Mobile Charging issues and work arounds

[MeadowShade]

I am confused about charging at camp grounds. I can’t get my mobile charger to even light up when I use a 50 amp extension cord from the wall plug to the charger.
Any ideas about that?
Can I use a 30 amp plug adapter to step up to a 50 amp plug on the mobile adaptor?

is it am impedance issue or could it be that the neutral and ground are not bonded?

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[Crissa]

Copied from the other thread: this is a better place to answe.

I am confused about charging at camp grounds. I can’t get my mobile charger to even light up when I use a 50 amp extension cord from the wall plug to the charger.
Any ideas about that?

Is there actually power?
Is there a wiring fault?

I carry a tester when dealing with dubious outlets.

Can I use a 30 amp plug adapter to step up to a 50 amp plug on the mobile adaptor?

Uhh... You can get a 30a plug for the Mobile Connector.
https://shop.tesla.com/product/gen-2-nema-adapters

It should be obvious why you shouldn't 'step up' to a higher amperage load. I know sometimes you have to do what you need to, and a Tesla can be instructed to draw less on a circuit than the outlet indicates, but be very careful not to exceed the circuit rating.

Tesla doesn't use the neutral while charging at 240v.

-Crissa

 

[mongo]

I am confused about charging at camp grounds. I can’t get my mobile charger to even light up when I use a 50 amp extension cord from the wall plug to the charger.
Any ideas about that?
Can I use a 30 amp plug adapter to step up to a 50 amp plug on the mobile adaptor?

is it am impedance issue or could it be that the neutral and ground are not bonded?

A 30Amp outlet at an RV park is a 120V TT-30(one phase, neutral, ground)
A 14-50 outlet is 240V (two phases, neutral, ground)
A RV 30A to 50A adapter results in the same 120V phase twice, neutral and ground. Since most all RV equipment (including AC) is 120V this is fine. However, it doesn't give the mobile connector what it needs since phase to phase is 0V instead of 240V

Tesla doesn't sell a TT-30 adapter, but others sell conversion cables. If going to 14-50 using one of those, it will be 120V (swaps neutral for the second 120V feed) and set the vehicle to pull no more than 24 Amps (80% of 30A)

The 14-50 at the campground may also be 120V only, in which case another conversion cable would be needed.

 

[Woodrick]

I am confused about charging at camp grounds. I can’t get my mobile charger to even light up when I use a 50 amp extension cord from the wall plug to the charger.
Any ideas about that?
Can I use a 30 amp plug adapter to step up to a 50 amp plug on the mobile adaptor?

is it am impedance issue or could it be that the neutral and ground are not bonded?

What extension cord are you using? They aren't recommended.

Here's an adapter for the TT-30. TT-30 Adapter for Tesla Model S/X/3/Y Gen 2 – EVSE Adapters

I would not suggest getting any of the other plug conversion things. They often don't work.

Oh, and I have to ask the really dumb question. Did you turn the breakers on? They are often turned off at campgrounds.

 

[MeadowShade]

What extension cord are you using? They aren't recommended.

Here's an adapter for the TT-30. TT-30 Adapter for Tesla Model S/X/3/Y Gen 2 – EVSE Adapters

I would not suggest getting any of the other plug conversion things. They often don't work.

Oh, and I have to ask the really dumb question. Did you turn the breakers on? They are often turned off at campgrounds.

First. THERE ARE NO DUMB QUESTIONS! Only stoooopid mistakes! Ha!

Our goal was to charge at camp grounds overnight for two reasons.

it is free (most places)
And it is a slow charge while we sleep so it saves a charging stop each day.
I understand the breaker issues and plan on step by step plug ins.

I will keep the amps turns down but my nephew who has a couple of phd’s in electricity says stepping the current through two adaptors and a 25 foot cable will not allow the charger to work at all.

At his house he has a 50 amp plug a NEMA that matches the plug on my Tesla Mobile Charger. I have a 25’ 30 amp cord. I assumed I could use an adaptor to step the plug down to a 30 amp plug, use the 30 amp cord and step the plug back up to the 50 amp plug at the mobile charger while keeping the amps at 20 or so would be fine.
But the mobile charger will not even light up. Ther is current on the plug and at the end of the extension cord. Ideas?

 

[Crissa]

The Mobile Connector has no idea how many extensions you added before it. So it'll do what you instruct it. If it's not working, the power is a weird signal, miswired, or just not providing the power.

The Mobile Connector does know which Tesla adapter is connected immediately to it, though, which is handy as it autolimits to that spec.

-Crissa

 

[mongo]

The Mobile Connector has no idea how many extensions you added before it. So it'll do what you instruct it. If it's not working, the power is a weird signal, miswired, or just not providing the power.

It's not miswired but is weird because RV 30 Amp outlets are only 120V.

At his house he has a 50 amp plug a NEMA that matches the plug on my Tesla Mobile Charger. I have a 25’ 30 amp cord. I assumed I could use an adaptor to step the plug down to a 30 amp plug, use the 30 amp cord and step the plug back up to the 50 amp plug at the mobile charger while keeping the amps at 20 or so would be fine.
But the mobile charger will not even light up. Ther is current on the plug and at the end of the extension cord. Ideas?

Like I said up thread, an RV/ Travel Trailer (TT) 30A outlet is just a higher current 120V source or Line-1, Neutral, Ground. An RV 30 to 14-50 adapter results in Line-1, Line-1, Neutral, Ground. When you use a Mobile Connector 14-50 adapter, it gets Line-1,Line-1, Ground. There is zero voltage potential between Line-1 and Line-1 since they are the same circuit.
A normal 14-50 is Line-1, Line-2, Neutral, Ground with 240V between Line-1 and Line-2 because they are opposite 120V phases.

The off-brand TT-30 adapter provides the MC Line-1, Neutral, Ground. It's only 120V (Line to Neutral), but it works.

keep the amps turns down but my nephew who has a couple of phd’s in electricity says stepping the current through two adaptors and a 25 foot cable will not allow the charger to work at all.

Nephew is wrong. If the vehicle sees too much voltage drop, it will reduce its charging current. However, you can charge via (properly wired) extension cord, just keep an eye on voltage drop and temperatures.

 

[Woodrick]

First. THERE ARE NO DUMB QUESTIONS! Only stoooopid mistakes! Ha!

Our goal was to charge at camp grounds overnight for two reasons.

it is free (most places)
And it is a slow charge while we sleep so it saves a charging stop each day.
I understand the breaker issues and plan on step by step plug ins.

I will keep the amps turns down but my nephew who has a couple of phd’s in electricity says stepping the current through two adaptors and a 25 foot cable will not allow the charger to work at all.

At his house he has a 50 amp plug a NEMA that matches the plug on my Tesla Mobile Charger. I have a 25’ 30 amp cord. I assumed I could use an adaptor to step the plug down to a 30 amp plug, use the 30 amp cord and step the plug back up to the 50 amp plug at the mobile charger while keeping the amps at 20 or so would be fine.
But the mobile charger will not even light up. Ther is current on the plug and at the end of the extension cord. Ideas?

Does the standard NEMA 14-50 adapter work when plugged directly into the outlet?

And no, your step down and step up solution won't work.
The NEMA 14-50 is 240V. The TT-30 is 120V.
You will need a NEMA 14-50 heavy duty extension cord and expect to pay about $200 for it.

 

[mongo]

At his house he has a 50 amp plug a NEMA that matches the plug on my Tesla Mobile Charger. I have a 25’ 30 amp cord. I assumed I could use an adaptor to step the plug down to a 30 amp plug, use the 30 amp cord and step the plug back up to the 50 amp plug at the mobile charger while keeping the amps at 20 or so would be fine.
But the mobile charger will not even light up. Ther is current on the plug and at the end of the extension cord. Ideas?

Oh, my bad. I confused the campground and house use cases.
Technically, you can do what you are talking about, but it will require non-standard adapters.
If it's a 30A RV cord with three wire, you could feed Line-1, Line-2, Ground from the 14-50 through it and then ideally put a 10-30 adapter [Edit 2: and then label it so that you never use it with an RV since it provides 240V. Be aware the 14-50's circuit breaker will be overrated for the cord] at the other end to match the cable rating.


TT-30 120V:

10-30 240V:

 

[Woodrick]

Oh, my bad. I confused the campground and house use cases.
Technically, you can do what you are talking about, but it will require non-standard adapters.
If it's a 30A RV cord with three wire, you could feed Line-1, Line-2, Ground from the 14-50 through it and then ideally put a 10-30 adapter [Edit 2: and then label it so that you never use it with an RV since it provides 240V. Be aware the 14-50's circuit breaker will be overrated for the cord] at the other end to match the cable rating.


TT-30 120V:

10-30 240V:

You may indeed be able to do it, breaking every related NEC code along the way.
And it still requires the TT-30 adapter that I mentioned earlier.

But why create a solution that only you know about? Just do it the right way.

And I make it a habit to not recommend bad solutions on public forums. There are many ways that *I* can do it, but then again, I'm an Electrical Engineer trained in this stuff.

 

[mongo]

You may indeed be able to do it, breaking every related NEC code along the way.
And it still requires the TT-30 adapter that I mentioned earlier.

But why create a solution that only you know about? Just do it the right way.

And I make it a habit to not recommend bad solutions on public forums. There are many ways that *I* can do it, but then again, I'm an Electrical Engineer trained in this stuff.

Well, since NEC covers permanent wiring and extension cords are temporary, one might ask if NEC even applies to them. If one takes the position that it does, then one would need to deal with typical extension cord usage violating the protection from damage clauses. I do agree with the base concern of unsafe wiring being unsafe.

So, if someone is already trying configurations that mix 120V and 240V, I feel it's better they be informed about why it's not aligned to their understanding. I did not intend to recommend the approach, and called out the 10-30 and voltage warnings specifically to reduce the chance of damaging a travel trailer.

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