Emergency towing Leaf with tow rope

[arnis]

First of all, this is NOT according to manufacturers recommendations.
Manufacturer strongly prohibits towing with driving axle on the road!

The reason for that, is that most EV-s have Permanent Magnet motors.
If vehicle has depleted HV battery (ready mode does not engage) or has
a problem that does not allow Drive to be engaged, turning electric motor
will generate "regen" voltage (with no current to go anywhere). At some speed,
voltage will overcome maximum voltage for inverter and BOOM :!:
It happens instantaneously with no warnings. This magic smoke release requires
inverter replacement, somewhat costly procedure.

BUT. I'm electrician and I weighted the risks and did come up with solution.

I did tow my Leaf, 2014, all 4 wheels on the road, with a tow rope. With one strict rule.
Maximum speed 30 km/h, 20 mph. I towed for exactly 10km (6 miles). Never
exceeding 32km/h. No explosions. Therefore, one should expect no MOSFET smoke.
At that speed, motor is turning at 2000rpm. That is 20% of maximum speed. This
speed did not create enough backEMF for failure.
PS! Leaf has a special brake booster. If 12V system fails completely, main brakes
WILL FAIL COMPLETELY. And I mean, completely. Pedal is not connected with brake lines.
My Leaf has a manual/foot emergency brake (also called parking brake). If your model
has electronical parking brake, that will fail with 12V and you WILL crash into the vehicle
that is towing you. There is no way to slow down. Do not open the door nor use the foot
Therefore: switch off headlights, switch off Climate control fan. Switch off wipers. Switch
off all heating. If windshield is fogging up, you CAN ONLY crack the windows. Keep your
hazards on (and the vehicle that is towing Leaf, should keep them off!)
At some point, 12V battery voltage (depending on the health) will drop to unsafe levels.
Unignorable warning with loud beep will inform you, that 12V system is unacceptable
and message "STOP NOW" will appear on the screen. At that point, you have about
1-5 minutes to stop. Brake booster does have a small capacitor, but I suspect that is
not good enough for more than few brake applications. Today I found out that my 12V
battery is old (SOH 30% or less). After message appeared I had around 4 minutes until
total failure. Good/fresh 12V battery will allow to tow for more than 30 minutes/15km.

In summary: Towing is possible, keep speed below 30km/h, keep the vehicle ignition on,
otherwise you might not see the warning message/speed. Call your friend who is towing
you. Always talk on the phone/handsfree - communication before brake events helps.
Even at 30km/h the one who is being towed should slow down both cars to keep the rope
extended. Keep all unnecessary power drawing items off to conserve 12V battery.
If the STOP VEHICLE IMMEDIATELY message appears, I would not consider continuing driving
at 30km/h for more than few minutes EXCEPT if you have a good foot operated emergency brake.
It is acceptable to keep portable 12V charger active under the hood.
Please stay at the curb side of the road and move to the left only for turns.
You are literally moving at bicycle speed so drive on that area where people walk/run/bicycle
(wherever you live, your curbs are what they are). Driving near the curb (experienced drivers)
is no worse than leaving Leaf stranded at the curb for hours at 0 km/h.

PS: I towed my Leaf with BMW i3 - really problematic - as soon as cruise control is disengaged,
strong regen event creates rope slack. It is possible to engage Neutral to avoid that.
PS2: Remove tow hook cover - it will fall off in the wind. Keep it in the glovebox.
PS3: if you bump the vehicle that is towing, at such low deceleration speeds, airbags should
not deploy, but bumpers will be somewhat scratched and poked by tow hooks.
PS4: Nissan has the tow hook "on the wrong side" compared to normal vehicles. Rope will be
diagonal, but at slow speeds it is bearable. It is recommended to use trailer hitch to compensate.
PS5: charge 12V battery, same day, otherwise it will lose capacity and you will need a new one.
If you towed your Leaf to charger, then don't worry, car will deal with 12V battery immediately.

Or avoid all this, call a flatbet or rent a towing dolly - cheap and might be faster.

 

[knightmb]

If the Leaf doesn't blow up components rolling fast down a long mountain in neutral, I don't see any reason why any damage would take place towing it in neutral.

That aside, everything else you mentioned is good advice. If the Leaf can't go into neutral, the brakes and everything else connected to the 12V system is subject to failure as well.

 

[GerryAZ]

There is some misinformation here--the hydraulic brakes will still function without 12V power (without power assist). The pedal will go close to the floor and require much higher effort, but it will still apply the brakes unless there is something wrong with the hydraulic system (my experience through testing of 2011, 2015, and 2019 USA models). It is safe to tow the LEAF if you can get it to go into neutral and release the parking brake. If you cannot get it to go into neutral, then you need to manually release the park pawl, manually release the electric parking brake (if equipped), and limit towing speed to avoid generating too much voltage (with no where for the current to go).

 

[arnis]

Neutral when READY is on, is not actually Neutral - if one opens Leaf Spy Pro, power to/from
motor can be seen there. Not much, but still power.
Neutral when READY is not lit, is actually Neutral. 0W of power flowing from/to motor.

Gerry, are you sure connection between pedal and brake master cylinder is strong enough
for acceptable braking action? And it wasn't capacitor bank that helped your braking action?


Has anybody towed Leaf faster than 30km/h for at least 5 minutes?