Return of phantom 16 amp charging

[rotor2k]

Maybe this is a "better" handling of the voltage fluctuations? The charger isn't happy with the voltage change, drops back down to "recalibrate" and then resumes at 32A rather than dropping permanently to 16A? All wild conjecture.

For the record I have *never* once had a 16A charge, so I suspect those who have that problem have it because of a local power issue that the M3 circuitry hasn't historically handled particularly well. Would be interesting to see if there's such a thing as a "Power Supply health logger" device that can be attached to the house's supply for a few weeks.

 

[Roy W.]

You could well be right, but I believe the voltage fluctuations are caused by the current falling and rising, not vice versa. I’ve always seen a similar voltage drop on my setup.

 

[rotor2k]

You could well be right, but I believe the voltage fluctuations are caused by the current falling and rising, not vice versa. I’ve always seen a similar voltage drop on my setup.

Wait, but the M3 has control over the current, it has no control over the voltage, right? So if the voltage fluctuates as a result of the current being pulled, that's not the M3's fault.

 

[Roy W.]

Wait, but the M3 has control over the current, it has no control over the voltage, right? So if the voltage fluctuates as a result of the current being pulled, that's not the M3's fault.

You’re right, but I didn’t mean it was the M3’s fault. When you’re pulling a heavy load it’s normal for the supply voltage to drop locally. My point is that I’ve always seen this sort of voltage drop on my setup when pulling 32A, for the five years that I’ve had an EV charger installed. The voltage stays well within the U.K. specs of 230V +10% / -6%, which is 216.2 to 253 volts. Therefore it shouldn’t trouble the car.

 

[rotor2k]

You’re right, but I didn’t mean it was the M3’s fault. When you’re pulling a heavy load it’s normal for the supply voltage to drop locally. My point is that I’ve always seen this sort of voltage drop on my setup when pulling 32A, for the five years that I’ve had an EV charger installed. The voltage stays well within the U.K. specs of 230V +10% / -6%, which is 216.2 to 253 volts. Therefore it shouldn’t trouble the car.

Ah OK, so you *have* been able to measure the nominal drop. The question then is: for any of the 16A "incidents" (or the hiccoughs seen above with 2020.28), can you see what the voltage was doing at the time? Because that is what I'm suspecting is the issue. i.e. nothing to do with the voltage drop caused by the 32A draw.

 

[Adopado]

Maybe this is a "better" handling of the voltage fluctuations? The charger isn't happy with the voltage change, drops back down to "recalibrate" and then resumes at 32A rather than dropping permanently to 16A? All wild conjecture.

When I spoke with an engineer about the issue before this latest software update they had analysed an example charge. I asked if it could be related to voltage drop at my location (being in the country and there being a long run from house to garage). He could easily have taken some pressure off Tesla's liability for the dropped charge rate by agreeing that his may play it's part ... but he didn't ... in fact he said that the voltage from the grid had been fine throughout the charge. I see lowered voltages during charges but they remain within the UK grid specification (ranges from 224 down to as low as 219 within a charge period from my observations). Not running Teslafi or Teslamate I do not have access to data tracking the voltage throughout the charge period so this is only from spot checks on the app or in the car.

 

[rotor2k]

You’re right, but I didn’t mean it was the M3’s fault. When you’re pulling a heavy load it’s normal for the supply voltage to drop locally. My point is that I’ve always seen this sort of voltage drop on my setup when pulling 32A, for the five years that I’ve had an EV charger installed. The voltage stays well within the U.K. specs of 230V +10% / -6%, which is 216.2 to 253 volts. Therefore it shouldn’t trouble the car.

My apologies, after seeing Adopado’s comment I went and checked and sure enough TeslaMate shows the voltage as well!

So if it isn’t the voltage, what else could it be?

 

[Roy W.]

So if it isn’t the voltage, what else could it be?

Another charging bug introduced with a software update? We’ve already had two charging bugs introduced with updates in the past 12 months!

 

[rotor2k]

Found a recent one with a current reset, and sure enough the voltage wobbles as well. Is the voltage wobble caused by the current resetting to 0? Or does the voltage wobble cause the current reset? Note this (and the screenshot in my previous post) were on 2020.24.6.9.

The charge in my previous post also has a current reset, with a smaller voltage wobble.

 

[rotor2k]

Another charging bug introduced with a software update? We’ve already had two charging bugs introduced with updates in the past 12 months!

Based on my own experience of 9 months charging at home and not having a single 16A session, the bug would seem to be triggered by external factors. So I guess the bug fix is “make the charging logic less sensitive to whatever that external factor is”.

Or there’s a known “bad” component in some of the cars, and the bug fix makes it more tolerant to wonkiness in that part?

 

[Adopado]

So if it isn’t the voltage, what else could it be?

The engineer who spoke to me said that the (previous) problem was related to how one of the 3 phases of the car's internal charger was behaving (depending on software control). Am I right in saying that the car charger has 3x 16amp chargers, with our normal single phase grid being split between 2 for the 32amps, and for 3 phase grid all 3 are in use for 48amp/11kW? I have to say that before the latest update I had a couple of unaffected charges despite the bug being present ... maybe the car just chose the right phases to use in its internal charger.

 

[NewbieT]

My car rarely did the 16A drop. I’m about a mile from a very big substation/pylons and so guess its a reasonable supply. The couple of times it did happen was correlated with plunge pricing or v. cheap rates. Possibly the grid less stable due to all these wind turbines and EVs charging on and off?

My guess is spikes or drops in voltage or frequency. The sampling from TeslaFi is unlikely to be high enough resolution to pick up anomalies - need better monitoring equipment to draw conclusions.

 

[NewbieT]

The engineer who spoke to me said that the (previous) problem was related to how one of the 3 phases of the car's internal charger was behaving (depending on software control). Am I right in saying that the car charger has 3x 16amp chargers, with our normal single phase grid being split between 2 for the 32amps, and for 3 phase grid all 3 are in use for 48amp/11kW? I have to say that before the latest update I had a couple of unaffected charges despite the bug being present ... maybe the car just chose the right phases to use in its internal charger.

That’s basically my understanding.

 

[MidhurstNigel]

The couple of times it did happen was correlated with plunge pricing or v. cheap rates

If this were the problem you would expect regular issues at 0030 when Octopus Go cuts in - the bang to the grid then must be much higher then than when price plunges hit. Here's my last night charge:

In case you can't see the details charging started at 0030 and the drop happened at 01:34. I would expect the voltage spike is because of the reduced charge rate - we are fairly close (maybe 500m) from a substation with newish underground cabling but our Ze (the external resistance of the supply circiut) is still enough to drop the incoming voltageby maybe 5 volts for each 16A drawn, so a drop of charging current from 32A to 16A would produce a 5V increase in voltage. Maybe it was some abnormality in supply voltage that upset the charge controller, but note from the green line the voltage does fluctuate all the time and it doesn't normally upset the charger. Also, nobody has reported more than one drop in any charging session which you might expect if the charger is reacting to some external problem? HeyHo, at least the average charge current is now back to something usable.

 

[Flatchat]

I had my first charge last night since updating to 2020.28 and although it charged at 32A it did have a quick drop down to 16A but then auto-corrected itself.

 

[Adopado]

I had my first charge last night since updating to 2020.28 and although it charged at 32A it did have a quick drop down to 16A but then auto-corrected itself.

Yes, I also have the impression that there seems to be some auto correction going on rather than a full solution to the inconsistent charging.

 

[Jason71]

Yes, I also have the impression that there seems to be some auto correction going on rather than a full solution to the inconsistent charging.

The car has always had a mechanism to drop the current if it detected unspecified anomalies in the charging session ( it's in the manual). And actually the idea that it drops to 16amp if it detects an issue but then returns to 32 if the problem goes away seems perfectly reasonable to me. What was not reasonable was leaving it there for the rest of the session. So this may not be a workaround. This may be the new normal. So long it isn't overly sensitive and repeatedly drops the current then shouldn't this be OK?

 

[MidhurstNigel]

I had my first charge last night since updating to 2020.28 and although it charged at 32A it did have a quick drop down to 16A but then auto-corrected itself.

Interesting that both M3DM and I had an 'incident' at 01:34 or thereabouts. Anyone else who did a charge last night have an issue at the same time? Also, does anyone on Agile know if this was a price plunge moment?

 

[NewbieT]

No, not a price plunge.

 

[Staypuffman]

Just noticed my charge is at 16 amp max.

Why is this? Charged at 32 before.