Engage Display

[dbspl]

Does anyone know how the major hash-marks are calibrated on the "engage display" for the engine and electric motor power bands? If I had to guess, I would say 10 kw, but after I thought about it, that seems a little low.

 

Any ideas?

[larryh]

For the empower screen, each mark represents 10 kW.  I'm not sure for the other displays.  The approximate power required for various speeds is shown below:

 

mph          kW

20             2.7

30             4.6

40             7.1

50             10.8

60             15.3

70             22.6

Edited December 15, 2013 at 01:50 PM by larryh

[dbspl]

Got it. Thanks.

 

I thought that was it, but I also noticed the display range isn't enough to represent the engine (or motor) power when under high/max loads. But I guess if you're driving the car that hard you don't need to be looking at the display anyway:) 

[larryh]

When switching between Engage and Empower, the marks don't seem to line up. The marks seem to represent about 12 on the Engage screen--but I can't be sure.  When power is as 20 kW, two marks, on the Empower Screen, the bar occupies less than two marks on the Engage screen.  If you accelerate hard, it could be that the car rescales the display.  I haven't tried it. 

Edited December 16, 2013 at 11:59 PM by larryh

[meyersnole]

For the empower screen, each mark represents 10 kW.  I'm not sure for the other displays.  The approximate power required for various speeds is shown below:

 

mph          kW

20             2.7

30             4.6

40             7.1

50             10.8

60             15.3

70             22.6

 

Larry, how would I read that second column? Is that the amount of energy consumed in an hour at that speed?

 

So I could look at it this way?

 

MPH   kW      20 miles   Time   Hours:mins

20       2.7      2.70           1          1:00

30       4.6      3.07         0.67       0:40

40       7.1      3.55         0.50       0:30

50      10.8     4.32         0.40       0:24

60      15.3     5.10         0.33       0:20

70      22.6     6.46         0.29       0:17

 

If that is correct, I must be doing something wrong. The above 20 mile chart suggests that you might be able to travel 20 miles at 70 mph, where I am almost sure that the range would be no where near that... what am I doing wrong? In the chart, it takes 17 mins or .29 hours to go 20 miles consuming 6.46 kW, right?

Edited December 17, 2013 at 06:23 AM by meyersnole

[larryh]

The second column is the rate at which energy is consumed.  So yes, if you were able to consume 22.6 kW of power for 1 hour, you would use 22.6 kWh of energy. 

 

As you have shown, going 70 mph for 20 miles would take 20/70 = 0.286 hours, or 0.286*22.6 = 6.46 kWh of energy.  However, you can only extract about 5.8 kWh of energy from the HVB before entering hybrid mode.  You might be able to go at most 5.8 kWh / 22.6 kW = 0.257 hours or 15.4 minutes at 70 mph, or about 18 miles.  It depends on how much energy you can extract from the battery.  The 5.8 kWh is what I have observed for going about 30 mph.  If you go faster, the ICE will turn on earlier, so you won't be able to extract that much.  If you look at the Empower display when it turns to hybrid mode, the threshold for turning on the ICE is about 20 kW.  At 30 mph you will be below the threshold and be able to extract more energy (up to about 5.8 or 5.9 kWh).  At 70 mph, you will be over the threshold and will not be able to continue to extract more energy from the battery. 

 

You can easily compute the power consumed at constant speed from the MPGe for that speed as shown on the car's display using a trip odometer.  MPGe is miles / equivalent gallon.  An equivalent gallon is 33.705 kWh of energy.  So at 70 mph, MPGe is about 104 MPGe.  That amounts to 1 / 104 = 0.00962 equivalent gallons / mile = 0.00962*33.705 = 0.324 kWh / mile.  You will go 70 miles in one hour, so you will have then consumed 0.324 * 70 = 22.6 kWh of energy.  The power required to go 70 mph is thus 22.6 kW.

Edited December 17, 2013 at 09:52 AM by larryh

[meyersnole]

Thanks Larry, so it is good to know the math was right I just had the numbers in my head wrong. I was comparing against the total battery ~7.1 kW and that just did not make sense.

 

That table was very helpful, I know that the section of my commute where I am going 55-60 is killing my range, now I can see by how much ;)