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Hack-charging on a generator
- Thread starter Dino Saver
- Start date
Mine was delivered with 50%
The car goes into power-saving mode when it gets low. so 50% SOC may last a year, but "dead" will be OK for a month or more IIRC.
If you charge the Model S from the generator with *nothing* else connected to it (because it's a standard "contractor's" generator -- one that doesn't have an inverter or an alternator designed for < 5% THD), that's safest. The Model S may still refuse to charge -- but having other stuff connected at the same time can distort the AC wave-form and cause issues.
I have done this myself, and it works like a charm.
The charger in my Think City once shorted due to water and road salt repeatedly getting sucked into it through a faulty seal as it cooled down after charging. The SoC was very low and I had to wait for weeks while the out-of-production charger was repaired. The Think will not "brick", but when voltage falls too low, it can't operate its main contactor, and then you have to remove its 270 kg NiCd battery to be able to charge it.
I asked my neighbor to tow me while I was regenerating. Some 20 minutes of this yielded 30% capacity, up from 5%, so we were charging at around 8 or 9 kW.
In a pinch I would much rather do this than trust some unknown generator. The regen is built to last and should be able to handle a mountain pass or two, and the Think with its 27 kW motor handled it just fine.
I would avoid charging above 75% in this way, I don't know how well the regen controls the charging process.
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Hmpf. That complicates my universal EV supercharger get-rich-quick scheme: A set of rollers powered by an electric motor with a diesel engine as backup in case of power outages. Park the EV with the drive wheels on the rollers, chock the other wheels and start the motor :biggrin:
We just used a strong rope and one of these $15 rubber mooring shock absorbers. The shock absorber worked extremely well, there were no jolts from the rope whatsoever. I'm not recommending this as a standard procedure, but there is no need to go "OMG - My car is gonna BRICK!!!" whenever there is a power outage. Just tow it for 15 minutes every few weeks. But be careful not to regenerate too hard, you don't want to ruin your neighbor's clutch.
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I think this is related but my parents have a home natural gas generator. In a big storm, would they be able to add on a 240V maybe 30 or 50A outlet (that may be too big) or even just a 110V outlet in the garage but backup charging? I realize this depends on the generator but was wondering what they should ask the electrician to add. Thanks.
Cottonwood
Roadster#433, Model S#S37
Just put in an RV, NEMA 14-50R. At the full, 40-Amp level this is 9.6 kW, but you can always dial this back to a lower current in the car if you need more for the rest of the house. Because most of these generators are connected to the houe via a backup transfer switch with the grid, this will give you a nice 40 Amp charge location when there is normal power as well.
You might want to see what the rating of the generator is. A lot of them are 10 kW or less and really can't deliver that for very long.
Johan
Ex got M3 in the divorce, waiting for EU Model Y!
How about something more like a treadmill setup, where the rollers may be small but they are not in contact with the wheel/tyre but insted the rollers are in turn driving a belt which form sort of a flat surface for the car's wheels to be driven by? Then the whole contraption still wouldn't have to be hughe (though it would have to hold the weight of the car).
I don't have any experience with that kind of set up, but to eliminate the tire problem it would have to be very stable so the tires didn't "push down" on the treadmill. This would make the treadmill very heavy because you'd likely be using something like the tracks on construction equipment to get the stability. You could purchase one heck of a generator system (and probably a dedicated Model S as well) for what that would cost you.
What I would do if I had to power generators or other equipment from the Model S is to create a power-take-off device. Basically this would be a pulley system that replaces the wheels and uses a belt to power the equipment. The tricky park is that the Model S doesn't have a drive shaft, and having one wheel stationary and one wheel turning wouldn't be even remotely good. So you'd have to have a system where each rear wheel position was powering a belt. The system would have to have a way to hold the Model S very solidly.
The economical way is to wait for a wrecked one and then use the battery, charger, and motor to power your device and you won't have the rest of the car to worry about. If you actually do this, then it should go in the Tesla Model S Firsts thread.
Note that these are Rube Goldberg devices rather than having any relation to something being engineered by John Ericsson.
My understanding is that in a disaster the best fuel is LPG. The reason is that natural gas is likely to have the pipelines cut, gasoline and diesel are likely to be in short supply, but LPG is easy to truck in (even if only small trucks can access the area) and a tank of it can stay good for a very long time (unlike gas and diesel). Solar panels or windmills would be fine as long as they aren't damaged by the disaster.
Cottonwood
Roadster#433, Model S#S37
OK, while researching backup generators for a friend on Long Island, I found a good solution to mate with an HPWC or 80A J1772 for rescue and field charging: Generac Magnum Lite Generator MLG 20
You probably want to turn the power on the Model S down to 72 Amps for continuos operation, but this should work pretty well. Of course you might want a diesel pickup to tow it and to carry extra diesel in a tank in the bed of the pickup. :biggrin:
You probably want to turn the power on the Model S down to 72 Amps for continuos operation, but this should work pretty well. Of course you might want a diesel pickup to tow it and to carry extra diesel in a tank in the bed of the pickup. :biggrin:
mknox
Well-Known Member
Exactly, my "universal EV supercharger" was intended as a joke. Just imagine the trouble making such a device safe for the average guy to use, someone would get cold rolled an inch thick before long. But a rope can sometimes be very useful.
Cottonwood
Roadster#433, Model S#S37
That is great! With standard regen and 50 mph, you can get 60 kW. That's almost as good as a supercharger at 80 kW. I will add a stretchy tow rope and a rubber boat snubber to my road kit very soon. This would be very easy with a tow truck and would have been way faster than the 10 kW RV plug when I wanted to get enough charge at HPR track last weekend. Besides they keep a tow truck at the track!
Let's see 60kW with losses is about 80 HP or a little more, but that should be fine from a reasonable truck.
It didn't occur to me until I read your post that if I really want to charge fast - tow the car instead of charging it! The Roadster will regen at 40kW but only charge at 17kW. Wonder how long it would tow before overheating? Or before the tow vehicle overheats? Kinda gives new meaning to "drafting."
The Racing Green guys also did this tow charge method with their SR0 when their charger let them down somewhere in British Columbia.
Johan
Ex got M3 in the divorce, waiting for EU Model Y!
This tow-charging makes sense - how can the car know if it's being towed or if it's rolling down a steep hill? However the method is totally contrary to Tesla's very strong warnings about NEVER towing (only flat-bed). Can someone please explain the reasons for the "No Tow policy"?
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