Mi/KWHR calculations vs. dash display

[jdunmyer]

My SV has been telling me that I'm getting about 2.7 Mi/KWHR efficiency, pretty consistently. I'm driving fairly conservatively, but running the heater full-bore most of the time, as it's been VERY cold, most every day since I took delivery.

When I installed my EVSE, I connected an old (1950 vintage) Sangamo KWHR meter in the circuit, just for the heckuvit. Today, I read the odometer and the meter, did the calculation, and it figures out to 1.9 Mi/KWHR, while the dash display said 2.7. I've reset the dash display and will perform the same ritual in a week or so.

Is this much discrepancy normal, or is there perhaps a problem with the Sangamo meter? I've not yet checked it, as it's just too darn cold in my detached garage. One of these days, I'll lash up some old electric stove elements to get some sort of read on it.

 

[WetEV]

My SV has been telling me that I'm getting about 2.7 Mi/KWHR efficiency, pretty consistently. I'm driving fairly conservatively, but running the heater full-bore most of the time, as it's been VERY cold, most every day since I took delivery.

When I installed my EVSE, I connected an old (1950 vintage) Sangamo KWHR meter in the circuit, just for the heckuvit. Today, I read the odometer and the meter, did the calculation, and it figures out to 1.9 Mi/KWHR, while the dash display said 2.7. I've reset the dash display and will perform the same ritual in a week or so.

Is this much discrepancy normal, or is there perhaps a problem with the Sangamo meter? I've not yet checked it, as it's just too darn cold in my detached garage. One of these days, I'll lash up some old electric stove elements to get some sort of read on it.

Are you preheating? The dash display doesn't account for preheat usage.

3.3kW or 6kW charger? The 6kW is more efficient, if you can charge at 6kW.

 

[dgpcolorado]

If you are charging at Level 1, 120 Volts and 12 Amps, you should see an efficiency of about 75% (that is, the amount of the energy that makes it to the battery from the wall is only 75% and the rest goes to charging and cooling system losses).

If you are charging at Level 2, 240 Volts and 3.3 kW, you should see an efficiency of about 86-89%. A bit higher if charging to 80%, a bit lower if charging to 100% most of the time.

If you are charging at 6.0 kW (requires an EVSE that can deliver at least 27.5 Amps at 240 Volts and a LEAF with the 6.0 kW charger on it) you ought to see an efficiency a bit higher than 3.3 kW charging (but I haven't seen any report from someone who has measured it).

If you are preheating, the apparent efficiency will drop by a lot and the numbers you get from your Sangamo meter will not be meaningful when compared to the number on the dash efficiency meter.

 

[jdunmyer]

Ahhh! Yes, I do some preheating, and of course it's at 3+ KW because of the extreme cold.

My charging is 100% Level 2, and the 2013 SV has the 6.6 Kw charger. It draws about 28 amps, according to my clamp-on ammeter. Also, I usually charge to 100%, so that will cut the efficiency a bit.

I think you guys have accounted for most of the discrepancy. It'll no doubt improve a lot when the weather warms up, but that's not in the forecast. We're supposed to have 3 relatively warm days this week, but next week's weather is showing cold again.

 

[essaunders]

We're supposed to have 3 relatively warm days this week, but next week's weather is showing cold again.

Don't you love it when warm means 34 degrees (F)?

 

[kovalb]

There will also be a difference between AC and DC efficiency. The car measures DC. The wall meter measures AC. AC efficiency will always be less due to overhead losses. I would expect something around a 15% difference.

 

[jdunmyer]

Don't you love it when warm means 34 degrees (F)?

It was supposed to hit 30 today and the forecast is for 50 on Thursday, but it's then supposed to cool down again, with lows near/at zero next week. We got several inches of snow last night, most of it in just a couple of hours.

I'm very, very interested in seeing what the range is on the Leaf in a bit warmer weather. There was a couple of days in January when it was near freezing and it seemed that the car was much happier than it had been when it was near zero. We went to a restaurant about 20 miles away when it was 8 degrees, and I was frankly a bit scared on the return trip, running with the heat 'off' much of the way. Ended up at 19% SOC, but it was dropping like there was a short-circuit somewhere.

This difference between DC and AC efficiency isn't real important except for cost calculations. The power company charges me for what comes out of the wall, so that's what it costs to drive the Leaf, not the Mi/KWHR reading on the dash.

 

[LeftieBiker]

The range is *much* better in mild weather, and even in hot weather if you use the A/C with the Eco setting. Have you tried using a 12V heated throw blanket, and lowering the air temp to, say, 71? I love my new Blankie. ;-)

 

[jdunmyer]

Can't use a heated blanket, that would do nothing for my wife. And you know what they say, "If Momma ain't happy, ain't Nobody happy!"

Besides, I've not really needed extended range, when any distance is involved, we take the Passat. The trips that have made me nervous were that trip to the restaurant, 40 miles R.T.,and the other day when it wasn't fully charged to begin with. In an attempt to be nice to the battery, and knowing it wouldn't be run on Friday, I didn't plug 'er in Thursday night. Figured I'd charge in the morning for 2 or 3 hours before leaving for lunch, but then decided to do some running first thing, after only a half-hour charge. Although we ended up OK, I was nervous once again, and was sparing with the heat. Fortunately, even though it was cold, the sun was shining and it was bearable.

 

[dgpcolorado]

...It'll no doubt improve a lot when the weather warms up, but that's not in the forecast. We're supposed to have 3 relatively warm days this week, but next week's weather is showing cold again.

Yes, your mileage will improve a lot when the weather warms.

Here the weather is very different: the two feet of snow I got at the end of January, early February is mostly gone. I had three days in a row with highs in the 50s and lows of 36º. This is February? Around here mud season has come early; likely the first of several.

 

[CMYK4Life]

I have a 2013 SV and it has been REALLY cold here this winter. I am in the 2.7mi per kwh Its been pretty hard on range (due to the cold and energy to heat).

Thankfully, I ran this scenario before I leased and as predicted I could still get around like I needed just no long trips.