Using MYLR wheels as an electric generator during an emergency

[qdeathstar]

Thanks. I don't have natural gas or propane. And California limits the kinds of gasoline generators that we can purchase. Plus, for a unit that sits idle most of the time there are maintenance issues. That's why I'm avoiding gasoline generators. I had several neighbors with portables, Generac, etc. and when it was time to crank them up, they didn't work for some reason (I'm guessing lack of fuel stabilizer, or oil issues, or the 110 degree heat, or ...). For two of them, their solutions were large ground-mount solar racks (but no batteries). The rest do what I do -- off to the movie theater the next town over; or to a hotel when more than 1-day outage.

Based on the comments (above), using 4 units is too problematic. And doing just 1 unit is bad for the diff/axle.


Thanks to all for the advice. Looks like the thing to do is to wait for a simple 400V solution. That big orange connector is awfully tempting

Thanks,

Scott

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MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021

Solar plus power wall then…

 

[e645824]

Thanks for the comments. My original post (#1) was about getting power from the wheels because of the difficulty of getting significant power out of my Tesla other ways. We've already ruled out the 12V system. And pulling from the 400V system might cause other issues with the various Tesla detection circuits. So I was thinking of just letting the car do its thing and spin the wheels.

But as everyone pointed out, pulling from 4 wheels is problematic due to synchronization, and pulling from just 1 wheel is a problem also. Having my Tesla on a dyna with a chain connecting front-to-back and driving a generator seems nice, but expensive and dangerous. I could imagine Junk Yard Wars cobbling this together, but simpler and safer solutions are probably better.

Likewise, folks have suggested a generator. I don't have natural gas, don't want a big propane tank, gasoline has issues even with fuel stabilizers, but diesel is interesting (thanks for that pointer). My home is all electric; free of volatile chemicals that catch fire and I'll keep it that way.

At this point, I can cobble together something with an LFP battery plus a couple of solar panels and an AIMS inverter to drive my 240V well pump, 120V refrigerator, and lights/computers/etc. But the big missing piece is my 240V 50A A/C system (heat pump). Or even my 240V 30A whole-house window unit that I have as a back-up (I've used it once in the past 3 years when my big unit stopped working for 2 days and needed service). When it is 118 degrees outside, having A/C is not a luxury, it is a requirement. And yes, my big unit is 5 tons and is sized precisely to keep the house cool when it is hot outside (efficiently plummets).

My point about the A/C is what drove me to thinking of how to get power out of the Tesla in the first place -- the need to make electricity, and seeing my nice shiny 80 kWh battery sitting in the driveway. In an emergency, I would like to use it but as folks have pointed out the ability to get power out of our Teslas is very limited.

I'm the perfect customer for solar+batteries, but can't afford it yet. Tesla says that 3 PowerWalls are needed to drive my load. That, plus panels, is very pricey. Ditto EnPhase's quote for their system to me.

Thanks to all,

Scott

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MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021

 

[jcanoe]

A diesel powered generator is one option. Diesel fuel requires added stabilizer for long term storage. Under the right conditions diesel fuel can become contaminated with algae. Propane has no long term storage issues.

 

[rrolsbe]

I for one do not think this idea is crazy but might not be practical or easy to safely implement. I actually mused almost the same idea a few years back. Another crazy idea that ran through my brain after seeing tow charging, assuming my home was next to fast moving river, rig up something to charge the battery for free (I will let the readers imagination go with this). Now that some of the Model 3 cars are beyond all warranty periods and have around 200K miles, I keep thinking someone will figure out a way to safely connect a powerful inverter directly to the HV DC battery connections to power their home and still leave the car driveable.

 

[Rocky_H]

We've already ruled out the 12V system.

At this point, I can cobble together something with an LFP battery plus a couple of solar panels and an AIMS inverter to drive my 240V well pump, 120V refrigerator, and lights/computers/etc.

I do wonder if this can be done in some hybrid way. The battery bank would be needed to run the heavy loads you have. But the 12V system may be something that could be tapped for a medium steady draw to refill the battery bank slowly, so the batteries are like a buffer storage system.

 

[e645824]

I reached out to DynoJet to see what their position was. They indicated that they would be willing to entertain thinking about a quote, but it would be in the $50k range. Basically they would remove their force sensors and eddy current load and replace it with a generator. So the cost is a wash from their existing portfolio. Very high quality and safe looking products.

I think that sums it up pretty well: a cheap solution is dangerous, and an expensive solution is safe. That 80kWh battery sitting in my driveway with the big orange 400V connector is going to look very tempting during a blackout. That's what's so frustrating, it is the equivalent of 6 Tesla Power Walls but is barely usable in an emergency.

But it seems I'll only be able to prop-up my standard refrigerator (using a modest inverter on the 12V battery terminals) to keep the food from spoiling, recharge some cell phones, and a handful of LED lamps.

Thanks to all,

Scott

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MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021

 

[davewill]

I guess if I was determined to do something like this, and didn't mind spending lots of time and effort, I'd look to hack the Supercharger or CCS protocol to access HV battery voltage from the charging port. I wouldn't be surprised if it turned out not to be possible, but it's the least intrusive and generally safest approach I can think of.

 

[rrolsbe]

I guess if I was determined to do something like this, and didn't mind spending lots of time and effort, I'd look to hack the Supercharger or CCS protocol to access HV battery voltage from the charging port. I wouldn't be surprised if it turned out not to be possible, but it's the least intrusive and generally safest approach I can think of.

I agree with you. Tesla could sell an external inverter that could handle say 360-402V DC input, 30-40A/240V AC output and a cable to make the connection. Then have a handshake protocol to close the DC fast charge contactors to allow the power to flow outbound instead of inbound. Given the newer LFP batteries last around 2.5 time longer, maybe Tesla might do this in the future.

 

[Rocky_H]

barely usable in an emergency.

But it seems I'll only be able to prop-up my standard refrigerator (using a modest inverter on the 12V battery terminals) to keep the food from spoiling, recharge some cell phones, and a handful of LED lamps.

Yes, exactly. That is an emergency. You don't get to run your whole house. Most of it stays dark, but you get to pick a few essentials to have.

If you want a whole home backup generator system, you need to get a whole home backup generator system. If you want to tap off the car to power just a few small power things, you can do that, and that's what you get as a bonus for emergency use from something that is not designed for that.

 

[JerseyShoreMY]

I guess if I was determined to do something like this, and didn't mind spending lots of time and effort, I'd look to hack the Supercharger or CCS protocol to access HV battery voltage from the charging port. I wouldn't be surprised if it turned out not to be possible, but it's the least intrusive and generally safest approach I can think of.

Seems there is little reason why the home should need another battery set when the Tesla is sitting there. Connected with your own inverter / solar charge UPS unit and you are with power. If anyone gets a tested hack on how to revert the HV power out and in safely, please let us know how you made out. Might be good to know in a pinch and certainly a money saver.

On the wheels driving a generator setup, one can wonder how the Tesla AP computer would react to no moving in the AI view but showing a speed of 45 mph? Want to bet if their QA team has looked at that? The ABS and perhaps AWD could be well confused with wheel speed imbalance??? Wonder what if after all that set up work, the computer applies the brakes every time?

 

[e645824]

I agree with you. Tesla could sell an external inverter that could handle say 360-402V DC input, 30-40A/240V AC output and a cable to make the connection. Then have a handshake protocol to close the DC fast charge contactors to allow the power to flow outbound instead of inbound. Given the newer LFP batteries last around 2.5 time longer, maybe Tesla might do this in the future.

There are 400V DC inverters that supply 240 AC. For example, here is one from Generac X7602 which is designed to work with their 400 VDC power cells (G0080040). The X7602 accepts 360-420 VDC and produces 120/240 VAC single-phase. This 7.6 kW unit is $4k. https://www.invertersupply.com/index.php?main_page=product_info&products_id=201323

The idea is to just unplug the big orange 400V cable from the Tesla battery pack and connect to the inverter (using a DIY cable of some sort with insulation rated for high voltage).

The problem is what will the car think. i.e. after the emergency is over and we reconnect the big orange connector, will the car's software shut everything down and/or fire the disconnect. Likewise, while the 400V battery is unplugged, then there is nothing keeping the 12V lead acid battery charged. And the car is definitely unhappy if that dies.

Scott

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MYLR | Red ext | White int | 19" | 5 seats | tow | no FSD | made/delivered Oct 2021

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