Warm is not necessarily abnormal, but of course there is a sliding scale of what is indicative of something going amiss.

Up to 'body temperature' (for typical humans) is OK. If it feels 'feverish' then maybe look more deeply, but doesn't sound like that is the issue.

Feel and stroke the cable to check for any 'knots' and kinks in the cores within the cable. If it feels twisted and gnarly inside then there could be an issue (which will be from unsympathetic twisting and coiling).

 

I know the cables can get warm as they have 30A through them for hours so not unusual for the plug to be the same.

 

Was it exposed to direct sun?

 

No, charging late evening

 

I assume you mean the plug at the car as it is a Rolec... just confirming

I assume it is an untethered cable if you are charging cars with different types of plug? If it is do you have another cable you could try? Could you borrow one perhaps?

I have never noticed a plug to the car get warm. It could be a connection getting loose in the plug. If it were me I'd get the cable checked out. I am no electrician but I would have thought that you would be checking for loose or bad connections. Perhaps remove the plug and check out the connectors where the cable connects to the plug then remake the connections so they are sound. Not sure I'd want to tinker with the plug like that though myself.

 

I assume it is an untethered cable if you are charging cars with different types of plug? If it is do you have another cable you could try? Could you borrow one perhaps?

It’s mentioned in the OP that the cable was replaced for a 10m one, so I’m assuming it’s tethered?

@natalie, I’d try charging one of your own cars in the evening and see what temp the handle gets to?

Presumably your own cars don’t have failed charges normally when they’re charged overnight either?

Just a hunch, but if your own cars continue to charge fine, then maybe it’s the visiting Tesla that has a problem.

I’ve had a very reliable VW granny charger for a few years, it gets used on those rare occasions when both our cars need some charge overnight. I used it on our Tesla and it faulted out a couple of times, but still works fine on the VW.

This post has reminded me that I need to send the Tesla EVSE back actually, that stopped working a couple of months back with an overheat flashing symbol, that won’t charge either car now.

 

Warm is ñormal, hot is not.

 

Consider that 6mm^2 has a resistance of around 3mOhm/m, so a 10m cable has 20m of that, so 0.06Ohm.

At 32A, I^2.R = 61W.

Resistance from the contacts in the plugs will be similar. Probably around 100W total is being lost as heat.

Now stick a loosely coiled cable directly under a 100W halogen/"old-fashioned" filament spotlight bulb that is set to shine its entire spot directly on it. How warm do you think it would get?

That is how hot you should expect it to be. Not cold, not super hot.

 

The contact resistance of an IEC62196-2 Type 2 plug or socket is way, way lower than the resistance of 10m of 6mm² cable. The IEC62196-2 Type 2 connector is rated to handle up to 70 A single phase, 63 A three phase with a contact resistance of 0.5mΩ maximum per contact, so just 1.66% of the loop resistance of 10m of cable. Consequently, the heat generated by 32 A flowing through the Type 2 connector will be less than 1.3 W, nowhere near enough to make a connector warm up to any noticeable degree.

I have now seen three Rolec cable failures, though. All three showed signs of the cores twisting internally, as the crappy cable Rolec uses seems to have an extremely soft sheath, one that is not well moulded to the internal conductors, so they seem free to move and twist internally. All three failed cables I've seen had broken control pilot conductors near the end of the cables. There were also signs of early failure of the power conductors as well, though, with broken strands visible when I cut the cables open to check. It seems possible that this may be a cause of localised heating, perhaps.

Another cause might be if anyone has tried to use some sort of contact cleaning spray on the connectors. I once spent half a day fixing a Leaf and it's associated charge point connector where a well-meaning, but misguided, chap had thought using contact cleaner was a good idea (it isn't). He was getting failed charges, not sure about overheating as he only charged at night, but bad contacts in the connector turned out to be the cause. What happened was that the area behind the thin leaf contacts in the free socket (at the end of the cable) and the area at the base of the fixed plug in the car, got clogged with dust that had stuck in place hard due to the residue left by the contact cleaner. Devil of a job to get both connectors clean, and needed the connector and loom to be stripped out of the car just to get it hung upside down to wash it out properly. With hindsight, replacing the connectors with new ones would have been a lot less work.

Easy to check the cause, though. Any electrician that has a charge point tester can quickly plug that in, initiate a dummy charge and measure the loop impedance at the tester. If that is high, then further investigation is needed, as that indicates a charge point side problem. Easy to then whip the cover off the Rolec and check the resistance of the cable, including the connector, again using the charge point tester. If there is enough of a resistance to cause the connector to heat up then that should easily show up when the end to end cable resistances are measured.

 

I'd turn down the charge speed on the Tesla by a few amps to see if that helps. It takes the full 7.4kWh when it's set to 32 amp like the Zoe does and with most of them having a much bigger battery they can make more heat.

I'd also check the charge plug and the charge port for crud as a poor connection won't help either.

How hot is hot? If it's comfortable to hold then it's likely fine. If it's a bit uncomfortable then that's too hot. A 10m lead is longer than normal so that might not help.

 

So this morning we reduced the power being drawn by the Tesla using the app and it seems to be charging okay. Hasn’t stopped yet…

After an hour the plug is definitely warm right around the part shielding the contacts. Not too hot too touch or grab, but definitely what I would describe as hot.

The cable isn’t hot. It’s tethered, not coiled, no kinks. Not driven on.

The Tesla definitely draws more power than the Leaf. My home energy usage when charging the Tesla is about 8kw vs 7kw for the Leaf.

 

8kW is pushing 35 amps, so that extra 4 or 5 amps is probably making all the difference for getting the cable hot. Warm is certainly normal after several hours of charging, but I wonder if 8kW is pushing the limit a bit, and causing issues with the charger in the Tesla not being happy and stopping.

 

I keep mine at 28 amp. I also have a geriatric rolec but it's a socketed one and I have a 3 phase lead that's about 5m long.

Normally if it's too hot the Tesla will reduce the charge speed down automatically. If it's not doing that then it's probably not hot enough to be an issue.

 

Is the 10mtr cable untethered? If so, are you able to get the car closer and plug in with the 5mtr cable that comes with the tesla? I would guess that it's a combo of the cheap rolec components and the difference in the way the tesla controls the charge compared to the leaf and zoe. Remeber that the tesla battery is larger so there maybe some variables in regards to warmth of components.

I'd say if you are worried, then gets some of these Hot Plug Indicators x20 - Safe Connect! and stick them on the: main overcurrent protection that supplies the rolec, the rcd on the rolec and the cables charging handle. If any go red, stop using the charger.

 

So I had an electrician that installs EV chargers come and look at it last week. He spent a couple of hours inspecting everything.

He was happy with the charger and could find no faults. The tethered cable was fine and the Rolec unit was fine. Everything worked and the charge tester he had also reported everything as good.

Great news.

Until this morning...

I charged my Leaf last night and part of the plug has melted. It initially wouldn't free itself from the car without a bit of a tug. What on earth do I do now? Is this a faulty charge plug? Do I need to look at getting the electrician back and swapping it for a new one?

 

I would diagnose that the thermal impedance of the crimp, or cable, at the back of the receptacle on the plug has degraded, or was never good enough in the first place.

I had something similar on the Renault-supplied lead to my Fluence back in 2012. I had an x-ray microscope at work and the crimp had not caught all the core strands. Electrical resistance looked fine, but it could not conduct heat. I relayed this to Renault and returned the lead, who paid me for a new lead in the meantime and gave me a replacement too when they eventually did a recall for those early leads as a result.

So, it does happen, despite what all the nay-sayers are about to say (I am sure).

This is why I keep banging on about 'thermal impedance' but the level of sophistication on this forum isn't quite up to understanding this subtlety.

It's not possible to do simple electrical tests for thermal impedance. Normally, but not always, electrical and thermal impedance are synonymous, so it is possible that resistance testing alone would not alert you to this.


What to do?....

My feeling is that the car socket has survived, albeit a bit ugly. Replacement cost = extortionate, so try to avoid that outcome.

The lead and plug are dead, never to be used again.

Replace the lead and plug, and try again. I think it will be OK after that so long as there is not further damage to the car socket, but you'll discover this soon enough with the new lead/plug.

HTH and it works out for you.

 

I would diagnose that the thermal impedance of the crimp, or cable, at the back of the receptacle on the plug has degraded, or was never good enough in the first place.

The lead and plug are dead, never to be used again.

Replace the lead and plug, and try again. I think it will be OK after that so long as there is not further damage to the car socket, but you'll discover this soon enough with the new lead/plug.

Yeah, I suspect that what you've said is right. I'm hopeful that the car socket is still fine because the car had charged to 97% and my energy monitor reports that the car was still charging when it reached the end of the charge schedule at 3.30am.

I've ordered a brand new 10m cable from EV Extras and I'll get the electrician back to fit it ASAP. Fingers crossed there is no other damage.

Is there anything I can ask the electricians to check after the new cable is fitted? I'm not exactly sure what tests they carry out.

 

Can you pop a picture of the damage on here?
Did you get some picture of inside the unit when your electrician was there?

 

Really useful info Donald. Thanks. I'm hopeful that the Leaf charging socket is okay, but only time will tell. I did notice in my photo that the black tip of the live pin seems to be missing. I can't say for sure what it used to look like, but presumably it was like the one on the right. What purpose does that serve?

I wonder whether it is worth finding out how much it would cost to replace the socket. I expect ££££.

 

It'll have melted I think. It's a plastic protection/insertion guide against scoring the inside of the plug's receptacle. It does run the risk of degrading your new plug if you misalign it as you insert it, just be careful.

Of course, you might prefer just to get on and have the socket replaced. I mean, it will degrade the value of the car in the future if you come to sell it, and there is also a small chance that the thermal impedance was actually a fault in the socket. It doesn't 'look' like that, but who can say for sure.

I mean, I'd ask the dealer, and/or HERVA garage, for a quote to swap it out, there's no pretending that it isn't damaged, and it might make sense to do that sooner than later. Depends on whether you are the sort of person who likes everything just so, and of course if you have the cash to do the job.