Grip in the snow?

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dargles
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Grip in the snow?

Postby dargles » Wed Jan 06, 2010 12:54 am

Hi, Folks.
Yet another dumb question from me :? ...

Looking at the videos of performance BEVs, they seem to provide loads of progressive power without wheelspin. I suspect that this might be because the electric motors tend to automatically compensate to deliver maximum power without losing traction. I haven't figured out an argument about what might be going on in terms of current flow or whatever, it's just a gut feeling derived from watching the videos and from experiences with Scalextric and radio controlled cars. ICE-driven stuff seems much more prone to "smoking the rubber" as it were.

1) Do you guys reckon this might be true? And
2) If this is so, does this mean that BEVs are better at keeping the wheels gripping in the snow?

Does anyone have any experiences that might confirm or go against this?
Regards, David

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timpootle
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Postby timpootle » Wed Jan 06, 2010 9:16 am

Not related to snow exactly, but having driven the Berlingo I like the way the available power increases with reducing roadspeed when climbing a hill, so you always reach a point of equilibrium where power required equals power available.

Contrast this with a petrol engine, where a steep hill forces you to change down a gear to get the revs high enough to deliver the power needed, ultimately forcing you to slip the clutch in first.

Give me an EV any day!
Tim Crumpton

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Jeremy
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Postby Jeremy » Wed Jan 06, 2010 2:12 pm

I found that my Prius (in EV mode) was reasonably OK in snow, although the eco tyres fitted as standard don't offer enough grip to take advantage of the ability to provide lots of torque at low speed.

Certainly it was very much better than my previous car, a Merc SLK. That was truly atrocious on anything over 1/2" of the stuff.

Curiously, my present car, a Honda CR-V, isn't much good either. Despite supposedly being four wheel drive it really struggled getting up my drive (in about 3" of snow) today; it sat there with the wheels spinning, going nowhere. Oh for a set of diff locks..............

I'd have thought that something like a Berlingo, with the added advantage of all that battery weight, should be pretty good, probably a lot better than my old Prius.

Jeremy

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ChrisB
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Postby ChrisB » Wed Jan 06, 2010 5:28 pm

Ah one of the great advantages of electric motors, max torque at zero rpm 8) thus far better power delivery to the wheels 8)

Surprised at the skinny tyres not proving to be good on the snow, I suspect if you dropped their preasure then this would improving things a lot :wink:

Yep anything with a large foot print aka wide sports wheels are rubish generally, again can be improved by dumping them to half preasure but then you can risk rolling them off the rim :roll:

I've been out and about all day in my front wheel drive Rover and I'm just amazed at folks total inability to drive correctly in snow :roll:
As soon as they get a bit of wheel spin its on with the brakes and stop :roll: they seem to get the idea that the throttle is on or off and theres nothing inbetween :? mind you its not helped with todays modern fly by wire ECU's which have a very strange way of delivering power from the throttle pedal to the actual wheels :?

Roll on more snow and more playing in the Snow 8)


ChrisB
I reject reality and substitute my own !!!!!!

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MB
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Postby MB » Wed Jan 06, 2010 7:16 pm

Both my G-Wiz and my iMiEV are very good in the snow. I think with the G-Wiz it is very much dependent on tyres - some people get on well with them whilst others struggle.

The low centre of gravity helps (the batteries in both vehicles are low down, close to the centre of the vehicle) and this, along with the characteristics of the electric motor, make them both very good vehicles in winter weather.

Regenerative braking helps as well, although you need to remember that both cars are rear wheel drive, so you need to make sure you are not braking on the corners! In the iMiEV they switch off regenerative braking under 10mph and start powering the motor again (to make it feel exactly like a petrol automatic :roll: ) which doesn't help, but otherwise it is very good indeed.
My new book is out: The 2011 Electric Car Guide is available from Amazon and all good bookshops.

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Night Train
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Postby Night Train » Wed Jan 06, 2010 7:58 pm

I've been wondering how electric traction would cope.

I don't yet have an EV running but I have found that my front wheel drive diesel estate has been fine in these conditons. Traction control, ABS and snow driving experience has been a great help and I have been helping others too.

I managed to get from Manchester to Burnley on Tuesday morning when we just had 10" of snow on top of the previous ice to contend with. I was one of the few to make it and then they closed the college.

My EV will be a rear wheel drive mid motored MR2 with no traction control or ABS so even if it were running I probably wouldn't have taken it out.

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MB
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Postby MB » Thu Jan 07, 2010 10:18 am

I used to have a mid-engined Fiat X1/9 (many years ago!) and that was a fantastic car in the snow. The only problem was the front spoiler was so low the car ended up being a snow plough! :lol:

I think that driving in snow is as much down to the driver as it is to the car. I've had people tell me that the G-Wiz is awful in the snow and they can't get anywhere, I've had other people say it is a fantastic vehicle for driving in the snow. I guess it comes down to driving style and the type of tyres you have fitted.
My new book is out: The 2011 Electric Car Guide is available from Amazon and all good bookshops.

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Peter Eggleston
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Postby Peter Eggleston » Thu Jan 07, 2010 6:36 pm

On any car knobley tyres will give better traction in the snow, but on an ev they will also cause more friction losses.
If you have regenerative braking on an ev, then this will slow you down without using the brakes in the same way as you would slow down in a normal vehicle by changing down the gears rather than braking.
My electric truck does not have regenerative braking, so as soon as you take your foot off the accelerator you are effectively free wheeling. This is not a problem on the level or going up hill, but going downhill the only way to slow down or stop is to use the brakes, which is what you are not supposed to do to avoid sliding.
Going down hill therefore I must go very slowly and use the brakes. On the level steady and anticipate stops.
Going up hill it is fantastic, no trouble, but I do have all terrain tyres.
Peter


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