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Charging From a Whole House Generator

I was getting an estimate today for a whole house generator. He looked at my panel and noticed the breaker for Tesla Charging and told me not to charge the Tesla while on the generator. Asked him why and he just said because sometimes weird things happen.

Anyone know why he would say that? I do have the Tesla Wall unit and could turn down the charging current when on the generator.
 

brkaus

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Jul 8, 2014
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Austin, TX
I was getting an estimate today for a whole house generator. He looked at my panel and noticed the breaker for Tesla Charging and told me not to charge the Tesla while on the generator. Asked him why and he just said because sometimes weird things happen.

Anyone know why he would say that? I do have the Tesla Wall unit and could turn down the charging current when on the generator.
Some generators do not have the ground and neutral bonded and it causes it to not charge. Shouldn't be a problem with a house generator.

If there is a big load generators can put out dirty power that the car may not like.

In general it should work, but you may have to manually lower the current when on the generator (of course depending on how big of a generator you get).
 
I was getting an estimate today for a whole house generator. He looked at my panel and noticed the breaker for Tesla Charging and told me not to charge the Tesla while on the generator. Asked him why and he just said because sometimes weird things happen.

Anyone know why he would say that? I do have the Tesla Wall unit and could turn down the charging current when on the generator.

here in australians outback some (road)houses run on generators. They frequently can't handle the powerdraw of the older Model Ses which could charge at 22kw via AC. With your little home generator you will probably overload it with 11kw too which will cause the generator to shut down.
 
If the generator is large enough to handle inrush it should work fine. Since it is tied to the house service panel then the ground and neutral will be connected properly.

I have a 6500W generator where you have a jumper point to tie neutral and ground together. I can charge at 120V, 15A but cannot charge at 240V, 30A. The regulator has trouble maintaining frequency at the higher loads and the car charger will drop out to protect itself.
 
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user212_nr

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If you have a 14.5 kW generator, for example, and a Tesla using 11.5 kW, then that would leave 3 kW for your home.

Even if you just use 1.4 kW, that is 10% of this example generator. I think the point is that, your panel is sized for a 100-200 kW (24-48 kW) load, but you probably did not buy a 48 kW generator. The voltage also may fluctuate as loads are turned on/off, which isn't so much harmful as it could cause the Tesla charger to think there is a problem.

Other than that though, if you know the power usage of your home, it shouldn't be a problem.

Another issue that you have is that you probably will have an automated transfer switch. It is likely that the Tesla will be charging at 12 kW when the power goes out, so I'm not sure what happens in that case, but it certainly won't work automatically unless you configure the system so that the wall charger is not automatically powered. Having a sub-panel with "essential loads" and then powering the Tesla off a regular socket is one option.
 

KenC

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Sep 4, 2018
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Anyone know why he would say that? I do have the Tesla Wall unit and could turn down the charging current when on the generator.[/QUOTE]
I have a 12kW GE whole house standby generator, with 200amp transfer switch, and have charged my Volt by accident. Obviously it takes a smaller load. If you dial back the amps on the Tesla, there’s no real reason it wouldn’t charge. For me, I wouldn’t do it, as it’s impractical in an outage. I have a limited LP supply, so would rather use it to keep house running. The car can charge at a supercharger during an outage.
 
I was getting an estimate today for a whole house generator. He looked at my panel and noticed the breaker for Tesla Charging and told me not to charge the Tesla while on the generator. Asked him why and he just said because sometimes weird things happen.

Anyone know why he would say that? I do have the Tesla Wall unit and could turn down the charging current when on the generator.

Unlike other EV's, Tesla cars are very picky about clean and stable electricity. Many non-inverter generators provide power that has too much frequency variation and/or harmonic distortions that cause Tesla cars to refuse to charge or charging to cycle on/off continuously.
 
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user212_nr

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Unlike other EV's, Tesla cars are very picky about clean and stable electricity. Many non-inverter generators provide power that has too much frequency variation and/or harmonic distortions that cause Tesla cars to refuse to charge or charging to cycle on/off continuously.

The "whole house generator" is unlikely to not have an inverter. That's why most of the answers here focus on just the capacity.
 
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The "whole house generator" is unlikely to not have an inverter. That's why most of the answers here focus on just the capacity.

It's actually not uncommon for "whole house generator", even large ones, to not have inverter. Here is a couple examples:

Generac 22000-Watt (LP)/19500-Watt (NG) Air-Cooled Standby Generator with Wi-Fi and Whole House 200 Amp NEMA3 Transfer Switch-7043 - The Home Depot

Briggs & Stratton 20,000-Watt Automatic Air Cooled Standby Generator with 200 Amp Whole House Transfer Switch-040621 - The Home Depot


The specs section clearly state no built-in inverter. OP can ask the contractor to clarify for the proposed generator.
 

KenC

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My 12kW GE whole house standby generator specs show 5% THD. As I mentioned, it charged my Volt, and I would think, it’s just as sensitive to dirty power as my Tesla. Next time I have an outage, I’ll check.

I wonder if anyone has done a YouTube video of it.
 
My 12kW GE whole house standby generator specs show 5% THD. As I mentioned, it charged my Volt, and I would think, it’s just as sensitive to dirty power as my Tesla. Next time I have an outage, I’ll check.

I wonder if anyone has done a YouTube video of it.

Your assumption maybe flawed. I have a non-inverter generator that works fine for charging Chevy Spark EV but doesn't work for Tesla with the same charging current limit.
 
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KenC

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Your assumption maybe flawed. I have a non-inverter generator that works fine for charging Chevy Spark EV but doesn't work for Tesla with the same charging current limit.
As circumstances would have it, my power went out at 11:30p. An hour later I remembered to check to see whether my whole house generator could charge my Tesla, and so I set the amperage to 12, and jiggered the SOC level to 60%, and it started to charge.
BA8849EB-80B5-4D63-BBB3-A6F92740C27C.jpeg

I watched for a couple minutes, then went back inside.
 
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user212_nr

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I was looking, just for fun, to see if there was an inverter that worked off the 120v socket and cleaned up the power. Don't take this too seriously.

All the inverters that I can find work off DC only and aren't cheap. I did figure out what kind of product would work though. You'll laugh, but the product is called a UPS.

A UPS converts A/C power to 12v and then from 12v uses it to power an inverter. It runs off the inverter even when not using the battery. Basically, this is the same thing exactly as a "power clean up inverter". The only concern, I think, is that they get expensive the more watts you allow for. A 900 watt system is $155 on Amazon, that could be used to power the UMC at 6A (720W).

I'm not seriously suggesting to use a UPS, since as we already know, you don't need to charge your car and/or it is already possible with most generators. Besides, if you did need to charge your car, you'd want much more than 720W.
 
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KenC

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I was looking, just for fun, to see if there was an inverter that worked off the 120v socket and cleaned up the power. Don't take this too seriously.

All the inverters that I can find work off DC only and aren't cheap. I did figure out what kind of product would work though. You'll laugh, but the product is called a UPS.

A UPS converts A/C power to 12v and then from 12v uses it to power an inverter. It runs off the inverter even when not using the battery. Basically, this is the same thing exactly as a "power clean up inverter". The only concern, I think, is that they get expensive the more watts you allow for. A 900 watt system is $155 on Amazon, that could be used to power the UMC at 6A (720W).

I'm not seriously suggesting to use a UPS, since as we already know, you don't need to charge your car and/or it is already possible with most generators. Besides, if you did need to charge your car, you'd want much more than 720W.
I have about 6 or 7 CyberPower UPSes with pure sine waves, on all my sensitive electronics, computers, TVs, router, pellet stove. You never know what device needs a pure sine wave, when on generator power, but my pellet stove does. A 1500 watt pure sine wave UPS, from APC or CyberPower, can be had for about $150 from B&H or Newegg, when they go on sale. Get on their mailing list, and it'll happen about once a month. Make sure you are looking at pure sine wave models, and not simulated sine waves, which are square waves.

Having said that, I never thought of using one to clean up the power to my Tesla, since as I wrote earlier, if there's an outage, I'll take it to a Supercharger. My LP storage is limited to the two big tanks I have and can only run my house for a week. Not going to waste it charging the car. One of the reasons why I went with the 12k generator and not the 17k or 20k, is those use twice as much LP/hr. Just like with the Tesla, you have to rightsize your generator.

Thinking about it, I'm not sure there's any benefit. You can probably only get 1kW passed thru.

Here's the most common one I have :
CP1500PFCLCD - PFC Sinewave UPS Series - Product Details, Specs, Downloads | CyberPower
 
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How often do you guys lose power to want a whole house?

I think we average 18 hours of outage per year. Some years half a day. Some years nothing. Worst case was 3 days.

Powerwalls I think would be pretty reasonable for up to 24h outages. A real shame my car can’t feed power back, I have a perfectly good 75 kWh battery sitting in my garage.
 

KenC

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Sep 4, 2018
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Maine
How often do you guys lose power to want a whole house?

I think we average 18 hours of outage per year. Some years half a day. Some years nothing. Worst case was 3 days.

Powerwalls I think would be pretty reasonable for up to 24h outages. A real shame my car can’t feed power back, I have a perfectly good 75 kWh battery sitting in my garage.
20+yrs ago we had a big ice storm and lost power for 2 weeks. My mom had just been kicked out of the hospital 2days after life-saving brain surgery, and so I bought a generator 3hrs away from her home, hooked up a 5000 watt generator to a 6switch transfer box, and cared for my mom for those 2 weeks with power only from that gas-powered generator.

After that, I vowed to build-in a permanent hookup where I was building a new home. Should I get a $2000 mobile generator and a $500 transfer switch, plus $500+ for the electrical, that I would have to fill with gas constantly? Or should I get the $3000 whole house generator that includes a 200amp transfer switch. The gas and electric hookup cost an additional $750.

I chose the standby generator. Power walls were not an option at that time. Nowadays, I would install solar and power walls with a generator as emergency backup for long outages.
 

user212_nr

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Aug 26, 2019
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How often do you guys lose power to want a whole house?

I think we average 18 hours of outage per year. Some years half a day. Some years nothing. Worst case was 3 days.

Powerwalls I think would be pretty reasonable for up to 24h outages. A real shame my car can’t feed power back, I have a perfectly good 75 kWh battery sitting in my garage.

Its always interesting to hear people's stories, but extended power outages are common in many parts of the U.S.

If you live in/on:
a) California, you have shutdowns due to wildfire and insufficient grid power
b) In the far north, you have the occasional blizzard/wind storm. Lots of trees knocked down all at once means and extended outage
c) the east coast, NY or below, a hurricane every 20 or so years. Not a strong one, but the area is not hardened for such storms
d) SC/Georgia/Florida frequent hurricanes
d) on the gulf coast, a hurricane as much as every year, threat of Cat 5

Most people go for the cheap generator, if anything, but then you have the issue of buying and storing fuel. You'll hardly have enough for an extended outage, and buying it in the moment is also not practical.

Besides, not all of us on this thread actually have generators.
 
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