tstrobel
Posts: 9
Joined: Sun Aug 06, 2017 9:13 pm

miles due to regeneration

Wed Aug 30, 2017 1:41 pm

Not sure this is the correct forum for my question, so admins please move if necessary...

My question is "Is there a way to determine how many 'extra' miles one has gotten thru regeneration?" I will occasionally see the estimated range go up slightly, but haven't found a setting to see how many extra miles of range due to proper use of "L" or coasting in D.

I suppose if i ended up with more than 238 on a charge, i can say "there's my extra", but i probably will never get down to empty...


Also, way off topic what do you call the pedal you step on to make the car go? :mrgreen: certainly isn't the gas pedal anymore!

stolenmoment
Posts: 33
Joined: Thu Jan 26, 2017 9:15 pm

Re: miles due to regeneration

Wed Aug 30, 2017 2:17 pm

Also, way off topic what do you call the pedal you step on to make the car go? :mrgreen: certainly isn't the gas pedal anymore!

"Accelerator" is the usual term.

tstrobel
Posts: 9
Joined: Sun Aug 06, 2017 9:13 pm

Re: miles due to regeneration

Wed Aug 30, 2017 2:22 pm

stolenmoment wrote:
Also, way off topic what do you call the pedal you step on to make the car go? :mrgreen: certainly isn't the gas pedal anymore!

"Accelerator" is the usual term.



Yeah, that makes sense :)

PackardV8
Posts: 138
Joined: Mon Jun 12, 2017 2:39 pm

Re: miles due to regeneration

Wed Aug 30, 2017 4:15 pm

I suppose if i ended up with more than 238 on a charge, i can say "there's my extra", but i probably will never get down to empty...
Minor point, but when the battery is totally full, regeneration will no longer activate. That's why the Hilltop/Mountaintop setting tapers off charging before full; so regen can always be available. There are some EV owners, such as those who live in Park City and have a 20-mile downhill run into Salt Lake City. They can garner substantial additional charge during that run, if there's room in the battery to accept it.

jack vines
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NeilBlanchard
Posts: 337
Joined: Tue May 31, 2016 4:58 pm
Location: Massachusetts

Re: miles due to regeneration

Wed Aug 30, 2017 5:01 pm

Regenerative braking is a good thing - but it is not magic. The best you can expect is to use less energy - so if you drive efficiently, you will use less energy per mile.

Friction brakes are 100% loss, and regen is at least 50% loss - so better, but you will still lose energy.

It is most efficient to accelerate as little as possible, then coast - which loses 0% (other than parasitic losses which are always there anyway). Coast in any situation where you need to carry speed, and then use regen only when you need to slow down.

Think of it this way: if you accelerate all the time, and then use regen, you have accelerated too much, and regen will only regain some fraction of what you used.

If you accelerate and then coast - and then use regen, you have used less energy, then regained the maximum possible to carry the car forward WITH NO ADDITIONAL ENERGY. And then you don't need to use regen as much.

So, you use less, and use it better, and then still regain some energy.

tstrobel
Posts: 9
Joined: Sun Aug 06, 2017 9:13 pm

Re: miles due to regeneration

Wed Aug 30, 2017 5:39 pm

NeilBlanchard wrote:Regenerative braking is a good thing - but it is not magic. The best you can expect is to use less energy - so if you drive efficiently, you will use less energy per mile.

Friction brakes are 100% loss, and regen is at least 50% loss - so better, but you will still lose energy.

It is most efficient to accelerate as little as possible, then coast - which loses 0% (other than parasitic losses which are always there anyway). Coast in any situation where you need to carry speed, and then use regen only when you need to slow down.

Think of it this way: if you accelerate all the time, and then use regen, you have accelerated too much, and regen will only regain some fraction of what you used.

If you accelerate and then coast - and then use regen, you have used less energy, then regained the maximum possible to carry the car forward WITH NO ADDITIONAL ENERGY. And then you don't need to use regen as much.

So, you use less, and use it better, and then still regain some energy.



not sure this tells me what i'm looking for. i guess the better, more "common" way would be "how many KWH did i recoup total"

SeanNelson
Posts: 1462
Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: miles due to regeneration

Wed Aug 30, 2017 5:40 pm

NeilBlanchard wrote:Friction brakes are 100% loss, and regen is at least 50% loss - so better, but you will still lose energy.

I think that might be a bit of a pessimistic estimate for regen efficiency, although I do agree that it is far less than 100%.

redpoint5
Posts: 76
Joined: Tue Apr 04, 2017 5:17 am

Re: miles due to regeneration

Wed Aug 30, 2017 5:47 pm

SeanNelson wrote:
NeilBlanchard wrote:Friction brakes are 100% loss, and regen is at least 50% loss - so better, but you will still lose energy.

I think that might be a bit of a pessimistic estimate for regen efficiency, although I do agree that it is far less than 100%.


The conversion process is; kinetic > electrical > chemical > electrical >kinetic.

Perhaps the first part of converting kinetic energy into chemical is above 50% efficient, but completing the conversion back into useful kinetic energy doubles the losses.

50% is likely a reasonable estimate. Earlier vehicles were reportedly only 33% efficient at capturing and reusing kinetic energy (regen).

MichaelLAX

Re: miles due to regeneration

Wed Aug 30, 2017 6:17 pm

tstrobel wrote:My question is "Is there a way to determine how many 'extra' miles one has gotten thru regeneration?"
When I drive from home in Los Angeles to Santa Cruz, I drive Interstate-5 up through the Grapevine to Hiway-46 west to US-101 in Paso Robles to a DCFC. This drive is 196 miles, but leaving Los Angeles I go uphill into the Los Angeles National Forest and burn more KWs than I would on a flat surface.

I seek to gain as much of these back as I can to make a comfortable drive to Paso Robles, especially with the air conditioning on in the hot Central Valley of California.

So going down the 5 miles of the 6% steep downhill grade of the Grapevine, I get in the rightmost "Truck" lane and follow one of these trucks.

Their speed limit is 35 MPH at this point, but many will go 40 MPH, even passing in the next lane those going 35!

I am not trying to "draft" these trucks; I am just trying to safely drive at the slowest speed possible for use of cruise control in "L" mode to maximize regeneration during these 5 miles.

I typically regenerate 1.5 KW at 45 MPH and 2.0 KW at 35 MPH.

So, doing the math at an average of 238 miles per 60 KW of full battery; recovering 2.0 KW will not only cause me to not use any energy during the 5 miles downhill of the Grapevine, but get me another 8 miles towards my trip to Paso Robles; for at least an extra 13 miles.

Not only can I drive more comfortably, but if there is a problem at the single CCS DCFC in Paso Robles, I can then drive the additional 30 miles to San Luis Obispo to use the DCFC there.

But of course, regeneration over the period of 200 miles, gives me much more than that!

SeanNelson
Posts: 1462
Joined: Tue Jul 05, 2016 2:43 am
Location: Vancouver, BC

Re: miles due to regeneration

Thu Aug 31, 2017 1:39 am

redpoint5 wrote:
SeanNelson wrote:
NeilBlanchard wrote:Friction brakes are 100% loss, and regen is at least 50% loss - so better, but you will still lose energy.
I think that might be a bit of a pessimistic estimate for regen efficiency...
The conversion process is; kinetic > electrical > chemical > electrical >kinetic.

Perhaps the first part of converting kinetic energy into chemical is above 50% efficient, but completing the conversion back into useful kinetic energy doubles the losses.

50% is likely a reasonable estimate. Earlier vehicles were reportedly only 33% efficient at capturing and reusing kinetic energy (regen).

Considering that the Volt's charger was found to be over 90% efficient, I'm still pretty skeptical that all the losses add up to that much. GM seems to have done a pretty bang-up job on the electrical systems in this car.

That being said, I of course wholeheartedly agree that momentum maintained is waste avoided.

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