towing failure

[Acm]

generally very pleased with vehicle having covered 5000 miles but yesterday my wife had significant problem while towing.

we occasionally tow horse trailer with 1 horse plus kit, total weight about 1200kg. It's ok with this load but struggles up hills a bit.

yesterday had 2 horses total weight probably just over 1500 kg with 3 in car.

charged overnight, drove to stables on SAVE to keep battery full and did all towing with CHARGE button engaged as we normally do.

Car got stuck half way up apparently quite steep incline requiring her to reverse down, unload horses and then tackle hill successfully. Car also got stuck on the flat with horses on board and trailer wheels in mud while driving across field. Traction wasn't the issue and she got round that particular problem with 3 people pushing. Getting stuck means PHEV just wouldn't move.

Clearly we were using the PHEV right at the limits of its towing capabilities. It's must be a combination of the weight plus the "off road" conditions. Slightly disappointed as I thought the headline engine power of over 200bhp would be sufficient for our needs.

I had bought the PHEV for a number of reasons, towing being one of them and had hoped it would be a reasonable substitute for my BMW X5 40d. I am just about to advertise this for sale but am having second thoughts. I thought the circa 200bhp of the PHEV would be reasonable albeit less than the circa 300bhp of the BMW which seems to cope in all circumstances.

The problem seems to be the amount of power available at the speed one would usually crawl up a steep incline.

Any thoughts? Anything I could try?

thanks

 

[anko]

204 bhp is only available at top speed (170 km/h). At 58 km/h you can have (with sufficiently charged battery) 160 bhp at your disposal. Half that speed means half that power.

 

[gwatpe]

Once the battery is depleted, as is usual with towing, then the only power at low speeds comes from the 80kW from the ICE and generator running at 4500rpm.

You mention that the PHEV did not lose traction, ie wheel spin but just did not have enough power to move by itself.

I am sure that if you had waited a short time and allowed some additional charge into the battery that the additional 60kW from the battery added to the generator would have supplied enough power to get you through.

The PHEV certainly has limits, but we need to plan to better keep within the limits.

 

[Acm]

The battery was close to full charge according to the range indicator ie had been in Charge mode as soon as the trailer connected

 

[anko]

The thing here seems to be a bit like this:

Looking Katy the amount of torque produced by the E-motors, you can see they cannot consume more than 60 kW each at 58 km/h. Calculating back to 0, they would consume no more than 30 kW each at 28 km/h and so on. Eventually, at 0 km/h they would consume no more than .... 0 kW. I always assumed 60 kW of either the battery or the generator would be more than the motors could handle below 28 km/h. So, with a charged battery, there would be no point in starting the engine. And with a running engine, it would not matter if the battery was charge or not.

One time I had to pull my 1500 kg caravan slightly uphill and out of a small ditch. When I pushed the gas pedal, there was a lot of noise. First, I though the noise I heard were the wheels spinning on the somewhat wet grass. But there was no wheel spin. It turned out to be the engine revving up, even though the battery was full charged. I was a bit annoyed because it was on a campsite and I wanted to show off .

Clearly there is a difference between behaviour of an E-motor at > 0 RPM and behaviour of an E-motor at 0 RPM. To produce torque at 0 RPM, a high starting power is required, which can be up to 6 or 8 times the nominal power, if I am not mistaken.

 

[Trex]

Looks like a perfect case for a torque converter for the electric motors that could later lock up ie let the electric motors spin up so more power is produced at higher revs.

Or another set of gears for low speed work.

regards Trex.

 

[PolishPilot]

Torque converter maybe would help, but there is a reason why
real off road vehicles have reduction gear box.

Pulling a 2 horses trailer out of mud certainly needs low gear.

Outlander PHEV seems rather a city SUV, than a working farm vehicle.

I tow my horses with my Hilux, just 120hp diesel, but with low gear
and permanently locked front and rear axle she does the trick.

 

[karl]

The Outlander could perform better offroad I think...

The manual claims that when getting stuck in mud, the ASC should be disabled. Maybe that would have helped.

Not sure about the incline though. Was it on grass aswell?

 

[discorduk]

Been a while since i studied electric motors, but from memory peak power and peak torque are not the same for electric motors. You should get maximum torque from a standstill, it goes down with speed not up, thats one of the reasons why trains use electric drive. For practical reasons the motor driver circuitry limits the torque at slow speed, otherwise you would be doing standing wheel spins every time you put your foot down.

so if the wheels aren't spinning, then you've exceeded the stall-torque for what little current the motor drive is permitting, and i doubt that is anywhere near what the batteries alone could deliver if allowed, never mind batteries+ICE.

An obvious target for firmware modders would be to add a sport mode by changing that permitted torque curve, like Tesla recently did for their top end model when they added 'insane mode'.

 

[outofyorkshire]

You also need to remember that the towing capacity of any vehicle is a simple calculation and not directly linked to the BHP on tap.
The usual calculation is:
'the gross vehicle weight subtracted from gross train weight'

So whilst in theory the PHEV can tow 1500kg....you need to consider what you tow and how you tow.
As others have said the PHEV is really a SUV .
There is a reason you see lots of horse boxes being pulled by Land Rovers...

 

[anko]

There is a reason you see lots of horse boxes being pulled by Land Rovers...

Both expensive hobbies?

 

[outofyorkshire]

There is a reason you see lots of horse boxes being pulled by Land Rovers...

Both expensive hobbies?

:lol: :lol:
Never had a horse , but can certainly say that Land Rovers 'aint cheap to run :shock:

 

[hdasmith]

Looks like a perfect case for a torque converter for the electric motors that could later lock up ie let the electric motors spin up so more power is produced at higher revs.

Or another set of gears for low speed work.

regards Trex.

I didn't think that would be necessary with electric motors. As I understood things, the low range box was to allow the wheels to get more torque at lower speeds. With an electric motor, you can get maximum torque at all rev ranges, hence why there isn't a gear box in the first place.

How certain are we that you were under the 1500kg towing limit? I wouldn't tow two horses with mine because I wouldn't have thought it would be under that. Depends on your horses though, and box.

 

[Trex]

Looks like a perfect case for a torque converter for the electric motors that could later lock up ie let the electric motors spin up so more power is produced at higher revs.

Or another set of gears for low speed work.

regards Trex.

I didn't think that would be necessary with electric motors. As I understood things, the low range box was to allow the wheels to get more torque at lower speeds. With an electric motor, you can get maximum torque at all rev ranges, hence why there isn't a gear box in the first place.

How certain are we that you were under the 1500kg towing limit? I wouldn't tow two horses with mine because I wouldn't have thought it would be under that. Depends on your horses though, and box.

Wasn't my horse of cause. :lol:

 

[hdasmith]

Wasn't my horse of cause. :lol:

No - confusing posters in my reply I think.

 

[Hypermiler]

I would be interested in size of horses and type of box, since even 2 small ponies in a double trailer with some kit would be getting towards the limit! I am considering getting a trailer and am very conscious of the weight limit - a fairly standard double plus 16hh horse is going to be pretty much at the limit so if they were horses rather than ponies, I am not at all surprised.
H

 

[anko]

Okay. Horses are heavy. But still .... Remember this pic? Guy said he had to climb a steep ramp to get onto an elevated road (sounded like something comparable to a boat ramp) and was very happy with the performance. Could have been better, but didn't cost him a new clutch, he said. Trailer + digger + wood weighing in at 2700 (!!) kg.

Perhaps if the wheels of the horse trailer had gotten a chance to sink into the grass. Then you would have to conquer a incline, much steeper than a boat ramp.