Not just the GOM range, is any stat from the Mini dash reliable?

A

AndysComputer

Well-Known Member
Hi all!

Long time lurker, first time poster...

We picked up our Mini Cooper SE a month ago and I've been spending some time testing its range under various conditions. I was finishing up what I hoped would be my first YouTube video on the car but doing some quick math to explain a few thing to viewers I ended up stumping myself so I thought I'd ask the hive mind!

I drove a test loop which according to my GPS tracker and Google Maps is 77 miles precisely.
The car trip meter shows 75 miles. Not a big deal, slightly under-reporting, nothing to see here.

I started with 100% charge and finished up with 56% remaining.

This means I used 44% of the battery to cover 75 miles (as far as the car is concerned).

The usable size of the battery is 28.9 kWh so we used 44% of that or 12.716 kWh.

So traveling 75 miles on 12.716 kWh gives an efficiency of 5.898 miles per kWh.
5.9 if we round the figure off.

The car trip meter said 5.2 miles per kWh. That's off by over 13% using its own trip meter numbers!

So not only is the GOM range hopelessly wrong (it insists I have only 126 miles of range on a full charge even after several hundred miles of highly efficient driving) so is the efficiency figure!


Now, if I use the figure of 33kWh (the total pack size) the numbers work out to 5.16 miles per kWh which is basically the 5.2 that the car trip meter claims but that just doesn't seem right...

The tests were done in Green+ mode so the heater/AC doesn't affect anything while I am sitting at a red light, but even so we are basing the calculation on battery % remaining so that shouldn't even matter unless the efficiency figure is literally for driving only and it doesn't take into account any usage while stationary? But that doesn't seem right either. There is no way I used an extra 13% just sitting at the lights when in Green+ mode anyway.

Anyone have any thoughts on why these numbers don't line up?

(on a side note, using the figure of 77 miles for the trip per the GPS the car returned 6.05 mi/kWh which greatly impresses me. It was all 45mph suburban and 60mph highway, no freeway and I was driving economically by anticipating traffic and not accelerating harder than the cars around me or exceeding the speed limit, but still, very impressive).
 
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The only two I have real confidence in is the distance traveled and battery percent. I suspect the instantaneous kWh/100km is probably accurate as well. My average kWh/100k is approximately correct (long term). I haven't used the single trip kWh/100km info. The battery is indeed 28.9kWh usable from a total of 33.6. Many people, myself included, have returned 6miles/kWh around town. I get about 5 long term average as I do a reasonable percentage on freeways. The GOM is so far out it is useless, but you can rely on the battery percentage - it has never let me down in over 15 months. The GOM has never been remotely correct, even when it registers 0.
 
I believe the efficiency really does calculate based on the full battery capacity (33 kWh), which seems dumb but there must be some logic behind it. That's why the car always displays low. If you use @GvilleGuy's MINI EV Range shortcut, it shows a much higher efficiency since he calculates based on 28.9 kWh. My car basically says I get 3.8 mi/kWh but using the shortcut I always show much higher. And using 28.9 kWh more accurately reflects how far I can drive on a charge.

The GOM bases its guess only on the previous drive, it's not cumulative. Driving hundreds of miles won't improve it. I've got 28,000 miles on my SE and the GOM is exactly as screwy as the first day.
 
I can appreciate that the GOM is very conservative as EV efficiency can be so easily affected by conditions like driving uphill or wind or low temperatures etc (although the latter could take the temperature sensor into account).
If feels BMW didn’t put much effort into the algorithm as even when charging the car after this test the GOM only showed 126 miles range. I can see how this might help avoid someone running out and I did read a post by someone recently on here who struggled to get 80 miles on a trip, but it’s definitely off putting for potential buyers who are not used to real world driving of an EV.
It’s also no excuse for them to get the trip energy meter wrong given they have the distance figure and battery percentage figures to go off. Doesn’t make sense to me that they should be so far off. I’ve never seen a gas car trip computer mpg report be 13% out… And again it reads lower than reality thus causing a customer to believe the car is not as efficient as it actually is…

I guess I’ll have to say that both the GOM and the efficiency figures are nonsense and people should only go by the distance travelled and battery percentage. Certainly that’s what I’ll be doing but it doesn’t paint the car in a very good light that all the figures are so far out on the dash. It was bad enough when I thought it was only the GOM…
 
I think its (GOM) just another tool in the tool box. Use it improperly and the results are unsatisfactory. As others have said, it seems to be designed for the casual driver. If you are adept, more than a casual driver, then there are better tools to use, just leave the GOM in the tool box, along with the plastic barbie scissors. :)
 
My only guess is that 0% isn't actually 0%, meaning that using from 100% to 0% is less than 28,9 kwh. In various tests the car does seem to have quite a large buffer when hitting 0%, making the calculations rather hard to make.
 
Rasmus Aage said:
My only guess is that 0% isn't actually 0%, meaning that using from 100% to 0% is less than 28,9 kwh. In various tests the car does seem to have quite a large buffer when hitting 0%, making the calculations rather hard to make.
Click to expand...
Whenever I've acquired a new car, one of the first things I would do was to put my lawnmower's gas-can in the trunk and run the car's gas tank dry to see how many miles it could go after the low-fuel LED came on. I have since heard that practice can cause problems in the gas tank of some cars (someone told me a Prius' gas tank could collapse, but I'm skeptical about that).

I really want to test how far my SE will go after the warnings start to appear and after the GOM reads 0. Of course, I can't carry a can of battery-juice with me so the problem is what to do after my SE rolls to a chargeless stop. "Honey, I'm on Dexter Road between Wagner and Zeeb Roads. Can you bring the generator and the book I'm reading?"
 
insightman said:
I really want to test how far my SE will go after the warnings start to appear and after the GOM reads 0. Of course, I can't carry a can of battery-juice with me so the problem is what to do after my SE rolls to a chargeless stop. "Honey, I'm on Dexter Road between Wagner and Zeeb Roads. Can you bring the generator and the book I'm reading?"
Click to expand...

It would be great to have that information, although there might be too many variables (temperature, grade, tires, etc.) that might make the information less than universally useful. Still, why not put the portable generator and book in your own SE before starting the test -- no need to disturb your wife!
 
Rasmus Aage said:
My only guess is that 0% isn't actually 0%, meaning that using from 100% to 0% is less than 28,9 kwh. In various tests the car does seem to have quite a large buffer when hitting 0%, making the calculations rather hard to make.
Click to expand...

That’s a very good point, 0 isn’t necessarily 0. The question is does the car use some of the battery over the 28.9 usable or does it only ever stick to that 28.9…
But thinking about it, if 0 doesn’t mean you have used up the full 28.9 then the the consumption number should be even better as you didn’t use as many kWh as you think so in my case the number would be even higher than 6.0kWh, and that puts the 5.2 displayed by the car as being off even more!
I think in my video I’ll go with battery percentage and assume 100-0 is 28.9kWh and point out the efficiency rating formula or measurement is just wrong.
 
I think there are some U tube videos of drivers running the SE till it stops.

The SE may be intentionally conservative.

Back when the Leaf first was released, Nissan had to buy back several in the Phoenix area due to the GOM range being way to generous and owners running out of “gas”. (This was also due to the lack of a proper battery heat management system, which is still the case.)


Sent from my iPhone using Inside EVs
 
One thing that was interesting in that video is that all but 2 cars (the Mini and the VW) ran out before their claimed range. One as low as 74%! The Mini did best by this criteria at 106% of its claimed range (154 Miles).
 
insightman said:
Whenever I've acquired a new car, one of the first things I would do was to put my lawnmower's gas-can in the trunk and run the car's gas tank dry to see how many miles it could go after the low-fuel LED came on.
Click to expand...

You and I are very different. I test the handling on tight 90 degree turns and force the car to understeer, long sweeping turns, high speed dips and hills, etc. I usually then tune the car, calculate the HP/torque, measure the 1/4 mile time, etc.

insightman said:
I have since heard that practice can cause problems in the gas tank of some cars (someone told me a Prius' gas tank could collapse, but I'm skeptical about that).
Click to expand...
That is crazy. Gas tanks have a vent to equalize the pressure.

The bigger problems with running an ICE car out of gas is the one, the fuel pump starts sucking air and heating up. It can cause it to prematurely fail. And second, if your car is under load and you run out of gas, you can go lean and cause the engine to detonate. If your gas light comes on, get gas. It is that simple.
 
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