Stupid question about charging tesla powerwalls FROM the R1T

[Jason]

I am curious to know if its possible to charge Tesla powerwalls using the 120volt outlets from my Rivian in case of an emergency. I can charge from my solar panels, of course, and also charge them from the grid, so I would think there should be some way to charge the powerwalls from another source. The 120V may be an issue, but I am not sure.

We had an outage for 4 hours the other week, and AC in Texas CHEWS through the 25% buffer I had left in my powerwall. I rigged a portable AC to help, but I think it would be MUCH better if I could charge powerwalls from my truck.

I reallllly wish V2H was ready, I really want to avoid a gas generator as that would be the only thing I have that used gas, and I don't want one. I am planning on adding more panels to help, but with the amount of power stored in the truck, it seems like a really ideal solution.

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[beatle]

Keep in mind that there will be two conversions happening in the path to charge your powerwall: DC truck battery >> AC output >> DC powerwall. Those conversions will both decrease the charge rate of the powerwall battery and waste a likely not-insignificant amount of energy in the process. Not sure if you can easily swap inputs on the rectifier (charger) going into your powerwall to make this AC>>DC conversion from the truck vs. the grid, but that'd be a requirement as well.

 

[Jason]

Not too worried about efficiency since it would be for emergencies only, but you have a good point on complexity....

 

[LivingInKaos]

I don't have Tesla PW's but I do have about 35kwh of Lifepo4's on my off-grid system and I just plug my truck into the AC feed side of my inverters and let them pull 15a overnight - mostly in the winter as a maintainer just so I don't have the generator kick in at night on the non-solar days.

 

[Jason]

I don't have Tesla PW's but I do have about 35kwh of Lifepo4's on my off-grid system and I just plug my truck into the AC feed side of my inverters and let them pull 15a overnight - mostly in the winter as a maintainer just so I don't have the generator kick in at night on the non-solar days.

This might be a good solution, I wasn't aware of inverters with an AC feed side, but that sounds really cool!

 

[LivingInKaos]

This might be a good solution, I wasn't aware of inverters with an AC feed side, but that sounds really cool!

Mine are hybrid inverters - they will charge from a grid-tie in, generator in, PV in. So, I just use one side of the split phase input grid tie and go with that. You have to keep in mind that when you try to pull 15a from the truck, it seriously crashes the voltage, down to 95-97V (don't ever acheive 1500w, more like 1400-1440w). So you have to be sure that it's not trying to pass-thru the power for usage - it needs to be sctrictly charge only.

 

[Jason]

Mine are hybrid inverters - they will charge from a grid-tie in, generator in, PV in. So, I just use one side of the split phase input grid tie and go with that. You have to keep in mind that when you try to pull 15a from the truck, it seriously crashes the voltage, down to 95-97V (don't ever acheive 1500w, more like 1400-1440w). So you have to be sure that it's not trying to pass-thru the power for usage - it needs to be sctrictly charge only.

Agreed, which is why I wanted to have it charge the powerwalls and NOT power the house directly. I think it would mean I would have to manually shut it down if they got too low so it didn't try to power from the house.

I was planning on adding more panels soon anyhow, so I will talk to the electrician about options. But even a 1.0 - 1.5 kw boost from the truck could make a big difference in a long outage.

ButV2H is still really high on my list of wants from Rivian.

 

[LivingInKaos]

Oh, I agree. Once we have a bi-dir charger we'll be golden.

For me, pumping 1400W continuously overnight gives me a bit of charge since there's not much running.

 

[Supratachophobia]

I am curious to know if its possible to charge Tesla powerwalls using the 120volt outlets from my Rivian in case of an emergency. I can charge from my solar panels, of course, and also charge them from the grid, so I would think there should be some way to charge the powerwalls from another source. The 120V may be an issue, but I am not sure.

We had an outage for 4 hours the other week, and AC in Texas CHEWS through the 25% buffer I had left in my powerwall. I rigged a portable AC to help, but I think it would be MUCH better if I could charge powerwalls from my truck.

I reallllly wish V2H was ready, I really want to avoid a gas generator as that would be the only thing I have that used gas, and I don't want one. I am planning on adding more panels to help, but with the amount of power stored in the truck, it seems like a really ideal solution.

The power walls are 240v (two 120v legs). So a single 120v source wouldn't work. Also, they will be playing with the frequency when disconnected from the grid and above 90%, so the Rivian might have a problem with that

 

[Electrified Outdoors]

I don't have Tesla PW's but I do have about 35kwh of Lifepo4's on my off-grid system and I just plug my truck into the AC feed side of my inverters and let them pull 15a overnight - mostly in the winter as a maintainer just so I don't have the generator kick in at night on the non-solar days.

Would love to learn more about your off grid setup. This stuff fascinates me.

 

[CharonPDX]

Not at present.

Tesla Powerwall only allows charging from "grid" or from solar.

You'd have to have your Rivian feed power in to your electrical panel *BEFORE* your solar grid cutoff, so the Powerwall thinks the Rivian is "grid" power. Which 120V, 12A ain't gonna do.

_MAYBE_ once the Rivian home integration CCS charger comes out, you could put that as the "grid disconnect" and put the Powerwall on the "inside", but the Powerwall thinking it is on the grid disconnect directly; so that when a power cut happens, it drains your truck first, then the Powerwall; but that probably isn't a very good solution either.

The Powerwall needs to know when there's a grid-cut so it can stop sending power to the grid (for the safety of the line workers.) The Rivian CCS home integration system would need to support solar itself, with the Powerwall taking the place of solar.

It would be a really convoluted system. (Unless Tesla and Rivian work together to allow for a holistic integration the way Powerwall + Tesla Universal Wall Unit + Cybertruck does. But I can't see that partnership happening.)

 

[Joe Hoffman]

As others have stated, I think there’s more complexity here than meet the eye. I suggest you consider that when you get into emergency power conditions simply dedicate the truck to critical loads, such as your refrigerator, phones, etc. Save your PW capacity for your A/C system which at some point you’ll have to abandon when your PW gets too low.

Remember, this scenario only happens when you lose power from the grid and have insufficient sunshine. If this unique scenario is important for you to be protected against, more power walls and more panels is really the right solution.

 

[SwampNut]

It's pretty easy using an industry-standard retroencabulator, and some heavy cabling.

 

[RivianRunner]

Not at present.

Tesla Powerwall only allows charging from "grid" or from solar.

False. Tesla Powerwall allows charging directly from a Cybertruck. If you only have a Rivian, you are out of luck. True fact.

 

[CharonPDX]

False. Tesla Powerwall allows charging directly from a Cybertruck. If you only have a Rivian, you are out of luck. True fact.

Which doesn't apply to the original poster, now does it?

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