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Re: Regen vs Neutral and speed for max range

Posted: Wed Nov 07, 2018 6:18 pm
by kiev
Is the bottom part of the hill (between mile 5 to 17) on an interstate? It seems that going 60-67 mph uphill would be using a huge amount of energy.

Of course it doesn't really matter too much because you know you can always coast or regen as necessary to make it back home--but what an awesome climb and return, thanks for sharing the data it's fun to see how these cars can perform such feats of strength.

Re: Regen vs Neutral and speed for max range

Posted: Wed Nov 07, 2018 6:58 pm
by Aerowhatt
kiev wrote:Is the bottom part of the hill (between mile 5 to 17) on an interstate? It seems that going 60-67 mph uphill would be using a huge amount of energy.

Of course it doesn't really matter too much because you know you can always coast or regen as necessary to make it back home--but what an awesome climb and return, thanks for sharing the data it's fun to see how these cars can perform such feats of strength.


Yes, that is I-40 east bound, Speed limit is 65 mph, the whole way to NM-14. I have the option of using old route 66 (which you can do 40 to 45 mph on most of the way instead but after more that 15 attempts I couldn't ever do better than 1% better SOC on old Rt 66 than on I-40, to the north 14 turn off. Often I did worse and it takes significantly longer, so no reason to do it IMO. I try for 66% SOC on the exit ramp from I-40 and usually achieve it. Actually though the miles/kWH average is around 3.6 at that point. As you can see by the destination numbers it gets much worse as the speed comes down and the grade gets steeper.

The car is pretty amazing and I picked the worst end SOC data (strong winds) that I have recorded for that particular trip. Often I get back with SOC from 12% to 19% from the same destination. But if that route were driven "normally" it would be impossible to get all of the way home! Glad you enjoyed seeing the details!

Aerowhatt

Re: Regen vs Neutral and speed for max range

Posted: Thu Nov 08, 2018 8:47 am
by JoeS
Aerowhatt, that is excellent and cohesive information, beautifully supporting your case! I wish I had your discipline in taking those CaniOn snapshots, and seeing your graph just reminded me to download my Tahoe trip Garmin GPS .gpx files.

A couple of procedural questions:

1. Do you push the button on your Android device to take screen snapshots of the CaniOn display during your trip or do you employ some other technique to record and subsequently display the CaniOn information?

2. How did you produce that great altitude and speed vs. distance graph?

Re: Regen vs Neutral and speed for max range

Posted: Fri Nov 09, 2018 12:36 pm
by Aerowhatt
JoeS wrote:A couple of procedural questions:

1. Do you push the button on your Android device to take screen snapshots of the CaniOn display during your trip or do you employ some other technique to record and subsequently display the CaniOn information?

2. How did you produce that great altitude and speed vs. distance graph?


For canion screen shots I’m using a cheap android tablet. It has a touch screen so I just use a single tap on the list on the left side of the canion screen which fairly reliably records a screenshot. With the tablet between the two front seats on the console I can get one at any time without looking away from the road.

GPS data is gathered by “pocket earth” (free) which is an app which that I highly recommend. I have it on my iPhone. By recording a “track” on it and exporting it as a GPX file. Then open the file on a desktop in Google earth pro (free). If you right click the name of the file in the left menu pane. One of your choices in the drop down list is “show” elevation data. This throws up the graphs that I posted below the map of the track. Then I pull the border of the graph map interface up to cover most of the map and enlarge the graph. Take a screen shot of it on the desktop computer (png) and edit away the undesirable edges in the photos app by cropping it. The resulting file is what you see posted on the forum.

Hope this helps,
Aerowhatt

Re: Regen vs Neutral and speed for max range

Posted: Fri Nov 09, 2018 10:11 pm
by JoeS
Aerowhatt wrote:...Hope this helps,
Aerowhatt
Yes, thank you!

Re: Regen vs Neutral and speed for max range

Posted: Fri Nov 16, 2018 11:11 am
by bradleydavidgood777
Aerowhatt wrote:It's not worth talking about it, is the point. Regen when you need to for speed control otherwise coast coast coast.
Aerowhatt


I think this is the best summary of this thread and I completely agree.

Which is why basically I drive in D and use N when appropriate if I'm on a long drive and need to watch my miles. Unless I was in the city with a lot of stop and go, in which case I may use E or B. But even when I've done that I just tend to use D and leave huge space cushions in front of me and partial brake pedal. I find that this is the most comfortable way to drive the car and extremely efficient when done properly.

This past summer I made many 75 mile trips and had about 15 miles remaining, so that's not too shabby. So for me I don't think it's worth making it any more difficult.

And I would recommend this style to any driver of the i-miev who wants a basic simple answer to this thread.

Re: Regen vs Neutral and speed for max range

Posted: Fri Nov 16, 2018 11:58 am
by JoeS
In case anyone is interested in further beating this topic to death, I came across these two applicable threads over on the Tesla TMC forum -

https://teslamotorsclub.com/tmc/threads/does-the-way-you-regen-make-any-difference-to-the-amount-of-charging-done.133056/

https://teslamotorsclub.com/tmc/threads/most-efficient-regen-speed-measured.133846/

Another way of expressing the point I was trying to make regarding aero drag, in one of the posts:

You should regen slowly to get better efficiency overall. Regenerating gently over a longer period of time will always end up using less energy for the same miles driven. Not because it is more efficient, but because your average speed is lower. If you start decelerating earlier and use light regen all the way to the stop, your average speed is slower than when you maintain speed to the last moment and then use max regen. Higher speeds = higher aero drag = higher overall energy loss = more energy used to drive the same distance.

With another poster countering -

Based on the test I did (see my link to the other thread I started) it makes almost no difference if you regen gently over a longer distance/time or regen stronger and shorter.

Whereas driving the i-MiEV I freely bounce around between Neutral and the other settings, when driving the Tesla I have not developed that skill as I invariably have Cruise Control enabled and simply never need to eke out every last kWh out of the battery.