-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
As explained to me by Tesla when this first happened to me, the car is trying to detect substandard premises wiring, or the use of undersized or ridiculously long extension cords. A large voltage drop on the current ramp up when starting a charge is able to determine, generally, if the wiring is sufficient for the current draw based on NEC and other guidance on voltage drop. If the car feels too much power will be released as heat in the wiring, it slows the charge and pops up with the message saying this, "Charge speed reduced, Extension cord or bad wiring" (or similar message). This makes perfect sense and should definitely be included in the firmware. The goal would be to help people who have bad premises wiring realize this and hopefully get it repaired/replaced since the car will be a continuous load that requires good wiring.
However, the problem is they've expanded this detection beyond the initial voltage drop calculation (the one that actually provides useful data) and monitor the voltage drop throughout the entire charge. When something unrelated happens on your power connection, not even on the same circuit or even in the same building, that causes a voltage drop, the car flips out and reduces charge current... even though there was no reason to so do.
In the case of the OP, it is obviously this expanded algorithm, combined with a business's normal power demands, that are causing the car to not want to charge at a normal speed.
spaceballs
Member
After my first discovery of that, I actually then connected a AC electronic controlled load connected to the roadster that was charging at 12-15 amps (as I can adjust charging current of both car and electronic load), I was doing this to see it's voltage sag limits to see it's where it dropped out.
If you fail to see how the roadster prevented the overload extension cord (by UL standards/NEC) I feel like your playing mind games at this point.
I'll make the scenario match the OP case.
Say the 14-50 is installed wrong and some how someone as tapped into the 14-50 outlet with another high power current draw (say another 14-50 or worse). Now add in a worn out main breaker that likes to stick closed (yes this does happen), start the Model S is charging and then 10 minutes later the other 14-15 outlet is then used at full load. Now the wires from the 14-50 back to the panel is overloaded. Now the Models S see the voltage sag and drop to a level that is hopefully safe or even better it disconnects completely.
I don't think I have much else to say, if you don't see how this could prevent a more serious problem.
Anyone not happy about the power Model S is pulling out of their walls should shut up and fix their wiring.
Or start saving up for the membership into a very hot club:
A responsible company errs on the safe side.
Or start saving up for the membership into a very hot club:
A responsible company errs on the safe side.
If the OP has provided voltages/currents during UMC charging, as read on the screen, then I've missed it. At least give us that.
The M in UMC means 'mobile' and not for repeated fixed base usage, esp since the HPWC was finally released. I've used my UMC maybe 3 times. If you allow sun to shine on UMC how can you feel it for internal overheating??
The W in HPWC means 'wall'. Step back and consider the implied usage intended by the designer/producer/mfr.
'useless junk' ~ 'odious piece of crap' [search on this].
--
The M in UMC means 'mobile' and not for repeated fixed base usage, esp since the HPWC was finally released. I've used my UMC maybe 3 times. If you allow sun to shine on UMC how can you feel it for internal overheating??
The W in HPWC means 'wall'. Step back and consider the implied usage intended by the designer/producer/mfr.
'useless junk' ~ 'odious piece of crap' [search on this].
--
Last edited:
Mobile is a feature, not a requirement for using a UMC. Who ever said it was not for repeated fixed base usage? I think my use is a very common scenario-- it stays plugged in the outlet in my garage, with the cord on a wall hook next to the outlet, except when I travel out of town I take it with me. I've used it that way since July 2013 without any issues. I know it can go bad, but I don't see how keeping it "fixed base" or using it just on trips would affect that.
Since the OP has gone through 6 UMC's and that it far, far more than the normal, I'd say the UMC is not up to the usage scenario he has.
Personally, I would never think of purging and unplugging the UMC daily. The wear and tear on the socket and connecter would be quite high. Also, since the UMC is known to get very hot during 40Amp charging, I would never charge at 40Amp while the UMC is exposed to direct, hot sun.
But if I decided to push the UMC and do the above two things against my better judgement, I would absolutely stop after the first (or at most second) UMC died. I would have dialed back to 35 or maybe 30 Amps or looked into installing a HPWC at work, and been done with it.
Personally, I would never think of purging and unplugging the UMC daily. The wear and tear on the socket and connecter would be quite high. Also, since the UMC is known to get very hot during 40Amp charging, I would never charge at 40Amp while the UMC is exposed to direct, hot sun.
But if I decided to push the UMC and do the above two things against my better judgement, I would absolutely stop after the first (or at most second) UMC died. I would have dialed back to 35 or maybe 30 Amps or looked into installing a HPWC at work, and been done with it.
I think there was another person on this forum that experienced the similar charging issues, with a factory close by with some noise on AC. I guess it might be that there are some problematic cases of UMC with AC with noise or surge or whatever. I don't know the cause for sure, but I believe Tesla is responsible for isolating the case and identifying the source of the problem and solve the issue, or at least explain technically to OP why it didn't work as designed. It's a consumer product admit should work like turning a key.
An A/C motor start up (like an air compressor) on the same service will often cause the Tesla to lower the voltage (this would be true with an HPWC as well). For Tesla to make a UMC that would be immune to this would be possible, but it wouldn't be very mobile and would cost quite a bit more.
Gotta love the Tesla apologists. Like I said, the building wiring is 100% fine. 6ft of #6 THHN in 1 inch metal conduit. The voltage drop on the dash is usually about 240V at 0A, 236V at 40A. I don't know what it was yesterday(didn't have time to monitor it, and had to have car fully charged in 3 hours). I can't imagine the drop was much different.
This is an issue of someone buying a car woth a certain use case scenario, that scenario being met for about two years, and then taken away with new firmware. Nothing less nothing more.
Toa all of the advice about getting an HPWC, nothing will change, the car is responsible for this BS. Not the charging cords.
Nobody but Tesla can fix this.
This is an issue of someone buying a car woth a certain use case scenario, that scenario being met for about two years, and then taken away with new firmware. Nothing less nothing more.
Toa all of the advice about getting an HPWC, nothing will change, the car is responsible for this BS. Not the charging cords.
Nobody but Tesla can fix this.
You most certainly may request it, but I don't see how it's relevant. If the same wiring and connections have been in place and the car has accepted them before, then all of sudden comes along a firmware update and bam it doesn't work... Well, let's just say it's a bit suspicious.
That is not how he is coming across, maybe that is how you are reading but that is not how he has presented it at all.
He is the one that said I HAD to update the FW. I have had long discussions with Jason, but not since last summer. This is a FW issue, so his hands are tied.
"I paid for 10kW charging, and received it. Now they are taking it back. Not cool." and "Tesla's choice to limit charging current after the fact is the entire problem." are the comments I'm referring to.
Tesla isn't 'taking it back' it appears they have tightened to tolerances allowed most likely for safety reasons.
I would think after 6 UMCs bad luck with getting a bad UMC might account for the first 4-5 of them but at some point there has to be something else going on to cause so many to break down. There have been issues with UMCs and some getting 2 or 3 different ones until they get one that works but 6 bad ones is a stroke of horrible luck if the wiring and everything else is working perfectly.
If an HPWC isn't an option maybe a robust ClipperCreek J1172 station and using the adapter might be an option at work.
I've charged at 40A for over 2 years and have never had this issue with any firmware version and in multiple locations. Not everyone has had the same experience charging at 40A with this software release. Obviously some have an issue (real or perceived by Tesla's software) that is causing it to limit the Amps delivered to the car.
Some of the time lower amperage charging is OK. That's not what this is about though. Like I told Jason, this current reduction is going to happen when you least want it to. It's NOT ok for Tesla to all of a sudden up RV park stays by hours after they have your money.
- - - Updated - - -
If you had bothered to read my posts, only 3 UMC's had some melting, and I'm far from the only one with that many UMC problems. Like stated up thread, a different charging connector won't fix the charge dial back issue.
We also must have different definitions of something that being taken away.
I am sorry you're having all of these issues and hope Tesla addresses them. Service always seems to go above and beyond. Has an electrician ruled out the building wiring or the outlet? Do you unplug your UMC from work every single day or do you leave it there?
I understand Tesla's position on this though. I've had my car for over 2 years. If I never updated and came in with an issue on software version 3.1 or whatever it was back then and this was known to be fixed 2 years ago with a newer version (but I refused to update) what should Tesla do? Should they continue to support know buggy versions 2, 3, 5 years after the fact?
I understand not being on the front line of software updates and Tesla should allow customers to hang back and let others update and find problems but at a certain point it makes sense for them to force an update. It's a rolling computer but it's still a car. If you don't update OS X for 2 years, nothing is likely to happen with your safety but if Tesla improves issues related to safety/charging along with the other 'fun' features they should probably push them out at some point. Also, Tesla doesn't have the staff to indefinitely support software versions that are years out of date.
- - - Updated - - -
This is a long thread so sorry if I missed it. 'Bothered to read' really isn't necessary. You are definitely (for whatever reason) getting less charging rate than you paid for. I hope Tesla can figure this out for you.
Have you tried charging on a HPWC at any other location? It sounds like there probably isn't one anywhere near you. Maybe another owner could come check out your work plug with their UMC and see if same issue happens.
There is obviously a lot of emotion here for some reason as noted in the title. Charging at 30 or 35A doesn't turn the car into a useless piece of junk. You're not charging at the rate you deserve and paid for you it hardly junks the car.
Can you not upgrade your garage at home to a 14-50 (I might have missed the reason why, I know you use 120V there now)?
Similar threads
