Charging at an off-grid Cabin (electrical advice)

[Mcdubjr]

We have an off-grid family cabin with a generator I'd like to be able to charge at.

Some background:

• We have a propane powered 12 kW/50 Amp generator (this model)
• We only turn generator on when needed, just some lights and outlets inside - very low draw.
• Ideally I wouldn't plan to charge at the cabin, just looking for something in case I need a small charge to get down the mountain if my R1T range is looking iffy.
• I'd be fine turning off all the other breakers if I actually needed to charge.
• It's very remote so don't want to hire an electrician, I'll do this myself (we installed the new generator ourselves after last one burned down in forest fire 2 years ago so I'm comfortable enough with the electrical work to install a plug)

I actually started wiring a 16-30r (30 amp) plug 2 years ago and just needed the correct type of circuit breaker to finish. Now I'm thinking I should have just put in a NEMA 14-50. There shouldn't be any problems if generator happens to provide less power than 50 AMP, right? Anyone with electrical experience have any advice? Thanks!

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[jphillips97]

We have an off-grid family cabin with a generator I'd like to be able to charge at.

Some background:

• We have a propane powered 12 kW/50 Amp generator (this model)
• We only turn generator on when needed, just some lights and outlets inside - very low draw.
• Ideally I wouldn't plan to charge at the cabin, just looking for something in case I need a small charge to get down the mountain if my R1T range is looking iffy.
• I'd be fine turning off all the other breakers if I actually needed to charge.
• It's very remote so don't want to hire an electrician, I'll do this myself (we installed the new generator ourselves after last one burned down in forest fire 2 years ago so I'm comfortable enough with the electrical work to install a plug)

I actually started wiring a 16-30r (30 amp) plug 2 years ago and just needed the correct type of circuit breaker to finish. Now I'm thinking I should have just put in a NEMA 14-50. There shouldn't be any problems if generator happens to provide less power than 50 AMP, right? Anyone with electrical experience have any advice? Thanks!

There will not be a problem if your generator provides less power... Biggest issue you might see is if the generator power is noisy but the charger should tolerate it OK.... Do not put in a 14-50 if the wires will not support it.... If you wired for 30Amps, do not put in a 50A breaker.... Safety wise, you would be OK using a 14-50 plug even on a 30A circuit but not the other way around

 

[CommodoreAmiga]

There shouldn't be any problems if generator happens to provide less power than 50 AMP, right?

You would need to make sure you limit the EVSE to only what power can reasonably be provided.

If you're using the Rivian portable EVSE and you can supply at least 32A then you're fine, as-is. If you are supplying less than that, or using a different EVSE, then you must configure the vehicle or EVSE to limit current.

 

[Mcdubjr]

There will not be a problem if your generator provides less power... Biggest issue you might see is if the generator power is noisy but the charger should tolerate it OK.... Do not put in a 14-50 if the wires will not support it.... If you wired for 30Amps, do not put in a 50A breaker.... Safety wise, you would be OK using a 14-50 plug even on a 30A circuit but not the other way around

Yeah, I would plan on re-wiring for the 14-50 with the appropriate gauge. Thanks!

 

[miasm]

Are you running the generator at 240V?

If not, change it over (120V charging is slow), even with a 30A receptacle. 240V with a 30A plug is fine. 50A better, but 30A is fine if 50A would be a big pain.

Then, when you show up, immediately run the generator and get enough charge to be able to confidently make it back down the mountain with a good amount of excess.

I do similar with a generator I bring while far off road.

Why do I do it immediately? Usually one bad thing you can recover from, but two or more at the same time turns a bad situation into a life threatening one. If someone gets a serious injury you don't also want to be worrying about how to get down the mountain, or run out of charge getting down or not have enough charge to race to get help, etc. So, remove "not enough electrons to get to safety / help" from the list of bad things that could compound on top of each other as soon as you are able to.

 

[lostpacket]

Just a thought in case it might pique your interest... Installing a few solar panels might be a fun DIY project. Especially if you have southern sky and room for a ground mount. Could always cover them with a tarp when you're not there.

 

[jwardell]

Most EVs won't charge off a generator because they test to see if neutral is bonded to ground. You may need to connect the two (Carefully...be sure it is neutral and not hot!). I actually carry a small plug that does just that.

You should get used to something I do quite often which is racing from plugging in a charger over to the UI to turn down the max charge current before it ramps up to the full 32A.

It isn't efficient and arguably not practical, but of course you certainly can charge from a generator if the need arises.

Of course if you're up a mountain you should be regenning power back as you head back down.

 

[Mcdubjr]

Thanks for all the responses, some more things to consider for sure!

Are you running the generator at 240V?

If not, change it over (120V charging is slow), even with a 30A receptacle. 240V with a 30A plug is fine. 50A better, but 30A is fine if 50A would be a big pain.

Then, when you show up, immediately run the generator and get enough charge to be able to confidently make it back down the mountain with a good amount of excess.

I do similar with a generator I bring while far off road.

Why do I do it immediately? Usually one bad thing you can recover from, but two or more at the same time turns a bad situation into a life threatening one. If someone gets a serious injury you don't also want to be worrying about how to get down the mountain, or run out of charge getting down or not have enough charge to race to get help, etc. So, remove "not enough electrons to get to safety / help" from the list of bad things that could compound on top of each other as soon as you are able to.

I think it's running at 240, but I'm actually not 100% sure. There is some family there now so I will see if they can verify (it's 6 hours from me so not easy to check!). Good point on wanting to keep that truck with decent SOC.

Just a thought in case it might pique your interest... Installing a few solar panels might be a fun DIY project. Especially if you have southern sky and room for a ground mount. Could always cover them with a tarp when you're not there.

Thats something we've always talked about doing but it's only a summer cabin and I don't think anyone wants to spend the money.

Most EVs won't charge off a generator because they test to see if neutral is bonded to ground. You may need to connect the two (Carefully...be sure it is neutral and not hot!). I actually carry a small plug that does just that.

You should get used to something I do quite often which is racing from plugging in a charger over to the UI to turn down the max charge current before it ramps up to the full 32A.

It isn't efficient and arguably not practical, but of course you certainly can charge from a generator if the need arises.

Of course if you're up a mountain you should be regenning power back as you head back down.

Hmm, that has me a bit concerned, perhaps I should consult an electrician.

Here's a pic of my 70s era electrical panel.

 

[ajdelange]

A 12RES generator will definitely charge the truck. It is a 120/240V single phase generator. I would put in a 14-50R receptacle simply because a 14-50R plug comes with the EVSE supplied by Rivian. Any other receptacle will require some sort of adapter. The 14-50R will need to be wired behind a 50a breaker with wire rated for 50A (e.g. THNN AWG 6). When the truck is plugged in using the Rivian adapter it will draw 32 A which is 64% of the generators capacity which should be a stable load for it (unless you have other stuff on too).

Most EVs won't charge off a generator because they test to see if neutral is bonded to ground. You may need to connect the two (Carefully...be sure it is neutral and not hot!). I actually carry a small plug that does just that.

You need not concern yourself with this as ground and neutral appear to be bonded in the panel. In any case be sure the earth wire (bare, goes to round pin the receptacle) is connecte to the generator's earth (ground) wire.

 

[Hopper]

Most EVs won't charge off a generator because they test to see if neutral is bonded to ground. You may need to connect the two (Carefully...be sure it is neutral and not hot!). I actually carry a small plug that does just that.

You should get used to something I do quite often which is racing from plugging in a charger over to the UI to turn down the max charge current before it ramps up to the full 32A.

It isn't efficient and arguably not practical, but of course you certainly can charge from a generator if the need arises.

Of course if you're up a mountain you should be regenning power back as you head back down.

I had the bonding issue with our portable generator during a recent 36 hour outage. Would you mind posting info about the small plug you carry? TIA!

 

[jwardell]

Yeah I was assuming plugging the truck into a portable generator. You have a residential installed generator with an electrical panel, you should have no issue.

@Hopper it's just a repair plug with ground and neutral tied. Can plug it to one of the unused outlets on a portable generator.

 

[Hopper]

Thanks!

 

[jwardell]

PS I tried the same adapter on the Rivian to see if it would charge itself, but the Rivian doesn't like it and shuts down AC output

 

[Hopper]

Yeah I was assuming plugging the truck into a portable generator. You have a residential installed generator with an electrical panel, you should have no issue.

@Hopper it's just a repair plug with ground and neutral tied. Can plug it to one of the unused outlets on a portable generator.

We isolate the main from the line with a lockout and “back feed” the panel from a 7kw generator. I used this to power the Rivian wall charger. The charger lit up white, but would not charge the truck.

 

[Mcdubjr]

Update:

I was able to successfully install a NEMA 14-50 plug at our cabin this weekend and charge. I did have some issues with charging stopping right after starting. The truck would start charging and then would hit 8kw in the UI and charging would stop. What I found is that I had to slowly ramp up the amps from the truck. So I'd start at 16 amps and tick it up 2 every 15-30 seconds or so. If I increased it too quickly charging would stop. I did this and was able to get the truck to charge at 32 amps for about 2 hours before charging stopped again.

Because of this I disconnected my wiring again and made sure everything was nice and tight. Problem remained. I don't think the issue is with any of my new work I've done. My best guess is the generator just has a hard time outputting the power or the wiring from the generator to the panel has some issue (it's probably from the 60s). The main 50 amp circuit breaker also looks a bit janky to me, I could try replacing it in the future.

Anyways, despite the issues I still consider it a success as I was able to charge at a pretty high rate. Solves my worry of being stranded up the mountain.

Thanks to everyone who provided advice here, I appreciate it!

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