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Charging by generator possible, in a pinch?

Please, I'm looking for knowledge, not guesses.

I'm planning a trip in a couple of weeks to a friend's cabin, and I'm wanting to know what happens in "worst case scenario".

First off, I can't make it from the nearest charger (Tesla or other public) and back again. Just not possible. So I have to charge on site. That *shouldn't* be an issue, but this is a cabin and I'm not sure the power situation is reliable. Also, there's been a ton of snow and it hasn't been cleared from the long, unpaved driveway so now they're telling me I may have to park down at the main road until it gets cleared (if it does).

So I'm looking at the distinct, but hopefully small, chance that I can't charge. In that worst case scenario... it has been suggested that I can use their portable generator to charge it enough to get back to a real charger. It is a Firman 3550 generator. Looking that up, I see it is rated for 3500W continuous (4550W surge) and has a 20A outlet, which I think the Tesla would pull 12A off of (12 * 120 = 1440W, so well under rated capacity @ 50). So it *sounds* like it would work...

But "should" work and "does" work are two different things. I once tried charging at my Grandmother's house by way of an extension cord... and the Tesla wouldn't charge at all. I don't mean "slow", I mean not at all. We plugged a lamp into the cable and it worked, so my assumption was that the Tesla has circuitry that determines if the power coming in is high enough and/or stable enough and it won't allow it if it doesn't pass the test. Generators are fairly notorious for putting out "dirty" power.

Anyway... should I cancel the trip? Or I'll be OK if I have to use a generator in a pinch.

Thanks.
 
It should work. I have a cabin in Montana that is WAY off grid and have a very similar generator (it's a Champion, but same approximate ratings). My generator runs off of propane, which shouldn't change the results, but just something to add in to the mix. It's a SLOW process, and an expensive one, but it worked for me. I only had to get 15 miles to an RV park and I wouldn't try to get any more than that range out of a generator, but it worked.
 
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iwannam3

Active Member
Aug 8, 2016
1,038
1,428
Washington
It may not be the generators fault, the AC to DC conversion in the Tesla may introduce total harmonic distortion (THD) and power factor issues the generator can't deal with and feeds it back to Tesla in a downward spiral of distortion of the sine wave and power factor losses. At work, a large fluorescent lamp load that had high THD and bad power factor needed a generator 3X the power need to turn the crappy power from the load back into a nice sine wave that was acceptable to the lamp load.
 
Even "IF" your generator will work, it is a very expensive, and time consuming, method of getting extra miles on the car. Your best bet is to plug in ANYWHERE there is grid electricity. You know how much electricity you are using and are able to pay for what you use.

Best to find a 240v plug, but even a 120v plug will give you better charging than a generator, and much cheaper.

If there is no Electric Grid within 100 miles of the cabin, may I suggest you rent an ICE for the last leg of your journey. Still cheaper than a generator. Also, most generators on the market are great for light use, but very few are designed for continual use. jmho
 
I *should* be able to park and charge at the cabin. This is a "just in case" scenario. If the driveway is impassible and/or something's up with the power.

It isn't cost I'm concerned about, so much. But let's look at that. The specs say that generator has a 9G tank and will run for 14 hours (or is that minutes?? it just says "14", but it can't be minutes, can it?) at 50%. I'd be using less than 50% but let's go with that. On a normal 15A circuit, I get 5 to 6 km per hour of charge. 5*14 = 70km which should be enough. 9G = 34L x $1.30/L = $44. That's STILL cheaper than the lowest price RV park I found :) And if I go to an RV park or stop at some random store/house... I have to kill that time. If I'm doing it while at the cabin, then it is time I'm spending doing what I intended to be doing, right?

Ideally I get to the cabin and just plug in. But I think the generator may be my next best option, if it works.
 
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The generator run time is usually expressed in hours. My generator (again, on propane), runs for about 10 hours at half load on a 20 lb tank of propane. Even if I were to run it for 10 hours, the dang thing would drive me nuts...they are REALLY loud and I go to my cabin to get away from noise. Having a generator running for that long would make everyone a bit miserable. If you have to do it, it works, but it's the least attractive of all options.
 
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chillaban

Active Member
May 5, 2016
3,723
6,599
Bay Area
How cold is it going to be? A 120v outlet (regardless from generator or cabin) may not be sufficient if the battery gets cold-soaked.

Yeah, indeed. If it's very cold, it may take multiple kilowatts just to operate the pack heater to get the battery pack to an acceptable temperature to BEGIN charging. On 120V in cold conditions, you may not make any progress charging at all. I'd say this is not a good backup plan given the circumstances.
 

Uncle Paul

Well-Known Member
Nov 1, 2013
6,299
7,642
Canyon Lake,CA
If the cabin is at a high elevation, you might be able to get some extra miles by coasting downhill and enabling regeneration. Maybe enough to get you to a 240V source.

In addition to RV charging, others have stopped at welding shops that will always have lots of voltage for their equipment. Just need to find the right plug. Even a 240 volt dryer plug can get you down the road.
 

iwannam3

Active Member
Aug 8, 2016
1,038
1,428
Washington
It may not be the generators fault, the AC to DC conversion in the Tesla may introduce harmonic distortion and power factor issues the generator can't deal with and feeds it back to Tesla in a downward spiral of distortion of the sine wave and power factor losses. A large fluorescent lamp load that had high THD and bad power factor needed a generator 3X the power need to turn the crappy power from the load back into a nice sine wave that was acceptable .
 

Rocky_H

Well-Known Member
Feb 19, 2015
8,180
10,462
Boise, ID
I've heard more "no" than "yes" about generator charging. It mainly is those two factors: the ground/neutral thing, which you can trick on some generators by a type of cheater plug in one of the outlets you're not using. (Google for that) And the other is how smaller/cheaper generators don't make a real sine wave in their AC signal, so it doesn't look very like normal AC, and the Tesla UMC is just picky enough it won't accept it.

Obviously the really large building-supply generators are built to have all those bases covered, but the smaller 3-5kW type of ones are built so simply, they frequently have those shortcomings.

RV parks only get added to Plugshare generally if someone has used them and decided to make an entry. So to find all of them, try a site like www.rvparky.com or www.allstays.com. They have maps of all of the camping sites, and you can check for the "30 amp" or "50 amp" amenities. In camping terms, the "30 amp" means a TT-30 outlet, and the "50 amp" is a 14-50.

And you mention all the campgrounds being more than $44 to use. You can usually talk and negotiate that if you're not needing a full overnight rental. When I first got my Tesla 4 years ago, I planned a trip through an RV park both ways. I called and discussed it. I said I would be car camping overnight on the way down, so I would pay the $32 or whatever for the overnight, but on the way back, it would be the afternoon, and I just needed a few hours to bridge the gap. She offered a 4 hour time window for $12, which was a great deal. So then I added it on Plugshare with those details, and other people have used it since then. So if a few hours of topping up will give you enough margin, offer them 10 or 15 bucks, and they'll probably take it, rather than getting nothing from you not going there at all.
 
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I live in NJ which got hit by a few storms the past week and have been without power for 7 days now. I was able to hook up my MS up to a 5k generator. I tried both the 120 plug on my generator and to the normal 14-50 plug in my garage and plugged the generator to the fusebox and both charged just fine.

I dropped the amps down on the 14-50 to 20 so as to not overload my generator. But it worked the first day I needed so I could get to another charger.

Another note, it's not very efficient. But works when you need it.
 
Another thing to consider, if you need to take the generator with you, then you also need to take gas, both in the generator and in a gas can. Both of these are not very nice to have in your car, to put it mildly. My wife will not even let us eat in our Tesla. Forget about having gas fumes in the car.
 

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