Voltage drop when using onboard 120v outlet w extension cord

[centexR1S]

Since many of us bought our Rivian to power 120v equipment in a pinch (grid down, camping or at a job site), you would think the tailgate voltage would be slightly higher than 120v to offset a little voltage drop. My utility provides my house voltage at 123v and it sure makes equipment run better on the end of an extension cord. I tested my Rivian using a 12g extension cord and a kill-a-watt meter and my refrigerator at compressor startup dropped instantly to 113v then built slowly over 30 sec back to 120v when the compressor was running. Is there a way via an OTA update or by adjusting the 1500W inverter to get the tailgate voltage up to 123V or 125V?.

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[zymolysis]

Which end of the extension cord was your kill-a-watt connected to? If it was the end by your fridge, then you are seeing the drop across the extension cord - that is not a fault of the Rivian inverter.
Use the shortest (and largest) extension cord you can. You might also consider cutting it to length (with a little to spare), and then replacing the plug end with an electrical box that has a high quality duplex outlet in it (better contacts with higher spring tension will drop less voltage).

 

[Zoidz]

I doubt that there is an OTA to adjust the inverter output. Some inverters have adjustable output voltage but many do not. There's really no way to know unless Rvian release detailed specs or somone reverse engineers the inverter.

In any case, I would not worry about this voltage drop at all. Small refrigeration compressors are typically designed to run as low as 103 VAC. Yours is sagging to 113 and recovering within 30 seconds. Measure the voltage at the output of the inverter. You may find that the inverter is sagging under start current and slowly recovering, instead of voltage drop on the extension cord.

Here are operating specs for small Embraco and Tecumseh refrigeration compressors.

 

[centexR1S]

Which end of the extension cord was your kill-a-watt connected to? If it was the end by your fridge, then you are seeing the drop across the extension cord - that is not a fault of the Rivian inverter.
Use the shortest (and largest) extension cord you can. You might also consider cutting it to length (with a little to spare), and then replacing the plug end with an electrical box that has a high quality duplex outlet in it (better contacts with higher spring tension will drop less voltage).

Thanks for the plug advice. I measured voltage at the fridge so I would know if I was starving the compressor. I used a 150‘ 12g extension cord since my fridge is 130‘ from the garage. Cutting the cord and using a better connection will help since the drop to 113V is slightly higher than the 12g wire ampacity charts say. I must be loosing a small amount voltage at the extension cord connection. If the grid is down for a long time I might have to park on the lawn and run the house with a 50‘ cord. If anyone ever figures out how to tweak the 1500W inverter to 123V please let us know.

 

[centexR1S]

I doubt that there is an OTA to adjust the inverter output. Some inverters have adjustable output voltage but many do not. There's really no way to know unless Rvian release detailed specs or somone reverse engineers the inverter.

In any case, I would not worry about this voltage drop at all. Small refrigeration compressors are typically designed to run as low as 103 VAC. Yours is sagging to 113 and recovering within 30 seconds. Measure the voltage at the output of the inverter. You may find that the inverter is sagging under start current and slowly recovering, instead of voltage drop on the extension cord.

Here are operating specs for small Embraco and Tecumseh refrigeration compressors.

Thanks for the compressor electrical data. Screen shots of the 2 most common US compressors really helps me not worry about the drop to 113V. Do you agree however that it would be nice to up the R1 tailgate voltage output to 123V or 125V in order to help a lot of extension cord situations?

In other words over the spectrum of equipment potentially plugged in, be it a refrigerator or a vasectomy machine - wouldn’t you prefer 123V to 113V?

 

[R1T Preds Fan]

I’ve got a 10g extension cord in my Amazon cart for exactly this reason to try and avoid the voltage drop… Both for use at the tailgate and in slow charging the truck from another outlet.

 

[VSG]

House power is typically 120V at 15A. That's 1800W.
The Rivian outlet is rated 120V/1500W.

If you try to draw too much current, the voltage will sag. On any system.

my refrigerator at compressor startup dropped instantly to 113v then built slowly over 30 sec back to 120v when the compressor was running

That's not surprising. In fact, it's expected when the compressor starts up. The sag might be more obvious on the Rivian because you have less power to begin with and the compressor is designed to be plugged into a higher power outlet.

Rather than voltage control, I would prefer that Rivian switch to a 20A/2400W outlet so that common tools and appliances wouldn't be limited to 1500W.

 

[Zoidz]

Thanks for the compressor electrical data. Screen shots of the 2 most common US compressors really helps me not worry about the drop to 113V. Do you agree however that it would be nice to up the R1 tailgate voltage output to 123V or 125V in order to help a lot of extension cord situations?

In other words over the spectrum of equipment potentially plugged in, be it a refrigerator or a vasectomy machine - wouldn’t you prefer 123V to 113V?

That's an interesting question and you will get multiple answers, lol. In the ideal world, it's best to run a device at its design voltage which is typical 120VAC in the US, or as close as possible. So in your example, I would prefer 123VAC because is is only 2.5% high, as opposed to 113VAC being 6% low. Lower voltage typically means mechanical devices might worker harder or be less efficient, and maybe get hotter, than running at design voltage. But if the choice was 6% high vs 6% low, I'll take the 6% low. Higher voltage causes electrical stresses. And when there are voltage surges/spikes, that 6% higher voltage might be just enough to cause electrical damage.

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