Wall charger not charging at 48A

Wall charger not charging at 48A


I have a Tesla wall charger connected directly to a 60A breaker on my sub panel. When I first installed it I confirmed it was charging at 48A. I normally set the charge time at 1AM so I haven't been monitoring the charge rate. I just checked this morning and it is only charging at 32A. Anyone know if any of the recent firmwares reduced limiting the charge rate? I have a LR RWD.


Magic 8 Ball | 18 maj 2019

Did you check when it was near end of charge?

tri_t_to | 18 maj 2019

No it is just starting. Actually I unplugged and replugged the charger couple of times and it is charging back at 48A.

Magic 8 Ball | 18 maj 2019

Glitch in the matrix ??? NIce you are back to normal.

tri_t_to | 18 maj 2019

Spoke too soon. Charging dropped back to 32A after about 5 mins. I am only at 60% charge.

kevin_rf | 18 maj 2019

What's your voltage? Close to 240v it down to about 210v? That would indicate a wiring problem and the car is protecting itself.

tri_t_to | 18 maj 2019

It's hovering around 231V.

kevin_rf | 18 maj 2019

While a little low, that shouldn't be it. Mines usually in the the 234/235v range. The car does measure the voltage before it starts charging, and if it drops while charging it can lower the current.

Have you tried charging frpom a low charge state, less than ~80 miles range left. That's the point the battery will be soaking up every election it can.

Tronguy | 18 maj 2019

@tri_t_to: So, nominal voltage at a house is 120 VAC on one phase, 120 VAC on the other phase, and, across the two phases, 240 VAC. At my place, it's around 243 or 245, depending upon the phase of moon, how many other people in the development have their air conditioners on, and so forth.
Next: Wires have got resistance. Voltage drop (Ohms Law) is V = I * R, where I is current.
Now, when the electrician wired it all up, he used a great big gauge of wire with really low resistance, the better not to burn up stuff. (Power dissipated in the wire is P = I*I*R; too much resistance and stuff starts smoking...)
Further, given that the Wall Connector runs on two phases and ground, in the schemes of What Could Possibly Go Wrong means that one wire might not be crimped/screwed/socketed down as well as the other.. which again leads to higher resistance and a drop in voltage as the current goes up.
In the interests of Safety, the Tesla will drop the charging current if it thinks that there's too much voltage drop from the open circuit (no current draw) to the max current draw case. For example: When I plug the mobile connector into the wall socket next to the breaker panel, it draws 12A. Put in a 30' extension cord, non-heavy duty, and the Telsa drops the charging current to 8A or less.
So, what's going on? Let me count the ways...
1. When the electrician put in the wires, he didn't screw something down like he shoulda.
2. When the electrician put in the wires, he used too small a gauge.
3. There's something buggered up in the switches in the Wall Connector. (I have seen buggered up fresh switches in my career, it happens.)
4. There's something wrong about your connection to the Civil Power Authorities on the breaker panel. (Watch those home improvement shows.. They sometimes get overly warm breaker panels, for all the wrong reasons.)
5. Something wrong about the detection of the voltage drop in the guts of the car charger. Lots of cars get built, one sometimes gets infant mortality.

OK. I'm a EE. My knee-jerk reaction to this would probably be to call the electrician who did the work and politely complain. Further: If you used a Tesla-certified electrician, the ones I used took pretty pictures of their handiwork and sent them into Tesla, I presume so that Tesla could do a little troubleshooting. So, you might call Tesla, if you used a Tesla-certified guy.

Now, I might do this, but I've worked around high-voltage stuff that makes house wiring look silly. Turn off the breaker, take off the TWC cover, tack a couple of 30 GA wires onto the business end of the cable inside the TWC, bring those out to a voltmeter, put the cover back on, carefully, being careful not to short anything, and turn the power on. Check the open-circuit voltage; plug in the car; read the voltage, check the current draw in the screen, and work up to R = delta-V/I. Then see if R makes sense with respect to the wall wire used. But - if you're not handy with stuff like that, Don't Do It.

surfpearl | 18 maj 2019

Are you seeing a yellow flashing light on the Tesla Wall Connector? The troubleshooting section of its manual (page 22) mentions 3 cases where the charging current is reduced because of high temperature detected in:
1. The Vehicle Connector (1 yellow flash)
2. The wall plug or on the input terminals to the Wall Connector (2 yellow flashes)
3. The Wall Connector (3 yellow flashes)

Are you seeing a blinking amber light on the car's charge port light? According to the car manual, that indicates Model 3 is charging at a reduced current. The car can limit the charging current and will sometimes display a message explaining the reason for it.

You can also lower the max. charge current on the flatscreen from 48 A to 40 A when starting a new charging session to see if further reduction will be done by the smarts in the car or the Wall Connector.

tri_t_to | 18 maj 2019

I drove the car down to 17% and still charging at 32A. There isn’t much load on the sub panel right now. Just a few recess lighting and the frig. The electrical work was done with permits and the inspector was very anal so I don’t doubt the electrician’s work.

Magic 8 Ball | 18 maj 2019

If you have a friend with a TESLA have them try your charger.

GHammer | 18 maj 2019

Sorry if this is a stupid question but have you checked the manual charge current setting in the car? Sometimes one of my wall chargers will exhibit a momentary drop in voltage because it's on the same subpanel as a heat pump which pulls a lot of momentary current. When this happens the current drops to 30 (from 40) and the car remembers this and will only charge at 30 until I manually change it back to 40.

jexlean | 18 maj 2019

I believe it is the PCS or Power Conversion System. I am having a similar problem with my car. I thought it was my Tesla Wall Connector, but brought the car to the Tesla SC and plugged it into their Wall Connector and sure enough I was only drawing the same max 32A which the display showed source at 48A. The one major difference in my case is that I had a display warning that I am not charging at the maximum rate and to unplug and plug again. Unplugging and plugging again didn't help. PCS is on back order and waiting for repair.

Tronguy | 19 maj 2019

Just a bit more under the What Could Possibly Go Wrong categories:
@jexlean: Cool. Plug the car into a known good system and Magic Badly Occurs, and associated with a buggered-up car internal.
@hammer: Spiffy. You get a voltage drop when the heat pump goes off and the logic of the car internals makes the car think that _it_ had caused that. Rube Goldberg, move over.
@Magic 8 Ball: Good idea. If one can't swap the charging establishment by taking the car to a SC with a known good WC, then check the home environment by swapping with a Known Good Car (KGC). Just have to make sure that the KGC is the type that can actually charge at 40A or more.
Finally: I said something previous about possible bad switches in the TWC. Actually, should have thrown possible calumnies at everything about the TWC. Could be bad electronics, switches, wiring, you name it. M8B's got the right idea. Now you need to find a friendly owner nearby :).

Magic 8 Ball | 19 maj 2019

Isolating variable is fundamental to understanding at this level.

007bond | 19 maj 2019

@hammer @OR-US this is what I thought too it happens to me once in a great while for no reason I find the car set to 32amps max and I just put it back to 48amps and problem solved. This has happen to me maybe 2-3 times in the past several months. I think it may have to do with when I use a public charger since many of them are limited to 32amps but not 100% sure.

tri_t_to | 19 maj 2019

Screen says 32/48A. I was able to temporarily get it to charge at 48A yesterday but replugging it a few times but I cannot get it to go to 48A at all since then. Thanks jexlean, I'll have Tesla SC see if it is the PCS.

surfpearl | 19 maj 2019

So what color is the Tesla logo on the charge port light when you get 32 A?

varun | 24 marts 2020

I figured out why my new model X was not charging on the old wall charger. Incase you have other customers facing the same issue please let them know.

The generation 1 and 2 wall chargers have dippers in side where you can set the Amp output. For older cars my charger was set to max 100 amp as the cars auto adjusted to 80amp if they had dual chargers. For the new cars max charge is 48amp but they can’t handle the 100 amp input. Once I moved the dips to 80amp it started charging the car at 48amp.

See manual for the dipper config

EVRider | 24 marts 2020

@varun: I got my wall connector about a year ago so I guess it's a gen 2. Mine is on a 100A breaker, and my 2018 Model S is able to change at 72A. Our 2018 Model 3 charges at 32A, but it has no problem with the 100A circuit, so I guess it depends on which Tesla model you have and when it was built.

Tronguy | 24 marts 2020

@EVRider: If your M3 is an SR/SR+/MR, 32A is what you get, max. If it's a LR or P, you can get up to 48A. If you've got one of the latter two and you're only getting 32A on a TWC with a 100A breaker, Something Is Wrong.
I've heard reports that one can contact Tesla Support and they have dedicated people for charging. If you're in the Something is Wrong class, dinging them may get somebody on a phone line that can help, be it switches or doing remote car diagnostics. (Based upon conversations with a co-worker who had some TWC issues when first installed..)

Lorenzryanc | 25 marts 2020

I had SAME issue... Turn off power at breaker, open wall charger and tighten the contacts and ground. Do the same at the breaker. My car would drop to 32 with a warning. After loosening, readjusting, and tightening the connections, it's back to normal. 6 gauge wire and about 30ft length for me. I also have a 60amp breaker and the charger switch set to 48amp.

Lorenzryanc | 25 marts 2020

Ohh.. I forgot. I took to a SC and charged successfully at 40amps (their max), service bulletin for the dead pins or whatever they're called, charged again successfully, still didn't work at my home. I also can force charge in car to anything less than 32 with no warning, but if you go to 33, it'll kick it down to 32 with a warning. Actually I was glad the car was smart enough to see a problem.

hokiegir1 | 25 marts 2020

@Lorenryanc - I *thought* (and could be wrong) that the charger switch is supposed to match the breaker and will then adjust the 80% load from there -- so if you are on a 60A breaker and set the charger to that, it will do up to 48A...but if you set the charger to 48A, it will max at 32A (80% of 48A)...except, I just checked my math and that doesn't work, so maybe never mind (48*.8=38...not 32). But I've typed this, so I'm leaving it with my error and all, just in case that's still part of the issue. :)

EVRider | 25 marts 2020

@Tronguy: I know that my MR Model 3 maxes out at 32A. My point was that unlike @varun, I didn’t have to change dip switches on my 100A wall connector to make that work.

Lorenzryanc | 25 marts 2020

@EV Yes, MR Model 3s will charge at 32 max. @hokiegirl I don't recall the switch location on mine. I remember the manual showing Breaker size and switch choice. 60amp breaker required "X" choice and gave 48amp charge. I set for that position.

My car used to work fine at 48amps, then one day it dropped to 32 with the error. Checking all the connections was a last resort, but from now on, it'll be a first resort :) My breaker actually had about half a turn on it to tighten. Also, my dad mentioned that some wire types can loosen more than others do to heat. Mine is copper.