CaptBreadbeard
Posts: 18
Joined: Sat Apr 18, 2015 7:23 pm

Range at Highway Speeds

Sat Apr 25, 2015 3:11 pm

Still researching the i3 before committing to a BEV.

Any anecdotes about the range of the BEV (or REX before the engine kicks in) when traveling at higher highway speeds? Traffic around here regularly flows at 70-80MPH and I'm a little concerned that the higher speeds may drastically reduce the range. Any insight is welcomed.

Thanks.

jadnashuanh
Posts: 3406
Joined: Thu May 22, 2014 2:07 pm
Location: Nashua, NH USA

Re: Range at Highway Speeds

Sat Apr 25, 2015 7:41 pm

How far do you need to travel at highways speeds? Drag increases very rapidly as you speed up. But, the car will easily reach its top speed.
Jim DeBruycker
2011 535i x-drive GT, 2014 i3 BEV

rabster
Posts: 24
Joined: Tue Feb 24, 2015 4:19 am
Location: West Malling, Kent, UK

Re: Range at Highway Speeds

Sun Apr 26, 2015 1:52 am

Anything above 70 mph will start hitting your range quite significantly. However, if you get the REX rather than the BEV then you don't really need to worry so much. I regularly sit between 70 and 80 on the motorways and usually get about 60-70 miles range out of electric only. What's your average journey distance and speed?
I3 REx, Andesit Silver, Neutronic Cloth, 428 Turbine Alloys - Ordered 28/01/15 - Arrived 10/04/15
Previous toys:
BMW E39 540i - Loved it
Audi S4 4.2- Unreliable
Audi S3 - Loved it
Renault ClioSport 172 - It's French...
Alfa GTV - It's Italian...

JTM
Posts: 33
Joined: Tue Dec 30, 2014 1:21 am
Location: Brisbane Australia

Re: Range at Highway Speeds

Sun Apr 26, 2015 2:34 am

See "Range for Speed" on the Swedish BMW owners site, Clear graphs which track the relationship between speed, energy consumption and thus range.

http://bmwi3owner.com/2014/05/range-for-speed-2/

JTM
JTM.
BMW i3 (BEV), Ionic Silver, Lodge, 428s, DC Rapid Charge,10.25" Nav Pro.
Supported by 5kWh Residential Solar System

alohart
Posts: 914
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Range at Highway Speeds

Sun Apr 26, 2015 6:22 am

JTM wrote:See "Range for Speed" on the Swedish BMW owners site

I find no mention of the ambient temperature during these tests. The 2 range vs. speed posts were in March and early May, so ambient temperatures were likely in the 40's, but they could have been in the 30's or 50's as well. There was a mention of preheating which suggests that the ambient temperature was relatively low which could have reduced the measured ranges but probably didn't significantly affect the percentage differences in range at different speeds. However, air density and thus aerodynamic drag are higher at colder temperatures.

The range vs. speed graph indicates a 62 mile range at a constant 62 mph which is certainly lower than many of us experience at higher temperatures, presumably. Also, the range vs. speed appears to be an almost linear relationship which is a little surprising considering that the power required to push a car through air is proportional to the square of the speed. As a result, I would expect the range at 74 mph (120 kph) to be a fourth that at 37 mph (60 kph), but it was measured to be just slightly less than half, so something else must be going on.

I recall that Tony Williams was able to drive an i3 for ~88 miles at a constant 62 mph over a standard flat circular course in Orange County at temperatures in the low 70's and with little wind. So using Tony's range at 62 mph and the measured 20% less range at 74 mph vs. 62 mph, one could probably reasonably extrapolate that Tony's range might have been 88 x 0.8 = 70 miles at 74 mph.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

peteinlongbeach
Posts: 37
Joined: Tue Feb 24, 2015 3:32 pm

Re: Range at Highway Speeds

Tue Apr 28, 2015 5:32 pm

With favorable breezes, temperature, speeds, and drafting, my electric range (no REX assist) from Palm Springs to Irvine on Monday was 101.7 miles, with 16 estimated remaining, at 6.0 miles / kWh.

On the same drive a few weeks ago I managed 90 miles before the REX kicked-in, but that was with cooler weather, less drafting, and higher speeds.

i3atl
Posts: 436
Joined: Wed Mar 05, 2014 10:47 pm
Location: Atlanta, GA

Re: Range at Highway Speeds

Wed Apr 29, 2015 9:09 am

Range chart here: http://bit.ly/bmwi3rangechart

There are notes on the "verified" cells detailing temps/terrain/etc.

TonyWilliams
Posts: 107
Joined: Tue Sep 09, 2014 8:31 pm

Re: Range at Highway Speeds

Wed Apr 29, 2015 2:02 pm

Range at 65mph (100km ground speed) on dry, hard surface level road with no wind or cabin climate control with new condition battery at 70F, battery capacity is "useable" amount, not advertised amount. Ranges are at maximum available charge and EPA rating is the maximum published.

Nissan
LEAF - 4 miles per kWh (250 wattHours per mile) * 21.3kWh = 85.2 miles / EPA 84

BMW
i3 - 4.7 miles per kWh (213 wattHours per mile) * 18.8kWh = 89 miles (the "REx" version has less electric range)

I3 "REx" (with gasoline engine) - 4.6 miles per kWh (217 wattHours per mile) * 18.8kWh = 86 miles minus reserve held for gasoline engine operation = 80 miles

Kia
Soul EV - 4 miles per kWh (250 wattHours per mile) * 27kWh = 108 miles / EPA 93


VW
eGolf - 4.1 miles per kWh (244 wattHours per mile) * 24kWh = 100 miles

GM / Chevrolet
2014 Spark EV - 5 miles per kWh (200 wattHours per mile) * 19kWh = 95miles / EPA 82

2015 Spark EV - 5 miles per kWh (200 wattHours per mile) * 18kWh = 89 miles / EPA 82

Mercedes
B-Class ED - 3.6*** miles per kWh (278 wattHours per mile) * 31.5kWh = 113 miles / EPA 87
*** Mercedes consumption meter is calibrated so that 3.6 miles per kWh will show 3.0 on the dash. The correction factor is 83.7%, or 1.2

Toyota
Rav4 EV - 3.4 miles per kWh (295 wattHours per mile) * 41.8kWh = 142 miles / EPA 113

CaptBreadbeard
Posts: 18
Joined: Sat Apr 18, 2015 7:23 pm

Re: Range at Highway Speeds

Wed Apr 29, 2015 7:56 pm

Thank you for all the replies. This is the information I was looking for. I understand that the answer is always "it depends," as this really is a multivariate problem. Over the last month I've been watching daily mileage, my worst case estimate on range was 50 miles/charge. I.e. if I drive 51 miles in a day, in the worst case I may have to charge before returning home. Regardless of the reason why (hot/cold, hilly, fast, etc.), Based on the information provided, it seems my 50mi estimate is a bit pessimistic, but no one has had these long enough to see how the batteries age. They're lithium-ion so it's well known chemistry, so "end-of-life," worst-case estimate of 50mi probably isn't too far off.

Thanks again.

TonyWilliams
Posts: 107
Joined: Tue Sep 09, 2014 8:31 pm

Re: Range at Highway Speeds

Wed Apr 29, 2015 11:54 pm

CaptBreadbeard wrote:Thank you for all the replies. This is the information I was looking for. I understand that the answer is always "it depends," as this really is a multivariate problem. Over the last month I've been watching daily mileage, my worst case estimate on range was 50 miles/charge. I.e. if I drive 51 miles in a day, in the worst case I may have to charge before returning home. Regardless of the reason why (hot/cold, hilly, fast, etc.), Based on the information provided, it seems my 50mi estimate is a bit pessimistic, but no one has had these long enough to see how the batteries age. They're lithium-ion so it's well known chemistry, so "end-of-life," worst-case estimate of 50mi probably isn't too far off.

Thanks again.


Industry standard "end of life" for automotive uses is 70%.

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