Snow, steep hills and the MG5 LR

[johnd973]

Hi,
So yesterday we had a couple of inches of snow and I live in a very hilly part of the country. Overall the car handled it well but it did scare the living daylights out of me a few times.

Going down a steepish hill, very slowly with regen on full, just feathering the throttle to control the regen/speed and without warning, the regen just cuts off! Car starts gaining speed rapidly and the only method of slowing it down was the friction brakes! Slid to a halt at the bottom of the hill, up against a dry stone wall. Luckily the only damage is a scratch to the mirror casing. Scary as hell. Without engine/regen braking, friction brakes alone are not great in snow!

Got the regen back on by turning the car off and back on but the same thing happened again a couple more times. I then realised I could actually make it happen. Low traction surface, steepish downhill, feather the throttle and sure enough the regen 'fails'.

Battery on the car was about 60% so this wasn't due to high state of charge preventing regen! It really is dangerous; I was just very lucky I never met anything coming the other way on the occasions when I was hurtling out of control. Car will be going to the dealer next week for them to investigate because this surely can't be by design.

Anybody else had anything similar happen?

Be careful in the snow folks!

 

[Kithmo]

You're better using less regen and feathering the brakes, that means you're in control the braking not the car.

 

[Jomarkh]

I wouldn't use Kers3 in poor road conditions.

 

[johnd973]

I wouldn't use Kers3 in poor road conditions.

I think it makes sense to use higher regen on steep hills, in the same way you would put an ice car into low gear to control the decent!

On steep hills you always want to maximise mechanical braking and minimise the use of friction brakes to avoid brakes overheating, disks warping and that lovely smell of burning asbestos you get when you follow a tourist riding the brakes in his motorhome down Countisbury Hill

 

[Lguk]

I believe the manual specifically states to not use regen3 in icy conditions, because it is likely to cause loss of traction.

 

[BugEyed]

I think it makes sense to use higher regen on steep hills

The manual says:

It is recommended to choose Light or Moderate levels on surfaces that have low adhesion levels (e.g. icy roads).

you would put an ice car into low gear to control the decent!

ICE are different - the engine will keep turning as it'll not go below below idle speed - KERS continues to apply at all speeds. Also, in slippery conditions you are recommended to use a higher gear than normal to reduce the effect of engine braking.

Low traction surface, steepish downhill, feather the throttle and sure enough the regen 'fails'.

We could argue about semantics - the regen doesn't fail, the ABS senses a locked or locking wheel and the car turns off the regen to stop the wheel locking/allow it to restart if it has locked. So this feels like the regen has failed as the car initially speeds up and it is a few seconds (5-10 in my experience) before it kicks in again. Much better not to resort to using the regen but instead to use the friction brakes.

Two other minor points:

• regen only operates on the front wheels, the friction brakes on all four. To achieve a given rate of slowing down in low grip situations it is better to spread the braking across all four wheels by using the friction brakes
• being front wheel drive the regen is operating only on the front wheels which are the last ones that you would want to lock up as you lose most of the effect of steering

 

[5teep]

I stopped using Kers3 completely, I worked out that having to accelerate to speed up again uses more power then I gain with regen.
But yeah, the 5 is not great in snow, the front end has no real weight on it (no engine) and it tends to ride over snow rather than dig through it making it quite slippy. I have brand new tyres on mine and I still have to be extra careful.

 

[Groober]

Hi,
So yesterday we had a couple of inches of snow and I live in a very hilly part of the country. Overall the car handled it well but it did scare the living daylights out of me a few times.

Going down a steepish hill, very slowly with regen on full, just feathering the throttle to control the regen/speed and without warning, the regen just cuts off! Car starts gaining speed rapidly and the only method of slowing it down was the friction brakes! Slid to a halt at the bottom of the hill, up against a dry stone wall. Luckily the only damage is a scratch to the mirror casing. Scary as hell. Without engine/regen braking, friction brakes alone are not great in snow!

Got the regen back on by turning the car off and back on but the same thing happened again a couple more times. I then realised I could actually make it happen. Low traction surface, steepish downhill, feather the throttle and sure enough the regen 'fails'.

Battery on the car was about 60% so this wasn't due to high state of charge preventing regen! It really is dangerous; I was just very lucky I never met anything coming the other way on the occasions when I was hurtling out of control. Car will be going to the dealer next week for them to investigate because this surely can't be by design.

Anybody else had anything similar happen?

Be careful in the snow folks!

Interesting as I had this happen a few months ago but not in snow or ice
. Going down a steep winding road and all of a sudden there wasn't any regen so I had to use the brakes. I was going pretty slow anyway but it did surprise me. Hasn't happened before or since so I took it as a one off glitch.

 

[RoadUser]

I've noticed the lunge behavior a few times when applying the brakes gently, where the car slows down and then there is sometimes a bit of lunge forward before the friction brakes like take over, at least that's the impression I got.