I have had a couple times since the update where my charging has reacted to apparent fluctuations in power, but here is where it is a problem. It does not reduce the draw 25% from where you set it, but 25% from maximum. My garage is only equipped with a 30A breaker. The total to the garage is only 50A and I don't want to have to pull a new feed from the house. Because of this at home I charge at 24A. When the car detects whatever it is looking for it actually ups my setting to 30A instead of reducing it 25% to 18A.
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Vger
Active Member
I am in the same boat.
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Wow, that is definitely not right! Just the kind of bug that gets introduced by a rushed f/w update!
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I wish Tesla would tell us explicitly what the algorithm is!
InTheShadows
Active Member
That could be a major problem. I would spring for the 14-30 plug and change the outlet so it matches the circuit and wiring. Pulling 30 amps continuous on a 30 amp circuit is dangerous and can cause a fire. In your situation you could have one unless the charger can shut off completely.
The 14-30 plug should limit your car to 24amps which is where it should be with your site setup.
I think they've got algorithm problems. My suspicion is it has fixed voltage limits. There's clear evidence for this. There's a particular CS-90 that I've used, which has the lowest voltage I've seen anywhere. I've been told it now always backs down 25%. My office charger is on the low side, and it backs down about half the time. I recently charged on a CS-90 with > 235 volts and it never backed down at all. So it's pretty clear there's a fixed threshold. Bad design.
Every location has a different nominal voltage. If it's three phase source it will be 208V +/- several volts. If it's two phase it will usually be in the range of 220V to 240V, but in my experience there's a lot more variation in this number.
The grid is a major source of voltage variation. I've observed it at my office - significant changes in a fairly short time period, and it clearly wasn't our load doing it because we don't really have that much (no car plugged in at the time).
You can't have fixed limits - it simply doesn't work. What it SHOULD do is record the nominal open circuit voltage when it first connects. It should then calculate a threshold voltage below that point, where it is going to trigger the back-off. Actually what it should really do is run the algorithm for 40A chargers only, because the hardware is far more robust in higher power charging stations. More to the point, if there's an issue with the UMC then there should be thermal cutout in the adapter.
Backing power down 25% increases the charging time by 33%. This is seriously impacting road charging, and will lead to people sitting for extra hours waiting for their cars to charge. I'd like to see this algorithm either fixed, or removed entirely and a more effective solution implemented.
Every location has a different nominal voltage. If it's three phase source it will be 208V +/- several volts. If it's two phase it will usually be in the range of 220V to 240V, but in my experience there's a lot more variation in this number.
The grid is a major source of voltage variation. I've observed it at my office - significant changes in a fairly short time period, and it clearly wasn't our load doing it because we don't really have that much (no car plugged in at the time).
You can't have fixed limits - it simply doesn't work. What it SHOULD do is record the nominal open circuit voltage when it first connects. It should then calculate a threshold voltage below that point, where it is going to trigger the back-off. Actually what it should really do is run the algorithm for 40A chargers only, because the hardware is far more robust in higher power charging stations. More to the point, if there's an issue with the UMC then there should be thermal cutout in the adapter.
Backing power down 25% increases the charging time by 33%. This is seriously impacting road charging, and will lead to people sitting for extra hours waiting for their cars to charge. I'd like to see this algorithm either fixed, or removed entirely and a more effective solution implemented.
Yipes! This stupid software update can now be the cause of a fire! What a bad bug. Please send an email to ownership telling them about this. This is not kosher. There are all sorts of reasons why someone would want to set the charge rate at a lower value, and then for the car to set it higher? Wow, that is seriously unsafe.
InTheShadows
Active Member
Actually the update is saving a fire in this situation. With the 50 amp plug the car could try to pull 40 amps on that circuit, the breaker should protect it. But, I have seen panels where someone, to avoid nuisance trips, goes to the local home improvement store and gets the next size breaker.
I disagree - travelinglites has an odd situation where he has a NEMA 14-50 plug, but only a 30A breaker. He tells that car to draw only 24A. But the software sees a voltage fluctuation and then INCREASES the charging current to 30A. If the software though it was bad at 24A, increasing it to 30A is really stupid and, in this case, a violation of a safety code (80% of breaker rating). No breaker will trip, but wires and breakers will get hotter than they should.
This BUG (there is no other way to describe it) also makes ALL HOMEMADE ADAPTERS DANGEROUS TO USE. Homemade adapters for a variety of plugs that Tesla does not support usually use Tesla's NEMA 14-50 adapter. So you might plug into a 20A 240V receptacle, dial it down to 16A and then the software bumps it up to 30A. Seriously bad behavior.
Well, today it charged at 240V @ 40A. But I had to dial it up myself from 30A to 40A. Yesterday, it didn't want to let me....
Please contact Tesla Motors directly, if you haven't already. They just might listen to you. This algorithm is unacceptable, prevents road trips, and I have been making a point of not "upgrading". The current algorithm wrecks charging at Sun Country Highway CS-90s, which invariably have a lot of variation in voltage, and are all just fine. 5.8.4 needs to be reverted.
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This is a good move. The firmware "bug introducing" update which can CAUSE fires by charging at too high an amperage was a bad move and hopefully will be reversed ASAP!
Otmar
EV Modder
Can you tell which happened first? I would guess that the voltage rise was due to the lower load after it tripped.
From what I've observed, I would think that the system is responding to fluctuations which happen quicker than what is displayed.
The other day I was charging at home during a wind storm, that was the only time I've had mine cut back. I wonder if trees on power lines in my neighborhood caused the cutback.
This is what I was going to say, except the first graph looks like voltage changed a while before? If you have a 'sensitive' handle or it is getting worn, then wind or anything that could jostle the handle will make it drop to 30A. Mine is really finicky now
The lost load accounts for only 1.0 to 1.2 V of the 2.9 V rise. The remaining 1.7 to 1.9 V rise occurred within 0.7 s of the trip. Either this rise triggered the trip, or it is a great coincidence that the utility voltage rose by 1.7 to 1.9 V <0.7 s after the charger tripped, the largest voltage rise during the charge.
Do you know what your sample rate is? I expect that Tesla is watching things in the 1-5 us range or so to detect frequencies in the 10-125kHz range.
Peter
Peter
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Power = 0.5 Hz, voltage = 1.5 Hz.
I suppose, if they have direct access to the ADC in software. I doubt this is a use case they anticipated during hardware design.
Brass Guy
Active Member
Mine has dropped to 30A on a few occasions in my garage. Maybe once/week avg. The only message I've seen is the check cable message, no extension cord message.
NEMA 14-50, #6 CU, about 80' run
244V no-load
234V after ramping to 40A
232V 10 min. into charge
I have only unplugged the UMC from the wall 2x in the 4 months I've had the car, so it should not be wearing out.
The only part of the system that seems to warm up at all is the 1[SUP]st[/SUP] 1' section of the UMC cable, which I'm told is "normal."
Twice last week I heard a high pitch buzzing when charge started, definitely from the controller on the UMC. The 1[SUP]st[/SUP] time I thumped it with the heel of my hand (like everybody does to a buzzing device) and it red lighted. The second time I called Tesla while it was doing it and they said it's charging at 40A, but I already knew that.
Tesla is still looking at my logs.
BTW the warrantee for the UMC is 12 months.
Agree it's too sensitive. I sure hope Tesla does something about this last revision soon, especially if the fault can cause an increase to 30A - unacceptable.
NEMA 14-50, #6 CU, about 80' run
244V no-load
234V after ramping to 40A
232V 10 min. into charge
I have only unplugged the UMC from the wall 2x in the 4 months I've had the car, so it should not be wearing out.
The only part of the system that seems to warm up at all is the 1[SUP]st[/SUP] 1' section of the UMC cable, which I'm told is "normal."
Twice last week I heard a high pitch buzzing when charge started, definitely from the controller on the UMC. The 1[SUP]st[/SUP] time I thumped it with the heel of my hand (like everybody does to a buzzing device) and it red lighted. The second time I called Tesla while it was doing it and they said it's charging at 40A, but I already knew that.
Tesla is still looking at my logs.
BTW the warrantee for the UMC is 12 months.
Agree it's too sensitive. I sure hope Tesla does something about this last revision soon, especially if the fault can cause an increase to 30A - unacceptable.
mnx
2018 M3P
I had my charge rate reduced from 40A to 30A once so far. The power in our neighborhood had been out for ~3 days. Once the power came back on I initiated a charge. Sometime during that charge it dropped the rate. I'm guessing the neighborhood load was a lot higher than normal etc. and caused a false positive.
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