JackHickey
Posts: 19
Joined: Thu Jan 22, 2015 1:37 pm

Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 9:11 am

I have had my Spark EV for a year with 8,000 miles on it. Most of those miles are in L mode. I have no problem maintaining a constant speed or a coasting speed. My mileage in warmer weather ranged from 100 to 120 on a full charge. Those numbers are with lights off. I also shift to neutral at stop lights.

My daily round trips are 6 miles, with an elevation change of 350 feet. I charge up at the higher elevation at home. With a FULL charge, I see little regenerative braking while going down the hill.

My carport is 15 feet above the street level.(a 4000 pound car takes 60,000 ft.lbs of energy to get up my driveway) When I back down my driveway there is no regenerative braking(even without a full charge).

I would like to see GM correct that problem. Braking in reverse should be regenerative. Also, it would help my mileage if they provided a means to set the maximum charge level to 90 or 95%. That way I would recover the energy used to climb the hill. (mostly the 1/10th of a mile from my home)

I may have to put in a circular driveway. ;)

nikwax
Posts: 571
Joined: Sun Apr 26, 2015 3:27 pm
Location: Birch Bay, Washington

Re: Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 9:32 am

why shift to neutral?
2015 Spark EV 1LT DCFC
BF Goodrich g-Force Super Sport A/S
ClipperCreek EVSE

JackHickey
Posts: 19
Joined: Thu Jan 22, 2015 1:37 pm

Re: Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 11:08 am

In D or L there is creep which requires a foot on the brake. That takes charge from the battery.

NORTON
Posts: 1380
Joined: Fri May 01, 2015 5:52 am
Location: KC,MO

Re: Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 11:59 am

JackHickey wrote:In D or L there is creep which requires a foot on the brake. That takes charge from the battery.
No, it does not take charge from the battery. Creep only happens when your foot is off the brake. Look at the display.

If shifting to neutral and finding a 'coast' driving in L makes you happy, fine !
I like the 'coast' the car provides by driving in D.
Also, lately I've been driving on ice and slick snow. There is NO WAY I would try to drive this car in L in those conditions.

If you live on the top of a mountain you should not charge 100%. There is nowhere for the Regen power to go so you end up using friction brakes like and old fashioned Gasser.

Lack of Regen in reverse concerns you !!?? Awesome !
Last edited by NORTON on Sun Jan 24, 2016 6:25 pm, edited 1 time in total.
'14 Spark EV 2LT w/ DCFC. 91k miles.
'17 Bolt Premier w/ It All! 59k miles.
GM needs Modern Troubleshooting tools for Modern EV's.
3 step Trouble Tree, 1st try, nope, 2nd try / cost $800. 3rd try fixed it.

bicycleguy
Posts: 45
Joined: Thu May 14, 2015 5:19 pm
Location: Torrance, Ca

Re: Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 4:58 pm

JackHickey,

Boy I love this Spark! What a fun toy.

Regarding reverse. Here's something fun to try. Put in reverse, grab your balls :o and head down that steep hill and without putting on the brakes slide the shifter into forward. Whalla, regenerative breaking in reverse ! Nice and smooth, just like in when moving forward. Press the gas to stop quicker !

If the hill isn't steep enough the car will come to a complete stop. On wimpy hills you may have to roll in neutral for a little to gain speed (a few mph) before shifting to forward. (Don't touch that brake pedal, thats what the gas is for :o ) The regen (braking effect) is more pronounced than L when moving forward on the same hill.

Not sure if theres any difference between D & L when doing this, I'll have to go play some more to find out !

Almost forgot:
1. Leave the wife at home when practicing this.
2. I have no idea if this hurts the car so I'll keep testing :)
3. Someone on the great internet will take this to extremes and break something :lol:

SparkevBlogspot
Posts: 499
Joined: Mon May 25, 2015 12:19 pm

Re: Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 5:12 pm

NORTON wrote:If you live on the top of a mountain you should not charge 100%. There is no where for the Regen power to go so you end up using friction brakes like and old fashioned Gasser.
I happen to live near top of a mountain, picking up 2 bars on the way down to town. I try to keep it at 80% or less, but sometimes I forget to disconnect (sleep through the alarm clock at 3 AM), and charge to 100%. It's annoying that I can't set it to automatically stop at X%.

SparkevBlogspot
Posts: 499
Joined: Mon May 25, 2015 12:19 pm

Re: Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 5:17 pm

bicycleguy wrote:Put in reverse, grab your balls :o and head down that steep hill and without putting on the brakes slide the shifter into forward. Whalla, regenerative breaking in reverse ! Nice and smooth, just like in when moving forward. Press the gas to stop quicker !
Umm. Doesn't this cause the motor to be powered even more to try to keep the car moving forward? Trying to creep forward takes power, not regen, no?

bicycleguy
Posts: 45
Joined: Thu May 14, 2015 5:19 pm
Location: Torrance, Ca

Re: Regenerative braking in reverse down a steep driveway

Sat Jan 23, 2016 5:33 pm

Restating using words for the actual direction and letters fro the gear position:

Regarding reverse (and R). Here's something fun to try. Put in R, grab your balls :o and head down that steep hill in reverse and without putting on the brakes slide the shifter into D. Whalla, regenerative breaking in reverse ! Nice and smooth, just like in when moving forward. Press the gas to stop quicker !

If the hill isn't steep enough the car will come to a complete stop. On wimpy hills you may have to roll in N for a little to gain speed (a few mph) before shifting to D. (Don't touch that brake pedal, thats what the gas is for :o ) The regen (braking effect) is more pronounced than L when moving forward down the same hill.

Not sure if theres any difference between D & L when doing this, I'll have to go play some more to find out !

Almost forgot:
1. Leave the wife at home when practicing this.
2. I have no idea if this hurts the car so I'll keep testing :)
3. Someone on the great internet will take this to extremes and break something :lol:
4. Put on your thinking cap before trying this. Once you try it all becomes obvious. (to me)

NORTON
Posts: 1380
Joined: Fri May 01, 2015 5:52 am
Location: KC,MO

Re: Regenerative braking in reverse down a steep driveway

Sun Jan 24, 2016 8:42 am

bicycleguy wrote:.. in reverse and without putting on the brakes slide the shifter into D. Whalla, regenerative breaking in reverse ! Nice and smooth, just like in when moving forward. Press the gas to stop quicker !....
This sounds like you are USING power to slow from reverse to a stop. Sort of like Electric Brakes, NOT Regen Brakes. Don't look at the display. Look over your shoulder !!

Is all this to avoid using those pesky friction brakes?
You know, the way this BEV goes through those brake pads you may have to install a new $45 set every 150-200 k miles.

You know, GM did a great job engineering the 'Blended Brakes' in this car. You are not using the friction brakes when driving in D and stepping on the brake pedal, until you feel that little bump at 2-3 mph when slowing to a stop. That's when the friction brakes take over. Of course any time you are pressing hard and go beyond the 'Regen' display limit those brake pads start working.

Brand T and B do not have blended brakes on their BEV brake pedal. The brake pedal is friction brakes, Only. They demand you drive this new '1 Pedal Method' in their BEV's. Lazy engineering?
I've been driving in ice and snow lately. There is no way I want full regen when I lift off the Go pedal
'14 Spark EV 2LT w/ DCFC. 91k miles.
'17 Bolt Premier w/ It All! 59k miles.
GM needs Modern Troubleshooting tools for Modern EV's.
3 step Trouble Tree, 1st try, nope, 2nd try / cost $800. 3rd try fixed it.

SparkevBlogspot
Posts: 499
Joined: Mon May 25, 2015 12:19 pm

Re: Regenerative braking in reverse down a steep driveway

Sun Jan 24, 2016 11:36 am

NORTON wrote:This sounds like you are USING power to slow from reverse to a stop.
That's what I thought, too, and posted as such. But he repeated himself, maybe there's some firmware bug that allows this? I'm not about to try it on my SparkEV.
NORTON wrote:Brand T and B do not have blended brakes on their BEV brake pedal. The brake pedal is friction brakes, Only.
Whoa? I had NO idea! I guess that's why T & B always complain about lack of 1 pedal driving, even for gas cars.

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