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Whats the largest Power Inverter you can use in a Tesla?

Whats the largest Power Inverter you can use in a Tesla?

  • 200 watts

    Votes: 20 21.5%
  • 400 watts

    Votes: 10 10.8%
  • 500 watts

    Votes: 6 6.5%
  • 1000 watts

    Votes: 14 15.1%
  • 1500 watts+

    Votes: 43 46.2%

  • Total voters
    93
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Correct, 12V is topped off from the HV.

I am converting a school bus into an RV. I have an LR Model 3. It would be amazing to get at least 1500 watts from the battery of the tesla to power our RV. I think 1500 watts would be enough to power a small AC or Mini Split. My Question, if I attach an inverter to the 12v battery on my tesla does the car keep it that 12v battery topped off as the power is drawn from the RV or is there a setting for me to keep the car on to keep that battery topped off?
 
I am converting a school bus into an RV. I have an LR Model 3. It would be amazing to get at least 1500 watts from the battery of the tesla to power our RV. I think 1500 watts would be enough to power a small AC or Mini Split. My Question, if I attach an inverter to the 12v battery on my tesla does the car keep it that 12v battery topped off as the power is drawn from the RV or is there a setting for me to keep the car on to keep that battery topped off?

It's charged all the time. But there are some warnings in the warranty about doing this. Tesla can likely see the extra 12V draw in the logs, and could deny warranty on the battery if you used it a lot. I don't think anyone has had that happen yet, but to be safe I'm only planning to use mine for backup power when the power goes out.
 
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I don't see how a direct quote from the text of the Tesla warranty has any uncertainty to it.

This isn't a 1985 Buick, it is a car with constant telemetry of exactly what the systems are doing at all times. If you think they can't show hours of 2kW load on the DC/DC converter and associate that to running an inverter in a way which voids the warranty on that part, you are mistaken.
I know this is an old thread, but people reading this should know that you simply ignored the most important part of that warranty exclusion.
It says that the warranty doesn't cover damage "caused by, due to or resulting from" the identified uses or misuses of the car. If you have any idea at all what you're doing, there's no reason whatsoever that installing an inverter for occasional use should cause the slightest bit of damage to the car. The warranty still applies to everything it would normally apply to, just nor damage caused by your use or misuse of the inverter.

Now, if you buy a Tesla and just drive if from a Supercharger to your off-grid cabin every day to power that cabin, you probably will wear out the high-voltage battery prematurely and Tesla will, quite rightly, tell you to go pound sand if you come whining that you want a new battery to replace the one you destroyed. But occasional use drawing well under the low-voltage battery's 600A capacity over the short-term and under the DC-DC charger's capacity over the medium term, shouldn't cause any damage unless you use inadequate wiring, don't use a fuse, buy a defective inverter that catches fire, etc.

Edited to add: Just for giggles, I checked an e-bay listing selling a Model S DC-DC converter. The converter is plainly labeled with a sticker indicating a maximum output of 2500W at 9-16VDC. That's a lot more than I expected, but probably only applies when the car is on and pumping coolant through the converter.
 
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I know this is an old thread, but people reading this should know that you simply ignored the most important part of that warranty exclusion.
It says that the warranty doesn't cover damage "caused by, due to or resulting from" the identified uses or misuses of the car. If you have any idea at all what you're doing, there's no reason whatsoever that installing an inverter for occasional use should cause the slightest bit of damage to the car. The warranty still applies to everything it would normally apply to, just nor damage caused by your use or misuse of the inverter.

Now, if you buy a Tesla and just drive if from a Supercharger to your off-grid cabin every day to power that cabin, you probably will wear out the high-voltage battery prematurely and Tesla will, quite rightly, tell you to go pound sand if you come whining that you want a new battery to replace the one you destroyed. But occasional use drawing well under the low-voltage battery's 600A capacity over the short-term and under the DC-DC charger's capacity over the medium term, shouldn't cause any damage unless you use inadequate wiring, don't use a fuse, buy a defective inverter that catches fire, etc.

Edited to add: Just for giggles, I checked an e-bay listing selling a Model S DC-DC converter. The converter is plainly labeled with a sticker indicating a maximum output of 2500W at 9-16VDC. That's a lot more than I expected, but probably only applies when the car is on and pumping coolant through the converter.
Good points. I hope you are right. It seems really reasonable to try it to run a fridge and freezer during a power outage.
 
I was able to successfully wire a 1000W inverter to my car's 12V battery this evening and ran it at around 450W of power for 1 hour without issues. The model S's 12V system remained at a steady 13.1V even though I was pulling ~40A from it. It looks like it is being topped up by the HV battery.
  1. 4 AWG wire with inline 100A fuse, wired to 12V battery terminals
  2. Connected to 1000W (2000W peak) pure sine wave inverter
I am trying to test if I can use it to charge my Jackery power unit which then powers a few circuits in my house during a black out. It works, but the main limitation is that my Jackery can only be charged at around 500w max, so that puts a limit on how much you can draw from it before it eventually drains as you can't fill it that quickly. This isn't very user friendly, but would work in an emergency.

1630121402785.png
1630121427563.png
 
I was able to successfully wire a 1000W inverter to my car's 12V battery this evening and ran it at around 450W of power for 1 hour without issues. The model S's 12V system remained at a steady 13.1V even though I was pulling ~40A from it. It looks like it is being topped up by the HV battery.
  1. 4 AWG wire with inline 100A fuse, wired to 12V battery terminals
  2. Connected to 1000W (2000W peak) pure sine wave inverter
I am trying to test if I can use it to charge my Jackery power unit which then powers a few circuits in my house during a black out. It works, but the main limitation is that my Jackery can only be charged at around 500w max, so that puts a limit on how much you can draw from it before it eventually drains as you can't fill it that quickly. This isn't very user friendly, but would work in an emergency. View attachment 702381 View attachment 702383
Nice setup for emergency use... well done.
 
So you're using the HV battery to charge the AGM battery to charge the Jackery to run the emergency equipment? It seems like the Jackery isn't adding much in the middle. Am I missing something obvious here?
The Jackery acts as a high wattage source and buffer. The jackery can output 1800w continuous and 3600w peak, so it can handle the load on the house if things turn on temporary. I don’t think it would be good to pull more than 1000w from the car as the DCDC is good for 2000w and there are other things that will need 12V power without notice (coolant pumps etc). So hence the car charges the jackery and jackery powers the house. I don’t then to use this much or at all, just wants to know it is possible just in case. The limit here is really the jackery 1500 as it can only be charged at 600w max (I think the larger 2000 model one can be charged at 1000w max).
 
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The Jackery acts as a high wattage source and buffer. The jackery can output 1800w continuous and 3600w peak, so it can handle the load on the house if things turn on temporary. I don’t think it would be good to pull more than 1000w from the car as the DCDC is good for 2000w and there are other things that will need 12V power without notice (coolant pumps etc). So hence the car charges the jackery and jackery powers the house. I don’t then to use this much or at all, just wants to know it is possible just in case. The limit here is really the jackery 1500 as it can only be charged at 600w max (I think the larger 2000 model one can be charged at 1000w max).
OK, that makes some sense.

Personally I'd just parallel in a 100Ah AGM alongside the normal battery and let it take the surge loads. $200 instead of $1500, one less conversion along the way. But if you've already got the Jackery and use it elsewhere I see how it can work as a surge tank.
 
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The Jackery acts as a high wattage source and buffer. The jackery can output 1800w continuous and 3600w peak, so it can handle the load on the house if things turn on temporary. I don’t think it would be good to pull more than 1000w from the car as the DCDC is good for 2000w and there are other things that will need 12V power without notice (coolant pumps etc). So hence the car charges the jackery and jackery powers the house. I don’t then to use this much or at all, just wants to know it is possible just in case. The limit here is really the jackery 1500 as it can only be charged at 600w max (I think the larger 2000 model one can be charged at 1000w max).
The tesla battery is good for 500 cold cranking amps where the voltage is guaranteed to be greater than 7.2 volts. That should provide about 3600 watts of surge power if the inverter can handle 7.2 volts on the input.
 
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Most inverters will shut off at about 11 volts. You want to aim for 2C or less on an AGM meaning doing a 3kW inverter with the stock battery is probably right on the edge with the DC-DC capacity. It would probably work but I would feel far more comfortable with at least another 50Ah in parallel there.
 
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What I found by searching is that inverters have a low voltage trip of 10 volts. If the battery voltage at 500 amps is 7.2, at 10 volts the battery should be supplying about 245 amps. At 10 volts that 2450 watts. With the 2000 watts of the dc/dc converter that gives a surge capacity of 4450 watts.
 
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The inverter will start screaming at you around 10.5-10.8 volts depending on brand. I don't know that I would fly that close to the sun. At that point you're asking the AGM to put out 6C which demands near perfect condition and a full charge to keep the voltage up. A 50Ah or 100Ah AGM to put in parallel is not very expensive.
 
CCA are at 32 degrees F. At normal room temperatures the voltage sag will be much less. The dc/dc converter will keep the 12v battery topped off. You don't want to pull more than the dc/dc can provide continuously. This is just for brief periods of surge, so any squawking the inverter does will be also be brief.

Using the car's12v battery for surge just seems like much less hassle. These batteries in ice vehicles supply high currents several times a day to crank the engine.
 
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I don't think it matters what the load is. If it exceeds the surge capacity of the inverter, the inverter will shut down. If it doesn't the battery can supply the cca for 30 seconds which is longer than the 10 to 20 seconds of max surge capacity of the inverters.
 
I reconnected things so the inverter cables are connected to DCDC side of the positive battery terminal and not to the battery side of the terminal fuse . I don't know what is the fuse size on the positive battery terminal (though it has a number 314 written on it, but 314A seems strange and too high). I know that the fuse of the DCDC is 250A and it supposedly can do 2000W.

When I pull 700W from the inverter (using the 2 x Jackery AC chargers), I measure 52A of current flowing from DCDC into the battery terminal area, with voltage around 13.5V. This means that nearly if not all of the power is coming from the DCDC and not from the 12V battery. This ran for about 10 minutes and I stopped the test. Note that while I am pulling 700W, the Jackery is only charging at 570W, so I am loosing 20% in this DC-AC-DC conversion process.

The reason why I have the Jackery in between instead of directly to the inverter is due to the following:
- In a blackout, my house will use an average of 500w of power for the most essential loads, but the load can be as high as 1800W for a minute, sump pump comes on while the furnace fan is running, lights are on at night.
- I don't want to pull more than 1000W from the car's 12V DC system, while the DCDC is capable of 2000W but the car may need some power for other stuff at any time. I have heard people connect 1500W inverter and the car throwing 12V system errors.
- In a worse case scenario if something bad happens, I want it to impact the Jackery and not the car, as the jackery is cheaper and is more built to handle unpredictable loads while the cars 12V system is not meant for this
- I already have the Jackery unit

The disadvantage of using the jackery is lost of around 20% efficiency as there is another DC-AC-DC step. And that your max average power is only 600W as that is the input limit of the Jackery unit. Use more than that on the average and your Jackery battery will drain.

The Jackery (or similar unit) provides such buffer as it can handle 1800W continuous or up to 3600w for a second or so. This keeps the load to the Tesla's 12V system a nice and stead 700W with the Jackery handling the spikes. My Jackery is not useful on its own as the battery capacity is too small at only 1.5kWh. So hence the car charges the Jackery, and the Jackery powers everything else. Note that there is a larger Jackery with 2kWh of battery and up to 2200W of continuous load, and can be AC charged at 1000w. If you are getting something for this purpose, I would suggest that instead.
 
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I reconnected things so the inverter cables are connected to DCDC side of the positive battery terminal and not to the battery side of the terminal fuse . I don't know what is the fuse size on the positive battery terminal (though it has a number 314 written on it, but 314A seems strange and too high). I know that the fuse of the DCDC is 250A and it supposedly can do 2000W.

When I pull 700W from the inverter (using the 2 x Jackery AC chargers), I measure 52A of current flowing from DCDC into the battery terminal area, with voltage around 13.5V. This means that nearly if not all of the power is coming from the DCDC and not from the 12V battery. This ran for about 10 minutes and I stopped the test. Note that while I am pulling 700W, the Jackery is only charging at 570W, so I am loosing 20% in this DC-AC-DC conversion process.

The reason why I have the Jackery in between instead of directly to the inverter is due to the following:
- In a blackout, my house will use an average of 500w of power for the most essential loads, but the load can be as high as 1800W for a minute, sump pump comes on while the furnace fan is running, lights are on at night.
- I don't want to pull more than 1000W from the car's 12V DC system, while the DCDC is capable of 2000W but the car may need some power for other stuff at any time. I have heard people connect 1500W inverter and the car throwing 12V system errors.
- In a worse case scenario if something bad happens, I want it to impact the Jackery and not the car, as the jackery is cheaper and is more built to handle unpredictable loads while the cars 12V system is not meant for this
- I already have the Jackery unit

The disadvantage of using the jackery is lost of around 20% efficiency as there is another DC-AC-DC step. And that your max average power is only 600W as that is the input limit of the Jackery unit. Use more than that on the average and your Jackery battery will drain.

The Jackery (or similar unit) provides such buffer as it can handle 1800W continuous or up to 3600w for a second or so. This keeps the load to the Tesla's 12V system a nice and stead 700W with the Jackery handling the spikes. My Jackery is not useful on its own as the battery capacity is too small at only 1.5kWh. So hence the car charges the Jackery, and the Jackery powers everything else. Note that there is a larger Jackery with 2kWh of battery and up to 2200W of continuous load, and can be AC charged at 1000w. If you are getting something for this purpose, I would suggest that instead.

A closer view of the hookup, note that the inverter cable has a 100A inline fuse and is connected on the other side of the battery terminal fuse, and not on the battery terminal side of the terminal fuse. When the inverter is running, the power is flowing from the DCDC and not from the battery. I've tested this up to about 800W for 15 minutes.

1630717395510.png
 
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As long as the dc/dc is able to keep the voltage at 13.5 the current will come from it because there is little voltage difference wrt the battery's internal volltage to draw current across its internal resistance. Once the dc/dc reaches its current limit its output volltage will begin to drop. As the load increases the voltage at the battery terminals will continue to fall and more current will come from the battery.
 
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