The First Mile or So

[Gigi]

I was surprised to see my FFE consuming nearly 500 Watts per mile for the first few miles I drove today. The heat was off. It was a balmy 55 degrees outside. By the time I had driven a mile and a half, my budget was -4 miles. What gives? What is the car doing or not doing to consume so much juice? Is the TMS drawing current warming the battery?

By the time I had driven 14 miles, my budget was up to 0 and my average Watts per mile was 235, which is just fine. I'm curious about what's going on.

 

[WattsUp]

I've noticed this too... I would suspect TMS.

 

[v_traveller]

For that first mile and a half, did you have a net elevation gain, and/or take the reading of 500 Wh/mi after accelerating to, say, freeway speeds? Could be a factor, along with TMS kicking in... I get that when I start my commute from one of my work sites where the freeway is elevated and I'm hustling up to 70mph in short order, within about a mile. Settles down to about 325-350 Wh/mi when cruising in the HOV lane at ~75mph (...but I was just keeping up with traffic, officer....)

 

[Gigi]

For that first mile and a half, did you have a net elevation gain, and/or take the reading of 500 Wh/mi after accelerating to, say, freeway speeds? Could be a factor, along with TMS kicking in... I get that when I start my commute from one of my work sites where the freeway is elevated and I'm hustling up to 70mph in short order, within about a mile. Settles down to about 325-350 Wh/mi when cruising in the HOV lane at ~75mph (...but I was just keeping up with traffic, officer....)

The terrain is slightly uphill from my driveway to the top of a ridge, maybe 8 or 10 feet rise in elevation. Then it's down to a creek maybe 80 or 90 feet. I regenerate on the way down and then expend that coming up the steep hill on the other side of the creek. Speed limit in the neighborhood is 25. There are two three-way stops that are generally treated as three-way rolls. By the time I've gone nine tenths of a mile to the entrance to my neighborhood, which is actually at about the same elevation as my house, I can be -3 against my budget.

 

[jmueller065]

I've noticed that as well: When starting out with a full battery and a reset trip meter it "burns" more (like 500 Wh/mile or so) even just down our street. It doesn't settle down to the 250-270 Wh/mile until after a few lights where regen seems to lower it into the usual range.

I see this as normal: It is very similar to resetting the mpg meter in our ICE Focus after filling the tank of gas. The mpg meter will read some very low values until you get to some steady state roads (45 MPH rural route or freeway).

 

[dmen]

The terrain is slightly uphill from my driveway to the top of a ridge, maybe 8 or 10 feet rise in elevation. Then it's down to a creek maybe 80 or 90 feet. I regenerate on the way down and then expend that coming up the steep hill on the other side of the creek. Speed limit in the neighborhood is 25. There are two three-way stops that are generally treated as three-way rolls. By the time I've gone nine tenths of a mile to the entrance to my neighborhood, which is actually at about the same elevation as my house, I can be -3 against my budget.

Are you sure your car is "regenerating" on the way down to the creek? If you're leaving the house with a full battery it probably isn't charging the battery on the coast down bc it doesn't have anywhere to put the energy. So the trip down uses a little rather than gaining. And the trip up, even if slow, can eat up enough energy to cause your observed results. If your average efficiency is 250 Wh/mi and getting up the hill and out of your neighborhood uses about 500 Wh to go a mile, the car predicts you'll continue to drive less efficiently and starts knocking down the range estimate. Of course when your driving then matches usual efficiency, the estimate comes back up.
If you're leaving the house with a not-quite-topped-off battery then yeah you should be regenerating and something else is responsible.

 

[paw160]

I've noticed this too, but I notice it especially if I have to reverse for any significant distance immediately after starting. At work sometimes I have to reverse halfway through our parking lot because it is so tight, and I've seen 999wh/mi when I put the car in D afterward.

I assumed that there was something funky about the way the software integrates power with negative speed.

I keep meaning to try parking backwards to see if it happens when I start the car pointed forward or not.

-Pat

 

[sefs]

I've noticed this too, but I notice it especially if I have to reverse for any significant distance immediately after starting. At work sometimes I have to reverse halfway through our parking lot because it is so tight, and I've seen 999wh/mi when I put the car in D afterward.

I assumed that there was something funky about the way the software integrates power with negative speed.

I keep meaning to try parking backwards to see if it happens when I start the car pointed forward or not.

-Pat

999 wh/mi happens every time I reset my trip meter. This is just because A: The efficiency calculation caps out at 999 wh/mi, and B: at initial start up, you have used the motor to start moving and there is very little distance in the calculation; therefore the efficiency calculation hasn't had a chance to average over any meaningful distance. This is akin to resetting your MPG in your car. Immediately after you do this, it shows that you are getting 1 or 2 MPG, but after some driving (adding distance and averaging high consumption with low consumption) you get a more representative answer.

 

[paw160]

sefs: Sure it's a small math problem. Divide by a little number and get a big number for short distances. But I think it's possible that their bad math might extend to the reversing condition.

This corresponds to some other behaviors, such as the budget surplus will jump to -10 or something after reversing and then recover back to near 0 after a short distance in drive.

 

[jmueller065]

This corresponds to some other behaviors, such as the budget surplus will jump to -10 or something after reversing and then recover back to near 0 after a short distance in drive.

And the "instant power" usage line going to the top when you stop. (that kind of bugs me)

 

[paw160]

And the "instant power" usage line going to the top when you stop. (that kind of bugs me)

jmueller065: that would actually be correct since it's in Wh/mi. When you aren't moving this number is technically infinite. I'd really like to see a kW meter (not per mile). It would also make it easier to accurately figure out the power used by different modules (heater, stereo, etc.)

 

[jmueller065]

jmueller065: that would actually be correct since it's in Wh/mi. When you aren't moving this number is technically infinite. I'd really like to see a kW meter (not per mile). It would also make it easier to accurately figure out the power used by different modules (heater, stereo, etc.)

Um yeah sure: divide by zero and all...I'd like to see it drop to zero at that point, but it can't because it also includes the power used by everything else (so it is (some value>0)/(0) instead of simply 0/0 ).

I'd still like that scale also have <0 values so that you can see how many Wh/mi are going back into the battery during regen instead of the silly circle that just indicates "you're regenerating" (you know a quantity might be nice--how much are we regenerating)... but I digress.

 

[WattsUp]

999 wh/mi happens every time I reset my trip meter. This is just because ... The efficiency calculation caps out at 999 wh/m

Haha, that reminds me... anybody else notice that they finally fixed the order of the "Zen Master" rankings on the MFM website? The rankings used to be sorted by "highest consumption" first, which obviously caused all the non-Zen drivers to "win" that ranking. But, what's worse (due to software bugs I'm sure) all of the top non-Zen cars had impossible (or at least ridiculous) rates of consumption, such as 2500 Wh/mi.

So, yeah, the sort order was recently fixed, and now it correctly ranks cars "lowest consumption" first. But (due to even more software bugs) all of the top cars still have impossible/ridiculous of rates of consumption... but this time it's 0 Wh/mi. This is almost certainly related to the same bug that causes my Trip & Charge Log to show "--" (likely due to a zero or missing value) as the rate of consumption for each trip. (My log had meaningful values for those rates before the October update, btw.)

It's all just sad.

 

[jmueller065]

This is almost certainly related to the same bug that causes my Trip & Charge Log to show "--" (likely due to a zero or missing value) as the rate of consumption for each trip. (My log had meaningful values for those rates before the October update, btw.)

My log has never had any values for those rates... I've pondered if the problem is with the car incorrectly sending the data out, or the website just not parsing the data from the car properly--still really can't tell at this point!

 

[Focused_Driver]

I wonder of the initially higher consumption could be due to greases and such needin to warm up so the car rolls easier, and maybe some brake drag? Brake calipers tend to hang near the calipers right after a stop and might cause some brake drag related losses?

Regarding Zen Master being flipped- Hooray!! They do need to only show drivers that have actually driven some miles, that might eliminate the HUGE number of 0's in the ratings.

 

[Gigi]

Are you sure your car is "regenerating" on the way down to the creek? If you're leaving the house with a full battery it probably isn't charging the battery on the coast down bc it doesn't have anywhere to put the energy.

I think you're on to something. The last time I left the house with a full battery, when I put the car in L going down the hill to the creek, it didn't seem like it did much to slow the car.

Update: dmen is right. This morning, leaving the house with a full charge, when I started down the hill, I put the car into L. I noticed that for the first little bit, it held the speed down, but then it was as if the car went into free-fall and I had to use the brakes to slow the speed. Apparently, when the battery is completely full, the motor stops functioning in regeneration mode.

This means that for my first nine tenths of a mile from my house to the front of my neighborhood, I've got a downhill that gives me next to nothing in regen and a steep uphill that takes a lot of Watts. No wonder I'm at -4 by the time I reach the end of the first mile.