50 Amp extension cord - ok?

[docwhiz]

You don’t have to extend the heavy duty side of the portable charger, you can extend the lighter car side
https://a.co/d/4lJ00GG

The same amount of current flows through both sides so a lighter car side could be a problem.
Lots of discussion here of light or heavy cords and quality but no one has mentioned the important objective specification factor which is wire gauge.
Current carrying capacity depends on wire gauge, length, and temperature.

https://images.app.goo.gl/ozNqA3BgNqHF89KX9

Derate for continuous draw, longer cables and higher temperature.

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[mikehmb]

The same amount of current flows through both sides so a lighter car side could be a problem.
Lots of discussion here of light or heavy cords and quality but no one has mentioned the important objective specification factor which is wire gauge.
Current carrying capacity depends on wire gauge, length, and temperature.

https://images.app.goo.gl/ozNqA3BgNqHF89KX9

Derate for continuous draw, longer cables and higher temperature.

OMG This, this, and all of this.

Please derate your charging for the lowest common denominator in your setup.

 

[Zoidz]

The same amount of current flows through both sides so a lighter car side could be a problem.
Lots of discussion here of light or heavy cords and quality but no one has mentioned the important objective specification factor which is wire gauge.
Current carrying capacity depends on wire gauge, length, and temperature.

https://images.app.goo.gl/ozNqA3BgNqHF89KX9

Derate for continuous draw, longer cables and higher temperature.

And due to the additional heat losses, the net charging rate into the battery will decrease. Minimal, but noticeable.

 

[SkyDave]

I use an extensions cords for two of my regular destinations to power my mobile Rivian EVSE.
A couple of tips:

As pointed out earlier, a 50’ 14-50 is very heavy and large. 75lbs sounds about right.
I carry a 50’ 14-30 cable with 14-30 to 14-50 adapter which is one third the weight and size. This extension cord/plug is rated to delivering 24amps continuously, which is more than enough for a destination charger. If you don’t trust yourself to always set the amperage charge rate, then this method isn’t for you, since this has removed the physical overdraw barrier. The Rivian mobile EVSE will draw 32 amps If left unconstrained.

Alternatively, do you need 50‘? 25’ feet is much more manageable.

Don’t leave the extra extension cords coiled up when using, but rather spread out a bit so as to dissipate expected warmth.

 

[xscotta]

The same amount of current flows through both sides so a lighter car side could be a problem.

The “lighter car side” refers to the Rivian charger which has a longer and lighter cable car side vs Nema socket side.

 

[SkyDave]

The same amount of current flows through both sides so a lighter car side could be a problem.
Lots of discussion here of light or heavy cords and quality but no one has mentioned the important objective specification factor which is wire gauge.
Current carrying capacity depends on wire gauge, length, and temperature.

https://images.app.goo.gl/ozNqA3BgNqHF89KX9

Derate for continuous draw, longer cables and higher temperature.

While definitely true, pragmatically speaking, unlike with the many gauges available for a NEMA 5-15 extension cord, it’s hard to find any commercially manufactured 14-50 extension cords that aren’t 6 gauge.

 

[docwhiz]

I use an extensions cords for two of my regular destinations to power my mobile Rivian EVSE.
A couple of tips:

As pointed out earlier, a 50’ 14-50 is very heavy and large. 75lbs sounds about right.
I carry a 50’ 14-30 cable with 14-30 to 14-50 adapter which is one third the weight and size. This extension cord/plug is rated to delivering 24amps continuously, which is more than enough for a destination charger. If you don’t trust yourself to always set the amperage charge rate, then this method isn’t for you, since this has removed the physical overdraw barrier. The Rivian mobile EVSE will draw 32 amps If left unconstrained.

Alternatively, do you need 50‘? 25’ feet is much more manageable.

Don’t leave the extra extension cords coiled up when using, but rather spread out a bit so as to dissipate expected warmth.

14-30 is 120 volts so half the power of 14-50

 

[xscotta]

I've used this one with every charge at home (and some out and about) for the past 3 years: https://a.co/d/6TRvDy2

Exactly!
I bought a similar J1772 extension for traveling where access to the nearest nema socket might need an extra 20ft.

 

[JM.]

But there isn't something else that explains why Rivian is so adamant about not putting anything between your charger and the socket, is there?

Fear of liability.

14-30 is 120 volts so half the power of 14-50

This is absolutely false, please be careful when making assumptions about electrical standards, it can be dangerous. The NEMA standard numbers tell us a lot, so at a glance, you can know that "14" is 240v and a certain layout, with ground, two hots, and a neutral.

 

[docwhiz]

Fear of liability.



This is absolutely false, please be careful when making assumptions about electrical standards, it can be dangerous. The NEMA standard numbers tell us a lot, so at a glance, you can know that "14" is 240v and a certain layout, with ground, two hots, and a neutral.

14-30 can be either 240 or 120 volts.
RV parks tend to have 14-30 wired as 120 volts

 

[JM.]

14-30 can be either 240 or 120 volts.

Of course, they all can be. The "14" standard allows for both.

RV parks tend to have 14-30 wired as 120 volts

Never seen it, but of course that doesn't mean it can't happen. It should not be stated as a blanket assumption which can be dangerous.

 

[docwhiz]

Of course, they all can be. The "14" standard allows for both.



Never seen it, but of course that doesn't mean it can't happen. It should not be stated as a blanket assumption which can be dangerous.

What's dangerous about getting 120 volts when you're expecting 240 volts?

 

[SkyDave]

14-30 is 120 volts so half the power of 14-50

No, it’s 240volt. NEMA 14-30 is actually same pin configuration and voltage as a NEMA 14-50. Both are single phase 240 volt.… (two hots, a neutral and a ground). At 80% for continuous draw, the NEMA 14-50 is rated up to 50amp*0.8 * 240v = 9.6kW. NEMA 14-30 is rated 30amp*0.8*240v=5.8kW.

 

[zymolysis]

Hi All: I tried searching for this and couldn't find it - apologies if it's been covered.

I'm pulling a travel trailer in some off-the-beaten-track areas - ie no fast chargers, but plenty of RV parks with 50 amp service. Aside from parks that prohibit EV charging (a whole other discussion) there are many with back in spots where my portable charger cord is too short to reach.

I'm aware that no extension is preferable, shorter is better, and the largest guage is the best. But assuming you adhere to these principles, what are your thoughts on using a 50 amp extension cord from an RV supply place on occasion?

Any guidance from my wiser/more experienced compatriots is appreciated!

It'll be fine - I've done it many times. I recommend running at a lower current, though. If I recall correctly the Rivian portable charger won't go over 32A, which is fine - that's nearly a 40% derating for a 50A extension cord and outlet. I also suggest that you should feel the cord and the plugs (with your hand) for excessive heat, after it's been charging awhile.

 

[beatle]

The same amount of current flows through both sides so a lighter car side could be a problem.
Lots of discussion here of light or heavy cords and quality but no one has mentioned the important objective specification factor which is wire gauge.
Current carrying capacity depends on wire gauge, length, and temperature.

https://images.app.goo.gl/ozNqA3BgNqHF89KX9

Derate for continuous draw, longer cables and higher temperature.

Wire gauge is important, but the J1772 side extension can be lighter since it doesn't have the heavy neutral that the 14-30 / 14-50 extension calls for. That said, the prices aren't that too far apart, and I wonder just how much lighter the J1772 extension would be.

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