Cool unscientific regen test

[jamnmon66]

So I drove from my house in Brighton (NE of Denver) to the top of Mount Evans today. It's about 160 mi. round trip (incl. a few errands on the way) with an elevation change from ~5000 ft. to ~14,000 ft. I charged to 100% just prior to leaving just in case we decided on a detour.

I used 57% of the battery to get up there (indicator showing 43%). I wish I would have thought to take a picture of the screen but the wh/mi was over 370.

On the way down, I was recharging the battery with regen. The wh/mi went to -180 after 20 miles or so (you read the negative number correctly). Again, I wish I would have thought to take a picture, but I didn't. The battery was back up to 48% at one point in Lakewood. By the time I got to the grocery store near my house, the battery was at 38% and my total wh/mi for the round trip was 260.

It was hot in Denver today. The car said 106 at one point before I left town. I had the AC set at 65 until we got pretty high up (it was in the mid 50's at the top). Also, I have a lead foot and I wasn't taking it easy. I My total wh/mi in 2800 miles of ownership is about 260 so the average on this trip was as if the mountain wasn't even there.

Fun test on a fun trip.

 

[jamnmon66]

Holy crap the car was fun to drive on this trip. Should have mentioned it in the first post. It's got so much torque... silky smooth, electric torque. And the handling... just so good. On the way down, the regen easily slowed me down on even the steepest parts of the drive. I only really used the friction brakes when I was going a little too hard into the turns. Often this was because I was trying out AP and it didn't slow down enough for the sharper turns.

And then, after all the fun, we hit rush hour traffic and I was spoiled by AP. Such a great car!

 

[ewoodrick]

So I drove from my house in Brighton (NE of Denver) to the top of Mount Evans today. It's about 160 mi. round trip (incl. a few errands on the way) with an elevation change from ~5000 ft. to ~14,000 ft. I charged to 100% just prior to leaving just in case we decided on a detour.

I used 57% of the battery to get up there (indicator showing 43%). I wish I would have thought to take a picture of the screen but the wh/mi was over 370.

On the way down, I was recharging the battery with regen. The wh/mi went to -180 after 20 miles or so (you read the negative number correctly). Again, I wish I would have thought to take a picture, but I didn't. The battery was back up to 48% at one point in Lakewood. By the time I got to the grocery store near my house, the battery was at 38% and my total wh/mi for the round trip was 260.

It was hot in Denver today. The car said 106 at one point before I left town. I had the AC set at 65 until we got pretty high up (it was in the mid 50's at the top). Also, I have a lead foot and I wasn't taking it easy. I My total wh/mi in 2800 miles of ownership is about 260 so the average on this trip was as if the mountain wasn't even there.

Fun test on a fun trip.

Just did a drive over the Smokies. 30 miles up and 30 miles down from 1,000 to 6,500 and back. My efficiency went above 800 wh/mi on the way up and below -200 wh/mi on the way down.

 

[ChadS]

For a car of this weight, you can expect to expend an extra 7 miles for every 1,000 feet of elevation gain. And get back about 4 of them on the way down.

At 9,000 feet, you would have used 63 extra miles going up, but got back 36 on the way down. So the net loss is about 27 miles.

The trip was 160 miles, plus the net loss means you burned 187 miles for the distance and elevation.

Now you need to adjust for weather and driving style. 106 is a nice temperature for batteries and would improve your range a bit. But you had AC on and drove aggressively, so that gain was no doubt overridden. Probably not by much though, I wasn't there but let's add 10 miles.

If you started with 310 miles and burned through 160+27+10, that's 197 used so you should have gotten home with about 113 miles left. That is 36.5%. you said you hit 38% shortly before home. So that is pretty close to the estimate.

 

[RedModel3]

You've discovered physics!

 

[dgpcolorado]

...Now you need to adjust for weather and driving style. 106 is a nice temperature for batteries and would improve your range a bit. But you had AC on and drove aggressively, so that gain was no doubt overridden. Probably not by much though, I wasn't there but let's add 10 miles...

Driving up a hill that long and steep should kick on the AC for the drive train even without using cabin AC. I see this a lot where I live.

 

[ChadS]

Agreed, pack HVAC is automatic. And from numbers i have seen in the past may be a larger hit than cabin HVAC, though of course that depends on conditions.

Still, Tesla's range estimation tool shows range going up as temperature increases (at least to 110 degrees) even though I *assume* pack cooling is included. Of course Tesla won't actually give us details like that.

 

[jelloslug]

Just did a drive over the Smokies. 30 miles up and 30 miles down from 1,000 to 6,500 and back. My efficiency went above 800 wh/mi on the way up and below -200 wh/mi on the way down.

We just did Mt Mitchell to Hickory a few weeks ago in our Model S and I saw -278 at one point. It did not zero back out until we had gone over 40 miles.

 

[jamnmon66]

You've discovered physics!

LOL. I know. I'm a total science fan boy. I just think it's cool that there's not some other loss somewhere... or at least it's minimal per ChadS's post.

 

[jamnmon66]

Just did a drive over the Smokies. 30 miles up and 30 miles down from 1,000 to 6,500 and back. My efficiency went above 800 wh/mi on the way up and below -200 wh/mi on the way down.

Very cool.

 

[ebmcs03]

Someone go try it up pikes peak.

 

[J X 3]

You did it wrong!
If you wanted to have some fun, you should have added weight at the top. As many rocks as you could fit or something.

Potential energy = mgh so adding weight is a good thing when going down. Ofc you have drag, rolling resistance and the efficiency losses of the system that will eat up a large part of that potential energy.
Anyway, add enough weight on your way down and you gain energy for the round trip.

We finally figured out why rocks were invented!

PS: if those rocks were pure gold, you could add over 8000kg in the 15 cubic feet trunk+frunk but with the average rock, you are gonna want to fold down the rear seats as you get about 8 times less weight per volume.

 

[ChadS]

Someone go try it up pikes peak.

I have. I don't recall the numbers now, but things worked as expected. There is a thread somewhere where someone posted their numbers for a Model S (which is notably heavier, so loses and gains more, for a somewhat larger net loss). Someone has done Haleakala as well.

Speaking of rocks: there are some enormous dump trucks working at mines that are never charged - they get all energy from downhill regen while full, then they drive back uphill empty. Obviously that only works for downhill loads.

 

[J X 3]

And that's how you hypermile forever.

 

[Skotty]

So I drove from my house in Brighton (NE of Denver) to the top of Mount Evans today. It's about 160 mi. round trip (incl. a few errands on the way) with an elevation change from ~5000 ft. to ~14,000 ft. I charged to 100% just prior to leaving just in case we decided on a detour.

I used 57% of the battery to get up there (indicator showing 43%). I wish I would have thought to take a picture of the screen but the wh/mi was over 370.

On the way down, I was recharging the battery with regen. The wh/mi went to -180 after 20 miles or so (you read the negative number correctly). Again, I wish I would have thought to take a picture, but I didn't. The battery was back up to 48% at one point in Lakewood. By the time I got to the grocery store near my house, the battery was at 38% and my total wh/mi for the round trip was 260.

It was hot in Denver today. The car said 106 at one point before I left town. I had the AC set at 65 until we got pretty high up (it was in the mid 50's at the top). Also, I have a lead foot and I wasn't taking it easy. I My total wh/mi in 2800 miles of ownership is about 260 so the average on this trip was as if the mountain wasn't even there.

Fun test on a fun trip.

Mountains are a great way to demonstrate the value of regen. Coasting down the mountain using only regen and watching your "fuel" level go up all the way down is a most awesome experience. I have family in CO so I've done it before.

 

[ebmcs03]

I have. I don't recall the numbers now, but things worked as expected. There is a thread somewhere where someone posted their numbers for a Model S (which is notably heavier, so loses and gains more, for a somewhat larger net loss). Someone has done Haleakala as well.

Speaking of rocks: there are some enormous dump trucks working at mines that are never charged - they get all energy from downhill regen while full, then they drive back uphill empty. Obviously that only works for downhill loads.

Re: Dump trucks That’s cool. I can see how that would work.

Oh ya. Haleakala would be a good one too. I’ve been at the top of both. Haleakala and Pikes Peak! =) not in a EV tho

 

[Polly Wog]

So, I'm the guy who has done Haleakala (a number of times) here on Maui with my Model S. The best I've ever done descending is a net gain of 35 rated miles, but I have averaged about 30 over the course of 50 plus trips. We received our Model 3 last week, and yesterday was my first chance to drive it up to the summit of Haleakala (10,000 feet elevation, for those not familiar). I took lots of pictures, but I'm still getting used to the display layout on the Model 3 and wasn't able to capture as much information in each shot as I could with my Model S. Still, I gathered a lot of data. Inserted below, I have 4 pictures that show the trip status at the following places: 1) Base of Haleakala Highway, at about 100 feet elevation; 2) summit of Haleakala when I arrived; 3) summit of Haleakala before descending; and 4) base of Haleakala highway after my descent. I gained 40 rated miles on the descent (about 9.5 kWh of energy). From the base of Haleakala highway to the summit and then back down to the base, I used 55 rated miles to go 70.9 miles. Damn impressive, as far as I'm concerned! I was stuck in slower traffic both ways, so I averaged about 30 miles per hour each way. Temperatures were around 55 at the summit and 85 at the base. I have the 18" Aero wheels with covers, and the tire pressure was 44 psi. @ChadS, your numbers are pretty dang close (4 miles gained per 1,000 feet on the descent - not counting miles traveled, and 5.9 extra rated miles used per 1,000 feet on the ascent).

 

[ChadS]

Thanks for the detailed numbers, Polly Wog. Your slower speeds helped use less energy too.

When I mentioned (above, this morning) doing Pikes Peak, I was in the Black Hills and forgot where we were driving today...we will go past the entrance to Pikes Peak in about 30 minutes. Probably too late to go up for today, but no matter. I have already been there in an EV, and OP and Polly Wog have also given us great numbers.