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Gen1 HPWC refuses to charge dual-charger P85D. How to troubleshoot?

gordo

Member
Jan 16, 2015
224
91
CA
I've had a Gen1 (80amp) HPWC and P85D (dual 40 amp chargers; MCU1; software 2020.48.37.6) for about 6 1/2 years now, and never had a charging issue until the last couple weeks. The car's now refusing to charge on the HPWC -- I get the message: "AC charging interrupted -- Check power source and charging equipment." I have the HPWC limited to 64 amps. I always get a green light (never red) on the HPWC. I've tried resetting the car, resetting the wall connector, resetting the circuit, same result each time. I even put the HPWC in test mode (via internal DIP switches) and confirmed that its contactors work as expected.

I confirmed no issues on the mobile charger (though I can only test it on [email protected] amps). I also tried a friend's 3rd-party 240V 30amp charger without issue.

What I'm trying to figure out is what's potentially gone wrong: has one of my on-board chargers died or is it the HPWC itself?

I believe that my dual chargers normally split the incoming 64 amps of AC, so it runs 32amps though each on-board charger. What I don't know, however is how the car handles a load of 40 amps or less. Does it push it all to one charger or does it split it to both? Similarly, how does it handle a 120V load from the mobile connector? Does it use only one of the chargers?

The reason I want to know is because it's possible that if any load 40 amps or below is passed to the one 'good' charger, I could simply have a bad on-board charger while my HPWC is fine.

Alternately, if the car splits literally *any* load across each charger, then it would suggest the HPWC is the culprit, as other chargers seem to work fine.
 
Last edited:
Oct 10, 2019
502
268
So-Cal
the easiest way to diagnose this is to go to a charger out in the wild and plug in and see what happens, and try a couple to verify the result. On the Nav screen you can select destination chargers, then you can tap on one at a time till you find one that lists 16kW and that is a charger that'll do all 80A vs the ones that say 8kW only do up to 40A.
Or you can just use the find us page and click around on various destination chargers to your local area.

Once you plug into the charger if you get the same issues as you do at home then its an issue with the car and the easiest way to solve that is to pay the $150 diag fee from tesla to find the issue and then go from there.

If it works just fine and you get all 80A like you should then its something wrong with your charger. I'd start by turning off the breaker and disconnecting all the power lines, and cleaning up all the leads and then putting it back together and ensure they are good and snug. and power it back up and if still no dice then i dono. perhaps someone else knows how to diag parts on the HPWC


 

Rocky_H

Well-Known Member
Feb 19, 2015
7,051
8,659
Boise, ID
I believe that my dual chargers normally split the incoming 64 amps of AC, so it runs 32amps though each on-board charger. What I don't know, however is how the car handles a load of 40 amps or less. Does it push it all to one charger or does it split it to both? Similarly, how does it handle a 120V load from the mobile connector? Does it use only one of the chargers?
Ah, I know this one. It sometimes pays to be a long-timer around here and remember when people were discussing all this old stuff.

There is a primary and a secondary one. Incoming current up to 40A will all be only through that primary charger. But if it is above 40A, then it does split it half and half between the two. So you could test that pretty easily on your existing wall connector by just turning the amps in the car down to something less than 40, so it would only be using the primary one, and that should show you by whether it works or not, which one of your onboard chargers has failed. If it only fails when it's above 40A, then it's the secondary one that isn't working.

You have some options, depending on which one failed. If it's your secondary that's failed, you could just charge at 40A or less and not need to do anything.

If it's your primary, and it just won't charge at all, then I remember hearing from some people here on the forum that got a service center to do a cheap repair by swapping them. Put the still-functioning secondary in as the primary, and again, you can charge at up to 40A. This was much cheaper than the several thousand dollars of them actually having to get and install an actual replacement charger.

Also, it runs in my mind that these occasionally had an issue of an internal fuse blowing in these chargers, and people have replaced those themselves, so if that's the issue, that could be done, but I would have to scour the forums to find some info on that.
 
Last edited:

henderrj

Active Member
Jun 16, 2014
1,033
882
Graham, WA, United States
Ah, I know this one. It sometimes pays to be a long-timer around here and remember when people were discussing all this old stuff.

There is a primary and a secondary one. Incoming current up to 40A will all be only through that primary charger. But if it is above 40A, then it does split it half and half between the two. So you could test that pretty easily on your existing wall connector by just turning the amps in the car down to something less than 40, so it would only be using the primary one, and that should show you by whether it works or not, which one of your onboard chargers has failed. If it only fails when it's above 40A, then it's the secondary one that isn't working.

You have some options, depending on which one failed. If it's your secondary that's failed, you could just charge at 40A or less and not need to do anything.

If it's your primary, and it just won't charge at all, then I remember hearing from some people here on the forum that got a service center to do a cheap repair by swapping them. Put the still-functioning secondary in as the primary, and again, you can charge at up to 40A. This was much cheaper than the several thousand dollars of them actually having to get and install an actual replacement charger.

Also, it runs in my mind that these occasionally had an issue of an internal fuse blowing in these chargers, and people have replaced those themselves, so if that's the issue, that could be done, but I would have to scour the forums to find some info on that.

I have a dual charger car and I thought I remembered the opposite. Sorry. I'm almost certain it splits the amperage no matter how much is going through the system. I believe @wk057 had some info on this at one point. Maybe we can get him to chime in.
 

tga

Supporting Member
Supporting Member
Apr 8, 2014
4,042
3,030
New Hampshire
I have a dual charger car and I thought I remembered the opposite. Sorry. I'm almost certain it splits the amperage no matter how much is going through the system. I believe @wk057 had some info on this at one point. Maybe we can get him to chime in.
Everything I've ever seen agrees with @Rocky_H <=40A primary charger only, >40 both chargers. Try setting the car to <40A or the HPWC dip switches to <40A and see if it works.
 
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Hank42

Legacy Supporter
Sep 30, 2012
551
352
United States - NY
From past personal experience:
You might want to try removing any crud from the contacts in the HPWC's handle as well as the Tesla port with some electrical contact cleaner and soft pipe cleaners.
I had a similar problem with the same setup as you. It ended up being the cable has jplasmd mentions. Cleaning it might work, for me, the pitting was so bad that the cable had to be replaced - which Tesla doesn't do(anymore) - replacing the charger with a new(old stock) V1 charger is one option, or if you're ok with lowering your output, get a gen2 or 3 charger that won't do 80 amps, but are readily available. -that's to say if you can confirm the charging cable is the culprit.
 

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