Range Meter After Full Charge - What Should It Read

[GregS]

I am now confused or concerned that my Level 2 is not giving me a full charge or and I doing something wrong. When I first got the car it read 71, 72, 73 or 74 for the range. After an issue, I went to the dealer for a software update and they fully charged the car and it read 94, which was great. It stay fairly high after driving the care before recharging. After recharging, not it on seems to go to 69 but show full on the gauge.

Is there some setting to get it to the higher charge or should I just not be concerned.

 

[Stretch2727]

You should look at the % charge meter not the range meter.

The range meter will vary base on you previous driving efficiency (miles per Kwh) and will vary quite a bit. In the B-Class it will generally read much lower than the actual range you have. The dealer may have reset the gauges giving it a higher reading for a time. The best way to gauge your range is to use the % of charge meter.

 

[wtzouris]

Your SOC (State of Charge) should read 100% after a standard charge and 100% after an extended charge. (The extra 12% is hidden above the 100% mark, which will not go down for 7-14 miles)
Your range meter is useless. USELESS. It is what reviewers use to criticize the poor range of EVs. You should reset your Trip Odometer, From Reset, From Start, and Eco Display every day. The range meter should say "I have no idea what your range is today (other than ambient temperature) since you haven't driven yet" Watch the From Start mpkWh meter as you drive. after about 20 miles driven, it begins to settle into a figure like 1.8 - 3.3 mpkWh. On a standard charge, (28 kW charge) , 2.0 mpkWh = 2.4 x 28= 68 miles range and 3.0 = 3.6 x 28 = 101 miles range. Always use a correction factor of 1.2 because the Mercedes displays wall to wheel efficiency in mpkWh and therefore factors in the 20% charger (energy) loss. Another excellent method is to divide the miles driven by the percent of charge used as a decimal figure to calculate range. So 25 miles driven and 25% charge used (75% remaining) is 25 / 0.25 = 100 mile range. All these figures are the most accurate when you have driven at least 50% of the range. Today when I start my day at 100% charge and I cycle through the Drive Mode programs E (Economy) , E+ (Economy Plus), back to E (Economy), and then S (Sport), and I get 3 different calculations of range: 74 miles, 90 miles, 82 miles, and then 74 miles. None are correct. The fact that E mode gives 74 at the beginning and 82 after cycling through E+ is a mystery. In fact if you drive conservatively in S mode and D- you get about the same range as E+ mode and D+ or D-Auto. I use all the modes and all the paddles for fun and to use the brakes as little as possible. Sometimes the D- mode really adds back charge through regeneration. Other times D+ really takes advantage of momentum and downhills -- it just depends on whether you are cruising on a highway for a long time (D+) or coming to a stop at the bottom of a huge hill (D-). D- Auto is pretty smart but as with all things it is more fun to choose for yourself sometimes.

 

[Comanchepilot]

When we picked up the car . . . it said 94 miles. Yup. Completely reset by dealer.

Wife drove 71 miles home at 75 mph UP HILL - could there be any worse drain on an electric car? She arrived home with 17% charge.

Forget the range meter - its meaningless. What matters - and only matters - is the % charge remaining.

What would be nice is a 5 min avg read out on mileage [miles per Kwh] THAT is what matters short term.

Hey - wife drives 37.4 miles each way - mostly downhill there - and mostly uphill back - she gets around 44-50 miles on e in a Volt.

Now she has a charger plug at work - given the range of the Benz - she's bought her last tank of gas to commute for the next 3 years. . .

 

[JeffRay]

CP, sounds like the perfect commuter car for her. Luxury, reduced price, no more stopping at yucky gas stations, charger at work, etc. Look forward to future posts from her by you.

 

[rdavis0521]

When we picked up the car . . . it said 94 miles. Yup. Completely reset by dealer.

Note, if you run through the screens using your left hand controls, you'll find two screens that have miles/kwH and time and mile readings.

One says "Since Start", and the other is "Since Reset".

If you reset the "Since Reset" meter by pressing the center button, you'll get 83 miles indicated on a regular charge, and 94 on a range charge. This might be plus/minus 1 or 2, but generally I get 83/94. That is likely what the dealer did.

 

[TonyWilliams]

Exactly what Ray said above.

Just reset the data and you'll get the range of the GOM to a "rated" standard at 3 miles per kWh consumption. The battery needs to be near room temperature.

Mercedes B-Class ED battery

36.0kWh total – 100% SOC (never used)
31.5kWh usable- 90.0% SOC (3 miles per kWh * 31.5 = 94 miles)
28.0kWh usable- 80.0% SOC (3 miles per kWh * 28.0 = 84 miles)
1.0 kWh unusable- 2.7% SOC

*** Mercedes consumption meter is calibrated so that 3.6 miles per kWh will show as 3.0 on the dash, as will 3.0 miles per kWh show as 2.5 on the dash. The correction factor is 83.333%, or 1.2

As the battery degrades over time, those mileage figures will drop. Also, know that if your car's battery is at room temperture, you can reset the GOM and know that whatever miles are shown with a "full charge" (either normal 80% or extended charge at 90%), if you divide by 3, that is the usable kWh.

Then , you can calculate the degradation over time. At 87 miles shown with a extended charge, 87 / 94 = 92.5% of new capacity.

 

[tcoombes]

After 14k miles of use on my B Class Electric, my reset GOM shows 83 miles available after full charge at 80% battery capacity. It has reduced slightly from the original 84 miles, but not significant yet.

 

[RicR2]

My experience is that the Range Meter is pretty accurate, and it definitely is based on my past KW-per-mile rate .

At full charge, the Range Meter usually said, 64 miles. Then The Dealer installed a software update that was supposed to incrtease my range by 40%. Immediately after the dealer performed that software update, the Range Meter said . . . 108 Miles! However, over the next few days, that 108 miles steadily went down, and now it's back to . . . that same 64 miles.

 

[TonyWilliams]

I do t know how safe it is to use the range meter (after reset) to determine degradation.

Sadly, many (most) manufacturers use one method or another to mask degradation.

 

[wtzouris]

The Range Meter, aka GOM, Guess - O -Meter. will say various things at various times.

1. You should reset the Odometer, From Reset Screen, From Start Screen, and Efficiency screens. (The last two are the same in terms of reset)

2. Previous Driving Efficiency -- the computer bases its range on your past habits -- over time, the average gets more accurate-- unless you perform a full reset of the computer/settings. I'm not sure how far back in history the computer goes -- maybe just the last few trips..

3. Program Mode: S (Sport) gives lower estimated "Range" than E (Economy)

4. Outside Temps - not sure if the computer adjusts based on that..

Bottom line, drive 20-25 miles, and look at the mpkWh number in the From Start screen. If the remainder of your driving on that charge
will be under the same approximate conditions, then do the following:

How to calculate actual range: (Multiply the mpkWh (From Start or From Reset screen) x 1.2 (Mercedes correction factor for 80% charger efficiency) x 28 kW (regular charge) or 31.5 kW (extended range charge) = total miles of range

Typical Winter Driving: 2.0 mpkWh, 68-76 mile range, (regular charge/extended range charge)
Average Driving: 2.5 mpkWh, 84-95 mile range, (regular charge/extended range charge)
Efficient/Summer Driving: 3.0 mpkWh, 101-115 mile range, (regular charge/extended range charge)

I wouldn't expect the batteries to degrade much in the first 3 years/ 20-30k miles of ownership. Maybe you'l be down 10% by 50k miles.

 

[TonyWilliams]

I wouldn't expect the batteries to degrade much in the first 3 years/ 20-30k miles of ownership. Maybe you'l be down 10% by 50k miles.

I'm at 12% degraded at 53,000 miles / almost three years on the Toyota Rav4 EV (same cells as the B-Class ED).

 

[hybridbear]

Always use a correction factor of 1.2 because the Mercedes displays wall to wheel efficiency in mpkWh and therefore factors in the 20% charger (energy) loss.

We live in an apartment where we pay a flat price per month for our electric use for our BEV & PHEV. I track our electricity consumption monthly with the trip meter on each car to make sure we aren't using more electricity than we are paying for. I have always taken my total kWh reported by the two cars combined and divided by 0.8 to account for charging losses. Are you saying that the BCED displays of kWh used already factor in charging losses? That's very different! Does any other EV do that?

 

[Stretch2727]

Always use a correction factor of 1.2 because the Mercedes displays wall to wheel efficiency in mpkWh and therefore factors in the 20% charger (energy) loss.

We live in an apartment where we pay a flat price per month for our electric use for our BEV & PHEV. I track our electricity consumption monthly with the trip meter on each car to make sure we aren't using more electricity than we are paying for. I have always taken my total kWh reported by the two cars combined and divided by 0.8 to account for charging losses. Are you saying that the BCED displays of kWh used already factor in charging losses? That's very different! Does any other EV do that?

Yes, you are double counting for the charging losses. Using the straight mpKwh measurement from the vehicle is more accurate in this case as it accounts for the charging loss. It is not perfect but is pretty close to account for the charging loss.

Yes the MB is the only vehicle I know of that does this. It is silly way measure efficiency as you just want to know what you have used from the battery not the wall. I believe it has also caused the low reading in the GOM (guess o meter) and their EPA efficiency ratings. EPA ratings also seem to have double counted the charging loss as well.

EPA says 40kWh per 100 miles (wall to wheels)
My car - 33kWh per 100 miles (wall to wheels) over 2500 miles. (3.0 mpKwh reading)

If you multiply 1.2 x 33= 39.6 close to 40. This indicates they counted the losses 2x as the car (battery to wheels) car itself is only using about 28kWh to go 100 miles in my case.

You could argue somehow my driving style is better than the EPA rating.

-My Ford Focus Electric was matching the EPA ratings with the same weather, drive style and routes.
-It is pretty hard to be 20% better than the EPA rating as anyone knows from their mileage in an ICE car.