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Discussion Starter · #1 ·
I'm still about a month away before I get a commando socket installed for faster charging.

After a recent charge on a hot day, one of the pins on the tough leads extension cable plug was very hot and the plug itself and the built in RCD were a bit warm.

Is there a setting in the car or other physical device that can limit the current to say 8A to see if that helps?
 

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E-Niro 64kWh '4' since 9/20 (was Prius)
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On the UK granny lead box there is a button on the rear where you can set 6,8,10 Amps. It defaults to 10 Amps (~2.3kW).
 

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I'm still about a month away before I get a commando socket installed for faster charging.

After a recent charge on a hot day, one of the pins on the tough leads extension cable plug was very hot and the plug itself and the built in RCD were a bit warm.

Is there a setting in the car or other physical device that can limit the current to say 8A to see if that helps?
I believe there's a button on the back of the granny lead control unit to step through 12 - 10 - 8A. It's 10A by default in the UK. Plugs can get quite hot with extended use. How hot is worryingly hot, though? I've only noticed hot plugs when using an extension lead and I'm not sure whether that was the plug or a dicky 13A socket. Your charging losses might be even greater at 8A, though.
 

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Discussion Starter · #4 ·
Thank you, I've found it now - you have to press and hold the little black button in the back.

I will try out 6A and 8A to see if it makes any difference.
 

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The "how hot is too hot?" question is a good one. The maximum allowable internal temperature of the plug will be around 70掳C, as that's the max temperature for most PVC cables. The external temperature when the inside is this hot will be a lot lower, and I'd start to get worried if the surface temperature reached about 40掳C. 40掳C is roughly the temperature of a hot shower, so if the surface of the plug is around that temperature then I'd take action.

Perhaps most importantly, the temperature of the plug should not get anywhere near that hot if the plug and socket are in good condition. If any plug is getting much over 30掳C at its surface then the thing to do is not to turn down the current, it's to stop using it and find out where that heat is coming from. First thing to check is the terminations inside the socket (after safely isolating the power), making sure the wires are fully home and that the screws are torqued up correctly. The torque required on socket terminal screws is higher than some may think, typically around 2 Nm.
 

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i had this found the extension cable was too thin to carry a high load for long periods of time, I made a 10m cable with 3x2.5mm rubber flex, heavy duty plug an single trailing socket. the plug no longer gets hot or even warm to the touch.
 

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From your description I get the impression you are plugging the "granny" cable into an extension lead. Firstly this lead should be rated for use at 13A load. Many extension leads on the market are rated at less than this. Secondly the lead should be fully uncoiled to prevent it representing an inductive load that will in itself cause the lead to heat up when loaded. The lead should be kept as short as possible. Again as said above check the wiring in the plug, and if possible the socket, to make sure all connections are secure and tight. It might also be worth plugging in to a different 13A socket in case there is a problem with the socket you are using.
 

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From your description I get the impression you are plugging the "granny" cable into an extension lead. Firstly this lead should be rated for use at 13A load. Many extension leads on the market are rated at less than this. Secondly the lead should be fully uncoiled to prevent it representing an inductive load that will in itself cause the lead to heat up when loaded. The lead should be kept as short as possible. Again as said above check the wiring in the plug, and if possible the socket, to make sure all connections are secure and tight. It might also be worth plugging in to a different 13A socket in case there is a problem with the socket you are using.

Good advice, but coiled cables don't have any appreciable inductance, and the current flowing in the line and neutral conductors cancel each others fields out. The problem with coiled cables is that the cable cannot dissipate heat as well, so under a high load the heat builds up in the cables that are touching each other within the coil. The Toughleads extension cable being used is one that is fine for the 10 A current a portable charge point needs, and one that several here (me included) have recommended. That's why I suspect that there may be something awry with the terminations at the socket, or. perhaps, a fault in the granny lead plug, as these leads use 1.5mm虏 H07RN-F cable that is plenty big enough for a constant 10 A load (it's rated at 15 A).
 

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What he said, 100%. It鈥檚 nothing to do with inductance whatsoever. Everyone says that but it鈥檚 a myth. It鈥檚 resistive heat generated which builds up in the reel. When cable is extended, the exact same heat is dissipated, but it鈥檚 spread out across the length of the cable.

Back to the OP. I bet the Very hot pin he was referring to was not the one on the actual granny plug itself but the one on the extension lead plug? Also, I bet it was the L pin?
Its very often caused by crap (resistive) connection to the 13A fuse end caps. It can be due to old oxidised fuse caps, or fuse holder clips. Also the fuse holder clips often have inadequate tension onto the actual fuse. What happens then is they can heat up, which then causes even less tension and even more contact resistance and even more heating. Before you know it the plug can self destruct with a kind of thermal runaway.

Another cause of heating pins is lack of contact tension in the wall socket, possibly combined with old oxidised mating surfaces on plug pins and contact clips in the socket. Then add to that gradually self loosening screw terminals and even solder tinned stranded wire ends which is a really big no no, yet often seen. Even an ageing or poor quality 13A fuse can cause heating on its own.

Sadly our so called 13A plug and socket system isn鈥檛 great, and often cannot safely handle it鈥檚 rated current continuously. This is then made even worse with lots of inferior imported units and a complete lack of proper type approvals or regulation. I鈥檝e seen lots of heat damaged 13A plugs, sockets and adapters etc in my time.
With a bit of TLC they can be made to work ok at full load, but need regular checking and maintenance which they rarely (if ever) get. Peter
 

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Discussion Starter · #10 ·
Yes, it was the L pin in the extension lead that was very hot. The extension lead is less than a month old so while possible I don't think it is the issue.

I suspect the wall socket is the issue - when I took the plug out it came out too easily. When the kids are at school tomorrow I'm going to check the socket to see if there are any visible signs of damage but I don't think I'll be using that socket again until it's been checked by a qualified professional.

If the socket should be replaced, are there any brands that cope better with the consistent high load?
 

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Very likely that the socket has lost some of the tension in the springy brass contacts, something that is often caused by heat from the fuse travelling down the pin of the plug. Over time the contact resistance increases, which makes the socket get warmer around the line pin, and that in turn tends to reduce the force the springy contacts apply, which in turn makes the contact resistance higher, so increasing the heat further.

Burning around the line pin of a plug/socket is a pretty common problem, partly caused by heat from the fuse, partly caused by running loads that are greater than the 10 A continuous current rating of the plug and socket (the 13 A rating in BS1363 is not a continuous one, it's a short duration maximum).
 

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Yes, it was the L pin in the extension lead that was very hot. The extension lead is less than a month old so while possible I don't think it is the issue.

I suspect the wall socket is the issue - when I took the plug out it came out too easily. When the kids are at school tomorrow I'm going to check the socket to see if there are any visible signs of damage but I don't think I'll be using that socket again until it's been checked by a qualified professional.

If the socket should be replaced, are there any brands that cope better with the consistent high load?
Make sure the 13A fuse is securely held in the clips in the plug. If needed, remove the fuse and pinch the clips together to increase the contact tension. Even though the extension may be brand new, sadly it doesn鈥檛 guarantee good quality. There's a lot of quite tacky stuff around, even when new!

Regarding best socket brand, IMHO MK is probably the most trusted make and as good as they get. It鈥檚 very possible sometimes to tighten up the socket spring contacts if you know what you鈥檙e doing. However, please don鈥檛 attempt this yourself, unless you are really experienced and knowledgeable in such things. Peter.

PS. The best way by far is to not use the plug in granny lead at all. Get a properly installed EV charge point If possible.
 

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Even though the extension may be brand new, sadly it doesn鈥檛 guarantee good quality. There's a lot of quite tacky stuff around, even when new!
As mentioned before, these particular extension leads are really top notch, please have a look at one before condemning it. I have and cannot fault them, they use decent brand name fittings and first rate H07RN-F cable.
 

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As mentioned before, these particular extension leads are really top notch, please have a look at one before condemning it. I have and cannot fault them, they use decent brand name fittings and first rate H07RN-F cable.
Well that鈥檚 fine then Jeremy. I鈥檓 certainly not familiar with that (or any other specific extension reels). My statement was really more in the way of a general advisory broadcast intended to help anyone reading this, who may also be using a granny lead EVSE with extension cable. There's some real crap around typically, as I鈥檓 sure you would agree. Peter.

PS as a matter of general interest, the Kia granny lead has an over temperature sensor right inside the 13A plug. The EVSE will shut off (or maybe just reduce the car charge current??) if the plug gets excessively hot. Of course that provides no protection at the 13A plug end on any attached extension lead.
 

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Well that鈥檚 fine then Jeremy. I鈥檓 certainly not familiar with that (or any other specific extension reels). My statement was really more in the way of a general advisory broadcast intended to help anyone reading this, who may also be using a granny lead EVSE with extension cable. There's some real crap around typically, as I鈥檓 sure you would agree. Peter.

PS as a matter of general interest, the Kia granny lead has an over temperature sensor right inside the 13A plug. The EVSE will shut off (or maybe just reduce the car charge current??) if the plug gets excessively hot. Of course that provides no protection at the 13A plug end on any attached extension lead.

The key was in the first post, that stated this was a Toughleads extension cable, as recommended on here by several people that have bought them. They are specifically sold for this purpose: Electric vehicle leads

There are several other threads here relating to extension leads, and the fact the most sold by DIY sheds and the like are not safe to use for long periods at 10 A, and also where several people (including me) have made the point that the majority of EV manufacturers and portable charge point manufacturers specifically state that extension leads should not be used. My view is that they are OK as long as they are of a decent quality, and as long as the person using it understands that they may be doing so against the advice of the EV/charge point manufacturer. FWIW, I made up this weatherproof cable, with both a 16 A commando and a 13 A adapter led (with RCD plug) and always carry it in the car, have done for years. It's only been used a handful of times, but has been extremely useful to have on those occasions:

145977
 

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Thanks Jeremy. I agree the tough leads extension looks like top quality gear. Peter.
 

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...even solder tinned stranded wire ends which is a really big no no...
Just out of interest, what's the problem with tinned copper terminations?

I only ask because years ago I had to use a specialised LV PSU (nothing to do with EVs) which ran at around 100A max. It sometimes gave problems, but never the connection block which used tinned copper connections internally. I assume it left the factory this way.
 

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Nothing at all wrong with tinned copper conductors, or tinned copper or brass terminations. The problem is if someone decides to solder stranded flexible cable, as this is pretty much a sure fire way to result in a broken conductor, as a consequence of fatigue. It's why crimps, spring or screw clamp terminations must always be used on stranded flex cables, as if soldered the solder will wick up inside, under the insulation, and reduce the ability of the flex to flex, resulting in a fatigue fracture from vibration or flexing.
 
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