32 Amp Single Phase UMC Charging - Current Dropping

[Keydien]

I recently had a 32amp single phase socket installed and purchased a 32amp tail for my Tesla UMC charger. The socket is wired directly into a dedicated circuit with its own RCBO.

It's been working great - part from the fact that if the current is set to 32a - then it drops down to 16a after about 15 minutes. If I set the current to 22a - then it either stays there or drops down to 16a after 30-40 minutes.

No messages in the car about why the car is dropping the current.

I've checked all plugs, wiring etc for damage. No damage, nothing overheating or even getting warm. The RCBO doesn't trip.

Not sure what's going on honestly. Anyone have experience with such a thing?

 

[cafz]

It is likely detecting excessive voltage drop, indicating too much resistance in the circuit. If you check the notification log under the Service menu there may be a message logged in there.

Do you know how long the cable run to the socket is, and what spec cable was used?

 

[Zoltrix77]

I recently had a 32amp single phase socket installed and purchased a 32amp tail for my Tesla UMC charger. The socket is wired directly into a dedicated circuit with its own RCBO.

It's been working great - part from the fact that if the current is set to 32a - then it drops down to 16a after about 15 minutes. If I set the current to 22a - then it either stays there or drops down to 16a after 30-40 minutes.

No messages in the car about why the car is dropping the current.

I've checked all plugs, wiring etc for damage. No damage, nothing overheating or even getting warm. The RCBO doesn't trip.

Not sure what's going on honestly. Anyone have experience with such a thing?

What is the voltage reading on the Tesla screen when its actually at 32A? As a guess I would say its a voltage drop issue.

 

[cafz]

What is the voltage reading on the Tesla screen when its actually at 32A? As a guess I would say its a voltage drop issue.

More importantly, what's the difference between that voltage and the no-load voltage before it ramps up the charging current.

 

[PC__LoadLetter]

Is it overheating? Is the T on the Tesla logo on the UMC flashing red? Does the issue occur if you borrow someone else's UMC?

 

[OzTzlaBloke]

Exactly cafz. Causes can be multiple - another cause can be the 32A is contended amongst other loads.

Service mods logs or it didnt happen

 

[Keydien]

More importantly, what's the difference between that voltage and the no-load voltage before it ramps up the charging current.

Voltage drops from around 234v no load down to 222v under load at 32a.

Total cable length (including an estimate for in-wall cabling from the switchboard to the socket) is around 16m.

Cabling has been done with 6mm cabling. Using an online voltage drop calculator, it gives a theoretical voltage drop of around 4v just from the resistance of the cable, but I'm seeing 12v of drop. Not sure if that's indicative of an issue or not.

I've triggered it to happen again and then went into service mode to get some information. It's flagged alert 'UMC_a017', which is saying that the wall plug temperature is high. I've checked all plugs and sockets and everything is cool to the touch - so the temperature is definitely not high.

I'm wondering if it could be an issue with the temperature sensor inside of the UMC 32a tail that I purchased mis-reading?

 

[OzTzlaBloke]

Cabling has been done with 6mm cabling. Using an online voltage drop calculator, it gives a theoretical voltage drop of around 4v just from the resistance of the cable, but I'm seeing 12v of drop. Not sure if that's indicative of an issue or not.

That length cable run would be compliant on 4mm, 6mm is good. About the same as mine. Rule that out.

Look for any dry joints loose joints etc in the industrial socket / fuse box / tail being fully inserted into UMC etcetc Suspect something amiss here

Remember too, that expected 4V drop is just cable run. Youll drop on the industrial socket the tail the UMC the type 2 plug the charge port the charge able to the penthouse the penthouse socket to the actual board running all the PCS systems. In my situation its about another 4 volts there.

On my suspicion your about 4V down on what I measure. Probably a bad joint somewhere. The other possibility is you have contended loads. I would momentarily turn off all the other circuits in the fuse box and do an experiment where that dedicated 32A circuit is only active and measure up everything then. If that ends up being the issue well clearly were talking about loads overall then at the resdence and it being contended.

 

[Borgy]

your tail is in the shade? I’ve had the amperage drop because the plug was in the sun

 

[Quickst]

Voltage drops from around 234v no load down to 222v under load at 32a.

And what's the charging Voltage when it derates to 16A?

Have you found a charging rate where it does not derate?

 

[Keydien]

That length cable run would be compliant on 4mm, 6mm is good. About the same as mine. Rule that out.

Look for any dry joints loose joints etc in the industrial socket / fuse box / tail being fully inserted into UMC etcetc Suspect something amiss here

Remember too, that expected 4V drop is just cable run. Youll drop on the industrial socket the tail the UMC the type 2 plug the charge port the charge able to the penthouse the penthouse socket to the actual board running all the PCS systems. In my situation its about another 4 volts there.

On my suspicion your about 4V down on what I measure. Probably a bad joint somewhere. The other possibility is you have contended loads. I would momentarily turn off all the other circuits in the fuse box and do an experiment where that dedicated 32A circuit is only active and measure up everything then. If that ends up being the issue well clearly were talking about loads overall then at the resdence and it being contended.

Thanks for the info.

So I believe I've identified the issue.

I bought one of these for my UMC tail: Tesla Gen2 Mobile Connector Adaptor - EVchargers - EV cables and adaptors

On that page - they say the following:

"This adaptor has an internal circuit that monitors the plug temperature and communicates with the car when to initiate the charging session. NOTE: the chip monitors temperature and quality of the current – some owners have reported reduced charging power at some 32A locations. This is due to the wiring and how the chip is managing the incoming current to safe levels."

Out of interest, I opened the tail at the temperature sensor location which was inside an outdoor rated cable cover like the one in this photo: https://evchargers.com.au/wp-content/uploads/2022/08/gen2-Adaptor.jpg

It was apparent that the producer of the tail had spliced a shorter tail to a longer run of cable to produce the 3m tail I purchased. The individual wires appeared to be connected together with spade connectors and heatshrinked (possibly also soldered - I didn't check). But encased and buried in the middle of all of this heatshrinked bundle of wires was a small temperature sensor.

At this point I thought - 'what the hell', and cut out that entire section. I spliced each of the wires back together directly with solder, heatshrink and electrical tape rather than using spade connectors. Once joined, I bundled the wires together, electrical tape and then heatshrinked over them. I then layed the temperature sensor on top of that, electrical taped and heatshrinked over it to ensure everything was together, covered and the temperature sensor was still close to the wires themselves.

Tested my modified tail - working perfectly. No current drop. Happily charges at 32a (tested for over 90 minutes) and the cable, connector and plugs all remain only slightly warm to the touch.

This (combined with the note on the sellers website) leads me to believe either that the temperature sensor is faulty, or, that the way in which they themselves create the extended tails is problematic and causing customers issues.

 

[OzTzlaBloke]

Mate Im a big fan of Jason and the crew @ EVchargers. Im pretty shocked one slipped through their testing process before being mailed out Ive discussed this with Jason before making my purchase decisions with them. Ive bought al my gear in this area which is substantial from them. Im pleased ya fixed it but Id encouragre hooking into Jason and helping them understand where they went wrong. Im sure hed help you out as customer they stand by their warranty hard core.

PS: No affiliation or anything - I pretty much nailed Jason hard in me trying to identify a suitable group who was reliable to meet my needs and they survived my interrogations I do allot of remote military work and reliability/testing/qa is a huge factor in my work travels in the car when its business use. No one to come help and often no cell coverage either, sat phone only.

 

[Quickst]

It was apparent that the producer of the tail had spliced a shorter tail to a longer run of cable to produce the 3m tail I purchased

It sounds a bit dodgy....
If Im buying a charging cable I would prefer an end to end cable with no splicing.

 

[Raph_]

What RCBO are you guys running with your 32amp socket? 32A OR 40A? And is it a type A or type B RCBO?

 

[sishome]

What RCBO are you guys running with your 32amp socket? 32A OR 40A? And is it a type A or type B RCBO?

I had this discussion recently with an electrician. Essentially, IEC62955 applies only to Mode 3 charging, which is necessarily a dedicated, fixed, hardwired charging station. If you have UMC, (1) you rather obviously cannot demand from every power point in the park or by the pub you usually go to have RCBO type B; (2) you have Mode 2 charging, for which EIC62955 does not apply. Therefore, you don't need Type B RCBO for a 3-pin 32A single phase power point to use it with UMC, Type A is sufficient. The electrician confirmed that it would be unrealistic to demand Type B RCBOs from every power point UMC is plugged in.
I mean, you can install Type B, of course, but it costs just a tad less than a medium-sized spaceship.
Mode 3 charging is a different business, but as I understand, Tesla chargers nowadays have the necessary level of protection.

 

[Raph_]

I had this discussion recently with an electrician. Essentially, IEC62955 applies only to Mode 3 charging, which is necessarily a dedicated, fixed, hardwired charging station. If you have UMC, (1) you rather obviously cannot demand from every power point in the park or by the pub you usually go to have RCBO type B; (2) you have Mode 2 charging, for which EIC62955 does not apply. Therefore, you don't need Type B RCBO for a 3-pin 32A single phase power point to use it with UMC, Type A is sufficient. The electrician confirmed that it would be unrealistic to demand Type B RCBOs from every power point UMC is plugged in.
I mean, you can install Type B, of course, but it costs just a tad less than a medium-sized spaceship.
Mode 3 charging is a different business, but as I understand, Tesla chargers nowadays have the necessary level of protection.

Thanks for the info mate.

Would you also say that a 40amp RCBO is better than a 32amp?
I can't imagine running a constant 32amp line with a 32a RCBO is good. Essentially running it at 100%.

 

[cafz]

What RCBO are you guys running with your 32amp socket? 32A OR 40A? And is it a type A or type B RCBO?

Mine (at the holiday house) is a 32A Type A.

Mode 3 charging is a different business, but as I understand, Tesla chargers nowadays have the necessary level of protection.

The UMC has always had built-in DC fault protection, too.

 

[sishome]

Thanks for the info mate.

Would you also say that a 40amp RCBO is better than a 32amp?
I can't imagine running a constant 32amp line with a 32a RCBO is good. Essentially running it at 100%.

Does the wiring allow using 40A RCBO? If not, never use 40A

 

[Raph_]

Mine (at the holiday house) is a 32A Type A.

The UMC has always had built-in DC fault protection, too.

Great to hear. Cheers for that.

Does the wiring allow using 40A RCBO? If not, never use 40A

I'm going to say it probably won't allow a 40a RCBO thinking about it.
Its a 6mm2 cable, and cable length is max 15 meters if that, and that's being very generous.
If I want a 40a RBCO I would probably say that I'd need to upgrade the cable to 10mm2 (correct me if I'm wrong).

 

[Rolond]

How is the cable run, in conduit, in the wall, surface mounted?