limitation to permanent power will set in - which is 75 kW and a longer acceleration time.

Frank
Germany
expecting i3 REx early June

 

[sasman]

Well we will be driving like that! ..I am purchasing the car for my girlfriend to replace her mini cooper s... and she likes to use the performance...and will be doing even more so with the I3..

 

[Sprinty]

Unless your girlfriend is using it on the track it's highly unlikely she will have those heat problems.

Stop to 70 to stop to 70 to stop and so on with periods of waiting still (for timing gear to reset I assume) will have a very different effect than spiritedly driving around, even if you gf is a racing driver professionally.

 

[ultraturtle]

Well we will be driving like that! ..I am purchasing the car for my girlfriend to replace her mini cooper s... and she likes to use the performance...and will be doing even more so with the I3..

Not likely on most terrain. Full power for only 20 seconds or so on flat terrain will accelerate the i3 to its maximum speed at which time power will necessarily reduce to a small percentage of that to maintain max speed.

The situation described could only happen climbing an incline steep enough to demand full throttle for several minutes in order to accelerate or maintain speed. That might happen on the few places on earth that have long, steep inclines straight enough to allow for sustained high speed.

Even the reduced power level of 75 kW is roughly 3 times what you would need to sustain 70 mph on flat terrain.

 

[fdl1409]

I think it is impossible to use that much power on any public road. With my Mitsubishi i-MiEV, which had only 49kW and roughly the same weight as the i3, I was able to accelerate to 110 km/h on a steep road uphill.

On a flat road, driving 150 km/h draws only about 30 kW. With 125 kW, you can maintain 150 km/h and climb 7.5 meters per second. So in 5 minutes you could climb from sea level to an altitude of 2.200m. There is no road like this in the UK or any other place I know...
You can only do that with deliberately accelerating and braking in rapid succession for several minutes. Nobody drives like that except on a race course.

Frank
Germany

 

[ultraturtle]

To put into perspective how much power sustained 125 kW is, consider that you would completely discharge the useable capacity of the battery pack in only 9 minutes. Granted, the system will not allow you to do that. Just saying that it is highly unlikely that a normal driver would need to sustain that level of power usage for several minutes at a whack.

 

[Surge]

See post about the test where they drove the i3 on a track. The range was only about 23% of what the range display showed at the start.
Up to you how you drive, but suffice to say that spirited driving will reduce the range considerably.

Same thing happens in gas cars. But I think the difference is that you have a lot more range, so it's not as apparent.