B-Class range update

[user 688]

I owe this forum an update after a few nervous nelly early adopter posts. After clearing the history of my slightly used b-class lease back, the GOM leaped from barely 60 miles to 84. After driving for a few weeks, the GOM now reads 95+ after a full charge. I have commuted, round-trip, non-recharged, successfully for months and I could not be happier with the B-class performance.

 

[mikegerard]

Remember that the GOM is just an estimate based on past driving.

In my experience (in a Rav4EV, same Tesla components as B-Class) it is very pessimistic and I have never had trouble exceeding the range of the GOM. But if you did have some unusual circumstance (stuck in traffic with ac or heat blasting for an hour) it would be possible to throw off the estimated range.

Here is a discussion on how to reset the GOM on the Rav4. This should work on the B-Class since the Tesla bits are the same as the Rav4.
http://www.myrav4ev.com/forum/viewtopic.php?p=20518
We have also been using it to estimate battery degradation on the Rav4. So far, those numbers have been much better than expected.

Mike

 

[wtzouris]

So if you want to check battery degradation you have to charge the car and disconnect the 12v battery for a while. But an easier solution is to reset your screens all the time. From Start, From Reset, and Odometer.

 

[Stretch2727]

As has been stated many many times on this forum the GOM is completely wrong even when reset.

The consumption meter on the MB seems to calculate a wall to wheels consumption which is somewhere between 15-20% low. This is throws off the GOM.

Proof of this is if you take your nominal consumption(i.e 3.1 m/Kwh) divided into the mileage you drive.... say 100 miles. It is more than the actual battery capacity of 28.5 Kwh. I drove almost 100 miles on a standard charge at 3.1 m/Kwh which lead to a battery capacity 32.85Kwh. The battery is only 28.5Kwh when new so the m/Kwh reading is about 15% low. The GOM is low this same amount.

The best method is to reset or use the trip odometer and use the % battery meter. If you go 10 miles on 10% of battery you have 100 miles of range. In the summer I have seen 105-110 mile of range on a standard charge and about 120 miles on extended range charge.

In the winter this will drop to about 80 miles of range...but this will depend on the number of start stop cycles on your trip. The initial battery warm up consumes 3-4 kwH. So the more stops you have the less the total range.

 

[user 688]

From http://www.plugincars.com/mercedes-b-class-e-cell:

"every kilowatt-hour of capacity yields between three and four miles of range. Drive like a maniac to get closer to three miles per kWh. Take a chill pill and you could get closer to four miles."

I am quite certain that my driving is more on the chill end of the spectrum, but my average consumption over several thousands miles of commuting has NEVER topped 2.9 mpkwh.

 

[kish]

Check out this past discussion
http://www.mybclasselectricdrive.com/forum/viewtopic.php?f=8&t=325

One thing to keep in mind that Mercedes meter shows wall-to-wheel efficiency not accounting for charging losses.
Other cars show battery-to-wheel efficiency.

 

[Stretch2727]

One thing I have noticed with the B-class now that the weather is warmer is I am getting better range and efficiency this year than last. Likely the motor and drive train have loosen up a bit. My battery certification showed no degradation. 28.2 Kwh.

I just did a trip last weekend.

67 miles using 49% of battery capacity. The efficiency read out at 3.9 mi/Kwh. (it is a good route for max efficiency, few red lights and about 45 mph, temp was around 65 F., I cannot duplicate this efficiency on most trips. )

This is 136 miles of range on normal charge. (100/49) * 67 = 136

The GOM said 74 miles of range when I started with 100% normal charge. So it was only off by 62 miles .

Assuming range charge adds 12% (31.5Kwh/28kwh) this is 152 miles on a range charge.

The B-class is great in the warm weather. It takes a much bigger hit in the winter than my eGolf. In the winter I was keeping my trips under 90 miles with a range charge.

The car has 10K miles in one year of driving.

 

[camaroguy]

I am not convinced that the M/KwH calculations are actually off by 15-20% like everyone says.

I drove back to back 70 mile trips over the weekend and in both cases the M/KwH calculation was only off by 8%.

That said the numbers were pretty great. 3.0 actual at 2.8 indicated and 3.76 actual 3.5 indicated. The return trip 3.76M/KwH suggests I could have done 120 miles on the range charge.

My math was done assuming a range charge really is +12% which means the total capacity at start was 31.5KwH.

 

[oilerlord]

67 miles using 49% of battery capacity. The efficiency read out at 3.9 mi/Kwh. (it is a good route for max efficiency, few red lights and about 45 mph, temp was around 65 F., I cannot duplicate this efficiency on most trips. )

This is 136 miles of range on normal charge. (100/49) * 67 = 136

To avoid "What's wrong with my car's range?" posts, I think it's important for people that are researching EV's to note that 136 miles of range with a 28kWh battery is definitely NOT typical. While there are very efficient drivers that are able to squeeze every last mile out of a charge, there are drivers that do things like floor the pedal, accelerate to stop lights & slam on the brakes, blast the heat or AC, and generally have no concept of how preserving momentum uses less energy (or for that matter, care to do so). If you drive it like you stole it, you may have a tough time breaking 75 miles on a charge.