Blaine

451 ED Energy Usage vs Temperature

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Someone else may find this interesting.   This is a chart of our 451's reported energy usage in Wh/km vs ambient temperature.   It consists of 96 trips of at least 10 km from October to December.   I pulled it together from our fleetcarma vehicle tracker data.  Kudos to FleetCarma for a nice product.

 

Under 10 km there is a lot of variability, and particularly so as the trip distances drop down to 1-2 km.   I'd assume that's quick acceleration, hill climbing or something similar skewing the values for a short trip.

chart.png

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Am I reading this correctly, that there is no correlation between temperature and energy usage?

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Firstly, the number of data points is relatively low, so statistically it is a bit dubious to draw major conclusions.   However, this isn't the first time this kind of data has been shown for EVs.

 

In looking at these numbers you should be aware that we only use the cabin heater for defrosting the windows.  We have a set of seat warmers under the floor mats to keep our feet warm.

 

Roughly speaking I have a few observations from the data  

  • At any given temperature there is a lot of variability in energy efficiency.  So road, wind, traffic and driving style have a significant effect.   Maybe on the order of 50%.
  • As expected, there is a bit of an upward hook in energy usage when the temperature drops below -5C.   That's just physics.

Looking at our FleetCarma overview it says we have an average efficiency of 132 Wh/km over 2062 km.   Again, small data set.     Numbers for a Tesla Model S seem to be anywhere from about 175 to 225 Wh/km. 

 

So the 451 is a lot more efficient than a Model S, even though it has the aerodynamics of a brick. 

 

Under -5C the car becomes progressively less pleasant to drive.  Shorter range, weaker performance, battery sucking heating system. 

 

I'll try to remember to post an update in the spring, after we have more data.

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I have both a 2013 Tesla and had a 2013 Smart ED, now upgraded to 2017 Smart ED.

The Tesla is equally as efficient for my 40 km round trip city commute.

The new Smart ED is more efficient than the old Smart ED, by 15% less energy use on the highway, but similar in city.

New Smart ED has heated steering wheel, big benefit over my older EV's.

 

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Wow that's impressive for the huge heavy Tesla, or an indictment of the smart, or a bit of both!

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Car size matters less in the city where the average speed is 40 km/h for my commute, both cars have good energy recuperation on braking, the Tesla is a bit stronger which I prefer.

 

As for heating/cooling, the Tesla certainly can use more, but the heated seats in both cars usually mean I don't need to run a loud fan to heat the cabin.   I generally pre-condition the Tesla at my desk before going out to the parking lot, so that's a big benefit over the Smart in the winter for sure.

 

The Smart has a small cabin, so it heats up very quickly.   The Smart ED uses 3kW on average during the coldest days to heat the cabin, the Tesla can peak at 6kW, but once the cabin is up to temperature, and the heated seats are maxed out, the heaters pretty much stop and I "coast" home using only the motor energy.

 

I personally feel the Smart ED is less well engineered than the Tesla, by a massive margin, I commented to my wife tonight just how much stuff Tesla got right that Mercedes with all their years haven't.   Simple stuff like an app that can pre-heat the car without being plugged in.   Really sad indictment on how little innovation there is at Mercedes.   Even BMW got that right in the i3, good app support is a basic thing.    Ford is also lagging, their app routinely doesn't work for Focus EV customers, I see that reported on the forums.

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On ‎12‎/‎20‎/‎2017 at 7:38 PM, SmartElectric said:

I have both a 2013 Tesla and had a 2013 Smart ED, now upgraded to 2017 Smart ED.

The Tesla is equally as efficient for my 40 km round trip city commute.

The new Smart ED is more efficient than the old Smart ED, by 15% less energy use on the highway, but similar in city.

New Smart ED has heated steering wheel, big benefit over my older EV's.

 

 

Have you compared the Range of your new 453 with what you were getting with your old 451 yet? My wife has a 451 she wants to trade on the new one, but the reduced EPA rating of 58 miles versus the old 68 miles is really discouraging her off if it's true - it would not be possible to even make it to the M-B dealer for service etc. as she barely manages it now! Would appreciate if you'd shed some practical light on this issue if possible.

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I have heard that the 2017 test methods the EPA uses for range changed to become more conservative, so the actual range is apparently about the same as the 451 ED.

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I would like it if the EPA or others would mandate a four ranges be posted:  city and highway in both winter and summer for range with the interior at a comfortable temperature (i.e. using heat like one might in a normal car...)  It may temporarily dampen enthusiasm a bit, but would hopefully spur the companies to start taking dramatic loss of battery capacity (50%) when it gets cold for long periods of time, seriously.

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The range of the new Smart ED is better than the old Smart ED, that is for certain, confirmed both 15C and -15C weather.

Not by much, but better for sure.

 

However, last night in -22C the new Smart ED could not fully defrost the windshield.

The old Smart ED was also not great in -20C weather, but I recall it being more effective at defrosting.

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