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 Post subject: Re: B settings in icy conditions
PostPosted: Sun Dec 03, 2017 2:06 pm 
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Joined: Tue Aug 05, 2014 1:32 pm
Posts: 1365
Er, all very clever, anko, but rather incomprehensible (to me :lol:) and nothing really to do with the ABS which stops the wheels locking so as to offer assistance in a skid. My point is that the question about Regen & ABS is irrelevant as there is no interplay between them and by the time ABS gets involved Regen has long ceased to function - do you agree?


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 Post subject: Re: B settings in icy conditions
PostPosted: Sun Dec 03, 2017 9:56 pm 
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Joined: Mon Dec 01, 2014 11:30 am
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Location: Netherlands, Utrecht area
I do agree. My response was triggered by the "no actual braking occurs". Not by the ABS remark. Should have left that out when quoting you ;)


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 Post subject: Re: B settings in icy conditions
PostPosted: Mon Dec 04, 2017 2:39 am 
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Ah, yes I see. Of course, I meant no application of an external mechanical force to the wheels by the car to effect braking, when the energy conversion is into heat through friction. My understanding is that the use of the motors in reverse is to "suck" away the excess kinetic energy, which does produce a negative torque and slows the car - but then I failed A-level physics 50 years ago, so prefer to think in layman's terms. :oops:


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 Post subject: Re: B settings in icy conditions
PostPosted: Wed Dec 06, 2017 2:22 pm 
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Joined: Tue Nov 28, 2017 12:29 pm
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Thanks all for your contributions.

There is some really interesting discussion here but i am not sure we have established whether the scenario I presented is a real possibility.

For those that make the point that if the wheel isn't turning there is no regen., it does seem that traction and steering could still be lost under regen. with dramatic consequences.

For others who comment on the fact that regen. is not like traditional braking and, therefore, would not be linked to ABS, seem to be missing the point that ABS actually restricts the braking to allow the wheel to turn and provide traction/grip. This is why it is less useful in snow, as you find yourself with a car not stopping and a solid brake pedal!

The above happens because ABS is monitoring the individual wheel speeds and my question was really, is ABS linked to the regen. function. That is, is something monitoring the wheel speeds when regen. is active and would it be reduced stopped if traction is lost?

Thanks again.


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 Post subject: Re: B settings in icy conditions
PostPosted: Wed Dec 06, 2017 2:37 pm 
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Joined: Mon Dec 01, 2014 11:30 am
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Location: Netherlands, Utrecht area
TonyL wrote:
The above happens because ABS is monitoring the individual wheel speeds and my question was really, is ABS linked to the regen. function. That is, is something monitoring the wheel speeds when regen. is active and would it be reduced stopped if traction is lost?
If there was, it would have to be on a per-axle basis and not on a per-wheel basis, as regen is controllable per motor, hence axle, and not per wheel.

From what the Dutch distributer told me, regen was designed to provide a specific deceleration (for example B5 should result in 0.11 G or 1 m/s2 in B5). Regen power should be adopted to result in that specific acceleration. They said that when towing or heavily loaded, regen power should increase in order to result in the the same amount of deceleration (whether that is true?). But this would also mean that regen power could be increased when the car was not slowing down as fast as planned for ... because of wheel spin.

I cannot imagine they would be that stupid ....


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 Post subject: Re: B settings in icy conditions
PostPosted: Wed Dec 06, 2017 2:52 pm 
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Joined: Tue Apr 12, 2016 4:05 am
Posts: 127
Sorry for being late into this discussion but I thought I add my 2 cents.

First, ABS and E-regen (Electricity regeneration using B settings) are to my knowledge 2 totally separate systems. Have nothing to do with eachother. This is my assumption but I may be wrong (I do not think so though).

On ABS as there seams to be some misconceptions whether it is good in snow or not. In scandinavian countries since ABS has been introduced crashes in snow has dropped considerably. ABS is the best thing that has happened and there is almost no condition when it is not better than a very, very good driver. All ABS systems work roughly the same. Above a certain low speed (5-10 km/h) they work and below that they are switched off. When they work they quickly break each wheel until the wheel stops turning and then they release and start all over, this within 0.5 seconds or less ( the better system the shorter time). So effectively each wheel skids for a short time and then start breaking again. When breaking with ABS you should always break with maximum force (to enable ABS) and will feel the vibrations in the breakpedal from the ABS system.

B regen is just feeding power back to batteries and B5 is a fairly strong power feedback. I guess if it was black-ice (extremely slippery, so slippery that you almost cannot stand on 2 feets on a level surface) and you applied B5 all wheels would stop imediately and the car would start skidding. Of course the regen would then stop and the wheels be released but that would be TOO LATE. You would be heading for the ditch already and having a hard time recovering.

E.g. I was driving a Skoda Fabia Diesel some years ago on black-ice and realised too late that I was on black-ice. Took my right foot of the gaspedal in 5´th gear and both front wheels immediately skidded. Fortunately straight road so freewheeling fixed it but it was so slippery that it was impossible to increase speed without going into the ditch. Note that in Sweden all roads are slightly convex to get rainwater off the surface but that was enough to make it impossible to accelerate. And that was with top of the line winter tyres.

# Ankos latest post
Just saw it when I was uploading and decided to comment. I do not think the Dutch distributor is right. I have been towing a heavy load and did not notice a higher B5 regen, only same regen power and thus longer "stopping distance".


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 Post subject: Re: B settings in icy conditions
PostPosted: Wed Dec 06, 2017 3:01 pm 
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Location: Netherlands, Utrecht area
Steepndeep wrote:
B regen is just feeding power back to batteries and B5 is a fairly strong power feedback. I guess if it was black-ice (extremely slippery, so slippery that you almost cannot stand on 2 feets on a level surface) and you applied B5 all wheels would stop imediately and the car would start skidding. Of course the regen would then stop and the wheels be released but that would be TOO LATE.
Why would you think that releasing the wheels in case of of a regen induced skid would take any longer than it would with ABS brakes? Electronics versus hydraulics + mechanics. Electronics should be much faster (if programmed properly), if you ask me.


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 Post subject: Re: B settings in icy conditions
PostPosted: Wed Dec 06, 2017 3:40 pm 
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Joined: Tue Apr 12, 2016 4:05 am
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#anko
Well I did not think of it that way. But now when you say it I do not agree. It is not electronics vs hydraulics, it is sw brain with hydraulics actuation vs. sw brain with electrical actuation. And comparing hydraulic actuation (engineered to be fast in ABS system) vs electrical actuation (not engineered to be fast, just my assumption because it was not engineered for black ice but for regen) I assume the ABS wins. But I do not know, will test when suitable wheather arrives:-)


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 Post subject: Re: B settings in icy conditions
PostPosted: Wed Dec 06, 2017 9:33 pm 
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Joined: Wed Nov 22, 2017 12:36 am
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Location: Austria
Steepndeep wrote:
But I do not know, will test when suitable wheather arrives:-)

Thank you, that's great.


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 Post subject: Re: B settings in icy conditions
PostPosted: Thu Dec 07, 2017 1:11 am 
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Location: Netherlands, Utrecht area
Steepndeep wrote:
#anko
Well I did not think of it that way. But now when you say it I do not agree. It is not electronics vs hydraulics, it is sw brain with hydraulics actuation vs. sw brain with electrical actuation. And comparing hydraulic actuation (engineered to be fast in ABS system) vs electrical actuation (not engineered to be fast, just my assumption because it was not engineered for black ice but for regen) I assume the ABS wins. But I do not know, will test when suitable wheather arrives:-)
So, you don't agree with me because of something you assume? Interesting ;)

Have you ever used the CC? Have you noticed how well the PHEV maintains its speed over varying conditions? This is done using the same SW brain plus electronic actuation. Fuel consumption and ICE output is constant. But power to the wheels is manipulated by making the generator generate more or less power. Very effective.


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