Two HPWCs on 80A Breaker

[thodgdon66]

My garage installation has two Gen 2 Tesla Wall Connectors sharing an 80A breaker.

When only one car is plugged in and charging, I get a maximum of 37mi/hr charge rate. The question to the EE's in the crowd is, does that appear correct?

My initial assumption (which seems to be 100% incorrect) was that when only 1 car was connected we'd get the full 44mi/hr charge rate since the single HPWC would draw the maximum 48A for the Model 3 onboard charger.

Thanks for any insight!

 

[gfunkdave]

Have you checked that the internal switches are correctly set on the HPWCs? One of them should be a slave and the other should be set to an 80A breaker. That is, one of them should be set to F (slave) and the other to B (80 A breaker).

What does the car's screen say when it is plugged in?

 

[jmaddr]

What's the volts and amps when you get 37 mi/hr? Sounds like maybe you're only pulling 40A? If so, make sure your Tesla charging screen shows 48A.

 

[thodgdon66]

Thanks for the replies!! I'm going to take some photos tonight at home.

Quick one that you may not be able to answer - I think I recall the fasteners were something special on the Tesla HPWC, like security Torx?

Thanks!!

<EDIT> Found the T20 Torx driver in the manual...

 

[Sophias_dad]

Is that in a condo/apartment environment? Sounds like the 208V charger rate(200 at the charger).

 

[thodgdon66]

Nope house. Sorry couldn’t take the HPWCs apart yet. Tomorrow.

 

[Sophias_dad]

Did the electrician run the appropriate data wire between the HPWC's? As others have implied, both chargers are probably set to 40 amps and the data connection has been omitted. IIRC, it can be run through the same conduit if you use the right variety(temperature) of wire.

 

[thodgdon66]

Hey everyone, sorry for the delay.

Couple of things I found when I took the cover off the HPWCs...

1.) They look nothing like the ones in the HPWC installation manual you can download from the Tesla website. There is no set of DIP switches to set like in the manual. My HPWCs have a rotary switch to set the max output amperage on the main HPWC.

2.) The installer incorrectly set the max output current to 40A, which is Setting 8 on the rotary switch, probably because they didn't know the Model 3 has an onboard 48A charger. The correct setting is Setting 9 as shown in the photo after I changed it. And this from one of the electricians who supposedly does 3-4 HPWC installs a week. I would think they should know this basic installation fact about the Model 3.

So the bottom line is now that when one car is connected, I'm getting the correct 44mi/hr charge rate at 48A. Haven't seen what they get individually when both cars are connected, but I assume 22mi/hr.

Here are some photos of what I found (HPWC now correctly set at 48A).

Thanks to everyone who replied!!

Cheers

 

[Petrlol]

One of them should be a slave and the other should be set to an 80A breaker. That is, one of them should be set to F (slave) and the other to B (80 A breaker).

Going back to this, if you have the appropriately sized feed wires, the above settings are correct. This would allow you to share 64amps between the cars instead of just 48 amps, or it would let you charge other high power Tesla's at a higher rate.

 

[joelliot]

Hey everyone, sorry for the delay.

Couple of things I found when I took the cover off the HPWCs...

1.) They look nothing like the ones in the HPWC installation manual you can download from the Tesla website. There is no set of DIP switches to set like in the manual. My HPWCs have a rotary switch to set the max output amperage on the main HPWC.

2.) The installer incorrectly set the max output current to 40A, which is Setting 8 on the rotary switch, probably because they didn't know the Model 3 has an onboard 48A charger. The correct setting is Setting 9 as shown in the photo after I changed it. And this from one of the electricians who supposedly does 3-4 HPWC installs a week. I would think they should know this basic installation fact about the Model 3.

So the bottom line is now that when one car is connected, I'm getting the correct 44mi/hr charge rate at 48A. Haven't seen what they get individually when both cars are connected, but I assume 22mi/hr.

Here are some photos of what I found (HPWC now correctly set at 48A).

Thanks to everyone who replied!!

Cheers

View attachment 502845 View attachment 502847 View attachment 502843View attachment 502844

If you are on an 80 A and the sharing is setup correctly the master should be set to 64 A. That way you can get 32 A for both cars and up to the maximum, 48A, for an individual car.

 

[thodgdon66]

Have you checked that the internal switches are correctly set on the HPWCs? One of them should be a slave and the other should be set to an 80A breaker. That is, one of them should be set to F (slave) and the other to B (80 A breaker).

If you are on an 80 A and the sharing is setup correctly the master should be set to 64 A. That way you can get 32 A for both cars and up to the maximum, 48A, for an individual car.

Going back to this, if you have the appropriately sized feed wires, the above settings are correct. This would allow you to share 64amps between the cars instead of just 48 amps, or it would let you charge other high power Tesla's at a higher rate.

We have one recommendation to set the Master HPWC at 80A because it's attached to an 80A breaker.

The second recommendation is to set the Master HPWC at 64A.

I guess the question is, if I set the Master HPWC at something higher than the 48A onboard charger, will the car (or cars if both are plugged in simultaneously) pull the maximum amperage up to the 48A limit of the onboard charger?

Hmmmm....

<EDIT>

Found the Gen 2 installation manual. Says for an 80A breaker, you set the maximum current output to 64A.
Thanks everybody!!

 

[mongo]

We have one recommendation to set the Master HPWC at 80A because it's attached to an 80A breaker.

The second recommendation is to set the Master HPWC at 64A.

I guess the question is, if I set the Master HPWC at something higher than the 48A onboard charger, will the car (or cars if both are plugged in simultaneously) pull the maximum amperage up to the 48A limit of the onboard charger?

Hmmmm....

Use setting B 64A, the table in your unit is the 80% continuous current output limit. The table in the installation manual shows both and is copied below.
80 Amps (position D) in this case would correspond to a 100A breaker.
At the other extreme, 12 Amps is 80% of a 15 Amp breaker.

 

[thodgdon66]

Use setting B 64A, the table in your unit is the 80% continuous current output limit. The table in the installation manual shows both and is copied below.
80 Amps (position D) in this case would correspond to a 100A breaker.
At the other extreme, 12 Amps is 80% of a 15 Amp breaker.
View attachment 502910

Thanks!! I just found the Gen 2 manual also. Problem solved!!

 

[Sophias_dad]

Just to be extra super clear, you do have the data wire going between them and the slave set to the F position? Having two HPWCs set to 64 amps is a bad idea, and will correctly lead to trips if both cars charge at 48 amps.

 

[thodgdon66]

Just to be extra super clear, you do have the data wire going between them and the slave set to the F position? Having two HPWCs set to 64 amps is a bad idea, and will correctly lead to trips if both cars charge at 48 amps.

No problem and thank you!!

And yes, HPWC #2 has always been on “Slave”

Cheers!