RAV4 PHEV Snow conditions

[TonyFR]

Is there anything special one should be aware of driving an AWD hybrid such as ours in snow conditions? I vaguely remember reading something advising something - but I can't now remember those somethings!  (I am however fitting my new winter tyres shortly - Michelin Alpin, after much review reading)

[Flatcoat]

No different to driving any other 4wd in snow. Why would you think there might be? 

[philip42h]

Traditionally, RAV4s have been pretty simple to drive in the snow and ice - put the right tyres on, drive gently with a modicum of common sense, don't try to go too fast (because you might have to stop) and the systems on the car will ensure that you get the best of the available traction.

I haven't yet had the option to seriously test the electric rear drive system but expect that Toyota have designed it correctly - I'll be rather surprised if they haven't. The PHEV will probably have more torque than you need so be extra gentle on the accelerator but otherwise the car should just get on with it.

[ernieb]

I’ve no experience of driving the PHEV in snow but I’ve read that as the weather gets cold, Battery cold in EV mode, the energy regeneration due to braking can significantly reduced.  I’ve got the car set to heat and cool the Battery but it might be something to be aware of? Otherwise it’s the normal precautions of snow weather driving I would have thought.

[spicyhotone]

Ernie - how do you set the car to heat & cool the Battery? I thought that was just an automatic/default thing? Is there an option somewhere to switch this on?

[ernieb]

Like many settings I’ve made on the car they were some time ago and I think it was a selection in the vehicle settings on the MID. It is on by default in the manual but I’m sure mine was set to off, anyway it’s on now for sure.

[Flatcoat]

Given the countries where the RAV is sold and the winters they have, (including in Japan) this is not something that is remotely on my mind. Pretty sure Toyota will have it sussed. 

[nlee]

On a related point, would people use trail mode by default when there was a reasonable covering of snow, or only if they started to get stuck? My last car had different modes for snow, mud, sand, ruts, etc. so it's a bit different.

(It might say in the manual but I haven't got to that bit yet! I might get to it by the time it snows!)

[ernieb]

I think that Trail Mode acts as a ‘limited slip differential’ individually locking each wheel to send power to the other.  It’s not on by default as it would probably impact on fuel economy.  It’s operation is the same as on the HEV model so there may be people who can give us their direct experience of it’s use. I know it will work in either EV or HEV mode and I’ll probably use it if the conditions are very muddy, snowy or very slippery.

[ernieb]

I’ve watched this in the past and had it saved, see around 1:40 to see the display distributing the power and wheel locking.

 

[philip42h]

1 hour ago, nlee said:

On a related point, would people use trail mode by default when there was a reasonable covering of snow, or only if they started to get stuck? My last car had different modes for snow, mud, sand, ruts, etc. so it's a bit different.

(It might say in the manual but I haven't got to that bit yet! I might get to it by the time it snows!)

That's a good question - in the manual it says: "Trail Mode is a system that performs integrated control for the AWD, brake and drive force control systems to assist the drive power on bumpy roads, etc." and "Trail Mode is suitable for driving on bumpy roads, such as those where the tire on one side spins, there is a chance that Trail Mode may not be the most appropriate for other road conditions." And "Trail Mode is intended for use when driving on bumpy rough roads. Do not turn the switch on in other situations." So, going by the book, we should not be using Trail Mode in snow and ice ...

Earlier RAV4s (4.3s and 4.4s) had a 'diff lock' button - that didn't lock the diff but hinted to the management system that we would like to be in 4WD mode a little longer. Try as I might (and I did) I could never find a situation where pressing the 'diff lock' button was necessary or helped. As traction failed wheel by wheel the system would drop the power and apply the brakes to the spinning wheel[s] to shift power to the wheel[s] that still had grip. That was just how the AWD / traction control system worked and I rather hope the same is basically true of the 4.5.

Equally, the description of Trail Mode does seem to align with the normal behaviour of earlier RAV4s at the limit - so I'm a little puzzled ...

In the video posted by Ernie, the driver engages Trail Mode straight away (when I suspect he really doesn't have to) and never tries to get away in 'normal' mode. I'd hope that the traction control system would still work as it should to ensure power was delivered to the wheels with grip.

Anyway, until I know better I shall assume that Trail Mode is for bumpy trails only and continue to drive in Normal on snow and ice. And, in the unlikely event that I do get 'stuck' I can always try Trail Mode as a means of escape! 🙂

[ernieb]

Just to clarify, I’d would intend to use the Trail Mode under normal road  snow driving conditions but when I was starting off or in deep snow. I’ve used this mode in a number of Subaru and Skoda cars and found it’s use in these circumstances  a useful aid.

[Rav Rob]

I had a similar PHEV, the only issue in snow is weight, the manufacturers do a fairly good job of hiding it in general use. But on snow stopping is a lot harder, simple laws of physics, same tyre friction patch, half a ton extra weight to hold back. Winter tyres will help massively but bear in mind in the same situation the PHEV will take a lot longer to stop / be more prone to slides than the regular RAV.

The simple answer is keeping your speed well down and try to start losing speed extra early. With good 4wd traction its easy to get up to a speed that will get you in trouble when you need to lose it again.

[Lawnmowerman]

ABS is your enemy in fresh snow (not compacted).

The cycling of brakes on and off extends your stopping distance as the tyres will naturally lock up in snow.

The original Audi Quattro had an off switch for ABS so that in fresh snow or gravel the locked brakes would build up a dam of material and give shorter stopping distances.

Strange but true.

[ernieb]

Indeed it makes little difference how expensive and complex the car is it all comes down to tyres and the small patch that hits the road.  I recall a new Range Rover ploughing past me as I was progressing up a hill on semi compacted snow and I I went over the top he was half way down out of control and ploughed into a bank and hedge.  He was OK, shaken, very embarrassed but alive.  Traction is one thing stopping is another.

The Skoda Yeti, had a Traction button and an Off Road button.

"Traction button limits the spin of the driven wheels. The TCS is always on by default and is an important assistant during driving, especially on slippery surfaces. There are situations, however, such as driving on rough terrain or in deeper snow, when wheel spin is desirable. In this case, the driver can press a button to deactivate the system"

[philip42h]

When I read the original marketing blurb - The new Toyota RAV4 hybrid - I could well believe that Trail Mode was the only mechanism that controlled the distribution of torque left to right across an axle, and, on that basis you would want to use Trail Mode on any slippery surface ... BUT ...

This series of tests seems to at least partially contradict that view:

and suggests that Trail Mode actually allows more wheel slip than the car would in Normal mode - i.e. it can be used when you want the wheels to spin a bit to shift the loose stuff out of the way so that the wheel can find something to bite on.

Watching the video I get the impression that Normal is best under most circumstances, but Trail Mode seems to win when the two wheel on opposite corners have no traction - but I wouldn't swear to that! 😉

For now I'll stick with my preconceptions and switch to Trail Mode only when all else has failed! 🙂

[ernieb]

Philip, that’s exactly how it’s supposed to work as far as I can tell, allow more spin on a slippery surface.

[philip42h]

22 minutes ago, ernieb said:

Philip, that’s exactly how it’s supposed to work as far as I can tell, allow more spin on a slippery surface.

Ernie, yes, I agree (I think) - but where does anything from Toyota actually say that is what is supposed to happen? 

[Rosgoe]

I had a rav4 T180 which had a 4 wheel drive lock button on the dash which was supposed to put into permanent 4 wheel drive and would disengage at speeds above 30 mph. I believe the system would normally work by directing drive to which ever axle had the less grip and would most of the time be front wheel drive.

I also had a 1998 rav4 GX which had permanent 4 wheel drive and was far superior in the snow than the T180 was fitted with town and country tyres.

On you tube there is a video of a Range Rover spinning all four wheels in the snow and getting nowhere it is passed by with a small  2 wheel hatch back with winter tyres fitted! 

[ernieb]

Philip, the only I can find is a sort of reference…. “Such as those where the tyre on one side spins”

●Thoroughly check the road conditions before  driving. As Trail Mode is suitable for driving on  bumpy roads, such as those where  the  tire on  one  side  spins,  

[Rav Rob]

4 hours ago, ernieb said:

Philip, that’s exactly how it’s supposed to work as far as I can tell, allow more spin on a slippery surface.

Its supposed to be more proactive in braking a spinning wheel to 'diff lock' it and get some power to the gripping wheel. I have seen a few roller tests and some real off road tests on the RAV, one thing I had noted was it takes a long time of it allowing spin before it tries to diff lock, a surprisingly long time!! this doesn't come out in quick roller tests. The moral seems to be keep plugging away with some spin and the car will eventually decide enough is enough and apply lock, there is no doubt some good reason for Toyota to do this, perhaps its considered risky to the transmission so does it as a last resort..

[ernieb]

It does seem counterintuitive to keep pushing the pedal when at least of of the wheels is spinning hard.  I’ve also seem some of the YouTube videos and the amount of dust, stones and general much flying around does not look good. I can also understand that if this is overused it could do some damage to the mechanicals as well as the body.

[R@v]

On 10/27/2021 at 4:48 PM, ernieb said:

It does seem counterintuitive to keep pushing the pedal when at least of of the wheels is spinning hard.  I’ve also seem some of the YouTube videos and the amount of dust, stones and general much flying around does not look good. I can also understand that if this is overused it could do some damage to the mechanicals as well as the body.

Many 4x4 and awd vehicles need the power on so wheel and axle spin/slip is identified by the electronic gizmos so that they can adjust each wheel/axle to the best grip and slow or stop the spinning wheel. 

It can be quite un-nerving but having driven many of these type of vehicles in all types of terrain you get to understand how much pressure you need to apply to the throttle.

This is my 1st Rav4 hybrid awd but it does work when I am on slippery mud/grass. Not tried it in any deep snow yet but last winter it worked well on snowy lanes etc with stock tyres..........Michelin CC SUV will be on soon 

 

[Roger_N]

As the OP said winter tyres are a must for snow driving.

 This video on YouTube is worth a watch even though it’s the wrong car.

https://www.youtube.com/watch?v=mfuE00qdhLA

 

[Flatcoat]

According to the disciples of saint Greta, XR and other quasi religious groups, I thought snow was now an endangered species so no one will need specific tyres…..