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NEMA 14-50 Supply cable heat data

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daveo4EV

daveo4EV

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the temperature range on the cable is the “environmental“ temperature range - the cable is rated to operate properly from -30C to +70C - I was similarily confused, until I recognized that the cable would never be -30C as a target temperature for it’s operation.

this cable is rated to work outside in alaska during the winter :clap:
 

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I'd expect stuff to get pretty toasty at 40A. I don't think I'd be too worried about stuff under 100C.
75C (~165F) makes me a lot more comfortable - safety margin is a good thing.
 

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So I checked my charger after just over 2 hours of charge this evening. The 14-50 plug on the Porsche power whip (the supply to the PMCC) was 134.9F! The power whip itself was 119F. Even the box containing the 14-50 receptacle was around 135F. I had the electrician who installed the setup for me come check it (he does commercial grade electrical work in data centers and major office buildings so he actually DOES know what he is doing). He did say that a continuous draw of 39+ amps (39.6 actually) will generate a lot of heat. Still........

My car is going to the dealer on Tuesday for the WLG2 update. I have been in touch with the local Porsche FTM and I think he will be there on Tuesday to check it out. He did suggest bringing the PMCC in as well to see if any data can be pulled from it.

Good thing a working EA station is within 15 miles of my house. I'll be charging there until this gets resolved!

Toby
I just got my car and PMCC back from the dealer yesterday looking at this same issue as I previously posted. Keep in mind that if the dealership doesn't have a 14-50 outlet installed, they won't be able to do a similar comparison to your home setup or pull data from the charger unless they have another adapter cable to be able to plug in. My dealer did not, but to their credit, they brought their electrician in to install one so they could try to do the comparison and testing. They are able to pull certain charging session data from the car.
 

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Generally, I would agree. Only immediate issue I see is that the power whip for the PMCC shows a valid temperature range on its disclosure tag of a max of 122F. 139.4F is quite a bit outside of that range.
That’s the ambient operation temperature range, not the cable temperature range.
 

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I do not think there is much difference in energy loss when charging at 30A vs. 40A. Since I only use a tiny fraction of the battery (charging is done is few hours anyway), I did limit the charging current to 30A on the mobile charger. As nicely shown by @HelfFL , this reduces the temp quite a bit.
 

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I do not think there is much difference in energy loss when charging at 30A vs. 40A. Since I only use a tiny fraction of the battery (charging is done is few hours anyway), I did limit the charging current to 30A on the mobile charger. As nicely shown by @HelfFL , this reduces the temp quite a bit.
Pump the amps back up in winter, built-in garage heater!
 

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I think the NEMA 14-50 cable is getting too hot - probably due to inappropriate wire gauge - the label says rated for 16 amps - and thickness is appropriate for 16 amps - I'm betting they didn't do the proper gauge for North America, and instead are working European standards - 3 phase 16 amp rated wire - but what do I know.
Finally, the suspected heat culprit in the Porsche Mobile Charge Connect (PMCC) has been confirmed. The 14-50 input supply cable (photo below) is 10AWG (American Wire Gauge), the normal US electrical code size for a 30 amp circuit, not a 50 amp circuit. However, this cable is rated for 105C, much higher than most cables, and is a component of a system, not part of an external electrical circuit - different rules apply. The same cable is used on the 6-30 input supply cable in my possession. A #10-gauge wire can conduct 40 amps, but it will heat to ~90C (194F) at 20C (68F) ambient.

Both the 50 and 30 amp PMCC input supply cables have a tag with a 16A maximum rating, and the input connector to the charger is labeled 24A. 24 amps is the US code maximum continuous current for a 30 amp circuit (80% of 30A), not a 50 amp circuit. Why the system allows 40 amps with a 24A rating is unclear - most likely safe but uncomfortable and not recommended by me. The heat rise in an enclosure has caused some chargers to shut down - a good thing.

The original length of the input supply cable was 900 mm (3 ft.) but it has been replaced with a 300 mm (1 ft.) length. Porsche may have reduced the cable length to reduce the radiated heat:

Heat from Porsche Mobile Charge Connect Supply Cable – 10 Gauge
Current
300 mm (1 ft.)
900 mm (3 ft.)
40A
4.2 watts​
15 watts​
30A
2.3 watts​
7 watts​
24A
1.5 watt​
4.5 watts​

Bottom line: Strongly consider limiting your PMCC charge current to 30 amps and consider 24 amps. If your time schedule requires a 40 amp charge current, keep the supply cable well-ventilated and preferably, attended. Be safe.

Porsche_14-50_Supply_Cable.jpg
 

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Finally, the suspected heat culprit in the Porsche Mobile Charge Connect (PMCC) has been confirmed. The 14-50 input supply cable (photo below) is 10AWG (American Wire Gauge), the normal US electrical code size for a 30 amp circuit, not a 50 amp circuit. However, this cable is rated for 105C, much higher than most cables, and is a component of a system, not part of an external electrical circuit - different rules apply. The same cable is used on the 6-30 input supply cable in my possession. A #10-gauge wire can conduct 40 amps, but it will heat to ~90C (194F) at 20C (68F) ambient.

Both the 50 and 30 amp PMCC input supply cables have a tag with a 16A maximum rating, and the input connector to the charger is labeled 24A. 24 amps is the US code maximum continuous current for a 30 amp circuit (80% of 30A), not a 50 amp circuit. Why the system allows 40 amps with a 24A rating is unclear - most likely safe but uncomfortable and not recommended by me. The heat rise in an enclosure has caused some chargers to shut down - a good thing.

The original length of the input supply cable was 900 mm (3 ft.) but it has been replaced with a 300 mm (1 ft.) length. Porsche may have reduced the cable length to reduce the radiated heat:

Heat from Porsche Mobile Charge Connect Supply Cable – 10 Gauge
Current
300 mm (1 ft.)
900 mm (3 ft.)
40A
4.2 watts​
15 watts​
30A
2.3 watts​
7 watts​
24A
1.5 watt​
4.5 watts​

Bottom line: Strongly consider limiting your PMCC charge current to 30 amps and consider 24 amps. If your time schedule requires a 40 amp charge current, keep the supply cable well-ventilated and preferably, attended. Be safe.

Porsche_14-50_Supply_Cable.jpg
Thanks for this info. The question is will Porsche recognize and acknowledge they screwed up? And, replace the 30A supply cable with the correct one? I think I know what the answer is, unfortunately.
 
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this is simply unacceptable and should be addressed - Porsche should ship an appropriate gauge cable for a 40 amp charger.
 

evanevery

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... the only difference is the 4th wire for the NEMA 14-50 which is _NOT_ used by any EVSE...
I don't believe that is correct. If you look at most plug in EV chargers, you will find that almost all of them have a 4 pin plug. (Search Amazon) It was very hard to find one that only had a "3-Pin" plug as I wanted one that could be used with a simple adapter on a 4-pin circuit. In other words, I wanted a 3-Pin plug so I could ALSO use it with a 4-pin socket. (You can go 3->4 but you can't go the other way). The only one I found that had a 3-pin 220V plug was a 40A level 2 charger by Mustart.

I guess you could claim that the 4th pin on all those other chargers in simply not being used but I think that would be pretty reckless without actually disassembling them. There are lots of reasons that the 4th wire (Neutral) could be used by those chargers, not the least of which would be to provide a 120V feed for subsystem circuits.
 

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The extra pin on the 14-50 is for a neutral wire, so you can get 120V out of the socket too. EVSEs don't use it. My EVSE came with a 6-50 plug. It's a ChargePoint 32A charger.

To go from 14-50 to 6-50 an adapter just drops the neutral wire, which means you get 240V only.
 
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what @Miwa said - any EV charger that support either 14-50 or 6-50 plug adapters (Tesla, Mustart, Porsche, and others) or 14-30 and 10-30 or 6-30 - again a lot of EVSE‘s - don’t use the neutral.
 

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Thanks for this thread @daveo4EV and detailed posts by folks like @wmras. I also sent this off to my Porsche contact. I would suspect that there should be replacement NEMA 14-50 cables being sent to dealerships I hope soon. Till then I agree with others, just set max charging current to 24 or max 30amps. That's what I would do.
 

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Would anyone know the correct part # for the proper correct 14-50 plug supply cable that's specific to the 40A?
 

Toby Pennycuff

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KenU,

The part number for the "power whip" that connects the PMCC to a 40-Amp power supply is 7PP-971-678-ED. In Porsche "parlance" the part is called "Charge cable for mains socket".

Be aware that this supply cable is built from 10AWG wiring, which many here in this thread (me included) are questioning.

Toby
 

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