[Sean Nelson]

Regardless of truncation or rounding, in average it should not matter as it happens both with and without A/C?

Either way, your estimate can be out by quite a lot if you just compare the power meter with and without A/C. If the power meter reads "1kW" without and "2kW" with A/C, you'd assume that the A/C was consuming 1kW. But:

- with rounding the actual values might be anywhere from 0.8 and 2.5 (1.7 actual kW) to 1.5 and 1.6 (0.1 actual kW)

- with truncation it could be anywhere from 1.0 and 2.9, (1.9 actual kW) to 1.9 and 2.0 (0.1 actual kW)

So the power meter's lack of resolution really limits how accurately you can estimate things like this. That's why going to the kWh consumed display in the energy info screen can give you a much more accurate picture of what's going on.

 

[Ampera e]

Either way, your estimate can be out by quite a lot if you just compare the power meter with and without A/C. If the power meter reads "1kW" without and "2kW" with A/C, you'd assume that the A/C was consuming 1kW. But:

- with rounding the actual values might be anywhere from 0.8 and 2.5 (1.7 actual kW) to 1.5 and 1.6 (0.1 actual kW)

- with truncation it could be anywhere from 1.0 and 2.9, (1.9 actual kW) to 1.9 and 2.0 (0.1 actual kW)

So the power meter's lack of resolution really limits how accurately you can estimate things like this. That's why going to the kWh consumed display in the energy info screen can give you a much more accurate picture of what's going on.

This is almost trivial. And this is why I wrote "in average".

 

[Sean Nelson]

This is almost trivial. And this is why I wrote "in average".

I dunno - the difference between a potential consumption of 0.1 and 1.9kw based on what you read off the display seems nontrivial to me...

 

[keeperchris]

There is a pretty good thread here:
http://www.chevybolt.org/forum/9-20...t-ev-general-discussion-forum/5866-speed-vs-energy-efficiency-2.html#post366586


As others have noted, I am now seeing about 10% energy usage how that Houston is in upper 90's this week.


This is a summary of my first decent length trip from Houston to Austin (175 miles), although I think I had a bit morerange efficiency.
On the way there atan average of about 75 mph for about 150 miles (@2.9 m/kwh) and about 25 milesin city driving (@5 m/kwh), I pulled up to DCFC charger with about 15 miles(estimating 3 kwh) of range remaining. By those calculations, I used 56.7 kwh,with 3.3 kwh in reserve. Way to close for comfort, and was glad to hitstop-and-go traffic through Austin.
On the way home, Ileft the same DCFC charger at 89% (say 54 kwh capacity), prepared to stop atanother charger on the route. But driving home at 65 mph for about 170 miles(@3.6 m/kwh) and about 5 miles in city driving (@5 m/kwh) I made it home withabout 25 miles (estimating 5 kwh) of range remaining (no stop needed). By thosecalculations, I used 48.2 kwh, with 5.8 kwh in reserve (starting with about 6kwh depleted).


Small note, it isslightly uphill to Austin and downhill to Houston, so that would affect therange efficiency numbers slightly.

 

[Ampera e]

This is almost trivial. And this is why I wrote "in average".

I dunno - the difference between a potential consumption of 0.1 and 1.9kw based on what you read off the display seems nontrivial to me...

I wasn't referring to the difference but to your statement

 

[Ampera e]

BTW: It seems almost obvious that driving faster is less efficient. But driving (much) slower at some point also becomes less efficient. So, there must be a break even point. Pretty sure this is much slower than anybody is willing to drive.

 

[redpoint5]

BTW: It seems almost obvious that driving faster is less efficient. But driving (much) slower at some point also becomes less efficient. So, there must be a break even point. Pretty sure this is much slower than anybody is willing to drive.

On a tangent thought, I've always wondered where the breakeven point is for going up a hill. After all, it takes energy to merely maintain position on a hill (when the brakes aren't on), so going as slowly as possible up it isn't efficient.

 

[psyflyjohn]

I'd drive no faster than 60 mph with the A/C set at 78 degrees. Probably the most efficient combination. Also, stay away from driving Nissan electrics...

 

[Jeff N]

The most efficient speed for EVs is typically around 10 to 20 mph depending on the vehicle.

 

[Fivedoor]

On the question of speed and it's effect on range, I see people complaining about lack of adaptive cruise control.... I don't care for my daily commute (virtually zero traffic = no need for adaptive cruise) but when I go on a long highway run and I slowly pull up behind a semi when I have cruise set on 70 and I watch my KW usage drop from 21 or 22 down to 16 or 17 it makes me long for adaptive cruise as a "drafting on trucks" tool

Keith

 

[raitchison]

I see people complaining about lack of adaptive cruise control.... I don't care for my daily commute (virtually zero traffic = no need for adaptive cruise) but when I go on a long highway run and I slowly pull up behind a semi when I have cruise set on 70 and I watch my KW usage drop from 21 or 22 down to 16 or 17 it makes me long for adaptive cruise as a "drafting on trucks" tool

In general cruise control is going to be detrimental to efficiency because the system makes too frequent and too severe throttle adjustments in an effort to maintain speed as close as possible, this is especially true when going up even slight hills where the car will apply quite a bit of throttle to maintain the set speed when usually you would try to maintain a set throttle position and allow yourself to slow a bit or maybe only apply a little additional throttle to keep your speed from dropping too much on longer hills. I stopped using it years ago in my ICE vehicles because I can drive much more efficiently modulating the throttle myself. I do use it for brief periods on hours long drives to allow me to "stretch" my legs a bit and hive my calf muscle a brief respite.

Now of course it's certainly possible for a car company to design their cruise control to operate with economy in mind, but based on my limited experience testing it in the Bolt and other reports I've heard it does not seem that GM did so for the Bolt.

 

[GJETSON]

Great video for this topic.

Noticed his numbers at the end of the video indicate he has over 61 kWh usable...way more than my 56 kWh usable. :-(

He got the same calculated 61+ kWh usable on his winter run in February. I am soooo jealous. WTF GM.

 

[redpoint5]

If we're talking most time efficient speed on a long trip, I did the math and found somewhere around 75 MPH is the sweet spot assuming you can find a DCFC near to 10% remaining capacity.

That said, there are a lot of variables at play and 75 MPH isn't always the most time efficient speed.

 

[gern_blanston]

Since I got Torque Pro up and running a few months back, my "Usable" has varied from 59.7 to 60.5. It's showing 60.0 today. Doesn't seem to be related to temperature, charge habits, driving habits, charge status, etc. It changes every week or so if it's going to change at all.

 

[GJETSON]

Since I got Torque Pro up and running a few months back, my "Usable" has varied from 59.7 to 60.5. It's showing 60.0 today. Doesn't seem to be related to temperature, charge habits, driving habits, charge status, etc. It changes every week or so if it's going to change at all.

I have calculated our Bolt's capacity many times, using the info off the DIC, and energy screen. It has always been in the 55-57 kWh range. Last month I actually did a test from full to empty, and came up with 56 kWh. Pretty sad, but I know there is not a thing I can do about it. One of the beauties of buying an EV. You never know what you have, until it's too late.

Wouldn't it be great if they put the Torque Pro info on the energy screen, instead of that stupid chassis energy flow cartoon?

 

[gern_blanston]

Wouldn't it be great if they put the Torque Pro info on the energy screen, instead of that stupid chassis energy flow cartoon?

Post of the month!

 

[TDIwyse]

Did a little test today on the power draw when using AC while parked. I did this using Torque Pro and the Bolt PIDs. Below is the data showing the instanteous power consumption reported for when the car is off, then turning the ignition on and letting things "settle", then turning on AC (72F fan speed 4) until things "settle" (consumptions ramps up and then seems to ramp down and settle when the cabin gets close to the desired setting), then turning the AC and Fan OFF and letting settle, then turning on the ignition off.

Looks like the AC can draw considerable power if there is a large amount of cooling needed, but then settles down once the cabin is at/near temp. Maybe ~0.5-0.7kW consumption for a continuous draw (but I'm guessing this amount varies depending on how much hotter the outside is vs the cabin desired setting).

 

[GJETSON]

Looks like the AC can draw considerable power if there is a large amount of cooling needed, but then settles down once the cabin is at/near temp. Maybe ~0.5-0.7kW consumption for a continuous draw (but I'm guessing this amount varies depending on how much hotter the outside is vs the cabin desired setting).

It depends what you think of as considerable. From that graph, and what I gather from the kW load screen on the DIC, the car "idling" pulls between 0.5-1.0 kW. The AC at max output was pulling an additional 2 kW. That is pretty small compared to the heater's max of about 9 kW. Driving down the road at 40 mph takes 9 kW.

Using kWh/mi converted from miles/kWh, and average mph from the DIC, and the percent power to drive, climate, and battery conditioning, you can determine your average power use for each.

I did a ride in March, when it was in the mid to high thirties, rainy and overcast. Did 143 miles, averaging 45 mph. I set the heat to max/90F, and fan to 5. Heat averaged 3 kW, so was on about one third of the time to maintain 90F cabin temperature...more than the AC can pull on high.

 

[TDIwyse]

It depends what you think of as considerable.

The "steady state" with ignition on (after the car settled down with whatever initial stuff is coming on line) was pulling ~0.34 to 0.45 kW (the DIC only shows 0.5 kW resolution which is much more coarse than the OBD shows), so ramping up to 2.82 kW is ~2.82/0.4=7.05 times as much energy. I consider a 7000% increase "considerable"

From that graph, and what I gather from the kW load screen on the DIC, the car "idling" pulls between 0.5-1.0 kW. The AC at max output was pulling an additional 2 kW. That is pretty small compared to the heater's max of about 9 kW. Driving down the road at 40 mph takes 9 kW.

Agree it is smaller than the resistive heater can use. But again, the DIC is too coarse to get an accurate measurement of low power consumption, unlike the OBD that reports to MUCH higher precision.

Using kWh/mi converted from miles/kWh, and average mph from the DIC, and the percent power to drive, climate, and battery conditioning, you can determine your average power use for each.

Or you can just measure things directly from the OBD and isolate each variable and get better accuracy than relying on the DIC and it's coarse resolution.

I did a ride in March, when it was in the mid to high thirties, rainy and overcast. Did 143 miles, averaging 45 mph. I set the heat to max/90F, and fan to 5. Heat averaged 3 kW, so was on about one third of the time to maintain 90F cabin temperature...more than the AC can pull on high.

Good grief, that sounds miserable. 90F?!?!


I'm not sure the AC can't pull more than 3 kW ... I'll have to test that. I could set the temp as low as it would go (instead of 72) and put the fan on high ... based on the pretty easy test I did this afternoon, it wouldn't take much more to move it above 3 kW consumption.

 

[GJETSON]

I consider a 7000% increase "considerable"

That is like people talking about huge percentage increases in EV sales. Seven times nothin' is still nothin'.

Or you can just measure things directly from the OBD and isolate each variable and get better accuracy than relying on the DIC and it's coarse resolution.

I'd love to get one, just as soon as it is plug and play. I am no computer geek. I am terrified of screwing something up, playing with the OBD, and software. That is like a baby with a hand grenade. heck. I can't even figure out how to do a multi quote.

I'm not sure the AC can't pull more than 3 kW ... I'll have to test that. I could set the temp as low as it would go (instead of 72) and put the fan on high ... based on the pretty easy test I did this afternoon, it wouldn't take much more to move it above 3 kW consumption.

I look forward to your result. I did a ride last summer with the AC set to min/65F, but I forget the results, other than it was might cold.