Tow Charging EVs
Discussion
Parts of Berlin are suffering from a power cut because of a damaged cable. Fortunately, for me, our home is not affected but it’s got me thinking.
We have a Honda e which has a power socket in the dashboard. I could use the car as a power supply for the central heating boiler and other odd stuff until the power came back on. What if the Honda's battery got drained too soon?
Question: could I tow charge the Honda with a petrol car? The Honda would get the impression it was going down a very long hill and charge by regenerative braking.
We have a Honda e which has a power socket in the dashboard. I could use the car as a power supply for the central heating boiler and other odd stuff until the power came back on. What if the Honda's battery got drained too soon?
Question: could I tow charge the Honda with a petrol car? The Honda would get the impression it was going down a very long hill and charge by regenerative braking.
Not sure about the Honda e but towing a BMW i3 can knacker the EME
"Yes, towing a BMW i3 incorrectly, especially with the drive wheels on the ground (rear wheels for RWD i3s), can severely harm the
electric motor and transmission unit (EME), leading to costly damage, so it must be towed on a flatbed or with the drive wheels lifted. Incorrect towing can spin the motor, causing major drivetrain failure, and even improper 12-volt battery disconnection can damage the EME module.
Why Incorrect Towing Harms the EME:
Electric Motor Damage: The BMW i3 uses an electric motor that's directly connected to the wheels; if you tow it with the rear wheels on the ground, the wheels will spin the motor, acting like a generator, which can overheat and destroy the motor and transmission unit (EME)."
"Yes, towing a BMW i3 incorrectly, especially with the drive wheels on the ground (rear wheels for RWD i3s), can severely harm the
electric motor and transmission unit (EME), leading to costly damage, so it must be towed on a flatbed or with the drive wheels lifted. Incorrect towing can spin the motor, causing major drivetrain failure, and even improper 12-volt battery disconnection can damage the EME module.
Why Incorrect Towing Harms the EME:
Electric Motor Damage: The BMW i3 uses an electric motor that's directly connected to the wheels; if you tow it with the rear wheels on the ground, the wheels will spin the motor, acting like a generator, which can overheat and destroy the motor and transmission unit (EME)."
Edited by _Hoppers on Monday 5th January 16:33
I guess the description above is assuming the vehicle is turned off at the time. Makes sense that it'd cause problems.
It sounds like the OP is suggesting the vehicle is turned on, and in drive, an ten towed with foot off the accelerator. The theory seems to work, but not sure i'd want to practically try it!
It sounds like the OP is suggesting the vehicle is turned on, and in drive, an ten towed with foot off the accelerator. The theory seems to work, but not sure i'd want to practically try it!
Spare tyre said:
This is why I always leave my ev on top of a mountain just in case
Always been curious how much charge I could get from descending from a big mountain range
Well, if you parked a 2 tonne electric vehicle (e.g., a Tesla model Y) at the Glenshee car park (the highest public road in the UK) and managed to get it to sea level with no efficiency losses I think you might get about 3.5 kWh, so c.5% of a boggo EV battery.Always been curious how much charge I could get from descending from a big mountain range
bobtail4x4 said:
how will it know its not going downhill and regenerating?
I haven't got a clue, but according to Gemini:"The core difference is that during normal driving (including downhill regeneration), the electric vehicle's (EV) systems are powered on and actively
regulate the flow of energy back into the battery, which protects the drivetrain components. When an EV is towed improperly, this regulation is often absent, leading to potential uncontrolled power generation and severe damage.
Regenerating Downhill
Controlled Environment: Regenerative braking is a normal, integrated function of the EV's design. The vehicle's computer and Battery Management System (BMS) are fully operational and manage the amount of electrical power the motor (acting as a generator) can send to the battery.
Optimal Stress Levels: The forces involved in regeneration are within the motor and battery's designed operating limits, similar to or less than the stress of normal acceleration.
Energy Management: The system constantly monitors the battery's state of charge (SOC) and temperature. If the battery is full or temperatures are too high, the system automatically reduces or stops regeneration and blends in conventional friction braking to control speed, preventing overcharging or overheating of the battery/motor components.
Improper Towing
Lack of Regulation: When an EV is "flat towed" with its drive wheels on the ground and the vehicle systems are off (which is often the case during an emergency tow), the spinning wheels force the motor to generate electricity without the control of the BMS.
Uncontrolled Power Surge: This can lead to an unmanaged and potentially excessive flow of electricity that can overheat and destroy the motor components, inverter, or the battery pack.
System Disconnect: The vehicle's electronic systems, including lubrication for some components, may not be active, which exacerbates mechanical and electrical strain.
For these reasons, manufacturers universally recommend that EVs be transported on a flatbed tow truck with all four wheels off the ground to prevent any rotation of the drive wheels and potential damage"
I'd guess that if the car was turned on it might charge ok when being towed? I'd also guess that the towing vehicle would need quite a bit of power and torque to pull it?!
Edited by _Hoppers on Monday 5th January 17:01
_Hoppers said:
bobtail4x4 said:
how will it know its not going downhill and regenerating?
I haven't got a clue, but according to Gemini:"The core difference is that during normal driving (including downhill regeneration), the electric vehicle's (EV) systems are powered on and actively
regulate the flow of energy back into the battery, which protects the drivetrain components. When an EV is towed improperly, this regulation is often absent, leading to potential uncontrolled power generation and severe damage.
Regenerating Downhill
Controlled Environment: Regenerative braking is a normal, integrated function of the EV's design. The vehicle's computer and Battery Management System (BMS) are fully operational and manage the amount of electrical power the motor (acting as a generator) can send to the battery.
Optimal Stress Levels: The forces involved in regeneration are within the motor and battery's designed operating limits, similar to or less than the stress of normal acceleration.
Energy Management: The system constantly monitors the battery's state of charge (SOC) and temperature. If the battery is full or temperatures are too high, the system automatically reduces or stops regeneration and blends in conventional friction braking to control speed, preventing overcharging or overheating of the battery/motor components.
Improper Towing
Lack of Regulation: When an EV is "flat towed" with its drive wheels on the ground and the vehicle systems are off (which is often the case during an emergency tow), the spinning wheels force the motor to generate electricity without the control of the BMS.
Uncontrolled Power Surge: This can lead to an unmanaged and potentially excessive flow of electricity that can overheat and destroy the motor components, inverter, or the battery pack.
System Disconnect: The vehicle's electronic systems, including lubrication for some components, may not be active, which exacerbates mechanical and electrical strain.
For these reasons, manufacturers universally recommend that EVs be transported on a flatbed tow truck with all four wheels off the ground to prevent any rotation of the drive wheels and potential damage"
I'd guess that if the car was turned on it might charge ok when being towed? I'd also guess that the towing vehicle would need quite a bit of power and torque to pull it?!
Edited by _Hoppers on Monday 5th January 17:01
normalbloke said:
Care to show where that information is sourced from? Gushing quotations straight from Ai is becoming so fecking tedious on forums.
Very much agree with this. Not just because it kills conversation either. When you know a decent bit about a subject it quickly becomes apparent that AI answers are wrong a huge amount of the time. wolfracesonic said:
If you towed it on a conveyor belt you wouldn't even have to go anywhere, you'd be tricking the ICE car and the EV. Tilt the conveyor downhill to make it more convincing.
This reminds me of the thread about sticking a jet plane on a conveyor belt to see if it would take off or not :-)AC43 said:
wolfracesonic said:
If you towed it on a conveyor belt you wouldn't even have to go anywhere, you'd be tricking the ICE car and the EV. Tilt the conveyor downhill to make it more convincing.
This reminds me of the thread about sticking a jet plane on a conveyor belt to see if it would take off or not :-)normalbloke said:
_Hoppers said:
bobtail4x4 said:
how will it know its not going downhill and regenerating?
I haven't got a clue, but according to Gemini:"The core difference is that during normal driving (including downhill regeneration), the electric vehicle's (EV) systems are powered on and actively
regulate the flow of energy back into the battery, which protects the drivetrain components. When an EV is towed improperly, this regulation is often absent, leading to potential uncontrolled power generation and severe damage.
Regenerating Downhill
Controlled Environment: Regenerative braking is a normal, integrated function of the EV's design. The vehicle's computer and Battery Management System (BMS) are fully operational and manage the amount of electrical power the motor (acting as a generator) can send to the battery.
Optimal Stress Levels: The forces involved in regeneration are within the motor and battery's designed operating limits, similar to or less than the stress of normal acceleration.
Energy Management: The system constantly monitors the battery's state of charge (SOC) and temperature. If the battery is full or temperatures are too high, the system automatically reduces or stops regeneration and blends in conventional friction braking to control speed, preventing overcharging or overheating of the battery/motor components.
Improper Towing
Lack of Regulation: When an EV is "flat towed" with its drive wheels on the ground and the vehicle systems are off (which is often the case during an emergency tow), the spinning wheels force the motor to generate electricity without the control of the BMS.
Uncontrolled Power Surge: This can lead to an unmanaged and potentially excessive flow of electricity that can overheat and destroy the motor components, inverter, or the battery pack.
System Disconnect: The vehicle's electronic systems, including lubrication for some components, may not be active, which exacerbates mechanical and electrical strain.
For these reasons, manufacturers universally recommend that EVs be transported on a flatbed tow truck with all four wheels off the ground to prevent any rotation of the drive wheels and potential damage"
I'd guess that if the car was turned on it might charge ok when being towed? I'd also guess that the towing vehicle would need quite a bit of power and torque to pull it?!
Edited by _Hoppers on Monday 5th January 17:01
Edited by _Hoppers on Monday 5th January 18:24
Richard-D said:
normalbloke said:
Care to show where that information is sourced from? Gushing quotations straight from Ai is becoming so fecking tedious on forums.
Very much agree with this. Not just because it kills conversation either. When you know a decent bit about a subject it quickly becomes apparent that AI answers are wrong a huge amount of the time. Gassing Station | The Lounge | Top of Page | What's New | My Stuff