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Dark-Fx

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First off, standard disclaimer here because I discovered it's possible that there is potentially lethal voltages present when the inverter is disconnected, so don't try this at home without the proper equipment.

I wanted to do this to see if there was a way to flip it to 240V. If there is, it wasn't obvious. It could be a software thing and I made no attempt to look into that yet.

The inverter is under the passenger seat. You will have to remove and disconnect the seat to gain access to it. The bolts at all four corners are under these small soft touch plastic pieces. I don't think you actually need to remove them but I did. Should be a T20. One of mine was crossthreaded so a bit more difficult to remove than the others. The bolt was 15mm (actually felt a little loose, could have been an SAE size but I would be surprised).

Rivian R1T R1S 120V Inverter Teardown 1689712114105


Rivian R1T R1S 120V Inverter Teardown 1689712232027


It might be necessary to move the seat forward and backwards to gain access to the bolts. Probably less chance of damage at removal to have the seat in the most forward position. I scratched up some of my trim because the seat just barely fits through the door cavity.

Once you unbolt the seat, it gives you a lot more room to unplug the connectors. Two of these are for airbags so the secondary disclaimer here about how they could get activated unexpectedly applies. I didn't get a great pictures but they are pretty easy to remove. Seat can just be set on the ground. I didn't disconnect the seat belt.
Rivian R1T R1S 120V Inverter Teardown 1689712436549


Once that's out, we gain access to the protective plastic above the inverter. Just the single bolt in the middle to remove it and some normal automotive trim clips to pull against. The seat connectors are also trim clipped to this piece of plastic so also have to be disconnected. The upper connector in the photo is not connected to anything. I'll speculate that it could be a diagnostics port.

Rivian R1T R1S 120V Inverter Teardown 1689712579351


The inverter. Mine had been on for several days prior to my investigation here. I was going to hit it with my thermal camera but couldn't find it. It was hot enough to be painful after about two seconds of contact. I flipped off the inverter in the car and waited 15 minutes.

Rivian R1T R1S 120V Inverter Teardown 1689712602146


The bottom left connectors here are the input/output of the inverter. After unplugging everything, I metered 0 volts across the leftmost plug.

Rivian R1T R1S 120V Inverter Teardown 1689712705123


But then I told the truck to turn the outlets back on. Don't do this without proper equipment. I went and put my PPE on immediately after this. (For those interested, my HV battery was charged to 85% during this)

Rivian R1T R1S 120V Inverter Teardown 1689712802866


Then I pulled the inverter apart and took pictures.

Rivian R1T R1S 120V Inverter Teardown 1689712899990

Rivian R1T R1S 120V Inverter Teardown 1689712924510

Rivian R1T R1S 120V Inverter Teardown 1689713077467

Rivian R1T R1S 120V Inverter Teardown 1689713096048

Rivian R1T R1S 120V Inverter Teardown 1689713232070

Rivian R1T R1S 120V Inverter Teardown 1689712941879

Rivian R1T R1S 120V Inverter Teardown 1689712956641


After putting everything back into the truck, it seems fine now, but I still wouldn't recommend doing it. The truck acted wonky while the seat was disconnected and there's likely a chance you could end up breaking something.
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Awesome, thanks for this! It answers two key questions (with positive answers:

1. Does the 120V inverter draw HV DC straight from the battery, or does it draw (and is thus limited by) 12V from the DC-DC converter?

2. Is it easily accessible and unitized in a way that it could be easily upgraded if a higher-output option were to come to market?
 
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Dark-Fx

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Awesome, thanks for this! It answers two key questions (with positive answers:

1. Does the 120V inverter draw HV DC straight from the battery, or does it draw (and is thus limited by) 12V from the DC-DC converter?

2. Is it easily accessible and unitized in a way that it could be easily upgraded if a higher-output option were to come to market?
It is powered right from the HV battery. I have no idea what kind of fuse might be in-line with it, but I suspect it will be in the battery pack itself if it exists. I didn't pull back anything to be able to tell what AWG the wire is.

Since the vehicle will actually turn on the HV line with the inverter disconnected, it could be possible to upgrade it. It didn't show that it was on in the display after that and didn't offer a way to turn it off after though. I was pretty concerned about re-plugging it in after, but I did it as fast as I could.
 

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Dark-Fx

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Isn't that what Rivian always uses the orange cable for?
Anything not 12V seems to get orange, since the 120V output is also orange (and on mine it's 60VAC above chassis ground). Still good to know it isn't typical automotive voltages though.
 
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Dark-Fx

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You've got some serious ovarian fortitude...
Back when I was doing automotive controls, we worked hot on 677VDC equipment occasionally. I avoided doing it as much as possible, but it simply can't be avoided if you are trying to diagnose why a piece of equipment at those voltages wasn't working.
 

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In your opinion is it hot to the point where it is unsafe or unhealthy for the electronics nearby?
 
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In your opinion is it hot to the point where it is unsafe or unhealthy for the electronics nearby?
Probably not hot enough to worry about the electronics. I'd guess it was somewhere in the 130F range. With the amount of heat sinking on the inverter, it's probably pretty evenly heated.
 

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Very interesting stuff. Thanks for sharing. Glad to learn the inverter is powered by the HV battery and not the 12V. I regularly run a fridge 24hrs a day for several days in the bed. I'm always a little nervous about the idea of the 12V battery being in the middle (what I assumed was powering it) and having some issue keeping the 12V charged that left me stranded.
 

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I might have missed it: what was the motivation for the teardown? To see if you could retro a 240v inverter?
 

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Wow. That's something I know enough about to stay away from but that's my limit. Enough time on job sites to see the results of a couple arc flashes was enough for me.
 

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Wow. That's something I know enough about to stay away from but that's my limit. Enough time on job sites to see the results of a couple arc flashes was enough for me.
In this particular application, I'm assuming Rivian engineered the wiring and specifically the fusing such that DC Arc Flash is just not possible at the inverter wiring. Since the DC voltage is ~440 volts, the current flowing to the inverter should only be about 4 amps. Presumably the fuse would be sized properly, and would blow before Arc Flash could even propogate . But none the less, it's wise to highly respect any voltage over 50V, DC or AC.
 

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In this particular application, I'm assuming Rivian engineered the wiring and specifically the fusing such that DC Arc Flash is just not possible at the inverter wiring. Since the DC voltage is ~440 volts, the current flowing to the inverter should only be about 4 amps. Presumably the fuse would be sized properly, and would blow before Arc Flash could even propogate . But none the less, it's wise to highly respect any voltage over 50V, DC or AC.
Yup, I didn't know that so that just underscores the fact that I shouldn't be touching such things. Thanks for the info though. I always like learning new things.
 

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Good stuff here, so I cross posted this l link to this thread on openinverter.org.

Anyone have more detailed specifications for the input DC voltage this part looks for? And what controls it from turn on / turn off (dry contact, relay, CANBUS command, etc? )
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