Hybrid Miles per kWh Mercedes Me versus Actual

[JohnK47]

I would be interested to know what other MB Me users are noting regarding the Trip Data section including the From Reset data. My wife's GLE350de has completed 7,252.7 miles (of it s 9,499 total) on electric only and all charging has been from our ZAPPI single phase wall box. The ZAPPI indicates a total charge of 3920.6 kWh which gives 1.85 miles per kWh yet the Mercedes me app shows 2.8 m/kWh?. The latest trip shows an electric mileage of 41 a charge left of 1 mile and has used 26 kWh resulting in 1.61 m/kWh yet the app shows 2.3 m/kWh. Does anyone understand the formula that results in the Mercedes result?

 

[ALFAitalia]

Its a guess....but I would say a big chunk if the he variation is the difference between what you Zappi sent to the car and what your car battery actually received....typically 12 to 15 percent is lost....but some on here claim nearer a 20% loss. Due to the energy used controlling the charging process, heating the battery. other heat losses and of course resistance in the cables.

 

[KennyN]

Does anyone understand the formula that results in the Mercedes result?

Simple really - L x I + E = S

Its the one all manufacturers use these days.

Its like the advert for the latest electrical Renault thingy that advertises as having a range of 450 miles , the only problem is that its not available in the UK according the the "very" small print in the corner of the advert - so why is it allowed to be advertised (falsely) on UK TV ??

K

 

[JohnK47]

I am specifically referring to the Information needed. This is that the car has achieved a certain amount miles for each kWh provided at the charging socket. This is the only useful detail and allows one to calculate how far you are likely to travel based on this short term and long term data. A value based on the EV's battery discharge alone can only be useful with the caveat that it is after round trip losses in the order of X%. The distance the car will travel for a given amount of energy is another issue and as said relates to the difference in real world driving and the WLTP tests and test conditions on a rolling road, One of which I note is they are conducted at 23 degrees Celsius! In my case the battery is 32 kWh and a full charge takes some 26.5 kWh so i assume that it discharges to say 10% stops and charges to 90% and stops or some other combination. so using the car's data via Mercedes Me of a 42 mile journey at 2.3m/kWh gives a total discharge of 18.2 kWh and hence divided by the 26kWh supplied from the charger gives 70%. Here the overall real world energy requirement for that particular journey in combination with round trip charging losses are 70% of the charge from the wall box.
Multiplying the claimed 66 miles range by 0.7 gives 46.2 miles which is the order of what the car achieves in the terrain travelled and 9 degrees Celsius. To turn the data in to information the display should also take in to account (from heuristics to date) the charge level that will be available. Here, after charging with 26kWh it would show 18.2kWh available and a likely range of 42.6 miles.

 

[Bobby Dazzler]

I am specifically referring to the Information needed. This is that the car has achieved a certain amount miles for each kWh provided at the charging socket. This is the only useful detail and allows one to calculate how far you are likely to travel based on this short term and long term data. A value based on the EV's battery discharge alone can only be useful with the caveat that it is after round trip losses in the order of X%. The distance the car will travel for a given amount of energy is another issue and as said relates to the difference in real world driving and the WLTP tests and test conditions on a rolling road, One of which I note is they are conducted at 23 degrees Celsius! In my case the battery is 32 kWh and a full charge takes some 26.5 kWh so i assume that it discharges to say 10% stops and charges to 90% and stops or some other combination. so using the car's data via Mercedes Me of a 42 mile journey at 2.3m/kWh gives a total discharge of 18.2 kWh and hence divided by the 26kWh supplied from the charger gives 70%. Here the overall real world energy requirement for that particular journey in combination with round trip charging losses are 70% of the charge from the wall box.
Multiplying the claimed 66 miles range by 0.7 gives 46.2 miles which is the order of what the car achieves in the terrain travelled and 9 degrees Celsius. To turn the data in to information the display should also take in to account (from heuristics to date) the charge level that will be available. Here, after charging with 26kWh it would show 18.2kWh available and a likely range of 42.6 miles.

Unfortunately I can’t tell you how the car and app calculate consumption, I doubt meant people even know. One to ask Mercedes Cuatomer Services but I would be surprised if they are specific in their response, they’ll almost certainly say something generic like the following.

The car (and app) will be showing the energy consumption during the journey, and won’t factor in the energy losses during charging. To separately calculate the overall cost per mile you need to know the amount of energy “dispensed” by your charger, by that’s not what the car is showing.

Member @BTB 500 has researched charging losses and has found ADAC data suggesting that some cars lose up to 30% of the charge “dispensed” by the charger during charging, ie poweing battery management systems, battery heating/cooling, telemetry, etc.

That figure varies wildly depending upon the charger, the car, the rate of charge, the level of charge already in the battery, ambient temperature, sophistication of battery temperature control systems, and more. Leaving it plugged in after it’s finished charging can also increase losses.

Either was, the consumption is eye watering, even when factoring in the size and weight of your car. No doubt it’s still relatively cost effective if you charge 100% at home.

 

[JohnK47]

In a Which survey I reported our consumption for the GLE350de as typically 1.8 miles per paid for kWh. Fortunately we have solar panels and are on the intelligent Octopus Go tariff which currently provides electricity from 23:30 to 05:30 at 7 pence per kWh. We have 'Charge from the Grid' scheduled from within this period each night in our Zappi single phase charger. The maximum charge rate for the GLE350de is 3.75kW which is another sore point as when we ordered it, it was 7.5 kW from single phase. Over the Air updates reduced this to 3.75 kW. Our Zappi mode is set to Eco+ and a minimum solar export of 1.4kW before outputting to the car. In order to ensure it does not start to charge from the grid or our home storage battery immediately on connection (ie at peak times) it is necessary to ensure the Charge on Connection parameter is set to OFF.

The ideal Information to be presented for EV's is miles per 'purchased' or otherwise delivered kWh under a set of standard conditions.

 

[JohnK47]

I have now discovered that the usable capacity of a GLE350de (32kWh) battery is 23.4 kWh . Given that it typically takes 26.5kWh for a full charge indicates charging losses of 13.24%.

 

[Bobby Dazzler]

I have now discovered that the usable capacity of a GLE350de (32kWh) battery is 23.4 kWh . Given that it typically takes 26.5kWh for a full charge indicates charging losses of 13.24%.

Sounds about right. It seems 12-15% seems fairly common, and your sounds like it’s almost dead centre, however 25% and 30% are often what is said and some people remember.