View Poll Results: Have you expeienced charge current limiting?

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  • No, I have not encountered this.

    97 59.51%
  • Yes, my home charger has tripped this warning falsely

    52 31.90%
  • Yes, my home charger has rightly tripped this warning

    3 1.84%
  • Yes, a public charger has tripped this warning falsely

    10 6.13%
  • Yes, a public charger has rightly tripped this warning

    1 0.61%
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Thread: False Positives With FW 5.8.4 Charge Current Reduction?

  1. #81
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    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.

  2. #82
    Senior Member Vger's Avatar
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    Quote Originally Posted by efusco View Post
    I answered yes and tripped falsely...but how the heck would I know if it was false or not? AFAIK the connection is good...it's actually a 6' run from the breaker on appropriate gauge wire and a brand new connection and the voltage seems stable and I've had no past issues on this particular NEMA 14-50, but there's no way I can know if there were voltage variations.
    I am in the same boat.

    - - - Updated - - -

    Quote Originally Posted by travelinglites View Post
    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.
    Wow, that is definitely not right! Just the kind of bug that gets introduced by a rushed f/w update!

    - - - Updated - - -

    I wish Tesla would tell us explicitly what the algorithm is!
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  3. #83
    Senior Member Theshadows's Avatar
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    Quote Originally Posted by travelinglites View Post
    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.
    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.
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  4. #84
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    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.
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  5. #85
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    Quote Originally Posted by Doug_G View Post
    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.
    I could not agree more!

  6. #86
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    Quote Originally Posted by travelinglites View Post
    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.
    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.

  7. #87
    Senior Member Theshadows's Avatar
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    Quote Originally Posted by Cosmacelf View Post
    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.
    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.
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  8. #88
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    Quote Originally Posted by Theshadows View Post
    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.

  9. #89
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    Quote Originally Posted by pbrulott View Post
    First false positive at my house today. This crazyness times a thousand.

    I'm doing some tests these days after what happened to me on a road trip. So I purchased a 110V extension cord yesterday (gage 12). Wanted to try it at home on the usual 110 outlet I use when charging at 110V. Worked perfectly for the test i.e. 30 min @ 6km/h => 1.4 kWh, no reduction. I had charged in the morning at 47 km/h on my NEMA 14-50 outlet + a 50 feet 240V extension cord (240V, 40A). Again no issue. I go for a ride.

    Come back and plug again, this time, directly with the UMC (no extension). Decide to clean the interior, screen cleaning button and then after that I see the warning "charging problem", "check your cable".... @ 30A vs 40A.

    Insane, unstable, I want the new cable and this reduction feature off

    First time this happens to me at home. It happened to me on remote locations though.

    PB
    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....
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  10. #90
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    Quote Originally Posted by Doug_G View Post
    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.
    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.

    - - - Updated - - -

    Quote Originally Posted by laalan View Post
    Tesla announced we will receive new wall charger adapters with a thermal fuse in two weeks.
    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!
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