Poor range performance

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JupiterRed

Well-known member
Joined
Dec 6, 2014
Messages
60
Yesterday it was below 20 degrees all day. My wife averaged just 1.6 m/kWhr which is just awful range. Was it the cold, or was it just an unfortunate set of routes? She says she did not use the heated seats because the battery was draining so fast.
 
If you are on Facebook, there is some good threads about this happening right now. https://www.facebook.com/groups/218424681699164/

I'm not in a cold area, but these points were made:

1. Use the electric seat heater, rather than the regular heater/AC system.
2. Pre-heat the car before driving off, while on power.
3. If possible, store car inside.
4. Drive carefully, no quick start and stops.

A user in CT reported in that thread that he got 2.5 m/kWh when using these techniques. 1.6 seems low, however, not being in a cold climate area, it's hard for me to say. I generally average 2.7 to 3.0 on mine.
 
The GOM is almost useless in the cold. I have the Rav4 but the batteries, drivetrain and GOM are all from Tesla on both models.

I had a trip a few months ago year where I started with a range of 72 miles. I drove 36 miles at 30 degrees mostly at 65 mph and the heater on the whole way. Then I let the car sit for 9 hours. The temperature when I left was about 25 degrees. I drove another 36 miles mostly at 65 with the heater on. After the 72 miles of driving the GOM still said I had 20 miles left (and my guess is that I had at least 30.

My advice would be to not look at the GOM at all in the winter. Your range will be lower in the cold but you'll need to figure out how much. For example, when I'm driving a mile to the market and back I might only get 1.9 m/kWh. But my heater's running at full blast the whole way. On a longer trip I might get 2.5 because the car warms up and the heater cycles a bit more.

It is possible to still get decent range in the cold. Yesterday I drove 20 miles on the highway in 15 degree weather and got 2.7 and 2.6 m/kWh on the trip out and then on the trip back. I did try to minimize heater use and relied more on the seat heat.

Mike
 
mikegerard said:
...My advice would be to not look at the GOM at all in the winter...
I find the GOM unreliable at ALL temperatures. I routinely outpace the GOM by 15-20%. It is just an estimate and should be treated as such, I only pay attention to it when it is below 20mi. I believe that, like cars from last century, you should use the fuel gauge. For me it is a little over 21mi/qtr, ~85mi per 'tank' (your mileage may vary).

The m/kWh is also a not actual Battery-to-Wheels but almost dead-on Wall-to-Wheels. Not sure why they did that, but I have a meter on my EVSE and the dash m/kWh in the B-Class matches the number calculated by dividing the miles driven by the EVSE meter reading.
 
The m/kWh is also a not actual Battery-to-Wheels but almost dead-on Wall-to-Wheels. Not sure why they did that but I ave a meter on my EVSE and the dash m/kWh is quite accurate dividing the miles driven by that meter reading.

I'm curious about that comment. I've heard the same mentioned a couple of times. I don't doubt it, especially given you've measured output and miles and come up similarly.

However, I wonder about something. When the car is driving, I was assume it's possible to measure the kWh used. However, while measuring in the car while driving, wall-to-wheels doesn't seem to make sense to me. How can the loss between the wall and vehicle be measured and/or figured into the figure presented on the dash? I certainly believe there is loss in the charging process, and my understanding is it's in the 18-20% area. But, how would the be figured in when measured in car use?
 
rdavis0521 said:
I'm curious about that comment. I've heard the same mentioned a couple of times. I don't doubt it, especially given you've measured output and miles and come up similarly.

However, I wonder about something. When the car is driving, I was assume it's possible to measure the kWh used. However, while measuring in the car while driving, wall-to-wheels doesn't seem to make sense to me. How can the loss between the wall and vehicle be measured and/or figured into the figure presented on the dash? I certainly believe there is loss in the charging process, and my understanding is it's in the 18-20% area. But, how would the be figured in when measured in car use?
How could a car calculate Wall-to-Wheels (W2W)? Well that's just a simple derating of the kWh's consumed from the battery using measured efficiency losses of charging. If I drive 3miles and I used 1kWh from the battery and the Wall-to-Battery (W2B) charge loss is 18%, Battery-to-Wheels (B2W) is 3 m/kWh (3mi/1kWh) and W2W is 2.54 (3mi/1.18kWh). The real question is why did they display W2W? Maybe to let people know how much their car was really using on their power bill without having to buy a meter?

I usually got 3.8 m/kWh on my LEAF, but W2W was closer to 3.2 m/kWh, which translates to a ~18% W2B loss with a 3.3 kWh EVSE (if the LEAF dash calculation was accurate). I have yet to calculate the W2B loss in the B-Class, but it looks to be higher than the LEAF b/c 50% of the battery seems to need 20kWh. But I until there is an App that reads the CAN bus like LEAFSpy does, I will only be guessing the kWh's the battery is getting or using (b/c one wants a few decimal places...).
 
So, I believe you're saying, that they:

1. Measured charger efficiency losses at some point in the past (not live obvious).
2. And they apply that previously measured factor in derating the value they provide in the m/kWh display?

It just seems absurd to me that a company would purposely display a derated value that makes the car look worse on the gauge, confuse calculations, and make owners think the car is even more inefficient than it is.

I am not disagreeing with you. I just can't figure out why in the world they would do that.
 
I have uniformly gotten 1.2 to 1.6 mkWh when car is stored overnight outside and driven in weather below 35 degrees in stop and go traffic. So no surprise that as temperature drops, we will all lose range. Other than the tips already provided, I can only offer that my range is increased if I set the display towards "efficiency" I think it is. This is to modify my driving habits to limit battery use. No fast starts, coast rather than speed further before braking. An extra ten miles (from 30 to 40 range) is significant. It does however take the fun out of showing off a new beauty that is quick off the mark. I am looking for significant improvement when the weather returns above 50 degrees overnight but before the AC needs to be on.
 
rdavis0521 said:
It just seems absurd to me that a company would purposely display a derated value that makes the car look worse on the gauge, confuse calculations, and make owners think the car is even more inefficient than it is.

I am not disagreeing with you. I just can't figure out why in the world they would do that.
Dunno. Like I said not sure why they are doing it, my only guess was what I said about letting people know how much the are actually consuming on their power bill (kind of a German accuracy thing).

What I do know is that gauge in the car is very close to W2W. Since I don't know exactly how many kWh are being used in the battery as I drive, I can't question the veracity of the m/kWh gauge while I drive. So I can say is that either the battery has a larger capacity than advertised and the W2B (Wall-to-Battery) is nearly 100% efficient or that m/kWh gauge is not accurate for B2W (battery-to-wheels).
 
1.6 miles / kWh converts to 37 kWh / 100 km, which is the energy consumption figure I am getting in my Smart Fortwo Electric Drive in -20C temperatures running cabin and seat heaters full blast and doing many jack-rabbit starts. The energy consumption to heat the battery pack (the Smart ED has a heated/cooled pack) and the internal resistance of the battery due to the gel separator getting colder may have something to do with that consumption rate as well.

What I am saying is, this is not an unreasonable amount of power to be consuming in the winter based on my own experiences driving an EV for the past year.
 
I think most of us agree, the GOM is very irritating and has major limitations...

That said I wanted to post a comment on the cars standard range...

Today i had a reassuring experience: based on the car typically only showing us between 66 and 72 miles (GOM predicted range) I was a concerned setting out on my 63 mile round trip journey today.

Altitude change: 700 ft (our house is on a hill) but the remainder of the journey was basically flat with the exception of crossing the Dumbarton Bridge (SF Bay Area for those not familiar)

Temp: from 61-67 F

Charge: standard (did not use the range feature)

Driving characteristic: 80% freeway, 20% stop and go

Driver characteristic: conservative on the first 28.7 miles going to my destination, always trying to accelerate without exceeding the "economy" area of the dial (I did a few times on onramps) and I left the car in D auto mode the entire journey. On this leg I tried not to exceed 65 mph on the freeway

Returning leg of 34.1 miles I was feeling more confident so I spent 2/3 of the trip at 70 mph

At the end of my journey the GOM showed 27 miles predicted range and the battery capacity was around 28%. That would suggest an 89.8 mile total range. Not bad, maybe even impressive and quite reassuring.

This weekend I'm inclined to do a range charge and try an 80 mile round trip with the whole family in the car. If so I'll report the cars range and performance...
 
After driving 400 miles on 10 charges in Maryland over the past 2 weeks, GOM seems pretty accurate (miles driven/range predicted = 1.03). Range predicted after each full charge was: 71, 68, 71, 66, 67, 81 (Range ext), 70, 68, 74, 63 with temperatures primarily in the 30s and 20s. Looking forward to warmer weather, though that seems unlikely for a while.
 
Just got a computer update due to a shift error. It updated the entire computer. Range and charge lasts longer. Also, can't access the e+ mode anymore? If you haven't had the update may be worth your while to call the dealer and check if your car needs the update.
AZ
 
azEV said:
Just got a computer update due to a shift error. It updated the entire computer. Range and charge lasts longer. Also, can't access the e+ mode anymore? If you haven't had the update may be worth your while to call the dealer and check if your car needs the update.
AZ

Same thing happened to me. Got the computer update and lost the E+ mode. Noticed the GOM is a little better but watching the Battery % is still better.
 
My GOM always predicts at most 70 miles on a full charge without range extension and E/S set to E. Yesterday I needed to drive 61 miles round trip. I have the range extension, so I used that when I charged and drove very gently with E+ and D-; the climate fan but no heat or A/C; and mostly cruise control at 65 or 66. I came home with 45% charge left and 37 miles on the GOM. So the total predicted by GOM (in E+) = 98; by percent = 111 miles. Note that even though I used the range extension charging for this trip, the percent of charge on the System display started to drop from 100% immediately (roughly 1% per mile).
 
HarleyMYK said:
My GOM always predicts at most 70 miles on a full charge without range extension and E/S set to E. Yesterday I needed to drive 61 miles round trip. I have the range extension, so I used that when I charged and drove very gently with E+ and D-; the climate fan but no heat or A/C; and mostly cruise control at 65 or 66. I came home with 45% charge left and 37 miles on the GOM. So the total predicted by GOM (in E+) = 98; by percent = 111 miles. Note that even though I used the range extension charging for this trip, the percent of charge on the System display started to drop from 100% immediately (roughly 1% per mile).

What was the ambient temperature?
 
It sounds like there's been a change in your newer firmware with respect to range-mode charge. On mine (I don't have E+), when I range-charge, the SOC indicates 100% for about 9-11 miles, and then starts decreasing. This obviously makes range calculations via SOC very difficult.
 
@ClassESage I live in Southern California. It was about 70 on my way into town and about 75 on my way home.
 
HarleyMYK said:
@ClassESage I live in Southern California. It was about 70 on my way into town and about 75 on my way home.


As reported earlier, in Maryland, my GOM has been usually displaying 66-71, with temperatures mostly in the 20's and 30's. My driving is divided about 60-40 highway-city with 2.3-2.4 mpkWh.

Has anyone compared B-class range versus temperature relationship? HarleyMYK's experience versus mine seems to suggest relatively minor effect of temperature.
 
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