Extension before or after EVSE?

[camaroz1985]

This past weekend had to charge at my in-laws. The only way to reach the truck from their only 240V plug (30A dryer plug) was to use a 50 amp RV extension cord, and plug the Rivian EVSE into that. It worked fine (truck set to 24A), and this will only be a once a month setup, but that got me thinking, would it be better to use the setup like I did this week, or buy a J1772 extension cable to use between the EVSE and the truck?

For reference, the extension cord I used was something like this
https://www.amazon.com/dp/B0024ECIP0
The setup was 10-30 to 14-50 adapter -> RV extension cord -> EVSE -> R1T

And the alternative would be something like this.
https://www.amazon.com/dp/B09PGMQNX6/
This would be 10-30 to 14-50 adapter -> EVSE -> J1772 extension cord -> R1T


We probably will throw it in the truck and take it on other trips just in case we end up somewhere that we can't get an easy level 2 charge. Just wasn't sure if one setup was inherently better, or safer than the other (cost aside, and that is really not that big of a difference in the grand scheme of things). Again, regardless of how it is setup we would use it on 24A in this case, but depending on what we plug into other places we could go up to the 32A of the Rivian EVSE.

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[Birdowin]

Seems like the RV cord would be the most versatile since it plugs into a standard dryer outlet and could be used in many other places. The second option only plugs into a J-1712 plug as far as I could see.

 

[Cosmacelf]

Either will work fine. In the end, both are just extension cords, so the effect and theory of operation is the same. The J1772 extension cord would normally be used if you need to charge from a public charger that has too short a cable for your car, or is ICEd or whatever.

 

[ohseedee]

Seems like the RV cord would be the most versatile since it plugs into a standard dryer outlet and could be used in many other places. The second option only plugs into a J-1712 plug as far as I could see.

I actually think the J1772 would be more versatile (for an EV anyway). Reason being, the RV extension cord just extends the dryer outlet, you still need to connect to that (extended) outlet using the mobile charger. In this uesecase, both do the same thing, but the added use case of the J1772 extension cable is it extends any public charger. Think the charger is blocked and you need to park a few stalls down. The RV cord is cheaper though. I can't think of any additional use case for the RV plug that the J1772 wouldn't do (for EV anyway).

 

[camaroz1985]

I actually think the J1772 would be more versatile (for an EV anyway). Reason being, the RV extension cord just extends the dryer outlet, you still need to connect to that (extended) outlet using the mobile charger. In this uesecase, both do the same thing, but the added use case of the J1772 extension cable is it extends any public charger. Think the charger is blocked and you need to park a few stalls down. The RV cord is cheaper though. I can't think of any additional use case for the RV plug that the J1772 wouldn't do (for EV anyway).

This was the only case I could think of the J1772 having an advantage.

 

[Birdowin]

I don't know why everyone is buying the proprietary Tesla or Rivian chargers. You get just as much charge out of a NEMA 14-50 (dryer plug) on a 50A breaker. The difference is that you can charge any EV on the NEMA 14-50. We have a Tesla and a Rivian and one in the garage and one in the back of the house. We can charge either vehicle on those. I don't know for sure but I think most EV's come with the NEMA plug. Save the money.

 

[Dark-Fx]

I prefer

I don't know why everyone is buying the proprietary Tesla or Rivian chargers. You get just as much charge out of a NEMA 14-50 (dryer plug) on a 50A breaker. The difference is that you can charge any EV on the NEMA 14-50. We have a Tesla and a Rivian and one in the garage and one in the back of the house. We can charge either vehicle on those. I don't know for sure but I think most EV's come with the NEMA plug. Save the money.

You can only draw 40A out of a 14-50. 48A isn't a big step up, but it could be helpful if you drain the battery every day.

 

[Revelation]

I don't know why everyone is buying the proprietary Tesla or Rivian chargers. You get just as much charge out of a NEMA 14-50 (dryer plug) on a 50A breaker. The difference is that you can charge any EV on the NEMA 14-50. We have a Tesla and a Rivian and one in the garage and one in the back of the house. We can charge either vehicle on those. I don't know for sure but I think most EV's come with the NEMA plug. Save the money.

Not entirely. Most portable EVSEs only charge at 32A when connected to a NEMA 14-50. Whereas a hardwired EVSE can charge at 40A on a 50A breaker.

I know Rivian just released a portable EVSE that does 40A but most don't have it.

 

[Birdowin]

So are you saying that a Rivian will draw 48A on a Rivian charger. That would exceed what you are supposed to draw on a 50A breaker.

 

[camaroz1985]

So are you saying that a Rivian will draw 48A on a Rivian charger. That would exceed what you are supposed to draw on a 50A breaker.

I think he is referring to the wall charger.

Again for this exercise I am using the mobile EVSE (charger) that comes with the truck. It is limited to 32A max which would be on a 40A circuit, but I am limiting it to 24A anyway due to only having a 30A circuit.

I think I will grab a J1772 extension, that way I could use with the included mobile EVSE to get to an outlet that would be too far away, or a hardmounted EVSE if ever I needed a longer cord. The 50A cord is also very bulky, and overkill for what I would/could draw from it anyway given the 32A limitation of the Rivian EVSE.

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