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Multiple HPWCs: Communication Issue?

Jillmark99

Member
Feb 1, 2019
227
82
Ontario
I added a second HPWC in my garage and want to set them up as master/slave. I have them both wired up per Tesla manual and the communication cable wires between them. When I power them up I get 4 red flashes on the “slave” charger. I am pulling my hair out because it’s all wired and set up properly. I have double checked the wiring multiple times. I have checked the rotary switch multiple times. I have quadruple checked master/ slave configuration but not having any luck.
I have even tried switching the configuration around and when I switch it I get the 4 red flashes on the opposite charger.

Setup as follows;
Original HPWC charger rotary switch set to A. Communication +/- wires connected to output.
Second (new) HPWC charger rotary switch set to F. Communication +/- wires connected to input.
Both chargers are Gen 2.
I’m at a complete loss. I cannot get one set to master and the second set to slave.
I’m hoping someone else has encountered this and can provide a solution.
I have reset both of the chargers multiple times and powered cycled them multiple times as well.
If I disconnect the communication wire and set rotary switches on each unit to A they will both charge fine. I simply can’t get a “slave” charger when setting a rotary switch to F.
I would really appreciate your help.
Thanks
 

Missile Toad

Member
Aug 30, 2016
619
602
Houston
Some potential risks:
  • If the signal wire is routed in the power conduit with the power wires, the insulation rating of the signal wire should be equal to or greater than that of the power wires.
    Also, be sure your power at the circuit breaker is 'off', each time you change the DIP switch settings.
 

powaking

Member
Feb 1, 2018
434
264
Massachusetts
Thought I saw in an older thread that the HPWC do receive updates via the car. Is it possible the new HPWC has an older firmware than that of the current HPWC installed? Could the mismatch of firmware play a role? Also I assume the run for the communication wire is under 49'?
 

animorph

Active Member
Apr 1, 2016
2,143
1,538
Scottsdale, AZ
We didn't have a problem with our two. From the symptoms (master works, slave doesn't regardless of which HPWC is master) it sounds like the communication wire is not doing its job. Our comms wire runs outside the conduit and spans a 16 foot double garage door. If there is anything slightly odd about the current comms wire I would pick up some more and try a temporary comms connection.
 
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Rockster

Active Member
Oct 22, 2013
3,010
4,617
McKinney, TX
Are you sure that you have the comm wires going from Out to In?
The four red flashes indicate an over voltage or under voltage condition. How do you have power to the two units wired? My setup uses a multi-tap connector to split the 100 amp line from the breaker box. (See pic)
Could there be noise interfering with the comm wiring? How close is it running to the power. Mine is in a separate conduit (the blue conduit) to keep it away from the power conduit.

Wall chargers_wall open.jpg
 

Jillmark99

Member
Feb 1, 2019
227
82
Ontario
The communication wire is running outside of the conduit.
The chargers are less than 20’ apart.
Not sure about firmware, haven’t charged a car yet with the new charger more than a couple minutes.
I tried a secondary communication wire as well.
I always turn the power off when changing rotary switches.
Still no dice.
 

Jillmark99

Member
Feb 1, 2019
227
82
Ontario
Are you sure that you have the comm wires going from Out to In?
The four red flashes indicate an over voltage or under voltage condition. How do you have power to the two units wired? My setup uses a multi-tap connector to split the 100 amp line from the breaker box. (See pic)
Could there be noise interfering with the comm wiring? How close is it running to the power. Mine is in a separate conduit (the blue conduit) to keep it away from the power conduit.

View attachment 466008

yes I’m sure the communication cable goes from out to in. I checked it multiple times.
my power supply is similar to yours, split the supply before the two chargers. comm cable is run on the outside of the power conduit.
4 red flashes according to the Tesla manual means more than one charger set to master.
 

john pane

Member
Apr 6, 2017
84
59
PA, USA
  1. Set one Wall Connector as the master by setting the Rotary Switch Position from 1 to 8 depending on the maximum available output current.
Apparently you cannot set the master to A.
 

MorrisonHiker

S 100D 2021.4.18.2
Mar 8, 2015
9,834
9,203
Colorado
When all else fails: https://www.tesla.com/sites/default...nstallation_manual_80A_en_US.pdf?201612081439

  • If no green lights are on and there are four red flashes: Over or under voltage protection. Consult your electrician to ensure appropriate voltage on the circuit breaker that services the Wall Connector.
  • If the top green light is on and there are four red flashes: Circuit Breaker Sharing Network: More than one Wall Connector is set to Master. Only one Wall Connector can be set to a master configuration. All other linked Wall Connectors must be set to slave (position F). Set one of the Wall Connectors to Slave.
 

Jillmark99

Member
Feb 1, 2019
227
82
Ontario
And is your comm wire to spec?
Yes


When all else fails: https://www.tesla.com/sites/default...nstallation_manual_80A_en_US.pdf?201612081439

  • If no green lights are on and there are four red flashes: Over or under voltage protection. Consult your electrician to ensure appropriate voltage on the circuit breaker that services the Wall Connector.
  • If the top green light is on and there are four red flashes: Circuit Breaker Sharing Network: More than one Wall Connector is set to Master. Only one Wall Connector can be set to a master configuration. All other linked Wall Connectors must be set to slave (position F). Set one of the Wall Connectors to Slave.
I have the manual and have read it. Mine is flashing second bullet point you have listed. Top green light on and 4 red flashes.
 

Jillmark99

Member
Feb 1, 2019
227
82
Ontario
Thought I saw in an older thread that the HPWC do receive updates via the car. Is it possible the new HPWC has an older firmware than that of the current HPWC installed? Could the mismatch of firmware play a role? Also I assume the run for the communication wire is under 49'?
I will unhook the comm cable and try charging one of my cars overnight with the new charger and see if it updates firmware in the charger. Then will hook the comm cable back up tomorrow and set back to master/slave and see if it makes a difference.
 

john pane

Member
Apr 6, 2017
84
59
PA, USA
I will unhook the comm cable and try charging one of my cars overnight with the new charger and see if it updates firmware in the charger. Then will hook the comm cable back up tomorrow and set back to master/slave and see if it makes a difference.

That seems like a reasonable test.

Another is to set the master to 8 or lower, as recommended in the copy of the manual I am looking at.
 

Jillmark99

Member
Feb 1, 2019
227
82
Ontario
Well I am at my wit’s end with this.
I plugged in my car to the new charger and did a full charge and I’m guessing if there was a firmware update to the new charger it was completed.
So, tonight I hooked up the comm wire again and set them back to master/slave and I still get the same error. Top green light on and 4 red flashes on the slave charger.
I even tried replacing the comm wire and it makes no difference. I even switched the configuration to swap the two chargers master/slave and when I do the opposite charger gives top green light and 4 red flashes. Same issue just reversed. I have absolutely no friggin idea and I’m getting super frustrated. I have checked everything a hundred times. Everything is 100% per the Tesla manual.
I’m a very mechanical person so I know everything is correct. I even had a second set of eyes look at everything and confirm it’s 100% correct.
No matter what I do it won’t work in master/slave mode.
Not sure which way to go. Please help!!!
 
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SoCalNick

Member
Oct 10, 2017
203
111
SoCal
Dumb question.
What cable are you using as a communication cable? Is it Shielded Twisted Pair. Have you tried switching the +/- pair at one end?

I was going to ask you if you had tried switching master/slave, but your last post said that you had.

Have you tried installing a new communication cable between the two, just going across the garage floor, and not through conduit. Just to rule out a comm wire issue?
 
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Jillmark99

Member
Feb 1, 2019
227
82
Ontario
Yes I tried switching master/slave. Same results, doesn’t work. :(
My comm cable is exactly per Tesla spec. It’s an 18 gauge, 2 wire, twisted with shield.
Yes the + goes to + and the - to -
I replaced the cable with a second one running across the garage floor and yields the same results.

I have NOT tried switching the +/- at one end. That would yield + to - and - to +. Could that possibly damage anything??
 

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