# Wheel-generator for current cars to output 220V power



## EvanLin (Jun 3, 2017)

(edit: 240V in US)

Inspired by Elon's tweet about "party & camper mode" today.

Due to hardware change and regulation approval, current cars CANNOT output significant power.
I think a safely-designed wheel generator(like a dyno) from TESLA and an OTA update could make it happen.

It is possible to detect if the car is "jacked" in wheel-generator status.
The cost and efficiency should be practical for "party & camper" use.

Any thoughts?


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## garsh (Apr 4, 2016)

I'm not sure what you mean by "wheel generator". You'd need something to mechanically turn the wheel.

They could certainly turn the car into a "powerwall on wheels" if they wanted. That would use the energy already stored in the car's battery. Elon hinted about adding such a feature at one point, but who knows if it will ever happen.


__ https://twitter.com/i/web/status/1014634671735562240


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## Ed Woodrick (May 26, 2018)

EvanLin said:


> (edit: 240V in US)
> 
> Inspired by Elon's tweet about "party & camper mode" today.
> 
> ...


I can tell you that there is no way that you will EVER see that from a manufacturer. There is WAY too much liability with a jack failing and the car moving out of control. I'm not sure why you are saying that a hardware change and regulation approval is required. Maybe some hardware change, but I doubt if there is legal issues. Nissan already has the feature available for use in Japan and is looking to move it to the US. It is a little more dramatic, using the car battery for house backup.
Elon has already indicated that powering other equipment will be a feature of the pickup truck.


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## EvanLin (Jun 3, 2017)

garsh said:


> I'm not sure what you mean by "wheel generator". You'd need something to mechanically turn the wheel.


It's like a portable dyno with smaller rollers. Should fit in lower trunk bin.
Drive on it. Make sure wheels are in position. Turn the mode ON from screen. Output 240V power.



Ed Woodrick said:


> I can tell you that there is no way that you will EVER see that from a manufacturer. There is WAY too much liability with a jack failing and the car moving out of control. I'm not sure why you are saying that a hardware change and regulation approval is required. Maybe some hardware change, but I doubt if there is legal issues. Nissan already has the feature available for use in Japan and is looking to move it to the US. It is a little more dramatic, using the car battery for house backup.
> Elon has already indicated that powering other equipment will be a feature of the pickup truck.


It's for *current cars*. That's what matters.
A hardware change for 240V output is not possible due to regulation. An add-on package is feasible.

AWD is 100% safe. Just put in Park and use front wheels to generate 240V.
Use sensors (both torque and wheel rpm) to make sure it won't go off.
You don't need high rpm/torque to generate 240V for camping use like on a dyno.

RWD is a bit tricky though.


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## MelindaV (Apr 2, 2016)

Ed Woodrick said:


> It is a little more dramatic, using the car battery for house backup.


utilities do want to regulate this though because using something to power a house has the potential to do unpredictable things to the grid as a whole. that is in part why solar needs different meters and other safeguards added before it can go online (and why some utilities do not permit their users to generate solar energy at all unless they are completely off the grid - which then they wouldn't be involved anyway  )


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## garsh (Apr 4, 2016)

EvanLin said:


> It's like a portable dyno with smaller rollers. Should fit in lower trunk bin.
> Drive on it. Make sure wheels are in position. Turn the mode ON from screen. Output 240V power.


You don't even see that solution being used with regular cars. If you want to use an engine to power something, you don't jack up the car and use a dyno. You order your car (well, truck) with a PTO (power takeoff), and you connect whatever you want to power to that additional spinning shaft, which could be a generator. This way, you avoid all of the efficiency losses due to the vehicle's transmission and the friction losses between the tires and dyno.










The jack/dyno solution makes even less sense when you're starting with an electric car, and your goal is to produce electricity. Why go through all of the efficiency losses of turning that electricity into motion, then turning the motion back into electricity? The electronics to convert 400v DC to 120/240v AC already exists - it's included in every Tesla Powerwall. You'd just need a way to integrate that into the car.


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## Ed Woodrick (May 26, 2018)

EvanLin said:


> It's like a portable dyno with smaller rollers. Should fit in lower trunk bin.
> Drive on it. Make sure wheels are in position. Turn the mode ON from screen. Output 240V power.
> 
> It's for *current cars*. That's what matters.
> ...


Let's think about that a little bit. Sure, when the wheels are aligned exactly on top of the dyno and the differential is working with no power to the other wheel, yes, things may be somewhat safe. But what if the car shifts an inch or two, maybe from something as simple as opening the trunk to get something out of it? The car may then move and strike the area around the freewheel and either the car goes one direction or the dynamoter goes the other way. What if there is a little kid or a dog that sees the spinning wheel and wants to play with it.

I'm not a mechanic, but most of the dynamotor test pictures that I see are with the car in a separate room with all sorts of safety equipment doing things like chaining all of the wheels to the floor.

I'm still not sure what you mean that a hardware change is not possible due to regulation. The way the Leaf does it, plug an inverter into the charge port, connect the DC buss to the charge port as if you were fast charging. Viola, high voltage connected to the inverter to allow 220V or 110V. I'd be surprised if Tesla couldn't do the same thing. The inverter can easily sit in the bottom of the trunk, can constantly communicate with the car to assure safety and be relatively safe.


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## EvanLin (Jun 3, 2017)

The PTO & regulation thing is... it doesn't work on **current cars**. However, a package does.

If you add a 240V output on a new model-year car. This car must pass electric tests & regulations.
Most authorities won't let you make such a big change on old cars. Neither does TESLA.

Small rollers can be placed in a V-150deg status (seen from the front) to prevent lateral shift.
Again, it only takes some gentle rolling, not the violent thing on a real dyno.
Parking brake can do the work. No chains needed.

The biggest questions for me is how to generate stable *AC* from rollers in an easiest/cheapest way. I am not an electrician.


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## garsh (Apr 4, 2016)

EvanLin said:


> The PTO & regulation thing is... it doesn't work on **current cars**. However, a package does.


If you want something that works in current cars, give up on this wheel-driven generator idea and install an inverter.


> The biggest questions for me is how to generate stable *AC* from rollers in an easiest/cheapest way.


The answer is: it's impossible. You need to turn a generator at a fixed speed (60 rpm). So are you going to sit in the car and attempt to hold the accelerator at the exact position to maintain that speed?


> I am not an electrician.


I'm an electrical engineer, and I'm telling you that there are easier ways to get electricity out of a car.


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## EvanLin (Jun 3, 2017)

I know what a power inverter is. The problem is 12V outlet has tiny power & capacity compared with wheels.

60 rpm is not a problem. I mentioned it needs a "wheel-generator mode" with OTA update in post #1 & #4.


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## garsh (Apr 4, 2016)

EvanLin said:


> I know what a power inverter is. The problem is 12V outlet has tiny power & capacity compared with wheels.


Take a closer look at the inverters I listed. These aren't the dinky little ones you plug into the cigarette lighter. These are the kinds that you connect directly to a heavy-duty battery. These are the kind that require your engine to be running so that the alternator is supplying the power. In the case of the Tesla, the traction battery and DC-to-DC converter would be supplying the power.


> 60 rpm is not a problem. I mentioned it needs a "wheel-generator mode" with OTA update in post #1 & #4.


And that would require that the car know the diameter of your dyno rollers, and the amount of slip it is experiencing.

I'm sure you could get *something* like this to work. But there are so many better ways of accomplishing this goal. Tesla won't be implementing a "wheel generator mode".


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## Ed Woodrick (May 26, 2018)

EvanLin said:


> The PTO & regulation thing is... it doesn't work on **current cars**. However, a package does.
> 
> If you add a 240V output on a new model-year car. This car must pass electric tests & regulations.
> Most authorities won't let you make such a big change on old cars. Neither does TESLA.
> ...


Read my reply, you add an external regulator to the car and it is powered directly from the batteries, in the same fashion that they are charged. I believe that Elon has already said that they may be looking into this.

And to generate ANY quantity of power , 60 rpm isn't going to cut it. Think how much regen is created at 60 rpm - 0%. To get any power, you'll need to get to about 3600 rpm. Sure there are ratios and gears involved, but those also add weight.


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## garsh (Apr 4, 2016)

Ed Woodrick said:


> And to generate ANY quantity of power , 60 rpm isn't going to cut it. Think how much regen is created at 60 rpm - 0%. To get any power, you'll need to get to about 3600 rpm. Sure there are ratios and gears involved, but those also add weight.


I think I was the one who brought up 60rpm. That's the speed the generator side would need to run at in order to produce 240v at 60Hz. As you say, the car wheel may need to run at a faster RPM, so the dyno would need gearing to step the generator down to the required speed.


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## Ed Woodrick (May 26, 2018)

garsh said:


> I think I was the one who brought up 60rpm. That's the speed the generator side would need to run at in order to produce 240v at 60Hz. As you say, the car wheel may need to run at a faster RPM, so the dyno would need gearing to step the generator down to the required speed.


Two things about 60 rpm, yes it is important, but all generators generally spin at 3600 to give the 60 Hz. There's probably no way that you could spin the wheel at exactly the right speed.

A lot of generators, for multiple reasons, use inverters to create the 60 Hz these days. One of the big problems with a generator is that if you kick on a large load, the engine bogs down and the speed drops. Fast carburetor controllers help, but can't be perfect. Inverters on the other hand can do much better. That's what you will tend to see on all of the cheaper Chinese generators.


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