Charging Model 3 via HPWC - "Voltage Too High"

[eprosenx]

I looked into that years ago. J1772 is a standard. Sadly it specifically does not support 277v. It would be interesting to see what would happen if a non-Tesla used a J-adapter... hmmm that might be what the DIP switches do... stop a J1772 car from closing the relay if the HPWC is connected to 277v.

I am pretty sure the point of changing the dip switch is to tell the HPWC that it will only find voltage from one hot to ground. The other hot and ground should be at (or very near) the same potential.

In 120/240 split phase it will be able to test potential to ground on both legs.

i.e. I am pretty sure it has to do with the GFCI.

On another random note, I don't understand why they don't support the HPWC on 120v. While it would almost never make sense to install one on this low a capacity circuit, it could have value to someone (at least temporarily).

I would not be surprised if you could flip that dip switch (same as for 277v) and wire it up at 120v and have it work (if my hypothesis on what that switch does is true). Since 120v is also grounded on one leg...

 

[nwdiver]

I am pretty sure the point of changing the dip switch is to tell the HPWC that it will only find voltage from one hot to ground. The other hot and ground should be at (or very near) the same potential.

Sounds right... which would mean the only use for the DIP switches is a L-N configuration which is ONLY 277 OR 120

If the HPWC was only going to be connected to 240 or 208 that would always be L-L... right?

 

[cellogig]

Appreciate the input!!!

Quick question. Why all of sudden I can now charge my model 3 at an hpwc. My car would shut down and not accept the charge of 277v. Now it does.
I did not change anything on the car or go to a service center to change anything. I do not believe there was a software update either to accept a 277v charge. Do I need to have it reset to 250v?

Knowing now I could damage the vehicle and Tesla does not support 277v I should not use the 277v and have the car reset.

 

[nwdiver]

Knowing now I could damage the vehicle and Tesla does not support 277v I should not use the 277v and have the car reset.

I haven't seen any evidence of that. The comments I've seen imply that nothing has changed with the cars OR HPWC physically. Tesla obviously designed the S and X onboard chargers to accept 277v. It makes sense that Tesla removed reference to 277v to deter more problems with hitting the 282v fault point. Damage would occur beyond this so charging on 277v is still safe... there's just a higher probability your charge session will be interrupted.

I found some interesting comments regarding J1772 cars using a HPWC here;

 

[eprosenx]

Sounds right... which would mean the only use for the DIP switches is a L-N configuration which is ONLY 277 OR 120

If the HPWC was only going to be connected to 240 or 208 that would always be L-L... right?

Yup! That is my thesis...

Though technically they don’t support the HPWC at 120v. Though it may be fun to try out some day...

 

[nwdiver]

Yup! That is my thesis...

Though technically they don’t support the HPWC at 120v. Though it may be fun to try out some day...

IIRC the car limits current at 120v. I think the max is 20A.

 

[eprosenx]

IIRC the car limits current at 120v. I think the max is 20A.

Oh really??? I have not tested my TT-30 adapter yet at a campground. I will make a note to do that the next time I have a chance. If there is no limit I could charge at 24a on a 30a 120v circuit.

 

[nwdiver]

Oh really??? I have not tested my TT-30 adapter yet at a campground. I will make a note to do that the next time I have a chance. If there is no limit I could charge at 24a on a 30a 120v circuit.

I think it's different for pre/post 2014 cars. I've never tried... just heard about it.

 

[EfficientWatts]

Sounds right... which would mean the only use for the DIP switches is a L-N configuration which is ONLY 277 OR 120

If the HPWC was only going to be connected to 240 or 208 that would always be L-L... right?

I would speculate that if you took the North American HPWC to Europe, you would set the switches to L-N and it would work @ 230V. Though because you're maxed at 32A single phase pretty much you're better off just going with the Gen 2 mobile connector + the blue to 14-50 adapter for the same charging rate.

 

[nwdiver]

I would speculate that if you took the North American HPWC to Europe, you would set the switches to L-N and it would work @ 230V.

There's no such thing as 230v L-N in NA. Don't know about Europe. Pretty sure the sole purpose of N-L in NA is 277v... which is no longer 'supported'.

 

[EfficientWatts]

There's no such thing as 230v L-N in NA. Don't know about Europe. Pretty sure the sole purpose of N-L in NA is 277v... which is no longer 'supported'.

I know that, hence why I said specifically taking the HPWC to Europe as a hypothetical.

 

[Rocky_H]

IIRC the car limits current at 120v. I think the max is 20A.

I think it's different for pre/post 2014 cars. I've never tried... just heard about it.

Yes, this was a hardware difference in the very early cars. Here is the thread where that mystery was being unraveled:
Tesla

Up until about mid/late 2013, the onboard chargers had some kind of thing hard-coded where it would limit the current to only 20A if it detected a 120V source. This was independent of single or dual chargers. That was obviously frustrating people trying to use a TT-30 outlet at 24A. By about the beginning of 2014, they had fixed it so it didn't have that artificial limit.

 

[eprosenx]

Yes, this was a hardware difference in the very early cars. Here is the thread where that mystery was being unraveled:
Tesla

Up until about mid/late 2013, the onboard chargers had some kind of thing hard-coded where it would limit the current to only 20A if it detected a 120V source. This was independent of single or dual chargers. That was obviously frustrating people trying to use a TT-30 outlet at 24A. By about the beginning of 2014, they had fixed it so it didn't have that artificial limit.

Was the "fix" hardware or software? i.e. will some cars out there still see that?

 

[Bad Horse]

Is it more expensive because there are no transformers available off the shelf for that particular voltage ratio? In theory, a smaller ratio requires a smaller transformer, so it should cost less, all else equal.

Transformer size is based of the voltages (how much insulation you'll need) and the kVA/MVA power. Ratios has very little to do with physical size of the transformer, and you don't want it so small to have unnecessary losses between the high side and the low side by having like the bare minimum # of turns ratio.

 

[Rocky_H]

Was the "fix" hardware or software? i.e. will some cars out there still see that?

Well, I don't know quite how to define the term on that. It may have been something that was written in a line of "software" code somehow, (I would think an artificial limit like that would have to be) but it was apparently something inside a piece of equipment in the charging system of the car that couldn't be changed by firmware updates that get rolled out over the air. So it was quite a while into 2014 when people were figuring this out that it was strictly related to the build dates of the cars, and not on what overall operating system software version they had. So to this very day, I think the 2012 and 2013 cars still have this limitation.

 

[eprosenx]

Ok everyone-

While this thread was going on I contacted Tesla charging support and got some *fantastic* answers that I think explains a lot of what we have been confused about in this thread. I started a new thread to document this information going forward (so it was not buried in the middle of this long thread), and also because it covers the Model S, X, and 3 so I posted it in the general Charging forum for North America.

Info from Tesla - 277v feed to Wall Connector (HPWC) - Which Cars Support It

It explains a LOT!

@zkmusa
@cellogig
@Fiver
@quantumslip
@sammyfan711
@miimura
@Sophias_dad

 

[jjjord]

Here is my charger hitting 12,6kW without limiting the current.

Here's a pic of my new 3 charging at 269 volts at my workplace. Apologies for the quality, I hadn't planned to publish it when I took it.

It also hit 270 volts while I was watching, without faulting.

 

[Sophias_dad]

Here is my charger hitting 12,6kW without limiting the current.

My record seen is 274v/47A on that charger. For some reason, it just can't seem to use that 48th amp

 

[jjjord]

My record seen is 274v/47A on that charger. For some reason, it just can't seem to use that 48th amp

Well, as somebody mentioned above - it looks like the charger has a power limit:
I charged with: 48A at 263V is 48*263=12,624W and didn't hit that limit, since current is still 48A
Your screenshot shows 47A at 269V 47*269=12,643W so I'd just call it 12,6kW limit.
Since there is no decimals at tesla's app reading - yours might have been 46.6A and my reading might have been 47.6A
And 47A at 274V makes 12,878W so maybe that's the cap...

 

[fcharland]

Here is my highest voltage

287v ! And that was on a Tesla mobile charger. Didn't know I would catch this thing at a friend's house. (Most certainly a problem with the Utility)