Range at Highway Speeds

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.

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.

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?

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 said:

See "Range for Speed" on the Swedish BMW owners site

Click to expand...

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.

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.

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

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

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

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.

CaptBreadbeard said:

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.

Click to expand...

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

TonyWilliams said:

CaptBreadbeard said:

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.

Click to expand...

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

Click to expand...

That seems reasonable. If you don't mind, where does this EOL definition come from? Is there an automotive standard I'm not aware of? Thanks.

I'm not sure if there is an industry standard for a depleated LiON battery EOL, but BMW's warranty doesn't kick in unless the battery pack's capacity drops below 70%. What levels other companies use, could easily be different, assuming they warrant their batteries at all.

I was on the hiway with 50 km range left and i am only 25 km from home so figure i have plenty, then 10 km away from home i got this ! warning at 25 km left?? I got a little worry cause i was still on the hiway but not long i entered into city and the range of 25km warning only went down 3 km so yes hiway driving uses a lot of "juice"