Towing trailers with electric cars

wombat88 said:
Has anyone any experience of what towing does to the range of electric cars? This on the assumption that one can fit tow bars to them?

(I'm thinking about trailers with heavyish dinghies)
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As a half-way house, I run a Lexus self charging hybrid with a 3.5L petrol engine in it (quite economical compared to a normal 3.5L petrol ;-)). It was fitted with a tow bar when I purchased it 2nd hand but no electrics and the Lexus dealer was at pains to point out that they did not recommend towing. I was left with the impression that the more complex transmission was not properly up to the job of towing large caravans which is why Lexus (UK) was not keen. However, the US specification manual has a section on towing with no apparent cautions so it is do-able and the dealer will be adding the tow bar electrics to mine next week so that I can tow a camping trailer. I doubt that electric only cars are viable for most towing duties because of the range question as already flagged.
 
I run a Toyota Prius, not type approved for towing. Thats a nuisance because I too wanted to use a trailer for the tip, and occasioanlly tow a dinghy around. Our tip wont let me use my van nowadays.

I checked out: on the American market, the Prius IS approved fro towing, and apparently does it quite happily, even in the older 1.5 engine version. I read accounts of people towing up to and beyond the GVW without any problems either with the power unti being able to apply torque to start oon hills, or with regen braking. The consensus seemed to be that its a perfectly good towing vehicle. Remember that an electric motor can apply full torque at zero revs. Thats why its so common on the railways. No clutch to wear out either!.

Americans are less worried about fuel consumption as petrol is cheap, but if you put a heavy load on the towhook of in IC engine vehicle the MPG figures fly out fo your wallet anyway, so whats the difference? Except of course it takes longer to put the power back in an EV which we knew anyway!

I di wonder whther just to fit one anyway, but thats an 'unauthorised modification that invalidates insurance.
 
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halcyon said:
I know the answer, you don't understand the answer.

What is your problem with ... Stops brake snatching each time you take your foot of the accelerator ..... ?
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It completely avoids asking the question I asked. I have no particular problem with that, since nothing obliges you to answer my question, or indeed any question.
 
penberth3 said:
Wrong way round. I'm sure regen braking has been around longer than @halcyon.
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Rheostatic braking on railways has been around for a long time. Regenerative is harder unless you have a very large system or an external connection, because you need somewhere to dump the regenerated power. I would be suprised to learn that any cars were using it at the time of these entertaining reminiscences of trailer design half a century ago.
 
I suspect the reason for the lack of towing is cooking the battery.
For a non-towing car the limits are well defined - high acceleration gets you to the legal limit in x amount of time so no time for heat build up. As long as the car is designed to handle 70mph into a headwind indefinitely then everything will continue to work ok.
Once you put a caravan on the back all bets are off. 70mph pulling a big caravan is a much higher load on the system - particularly the battery cooling system. So it is much simpler and cheaper not to allow towing.
As the vehicles evolve and issues get ironed out then towing should become normal. I suspect that caravans will become much more aerodynamic.
 
When looking at the UK version of the page I linked they mentioned that the hybrid pepper pig (Porsche Cayenne) could tow up to 3500kg
review here: Porsche Cayenne S E-Hybrid review - Practical Caravan and it can run a fantastic 22 miles in pure electric mode! and at 28mpg petrol engine only, even my ancient RRS TDV8 can beat that fairly easily I get around 8l/100km(35.3mpg) to 9.5l/100km(29.7mpg @ 120km/h drop it down to 80km/h and she will do around 7.6l/100km(37.1mpg)
Mind you in towing 4tonnes back from Eindhoven it did drop a little... to 16l/100km @ 100km/h(17.6mpg)
 
JumbleDuck said:
Rheostatic braking on railways has been around for a long time. Regenerative is harder unless you have a very large system or an external connection, because you need somewhere to dump the regenerated power. I would be suprised to learn that any cars were using it at the time of these entertaining reminiscences of trailer design half a century ago.
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Do you have regen braking on your boat trailer ? your question was relative to your trailer which one assumes is mechanical overrun , though we did have electric braking in the 1960's.

If you had regen braking on your trailer you feed it into the tow vehicles battery, that's the problem with Product Design, you work with the future, the unknown, not copy what other people are making, or marketing tell you.

For your reference, in 1923 the Yosemite Lumber Company was using regen braking on it's logging inclines, feeding the power into the local grid.

Brian
 
halcyon said:
Fit trailers with wheel motors and regen braking, trailer draws power from vehicle battery, speed and braking in sync with tow vehicle, for long distance use the railway as per Euro tunnel.

What's the problem :)

Brian
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What if the load won't fit on a train?
 
andsarkit said:
I believe you are right about this. I wonder if it is just a matter of getting the documentation done or is there a physical reason to do with regenerative braking that makes it difficult.
My brother was going to fit one to his MG ZS EV anyway for occasional trips to the tip with a trailor. It depends a little on your attitude keeping strictly to the rules.
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Be careful: it may invalidate your insurance.
 
My mitsi phev towed a 16ft (heavy as fook) glass boat without any issues. In fact , I believe the rear end was more suited for towing as it was already uprated for the extra weight of the batteries. The regen brakes didnt bat an eyelid, and the onboard computer worked out when and where to distribute the power to the two electric motors.
 
Trickyh said:
My mitsi phev towed a 16ft (heavy as fook) glass boat without any issues. In fact , I believe the rear end was more suited for towing as it was already uprated for the extra weight of the batteries. The regen brakes didnt bat an eyelid, and the onboard computer worked out when and where to distribute the power to the two electric motors.
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How dare you come into this thread and contradict the armchair experts and their theories with mere facts!?
 
A simple solution: Just fit one of these in the trailer/boat/caravan ;0) It could even be run on gasoil. Caravans could also be fitted with solar arrays on the roof.

Regenerative braking with an overrun system could use electronic control rather than mechanical damping so could be off the shelf with an AI self-learning algorithm. Or it could tap into an as yet non-existent data feed from the tow wiring to the car's onboard braking and stability computer. Snaking and overheating brakes on mountain descents could be things of the past. This horse has a lot of mileage in it now, let alone once we are reliant on battery cars.

Best of all, tow a dirty great big wind generator, what could possibly go wrong? ;0)
 
Iliade said:
A simple solution: Just fit one of these in the trailer/boat/caravan ;0) It could even be run on gasoil. Caravans could also be fitted with solar arrays on the roof.

Regenerative braking with an overrun system could use electronic control rather than mechanical damping so could be off the shelf with an AI self-learning algorithm. Or it could tap into an as yet non-existent data feed from the tow wiring to the car's onboard braking and stability computer. Snaking and overheating brakes on mountain descents could be things of the past. This horse has a lot of mileage in it now, let alone once we are reliant on battery cars.

Best of all, tow a dirty great big wind generator, what could possibly go wrong? ;0)
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Glad to see you have joined the club, see #20 and #32 :D

Brian
 
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