Model S

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Seeking info on charging an MS with a gas generator.

edited November -1 in Model S
I have a remote old cabin we use 1 to 3 times a year. Everything runs LPG. I'm thinking of getting a gas generator that i can lock inside the cabin when I'm gone,to recharge the MS. I really do not want to get into a solar set up because of snow and cost. I'd like a recommendation for what to get.

What would be a minimum generator for charging in 8 hours and what would be the maximum for the fastest charge theoretically possible? Also how much gas would I need per charge? Money is not an issue. I am not an engineer, (spare me the jokes) so please keep it simple like you need a 60000 watt generator with a 220v outlet that uses a 20 hp motor that should burn 2 gallons an hour. Something like that.


  • edited November -1
    This is somewhat guessing, but feels like you would need approx. a 10kw generator run off of natural gas.

    But that would be a pretty inefficient way to get electricity to the car, if you already have electric service there? What is the cabin powered by right now?

    If you don't have strict time constraints on how fast it needs to charge, maybe 110v power (if you have it) would be enough. But I guess you don't for some reason, hence your question.
  • edited November -1
    @soma as everything runs on LPG, I'm guessing the cabin is powered by LPG.

    10KW would come close to charging in 8 hours. It looks (from a quick search for LPG Generator) that these are available for a tad over $2000 - of course you'd need a contractor to install it. You could probably get a gasoline generator for that ballpark, but do you really want to be carrying gasoline to your cabin in a Tesla?
  • edited November -1
    Careful, there are some videos and postings out there that the MS is very sensitive to the quality of the power, ground, etc. I think you would literally need to try if a specific generator works.

    You can charge in the US as far as I understand max. 80A one phase with dual chargers. 240V would get you close to the dual charger limit of 22kW. Single 40A, 11kW. If the power is good enough you could charge from 110V/10A I guess with around one kW, if you stay 85 hours in the cabin ;-)

    For a weekend, charging at 5 kW should do it, below 24 hours for complete charging. If you can find a generator the MS accepts as a power source...

    If you find one let the preppers in the Tesla community know, finally a way to use the MS after the sun faded and the grid failed ;-)
  • edited November -1
    Hi there,

    Unlike you I'm an engineer and glad to help.

    First you have to exclude all 110 V generators unless you want to compromise on your 8 hours charge time. Although your on-board charger is rated at 10 kW there are current limitations and it can not accommodate close to 100 A current to achieve 10 kW at 110V.

    Look for a LPG generator that has 220 V output and 10 kW continuous (as opposed to peak or momentary) electrical power. You shouldn't care about the power of the gas motor this is something for the manufacturer to care about.

    Keep in mind that motors are not most efficient at their peak ratings. You may consider buying slightly larger generator in order for the motor/generator to work more efficiently, less noisy and eventually have a longer life as well.

    I would consider buying 12 kW to 15 kW 220V generator if I was you.
  • edited November -1
    Maybe rent an ICE 1 to 3 times a year?

    Cost, noise, generator maintenance...does not seem like a good solution.

    If you do go the generator route, I'd suggest LPG not gasoline. My guess is 15 to 20 gallons of gasoline for a charge.
  • edited November -1
    So could certain types of generators cause harm to the charging circuitry?
  • edited November -1
    @WEB_SRFR: There's not as much danger as harm as there is of it just not working. The charging circuitry is very robust, but is picky about the quality.
  • edited November -1
    Bob W posted this video of using a generator to charge his Tesla. Perhaps it may help.

  • edited November -1
    You need a pure sine wave generator, not modified sine wave, and the regulation needs to be pretty good. For example, if the voltage drops too much, the car will stop charging because it thinks there is a bad connection causing the voltage drop. I doubt you will get one that you can lock inside your cabin - you are probably looking at a permanent installation to get the size/etc you want.

    I was planning on installing a whole-house backup generator at our house, and Tesla wouldn't guarantee there wouldn't be a problem and then Generac wouldn't warranty the unit if the car was hooked up without Tesla's ok (plus they wanted to put in load shedding relays since I have the HPWC and they were worried about the maximum load even if I wouldn't charge at 80A while running on the generator). So, I decided it was too much hassle - I may look at it again in the future.
  • edited November -1
    Is the area windy? Do you really need an 8 hour charge or is that just a a number you threw out for sizing?
  • edited November -1
    This is a subject I am very interested as well. I have a remote cabin totally dependent on solar, battery storage and modified sine wave inverter. I have been thinking about plugging my Tesla into the 115 VAC plug off the inverter (because that power is basically free to me) and I can leave it plugged in for the entire weekend at about 2 miles of charge per hour. I have also been thinking of plugging it into 230VAC plug-in of our 5KW generator. Although I can not seem to find an adopter that would work for this. So you've confirmed that Tesla would not work with modified sine wave AC, right? If that is true, both my plans will not work... I'll have to start shopping for true sine wave inverter. They are expensive...
  • edited November -1
    @hideiba: Is your generator L14-30? There's an adapter for that here:

    Though it sounds like from others' experience, without true sin it won't work even with the adapter.
  • edited November -1
    @hideiba - yes, Tesla said it absolutely would not work with MSW, and they wouldn't even confirm it would work with PSW. I suspect it would, but I wasn't willing to make the big investment without confirmation.

    A 5kW generator can't put out more than 20A at 240V anyway, but if it is PSW with tight voltage regulation, it should work if you turn down the current on the Model S.
  • edited November -1
    You should search the other Tesa site--there were a couple of extensive threads on the topic. I seem to remember that a regular generator would not work as it did not generate clean enough power so the on-board chargers would not kick-in.

  • edited November -1
    @Truefire: What are you going to that cabin for? If it is to get into a remote, silent place, maybe you should consider that short of getting a hilariously big generator only running 2 hours (40+ kW), you would charge for some time, maybe most of the time on the weekend. And none of those generators will be silent. I think my "remote old cabin experience" would be spoiled by that.

    If you go there to listen to heavy metal concerts and not disturb anyone at 110dB then you can go ahead and ignore this thought ;-)
  • edited November -1

    I am no engineer either but I assume if 60kW is good enough to electrify a whole house, including electric dryer, then it should be good for you Model S.

    The only draw back is $16,000 price plus professional installation and a cost of Tesla HPWC which can charge your twin-charger equipped Model S in about 5 hours.,1174083&returnShoppingUrl=

    Its noise is 72 decibels which is as loud as your favorite vacuum cleaner.

    Of course you can install it away from where you sleep (but does that means it's close to where your neighbor sleep?)
  • The pure sine wave inverter on my boat produces very clean stable power. Even changing from mains to inverter while watching TV does not produce the slightest flicker. You are totally unaware of the switchover. Virtually all electronic equipment fares better with true sine wave. I would not consider anything else. For your cabin why not a combo of solar, wind and battery?
  • edited November -1
    The on-screen owners manual that came with version 5.6 says that is a no no. They don't explain, but using individual generators for charging the Model S is noted as a hazard.
  • edited November -1
    They don't mention a full house generator as a hazard.
  • edited November -1
    I think a portable generator you buy at Home Depot for a few hundred dollars to power tools, is very different from a large, expensive, home backup generator. The latter is designed to provide clean power that won't harm all the delicate electronic toys in your house. I just don't think it is cost effective. You are talking $5K minimum for a small one installed. We spent around $10K to have a 20kW put in at our house.
  • edited November -1
    Perhaps the OP is at his cabin for a few months without internet...
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