Can you Tow Charge a Taycan?

[JimBob]

The scenario.

You are out in the country and your battery is dead. Can you charge a Taycan by towing it? There are several videos of Tesla's being charged by towing. I know the owners manual says no towing, but in a pinch could you?

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[Jhenson29]

I don’t see why not.

But I also don’t understand the no flat-towing rule in general. The motors (within their rated speed) can’t generate more back emf than their rated voltage and there’s no current if the circuit is open, so….what’s the issue? Anyone know?

 

[Jancha]

Maybe a safety concern, that with a flat main battery, there is no juice for proper braking? (Beyond recuperation limit)

 

[philbur]

Physics says yes. Lawyers say no. Physics doesn’t change its mind like a lawyer and provides clear answers that can be proven.

 

[Tooney]

Towing assumes you have the ability to shift the car into neutral, right? Which might not be the case if 12-volt battery is dead or isolated.

 

[Jhenson29]

Towing assumes you have the ability to shift the car into neutral, right? Which might not be the case if 12-volt battery is dead or isolated.

I don’t see why. You just backdrive the gearbox/motor.

 

[Tooney]

I don’t see why. You just backdrive the gearbox/motor.

I am new to this. If the car were in park, isn't a parking brake applied and perhaps something else to keep car from moving? If car is powered off, isn't park automatically engaged?

 

[Jhenson29]

I am new to this. If the car were in park, isn't a parking brake applied and perhaps something else to keep car from moving? If car is powered off, isn't park automatically engaged?

I see. Yes, any mechanical brakes would need to be removed/disengaged. I’m not sure on the specifics there. But that’s not the same as neutral as a decoupling of the drive system; at least, that’s how I think of neutral.

 

[philbur]

If you want to tow charge it I would be riding in the front seat and managing it. Or is the question can you tow it on its wheels and charge at the same time? I don’t think they have a mode for that by design.

 

[Vercingetorix]

Would be safer I think to tow to the top of a large hill, then use regen on the way down without being towed.

 

[JimBob]

Looked at the comments and did a little more research and I think this is the deal. Let me know if this is BS. Won't know until someone tries it. I am assuming you are not at the top of a hill. Maybe on a side road and a farmer is driving by in his tractor and can assist.

1. You can tow charge a Taycan but how?
2. You can't tow a Taycan long distance because the tow hook is off center, and towing will generate current into the battery which is going to generate heat and maybe burn something up. So no RV's towing Taycans or any other EV across the country. I am guessing someone is going to try though.
3. Is there a difference between tow charging at 0 SOC and 1% SOC? Maybe. The motor has a permanent magnet so it should generate current at 0 SOC but are the circuits in a state to handle this? Probably.
4. At 1% SOC. Probably.
5. So how do you set up the car to do this?
6. Need some liftoff regen so select the right setting.
7. But this is weaker than the Tesla so maybe a little brake riding to get higher regen?
8. Keep an eye on the battery temperature. The Tesla's videos showed quite a bit of battery heating after a few miles of towing.
9. Don't tell Porsche you did this

 

[Jhenson29]

and towing will generate current into the battery which is going to generate heat and maybe burn something up.

That’s the part I don’t understand/agree with. It generates voltage. Not current.

https://www.taycanforum.com/forum/t...ansmission-a-good-idea.6598/page-3#post-94709

If you take a PM motor and short the leads, you’ll feel the resistance if you turn the rotor by hand. But if they are open you won’t feel any resistance.

Even more curious to me is that I’ve seen this same “no flat tow” for async motor EVs and those wouldn’t even generate a voltage.

 

[JimBob]

That’s the part I don’t understand/agree with. It generates voltage. Not current.

https://www.taycanforum.com/forum/t...ansmission-a-good-idea.6598/page-3#post-94709

If you take a PM motor and short the leads, you’ll feel the resistance if you turn the rotor by hand. But if they are open you won’t feel any resistance.

Even more curious to me is that I’ve seen this same “no flat tow” for async motor EVs and those wouldn’t even generate a voltage.

That’s the part I don’t understand/agree with. It generates voltage. Not current.

https://www.taycanforum.com/forum/t...ansmission-a-good-idea.6598/page-3#post-94709

If you take a PM motor and short the leads, you’ll feel the resistance if you turn the rotor by hand. But if they are open you won’t feel any resistance.

Even more curious to me is that I’ve seen this same “no flat tow” for async motor EVs and those wouldn’t even generate a voltage.

For an AC generator, a change in the magnetic flux linked to an electric coil induces an EMF (voltage) in the coil. This induces an alternating electric current in the coil. Thanks to Mr. Tesla.

 

[Jhenson29]

For an AC generator, a change in the magnetic flux linked to an electric coil induces an EMF (voltage) in the coil. This induces an alternating electric current in the coil. Thanks to Mr. Tesla.

Jim, I’m just telling you my actual experience with actual motors. You have to connect the winding leads to something to create the resistance. We short them for finding or counting poles.

And, I don’t know if you read my linked comment or not, but I had an example where I ran a sinusoidal load with two PM motors connected to the same frame. I didn’t see the resistance from the back driven motor while running only one motor at a time. And it had to run a specific motion profile so I had to have a feed forward torque. I was very aware of the load/current profile.

You have to have a complete circuit for current.

Voltage? Yes. Current? No.
No current, no power.
No power, no work.

 

[JimBob]

Jim, I’m just telling you my actual experience with actual motors. You have to connect the winding leads to something to create the resistance. We short them for finding or counting poles.

And, I don’t know if you read my linked comment or not, but I had an example where I ran a sinusoidal load with two PM motors connected to the same frame. I didn’t see the resistance from the back driven motor while running only one motor at a time. And it had to run a specific motion profile so I had to have a feed forward torque. I was very aware of the load/current profile.

You have to have a complete circuit for current.

Hi Jeremey. I thought you were dealing with more than just a simple circuit but wanted to make the point that an AC generator does generate current. If control circuits are in the way then you have to figure out what they are doing. My responses are likely to be more on the theoretical side than the practical.

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