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Why I'm Scared to Leave My Tesla At Home

dgatwood

Member
Dec 20, 2017
788
866
Sunnyvale, ca
I just had a really bad experience while leaving my Telsa at home while on vacation, and I wanted to post about it here, both in hopes that it will get the attention of some Tesla Firmware engineers and to warn others about the problem so that they won't experience the same problem.

My Tesla Model X (2017) has always had issues with charging at home. It trips the groundfault breaker. The original breaker tripped instantly when I started charging, as soon as it started drawing power. The replacement GFCI outlet just trips randomly after half a day or so. :(

Anyway, when I left the car, thanks to a chaotic schedule during the last few days, I failed to charge the car. That was a big mistake. So I left it at home with... I think about 60-ish miles of range. About a few days (and 2200 miles of flying) later, my phone notified me that the battery was dangerously low, and that I needed to plug my car in, or it might not be able to start. Yay.

So I called my next-door neighbor, and I unlocked the trunk remotely so that he could get the charging cord out and plug it in. It got up to 80-ish miles before it tripped the breaker. And then it ran back down, and I called him and he reset it for me again. And then it got too low again, and I asked him to reset it, but had to leave a message on his answering machine that time, and didn't dare even check the car to see if it was plugged in, assuming that I'd have a better chance of the car being functional if I didn't wake it up.

That was also a mistake. The car did not automatically start charging again. When I got home, the car was below zero miles of charge. It remarkably did wake up, showing a red charge light, and unplugging and replugging the cable got it charging, so I'm guessing that either being tethered keeps the 12V battery alive even if the car isn't actively charging or I got really lucky and just happened to get there right before I would have had to manually pop the frunk and connect a 12V charger to my 12V battery. I'm not sure which. I'm guessing the latter.

During this fiasco, I called Tesla and asked them to send a field service person out. They did some pre-diagnostic work from the service center, and said that the car was waking every three hours. They had me change my password just in case something was talking to their API and waking the car. I did. No change in power consumption. They also suggested turning cabin overheat protection off, but there was no way to do that from the other side of the country.

In the end, Tesla said there was nothing that a mobile tech could do to diagnose it in the field. Had they sent a tech, the tech probably would have immediately noticed the giant power inverter plugged into the 12V power jack with its light lit.

But wait, you say. The 12V power jack is turned off except when the car is turned on, right?

Wrong.

The 12V jack is turned off except when the computer wakes up. And when cabin overheat protection is turned on, it can wake up a lot. So I had the double whammy of it being a hot couple of weeks and a power inverter with an 85W power supply (disconnected from any device, but still using power) connected to the accessory port. The result was that my car was burning through about 15 miles per day of range while sitting turned "off". So that three-week trip cost me $40 in electricity as a result, and the car's failure to restart charging nearly left me manually charging the battery.

Of course, when it gets below 20 miles, cabin overheat protection turns off, so it burned through its usual four miles per day down near the bottom, but that was just barely enough for it to survive from when I checked it Monday to when I got home late Friday night.

Tesla, PLEASE fix this. Specifically, please:
  • Make sure that every power management feature that is available from the console is also available from the mobile app. The worst time to realize you have a problem with power consumption is when you're away from home, and if there's no way to fix the problem, that's a huge flaw, made worse by the realization that it could be fixed with ten seconds in Interface Builder plus adding maybe twenty lines of code in total, spread between the app and the car.
  • Add code to detect unusual rates of power consumption while sleeping and warn the user. That power inverter had been plugged in and turned on for a while, but I didn't notice it because I was only making one trip out per week and charging all the way up each week. But the car knew that it was drawing way more power than usual, and could easily have warned me in time to switch that off before I left on vacation.
  • Automatically try to restart charging for any charging failure, regardless of cause, as soon as power is reapplied. Every. Time.
  • If possible, draw enough power off of the UMC to keep the 12V systems running even if you aren't actively charging the main battery.
  • Fix the UMC v2 design so that it doesn't leak enough current to constantly trip 110V GFCI outlets.

These sorts of problems just shouldn't happen. They just shouldn't.
 

bsbomber

Member
Oct 10, 2013
121
20
Denver,CO
Why in the h$&@ do you have your Model X plugged into a 110v GFCI !?? Ground faults and pop machines don’t mix because there is a delay with the current returning to the outlet when the compressor starts. If I recall, the GFCI only allows a 5 millisecond delay. Something like that might be occurring with your GFCI. Outlets are easy peasy to wire.
Please hire a qualified person to wire you a decent outlet to provide juice for your car.
 

diverbelow72

Member
Nov 29, 2018
10
4
Vancouver WA
dgatwood why would you plug in your UMC v2 in to an GFCI outlet? If I read correctly, you also had a power inverter connected to the accessory port?

Sounds like you have to find another non-GFCI 110V outlet, so you can charge your X.
the manual you aren't supposed to use a power inverter.
 

fmm

Member
May 19, 2015
90
102
Philadelphia, PA
sounds like a lot of over-engineering to fix a simple outlet problem you have with your specific configuration - which you could fix far easier then all of that you suggest.

further, don't know how long you've had your Tesla, but, you didn't know to turn off cabin overheat when you're taking a trip? You left your car with 60 miles of charge unplugged? And you think this is Tesla's issue to engineer around?
 

dgatwood

Member
Dec 20, 2017
788
866
Sunnyvale, ca
There are many cases when GFCI is not indicated. This sounds like one of them.

Unfortunately, the national electric code requires GFCI for all outdoor outlets, so unless you have an enclosed garage, you don't really have a choice.

sounds like a lot of over-engineering to fix a simple outlet problem you have with your specific configuration - which you could fix far easier then all of that you suggest.

further, don't know how long you've had your Tesla, but, you didn't know to turn off cabin overheat when you're taking a trip? You left your car with 60 miles of charge unplugged? And you think this is Tesla's issue to engineer around?

I know how to turn it off. I didn't know it kept the internal outlet on, I didn't know that the inverter was plugged into the outlet, and I didn't know the temperature was going to spike to 100 degrees suddenly while I was gone. And there's no way to turn it off after you leave.

Also, I was supposed to be gone for one week. I got sick on the way to the airport, and decided to cancel my return flight and get a coronavirus test. It took eleven days to get the results. Thus, my return trip was delayed by two weeks. So there were a lot of mitigating circumstances here. :)
 
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jimmym1981

Member
Oct 15, 2019
240
163
Chicago
It's trial and error a lot of times with these things, learning curves and what not on how your Tesla charges and reacts to certain situations. It sucks that you had the issue and I'm glad you didn't need a tow. Most definitely the outlet is probably the perpetrator. Swap it out to an industrial regular non GFCI outlet and I think you will be good to go. Lesson learned and move forward with the new knowledge and spread it around.
 

dgatwood

Member
Dec 20, 2017
788
866
Sunnyvale, ca
It's trial and error a lot of times with these things, learning curves and what not on how your Tesla charges and reacts to certain situations. It sucks that you had the issue and I'm glad you didn't need a tow. Most definitely the outlet is probably the perpetrator. Swap it out to an industrial regular non GFCI outlet and I think you will be good to go. Lesson learned and move forward with the new knowledge and spread it around.

I actually already did that. The original outlet tripped instantly. The new one trips every few hours. :)

Also worth noting that I have unlimited supercharging on this car, so I never need to put more than about twenty miles of charge on my car at home, just to give me a safe margin to get to a supercharger. Otherwise, I'd have installed a 220 outlet a long time ago.

I believe you are allowed a Non-GFCI outside, but it must be labeled as such. I have one outside that powers a water softener and we were having trouble with it tripping. Non-GFCI, labeled and problem solved.

Good to know. I'll look into whether that's allowed here, because it would take me all of ten minutes to switch it out again. :D
 

jimmym1981

Member
Oct 15, 2019
240
163
Chicago
I actually already did that. The original outlet tripped instantly. The new one trips every few hours. :)

Ah, I missed that one. Is the house grounded properly to the outlet? Might have to have an electrician come out there and take a look? Have you had anyone else with a Tesla plugin and see how it works?
 

mswlogo

Well-Known Member
Aug 27, 2018
6,015
4,627
MA, NH
I actually already did that. The original outlet tripped instantly. The new one trips every few hours. :)

Also worth noting that I have unlimited supercharging on this car, so I never need to put more than about twenty miles of charge on my car at home, just to give me a safe margin to get to a supercharger. Otherwise, I'd have installed a 220 outlet a long time ago.



Good to know. I'll look into whether that's allowed here, because it would take me all of ten minutes to switch it out again. :D

Sounds like you needed a whole lot more than 20 miles of charging without even driving it.

Unlimited supercharging is no excuse for a *sugar* charging setup at home.

Topic should be changed to. Don’t even think about using 110V to charge at home. 110V GFCI outlets are notorious for false tripping on EV and generally discouraged.

You’d be fine with a 220V 20A and up setup. I use 30A and one house and 50A at another and also have free supercharging. Charging sure came in handy lately that 110V would have never handled and I didn’t have time to deal with supercharging. I also prefer not supercharge when car is very hot and it’s over 90F if I can avoid it. I have Solar and effectively it’s use it or lose it energy.

You also have something fundamentally wrong with your car. My guess is you have a bad 12V battery and that is sucking down the main battery to keep recharging it. I can go a week and only lose a dozen miles at most.
 
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mswlogo

Well-Known Member
Aug 27, 2018
6,015
4,627
MA, NH
There are many cases when GFCI is not indicated. This sounds like one of them.

Dedicated EV outlets require GFCI using latest code. You simple need a GFCI that is compatible. 110V GFCI outlets aren’t a joke for EV charging. He got what he paid for. Eliminating a false tripping safety is not how you fix it. Do you just recommend removing say s problematic smoke detector too? Sorry that’s really bad advice.

Only the Wall Connector does not require GFCI, which is partly why I recommend them. All the units that plug into the wall require GFCI. Finding a GFCI that is compatible is that hard.
 
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dgatwood

Member
Dec 20, 2017
788
866
Sunnyvale, ca
Ah, I missed that one. Is the house grounded properly to the outlet? Might have to have an electrician come out there and take a look? Have you had anyone else with a Tesla plugin and see how it works?

The ground is fine. And GFCIs work even if you don't have a ground attached.

The problem is that the Tesla UMC apparently leaks a little bit into the ground whenever it does its ground integrity check, which it does right before it starts ramping up the charge current. And that's enough to trip many GFCIs instantly.

I'm not sure why it trips randomly after double-digit hours. I think in hindsight that I have a mini fridge on the same circuit, so it occasionally pulls more than the 80% derating, which could theoretically cause a slight voltage drop down at the far end of that circuit when the refrigerator's compressor kicks on, which might be fooling the GFCI into thinking that there's a leak when there isn't one. Or it might be that the Tesla UMC continuously leaks almost enough to trip the GFCI, and it randomly leaks more. I have no good way to known which. But since I almost never charge at home, it isn't really worth debugging it further.


Sounds like you needed a whole lot more than 20 miles of charging without even driving it.

Typically, no. Now that I switched off the power inverter, it is back down to its usual 4-ish miles of phantom drain per day, which is consistent with the way it has behaved since it was new.


Dedicated EV outlets require GFCI using latest code. You simple need a GFCI that is compatible. 110V GFCI outlets aren’t a joke for EV charging. He got what he paid for. Eliminating a false tripping safety is not how you fix it. Do you just recommend removing say s problematic smoke detector too? Sorry that’s really bad advice.

It's not really bad advice. The UMC basically has ground fault hardware build in. Chaining ground fault hardware like that is the surest way to get false trips. The right fix is for Tesla to disable all the ground fault hardware when on 110 VAC under the assumption that those are always plugged into a GFCI outlet, and use it only when connected to a 220VAC outlet, because those almost never are.


Only the Wall Connector does not require GFCI, which is partly why I recommend them. All the units that plug into the wall require GFCI. Finding a GFCI that is compatible is that hard.

Sadly, our neighborhood has inadequate power availability, and I'm stuck with a 100A circuit. (Homes in the older section of the neighborhood are even worse, with only 60A service.) So adding a 220V outlet, even at 30A, is a non-starter. Otherwise, I would have done that long ago.
 

dmurphy

Woof.
Dec 7, 2018
3,463
4,674
New Jersey - Morris County
Or it might be that the Tesla UMC continuously leaks almost enough to trip the GFCI, and it randomly leaks more. I have no good way to known which. But since I almost never charge at home, it isn't really worth debugging it further.

I recently had to use our UMC on 120v at home. We added a Model X, but our electrician was backed up for a few weeks, so we only had one HPWC. The outdoor outlets were all GFCI and never tripped once with the UMC. so I don't think it's leakage per se; at least not by design, anyway.
 

mswlogo

Well-Known Member
Aug 27, 2018
6,015
4,627
MA, NH
The ground is fine. And GFCIs work even if you don't have a ground attached.

The problem is that the Tesla UMC apparently leaks a little bit into the ground whenever it does its ground integrity check, which it does right before it starts ramping up the charge current. And that's enough to trip many GFCIs instantly.

I'm not sure why it trips randomly after double-digit hours. I think in hindsight that I have a mini fridge on the same circuit, so it occasionally pulls more than the 80% derating, which could theoretically cause a slight voltage drop down at the far end of that circuit when the refrigerator's compressor kicks on, which might be fooling the GFCI into thinking that there's a leak when there isn't one. Or it might be that the Tesla UMC continuously leaks almost enough to trip the GFCI, and it randomly leaks more. I have no good way to known which. But since I almost never charge at home, it isn't really worth debugging it further.




Typically, no. Now that I switched off the power inverter, it is back down to its usual 4-ish miles of phantom drain per day, which is consistent with the way it has behaved since it was new.




It's not really bad advice. The UMC basically has ground fault hardware build in. Chaining ground fault hardware like that is the surest way to get false trips. The right fix is for Tesla to disable all the ground fault hardware when on 110 VAC under the assumption that those are always plugged into a GFCI outlet, and use it only when connected to a 220VAC outlet, because those almost never are.

Sadly, our neighborhood has inadequate power availability, and I'm stuck with a 100A circuit. (Homes in the older section of the neighborhood are even worse, with only 60A service.) So adding a 220V outlet, even at 30A, is a non-starter. Otherwise, I would have done that long ago.

I said 20A 220. It is extremely rare that adding a 20A 220V would tip the scales. There are boxes that can even be inserted between a dryer or hot water heater that gives the EV low priority. There is almost always a way of doing better than 110V.

Chaining ground faults has nothing to do with it. The GFCI in the Mobile adapter does not supersede the need to GFCI the outlet. It’s the AC-DC converter in the car that causes problems with some GFCI. The GFCI in outlets are the worst. Put in a Siemans GFCI breaker (if compatible) and remove the GFCI outlet. Or if necessary add a Siemans Subpanel.

I have a 100A service with Central A/C and a pool. 30A going to the car. I added an A/B to an Electric heater I rarely used in the garage. No added load to panel, easy breezy. Both the Pool and the A/C are ultra efficient. Typically (except when charging) ever exceed 20% utilization.

Install a house power monitor to see what your really at. Highly recommended for any home owner. That is what got me to upgrade the A/C and the pool and cut my electric bill in half. Enough to cover all EV charging.
 
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dgatwood

Member
Dec 20, 2017
788
866
Sunnyvale, ca
I recently had to use our UMC on 120v at home. We added a Model X, but our electrician was backed up for a few weeks, so we only had one HPWC. The outdoor outlets were all GFCI and never tripped once with the UMC. so I don't think it's leakage per se; at least not by design, anyway.

There seems to be a wide range of trip current settings on GFCIs, and unfortunately, that spec isn't always mentioned when you're looking these things up on the Home Depot or Lowe's website, or at least I couldn't find it a couple of years ago; maybe that has improved.

Anyway, enough people have complained about this problem over the years that I'm pretty certain it isn't just me. But it is highly variable, depending on the GFCI (and possibly depending on the UMC or the car, for all I know). What's interesting is that there are approximately zero reports of this problem with UMC v1, and many folks who have had this trouble with UMC v2 have not had any trouble when using UMC v1 in the same outlet.

*sigh*


I said 20A 220. It is extremely rare that adding a 20A 220V would tip the scales. There are boxes that can even be inserted between a dryer or hot water heater that gives the EV low priority. There is almost always a way of doing better than 110V.

I also don't have room in the breaker box, which means adding another tandem breaker. And yes, I would probably have to have one of those boxes. If I were going to be charging regularly at home, I would do that. But I have unlimited supercharging and charging at work, so I literally charge at home approximately never.
 

immolated

Member
Oct 3, 2016
223
291
Las Vegas
Spend a couple hundred on a real 220v outlet. You can still change the max current to something like 5 or 10a in the settings.


And absolutely take the fridge off the same circuit, that's making it worse for sure.


I would even swap out the GFCI for a normal outlet, just the circuit breaker is safe. Don't need things to be in code unless you're selling, as long as you know what you're doing.

And don't use the supercharger daily! They weren't designed for that and you're going to get permanently throttled. Teslas were designed for daily 220v top offs.
 
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dgatwood

Member
Dec 20, 2017
788
866
Sunnyvale, ca
And don't use the supercharger daily! They weren't designed for that and you're going to get permanently throttled. Teslas were designed for daily 220v top offs.

I'm in California. At our extortionate utility rate, given the number of miles I drive each week (at least when the coronavirus doesn't have everything shut down), I've calculated that I would spend about $66 per week in electricity if I charged at home. That's over three grand per year. If a replacement battery costs $15k, then at five years, the power savings from supercharging has more than paid for the cost of a replacement battery. The warranty on the battery is 8 years. It makes zero sense to charge at home.

Also, AFAIK, they aren't throttling 100Ds.
 

mswlogo

Well-Known Member
Aug 27, 2018
6,015
4,627
MA, NH
There seems to be a wide range of trip current settings on GFCIs, and unfortunately, that spec isn't always mentioned when you're looking these things up on the Home Depot or Lowe's website, or at least I couldn't find it a couple of years ago; maybe that has improved.

Anyway, enough people have complained about this problem over the years that I'm pretty certain it isn't just me. But it is highly variable, depending on the GFCI (and possibly depending on the UMC or the car, for all I know). What's interesting is that there are approximately zero reports of this problem with UMC v1, and many folks who have had this trouble with UMC v2 have not had any trouble when using UMC v1 in the same outlet.

*sigh*

I also don't have room in the breaker box, which means adding another tandem breaker. And yes, I would probably have to have one of those boxes. If I were going to be charging regularly at home, I would do that. But I have unlimited supercharging and charging at work, so I literally charge at home approximately never.

I have unlimited super charging too. But it pays to have good charging at home. like the other day I wanted to do a full 270 mile round trip and not stop for supercharging. I kicked off topping off my battery to 100% at 6AM, left at 9AM came back late with 20% or so and plugged it in. No stopping. What it's meant to be. I could bring it up to 40% and bring to super charger when convenient if I want to save a few $$. That would not have been an option on 110V. It would take a day to add 30%, which is ridiculous.

You keep justifying how great it is being on 110V and them blaming firmware and how you're scared to charge at home on a BAD setup. Sorry you can't have it both ways. Why bring it up at all if you don't need it? If you do "need it", even when it's only in a pinch, you'll probably want to be faster than 3 mph.

You'd have to be constantly pulling more that 80A 220V to say you have maxed out your 100A panel. If you have 100A panel I doubt you have electric heat. If you don't have electric heat I bet you're not using more than 50%. I replaced my tiny 100A panel maxed out with all twins to a 30 Slot 100A. All I needed was space for more circuits. But I'm not adding 2 ovens or Electric Hot Water. Ovens, Electric Water, AC and Electric heat are about the only big consumers. With better and better energy efficient, I'm using less electricity than the house was designed for 50 years ago (except for the EV ;)). TV is better, AC is better, Pool is better, All lights are better and probably other stiff I forgot.

A 100A is a TON !!. You might need new panel (not that expensive) or a sub panel. But I bet you have plenty of headroom. A 20A 220 circuit should not be tipping the scale. If it is, you need a new service before you added EV.

Being forced to not charge at home because of a poor setup just makes owning an EV less convenient. It absolutely pays to have better charging options at home. Charging at 3 mile hour is almost useless. It's also inefficient. And like you found works horrible on the outlet based GFCI. I didn't read every post and someone mentioned your running the fridge on the same circuit? Typically fridge should not be on GFCI (Fridge not a electricution risk and not worth the risk on a false trip losing all your food). EV's (that plug in, AT THE WALL) are a risk. Putting your EV on a dedicated circuit doesn't add any more load than you already have. It's just better isolation of circuits.
 

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