Regen fail - scary

[ElSupreme]

Another advantage for a dual motor / AWD setup. If battery is too olod or too full, the second motor could use up the regen energy for 'braking'. Would create a much more consistent regen behaviour.

This isn't really possible. You would be destroying energy. You have to dissipate the kinetic energy of the car into heat, or electrical/chemical energy in the battery.

When an AC induction motor is moving forward you can't 'power' it the opposite direction. When you go reverse to drive you can notice a quick 'jostle' where the car has applied the e-brake and the car starts moving the opposite direction.

 

[T@oo]

In my ICE, assuming full throttle and 35% efficiency, the cooling System would need to cope with about 100 kw of heat. And that just a mid sized Diesel Engine... imagine a Veyron.

 

[ElSupreme]

In my ICE, assuming full throttle and 35% efficiency, the cooling System would need to cope with about 100 kw of heat. And that just a mid sized Diesel Engine... imagine a Veyron.

Most of that heat is being dumped into the atmosphere from drag, and tailpipe emissions temperature. When you stop your brakes get hot and radiate the heat to the environment.

Sure you have a coolant loop, and it is much bigger than the Model S. But remember that the motor in the Model S is about 1/4 the size of an ICE. And runs MUCH cooler, so no radiation losses to speak of.

 

[Zextraterrestrial]

This isn't really possible. You would be destroying energy. You have to dissipate the kinetic energy of the car into heat, or electrical/chemical energy in the battery.

When an AC induction motor is moving forward you can't 'power' it the opposite direction. When you go reverse to drive you can notice a quick 'jostle' where the car has applied the e-brake and the car starts moving the opposite direction.

I'm not sure about that.
when I park I use my reverse to stop my forward rolling. No e-brake is applied. sometimes it won't let you put in in R while you are rolling forwards too fast though.

you can do the same on a hill in 'drive', start rolling backwards a then accelerate

 

[DriverOne]

Oh, that's what that dashed line on the energy dial means? I thought it was a software bug when I once saw it!

 

[ElSupreme]

I'm not sure about that.
when I park I use my reverse to stop my forward rolling. No e-brake is applied. sometimes it won't let you put in in R while you are rolling forwards too fast though.

you can do the same on a hill in 'drive', start rolling backwards a then accelerate

I think if you are in reverse, and use regen as you slow down, and change directly to drive while still moving backwards, the e-brake engages for a second, while you swap leads to the motor to change direction. I get a noticeable 'jostle' when I do that. I have not ever gone from D to R without stopping 100%, it has a much lower threshold for speed it seems.

 

[agentsmith1612]

The Volt has 2 regen settings associated with the D and L positions on the shift lever. L gives the highest regen. And, yes, when you let off the accelerator pedal, regen kicks in.

Thats right but a slight correction.
If you take in D and get of the pedal a normal regen starts. If you take on the breaks very carfully the regen goes to a maximum, before the mechanical breaks starts working.
In L, there is the same procedure with the differents that the "first" regen is stronger. But in L and taking on breaks the regen increases a little bit more, some engineer who measured the power on the motors while regenerating.
He told me that in position L and taking on breaks (very carfully) you can maximize regeneration.

Sorry for off topic.

 

[T@oo]

What happens when the battery is full but you're decelerating in low?

I knew I've got the idea from somewhere. Not having a planetary gear in the ModS would prevent it from doing EXACTLY the same.

But having a traction control capable of utilizing the brakes, why does it not using rear brakes to simulate regen deceleration?

 

[mitch672]

What happens when the battery is full but you're decelerating in low?

I knew I've got the idea from somewhere. Not having a planetary gear in the ModS would prevent it from doing EXACTLY the same.

But having a traction control capable of utilizing the brakes, why does it not using rear brakes to simulate regen deceleration?

My guess: complexity. It would probably be simpler for them to use the heating elements in the pack as a resistive load to dump the energy into, because the energy is from the motor.. Of course the heater probably isn't large enough to handle the power required, so that's probably why they aren't doing it. They could have a resistive load just for this purse, but that would add cost and take up space as well...

 

[Vger]

Oh, that's what that dashed line on the energy dial means? I thought it was a software bug when I once saw it!

And you will also see another dashed line in the top (discharge) portion of the power meter when the battery is quite low. Motive power is limited to help you hypermile to your charging destination.

 

[RDoc]

My guess: complexity. It would probably be simpler for them to use the heating elements in the pack as a resistive load to dump the energy into, because the energy is from the motor.. Of course the heater probably isn't large enough to handle the power required, so that's probably why they aren't doing it. They could have a resistive load just for this purse, but that would add cost and take up space as well...

What would be complex? It seems likely the anti-lock braking is controlled by the same computer that manages the regen, or one that communicates with it, so why not just apply the brakes to emulate the regen? I can understand why it might take a while to put the code in, but it certainly doesn't sound any more complex than what they've currently got running.

 

[mknox]

And you will also see another dashed line in the top (discharge) portion of the power meter when the battery is quite low. Motive power is limited to help you hypermile to your charging destination.

And I think to protect the battery pack. You don't want to be drawing large currents from a pack at a very low state of charge... bad for the cells.

 

[strider]

Anyway, back on topic. ddenboer, if you didn't see the reduced regen line then my bet is on a traction issue. Perhaps the rear wheels were on a bit of road paint, damp section, or bumpy area. If regen kicks in but the rear tires lose grip it will decrease regen to allow the tires to regain traction.

 

[Puyallup Bill]

My Leaf (using it for a couple of days while my S is having elective inpatient facelift surgery :redface: (full wrap)) ... it only regens when I apply the brake ... and then hardly slows the card down at all.

Not the way my '11 LEAF behaves. In 'D' there is not much regen - more in 'ECO' and it becomes greater with brake pedal application. But regen does indeed start when releasing the accelerator - no brake pedal pressure required.

 

[ddenboer]

Anyway, back on topic. ddenboer, if you didn't see the reduced regen line then my bet is on a traction issue. Perhaps the rear wheels were on a bit of road paint, damp section, or bumpy area. If regen kicks in but the rear tires lose grip it will decrease regen to allow the tires to regain traction.

So I should have added some detail but it was late, I was tired (yada yada yada)

This was around 7:45am, and outside temp was 48. Car was plugged and charging 15 minutes prior, and heat was on for around 10 minutes to warm up to the back seats for the kids (because after we start driving and I turn the heat off, they need as much as they can get). No regen dotted lines. No reduced power dotted lines. Standard charge, showing 241 miles when we drove off.

Traffic was typical 101 traffic -- no one is doing the speed limit -- most are 70-80 and braking/accelerating constantly until our 4th lane gets added after Cochrane Rd.

Anyway... It has not happened since (and I hope it doesn't). It was just a very odd feeling that made it necessary to hit the brake to avoid collision (way too many crazy drivers on 101 on a daily basis).

 

[kinddog]

and by "scary", you mean "not scary", right?

 

[joshuaeven]

Not the way my '11 LEAF behaves. In 'D' there is not much regen - more in 'ECO' and it becomes greater with brake pedal application. But regen does indeed start when releasing the accelerator - no brake pedal pressure required.

Mine behaves this way as well. You can 'one-pedal drive' quite a bit with the Leaf in Eco-mode. If I recall from my MS test drive (feels like ages ago) the regen was more aggressive in the MS, but the Leaf definately does it.

 

[neroden]

In those cases, you should see a yellow dashed line on the lower right portion of the speedometer indicating how far the regen is limited. I noticed that line there at the 30kW mark on a cold evening, coming back from a 3-day trip. It disappeared after a few minutes driving.

I've had that dotted line present for pretty much all my driving since I got the car (2 weeks). That's the combo of winter weather and very short trips. However, my very conservative driving style means that 30 kW regen is plenty to slow me down much faster than I need, so it hasn't been an issue.

I've never had the dotted line limit regen more than that. Perhaps after a range charge? Perhaps in much colder weather?

- - - Updated - - -

Anyway, back on topic. ddenboer, if you didn't see the reduced regen line then my bet is on a traction issue. Perhaps the rear wheels were on a bit of road paint, damp section, or bumpy area. If regen kicks in but the rear tires lose grip it will decrease regen to allow the tires to regain traction.

Quite possible. I've already had the "fun" experience of losing traction (on ice), and I had to hit the brakes. The brakes went into anti-lock mode immediately, which gave me a pretty strong clue as to what was going on. (The anti-lock brakes were highly effective.)

 

[Robert.Boston]

I've had that dotted line present for pretty much all my driving since I got the car (2 weeks). That's the combo of winter weather and very short trips. However, my very conservative driving style means that 30 kW regen is plenty to slow me down much faster than I need, so it hasn't been an issue.

If you pre-heat the cabin using the smartphone app, you can reduce or eliminate the regen limitation on cold days.