Driving the PHEV in the mountains - tips please!

[jamerg]

Hi everyone

After an abortive attempt to drive to our skiing holiday in the PHEV last year (when some *$%£@** rear-ended it the day before we were due to leave) I'm looking forward to driving it from the UK to the Alps in a few weeks.

Got the winter tyres on and raring to go (I'll take snow chain for legal reasons, but don't imagine I'll need them).

Just wondered if anyone had tips for driving in the mountains.

In particular:

1. I've seen it suggested on here in the past that you should charge the battery (I'll do this using the "charge" button if necessary
- can't see the point on stopping to recharge on this sort of trip) before getting to the mountains. Why is this? Does the PHEV need the battery power as well as the ICE to tackle the mountains or something?

2. I've also seen people say that when you engage "4WD lock" (which I intend to do when I hit snow) you should also disengage the traction control. I don't fully understand this. Is it necessary on snow-covered roads, or is it just something to do if stuck in deep snow?

Also very happy to receive any other tips or suggestions.

Thanks in advance,

Jamie

 

[jaapv]

1.Yes, the car needs the battery for full power. For sustained full power it needs a lot of battery.
2.Traction control works by braking a spinning wheel. If you brake one wheel and another one starts spinning, it gets braked as well, etc. The end result is a car trying to drive with the wheels locked.
This is the case for all cars with traction control in deep snow uphill.

 

[jamerg]

Thanks jaapv - that's really helpful.

Am I right in thinking that I should therefore only turn off traction control if I encounter deep snow / get stuck? As long as you don't need all wheels spinning together to get going (i.e. some of the wheels have reasonable traction) I'd imagine you're better off with traction control on?

 

[jaapv]

I found myself - both on my previous car and this one too, to a lesser extent because of better 4WD traction, wondering why it would gradually struggle more and more to get up a moderate slope in the snow.

 

[NightPHEVer]

In Scotland recently I discovered while driving up very steep (tarmac - dry weather) mountain roads whilst in 'Save' mode (about a quarter of battery charge left) that the PHEV responds considerably better if you press the 'Charge' button. Otherwise in 'Save' the motor seems to rev in a somewhat peculiar way - a bit like a slipping clutch with a conventional manual gearbox would - that doesn't appear to correspond to the amount of power needed to make encouraging forward progress.

Haven't had the opportunity to drive in snow yet although we have some forecast. Haven't been able to afford another set of wheels and some winter tyres yet either.

 

[jamerg]

Let me know if you make any other discoveries when the snow arrives!

Why would you need another set of wheels for winter tyres? I just had the winter tyres put on the wheels that came with the car - is that wrong?

 

[jaapv]

Not at all. A second set of wheels is just a bit more convenient.
Anyway, the PHEV on decent winter tyres is just amazing in snowy/hilly conditions. It outperforms quite a few "serious" offroaders.

 

[elm70]

Should we use 4wd lock in snow conditions ?

The car is always 4x4 all the time ... but I'm wandering if the lock could help on the snow

Quite some snow in these days on my streets .. (not hill nor mountains ... but still also on flat streets with snow extra grip is welcome) .. on un-cleaned street I tent to push the 4x4 lock ... but .. maybe it does not do any help

My PHEV winter tyres must not be the best (some Michelin if I recall right) ... I had so far already a couple of "lucky" turns ... some extra slide before slow into a turn, that luckily did not cause any "issue" ... but ... when car start to slide even at very slow speed .. the heavy mass does not play well for have a quick recovery ... in this aspect .. my old Duster 4x4 with cheap winter tyres was doing better (never had a single slide)

 

[Steepndeep]

As has been stated previously, if you want to maintain high speed in steep climbs you need high SOC to start with. So hit Charge way before reaching the incline so you have decent SOC.

As for driving in snow or on ice, yes having 4WDLock engaged stabilizes the car and it is less likely to fishtail. Works at speed pretty much as advertized, i.e. like a centre diff lock. At crawl speed off-road that is not really the case, but then again the car is not a tru off-roader.

Regarding the anti-spin function I have yet to see that as useful feature to have always on. I see two cases for it

1 For people who cannot drive on ice and just floor the pedal to get away. For some reason these people seem to increase every year :lol:
2 As an indicator that it is really slippery conditions.

There are two situations when Antispin does not work, and one is really dangerous.

1 In deep snow or mud, as stated before.
2 When you want to overtake and need to cross the (at least in scandinavia) sometimes deep snow/sludge string separating the lanes. You do this at high speed and then need continous traction propelling the car forward and spinning the wheels is necessary just passing the sludge. Antispin kicking in can then break a wheel at high speed causing the car to fishtail (compensated hopefully by anti skid which cannot be turned off) or halt the attempt to overtake. If that happpens not at the start of the pass but once you have passed and return to your lane ahead of the passed car, that driver will be really suprised when you dive in infront of him and breaks.

 

[Steepndeep]

@elm

No the car is not 4x4 at all. There is a huge difference between 4x4 and AWD. 4x4 means that you have CONTINOUS drive on all 4 wheels always. My Suzuki has that through a center diff. A Volvo XC 90 is AWD which is implemented by viscous (or electrical) clutch which is activated AFTER a speed difference is detected between front and rear wheels. This is always worse than 4x4 in offroad conditions and has been discussed in other foras for years. The PHEV is AWD and engages the front Emotor only after a slip is detected. Engaging the 4WDlock mimics the center diff by software and then drives both Emotors continously. Works pretty well driving at speed I must say.

As an example; Driving up my really steep driveway the detection phase to engage the front Emotor takes enough time to make the car slow down and when it engages the front Emotor it may be too late. It also may yerk the car if the front is engaged suddenly and happen to be on better friction on one wheel. Having 4WDlock activated you always avoid the detection phase which is much better. Specifically when overtaking at high speed on snowy roads.

 

[geoffshep69]

I’m also a bit confused by all of this. Am I right in thinking that the advice is that you should never have the 4WD lock and traction control activated at the same time ?

So for normal driving, 4WD lock is off but traction control is on. But for winter driving, e.g. in snow, its better to activate 4WD lock and then turn off traction control ?

 

[jaapv]

Steepndeep has it right. 4WD lock does one thing only: distribute power evenly to all four wheels. This helps in difficult driving conditions, but does not turn the car into a full-fledged offroader as it does not have locking diffs.

It is not needed to switch TC off in general if 4WD lock is engaged (if it were Mitsubishi would have made it automatic, which not), except in deep snow or mud, especially uphill to prevent the car being bogged down by its own brakes.

I suspect that traction control might help in a cross-axle situation.

In any case the buttons can never replace driving ability, which includes driving with a light touch in slippery conditions and skid recovery, which is not easy on a permanent 4WD car without clutch. Mitsubishi fitted Automatic Yaw Control for that reason.

 

[elm70]

@elm

No the car is not 4x4 at all. There is a huge difference between 4x4 and AWD. 4x4 means that you have CONTINOUS drive on all 4 wheels always. My Suzuki has that through a center diff. A Volvo XC 90 is AWD which is implemented by viscous (or electrical) clutch which is activated AFTER a speed difference is detected between front and rear wheels. This is always worse than 4x4 in offroad conditions and has been discussed in other foras for years. The PHEV is AWD and engages the front Emotor only after a slip is detected. Engaging the 4WDlock mimics the center diff by software and then drives both Emotors continously. Works pretty well driving at speed I must say.

As an example; Driving up my really steep driveway the detection phase to engage the front Emotor takes enough time to make the car slow down and when it engages the front Emotor it may be too late. It also may yerk the car if the front is engaged suddenly and happen to be on better friction on one wheel. Having 4WDlock activated you always avoid the detection phase which is much better. Specifically when overtaking at high speed on snowy roads.

Interesting

I though that since the eMotors are both always connected to the wheels ... it would have made more sense to "drive" always both motors

So ... I was assuming that 4x4 lock was only a way to force the same power sent on both axes .... else the distribution of energy between axes is defined by some car logic ... which could have been smarter then a "lock"

Due to limited toque at zero speed ... I can't feel the difference on the PHEV .. on my old duster 4x4 I could easily slide front wheels on a fast start up ... but never when manually force the 4x4 mode ...

 

[geoffshep69]

Steepndeep has it right. 4WD lock does one thing only: distribute power evenly to all four wheels. This helps in difficult driving conditions, but does not turn the car into a full-fledged offroader as it does not have locking diffs.

It only functions up to 50 kph.It is not needed to switch TC off in general if 4WD lock is engaged (if it were Mitsubishi would have made it automatic, which not), except in deep snow or mud, especially uphill to prevent the car being bogged down by its own brakes.

I suspect that traction control might help in a cross-axle situation.

In any case the buttons can never replace driving ability, which includes driving with a light touch in slippery conditions and skid recovery, which is not easy on a permanent 4WD car without clutch. Mitsubishi fitted Automatic Yaw Control for that reason.

Thanks for clarifying. So on slippery ground, snow, etc. its fine to activate 4WD lock and leave the traction control turned on, but if the car starts to struggle or gets stuck then the two systems can conflict with each other so in that case you’d turn off traction control, is that correct ?

 

[jaapv]

Drive is always on to both motors, but in normal mode the computer will adapt the power distribution between front and back axle with the emphasis on the front according to driving demand. 4WD lock overrides the power distribution by supplying equal power to front and rear. It functions up to 50 kph IIRC.

 

[jaapv]

Steepndeep has it right. 4WD lock does one thing only: distribute power evenly to all four wheels. This helps in difficult driving conditions, but does not turn the car into a full-fledged offroader as it does not have locking diffs.

It only functions up to 50 kph.It is not needed to switch TC off in general if 4WD lock is engaged (if it were Mitsubishi would have made it automatic, which not), except in deep snow or mud, especially uphill to prevent the car being bogged down by its own brakes.

I suspect that traction control might help in a cross-axle situation.

In any case the buttons can never replace driving ability, which includes driving with a light touch in slippery conditions and skid recovery, which is not easy on a permanent 4WD car without clutch. Mitsubishi fitted Automatic Yaw Control for that reason.

Thanks for clarifying. So on slippery ground, snow, etc. its fine to activate 4WD lock and leave the traction control turned on, but if the car starts to struggle or gets stuck then the two systems can conflict with each other so in that case you’d turn off traction control, is that correct ?

Yes, it is, but it is a good idea to anticipate and switchoff before it starts to struggle. Driving at constant speed in deep snow or sand, etc will get you through, stopping and trying to drive off may get you stuck.

 

[Grigou]

Steepndeep has it right. 4WD lock does one thing only: distribute power evenly to all four wheels. This helps in difficult driving conditions, but does not turn the car into a full-fledged offroader as it does not have locking diffs.

It only functions up to 50 kph.It is not needed to switch TC off in general if 4WD lock is engaged (if it were Mitsubishi would have made it automatic, which not), except in deep snow or mud, especially uphill to prevent the car being bogged down by its own brakes.

I suspect that traction control might help in a cross-axle situation.

In any case the buttons can never replace driving ability, which includes driving with a light touch in slippery conditions and skid recovery, which is not easy on a permanent 4WD car without clutch. Mitsubishi fitted Automatic Yaw Control for that reason.

Thanks for clarifying. So on slippery ground, snow, etc. its fine to activate 4WD lock and leave the traction control turned on, but if the car starts to struggle or gets stuck then the two systems can conflict with each other so in that case you’d turn off traction control, is that correct ?

That's what I always do on snow. But you will see that it's difficult to get stuck in 4WD mode ! Even with the factory's all-seasons tyres (I don't have winter tyres to drive in the Alps, but sometimes I put the chains in the cargo ... in case of "panic" of the authorities, during a snowy storm on Saturday ).

Don't forget to activate 4WD lock on snow even when driving downhill : in B4 or B5 the 4 wheels will slow the car down, in a curve it's better than only the front wheels IMHO

 

[jaapv]

Yes, but should you go into a full skid it is safer to have the car in B0, far easier to correct.

 

[anko]

Drive is always on to both motors, but in normal mode the computer will adapt the power distribution between front and back axle with the emphasis on the front according to driving demand. 4WD lock overrides the power distribution by supplying equal power to front and rear. It functions up to 50 kph IIRC.

In serial mode, both e-motors provide the same amount of power. Torque is a bit different, but due to different gearing front and rear, force at the wheels is the same.

In parallel mode, the ICE drives the front wheels. A little power is applied to the from e-motor to eliminate E-drag. A little bit more power is applied to the rear motors, in order to make the rear wheels push the cars, rather than the car pull the rear wheels.

In parallel mode with 4WD lock engaged, the rear e-motor provides about as much power as the ICE.

So, per definition of steepndeep, it would be a true 4x4, right?

 

[Grigou]

Yes, but should you go into a full skid it is safer to have the car in B0, far easier to correct.

You're probably right

If you prefer going downhill on a snowy winding road in B0, it's up to you ! For my part, I love to drive the PHEV in 4WD mode + B3-B4-B5 in these circumstances.
As much as possible I avoid to go into full skid, and for this purpose the regenerative breaking helps a lot