Hv charger cable mm

[asti1488]

Hi I have an ohme charger with an 8 metre tethered cable. When charging is it better to uncoil all the cable or can some be left coiled around the charger . Would the coiled cable overheat like a coiled extension cable, or even damage the charger. I'm a newbie and haven't charged a car yet !

 

[Caramaddy]

Are there any guidelines / instructions on using your Ohme charger?

 

[Ian Key]

As long as the cable lies flat along the ground so it doesn't act as a tripwire I very much doubt the remaining cable could be wrapped tight enough to overheat.

 

[asti1488]

The ohme charger booklet doesn’t mention coiled cables but other chargers say it’s ok as the cables can carry 32 amps may get warm but not enough to damage charger. Extension leads are more tightly coiled and can overheat if overloaded . So I think I’ll be fine , just a newbie panicking !

 

[Lovemyev]

I know it looks much neater when the type 2 cable is tightly wrapped around the external case of a wall box, especially if the box in on the front of your house.
So it is very tempting just to uncoil just the minimum amount of cable you need, just to reach the socket on the car.
But I don't really think this best practice tbh.
When charging over longer periods of time, heat builds up and it has no room for it to
easily escape.
If the excess of cable was loosely wound in larger loops, around the wall box, then this much better I feel.
Then any heat build up can be displaced better, but completely unwound has to be the best bet option really.
I replaced the standard 5m tethered cable on our wall box about 2 years ago, after about four years of use, it was starting to develop twists in the outer case of the cable, partly down to use and coiling it around the wall box case in tight loops.
When ordering a replacement, I went for the longer 7.5m cable.
Which at the time, was way too long to reach the front charge port on our ZS EV.
Therefore I did only use the first couple of metres of cable when charging.
I found winding the excess cable in large deep loops around the wall box left, when not in use was the compromise.
Now we have updated to the MGS5 - I find all of the 7.5m cable is required to reach the charging port on the N/S/R quarter panel.
Almost 95% of the cable is now outside when charging and nothing is wound around the case.
Coiling it around the wall box loosely in deep loops after use, will help prevent the twists developing in the cable.
TOP TIP :- I strongly suggest when considering a wall box, you ensure that the type 2 cable WILL reach all four corners of your EV.
As the charge port on your next EV could well be in a different place.
Most tethered wall boxes come supplied with a 5 metre cable, but some companies will allow you to upgrade for about £30.
Which is a much better option than having to buy a new cable and have it installed thats for sure !.
I was in luck, because mine required replacement anyway, so glad I went for the 7.5m cable now.

 

[EvTek23]

I've often wondered about those nice neat coils besides the car at public charging points, or the coiled cable over a post and the effect of heat or electromagnetic induction into the post and hence a power loss in charging. Having done some research I haven't found much information about any problems people have had so I guess it isn't a big issue. Obviously a tight coil will produce more heat, but generally as air cooling is taking place it isn't a problem. I did come across a car charging parked next to myself with a coiled cable, it didn't feel any hotter than my own at around 6kW.
I always use the figure of 8 technique for the cable run for the excess if the full length of the cable isn't needed.

 

[5teep]

Hi I have an ohme charger with an 8 metre tethered cable. When charging is it better to uncoil all the cable or can some be left coiled around the charger . Would the coiled cable overheat like a coiled extension cable, or even damage the charger. I'm a newbie and haven't charged a car yet !

Yes it could overheat, best practice is to always fully uncoil the cable when you are charging. Better safe than sorry etc.

 

[Everest]

I've often wondered about those nice neat coils besides the car at public charging points, or the coiled cable over a post and the effect of heat or electromagnetic induction into the post and hence a power loss in charging. Having done some research I haven't found much information about any problems people have had so I guess it isn't a big issue.

Unlike a transformer or inductor coil, the type 2 cable contains both phase/live and neutral conductors. Hence the resultant EMF will be cancelled out by each other.

i.e. the same principle as to why a CT clamp only works around one conductor and not a cable with flow and return. Or why BS7671 regulations require Live, Neutral and Earth conductors enter a metal consumer unit through a single hole.

Overheating can be an issue for a tightly coiled cable, but the power loss will be the same whether coiled or linear. P= I^2 x R.

 

[Caramaddy]

I read that the size of the cable is large enough to prevent a build up of heat at 32amps. If it was going to be a major issue, I think it would be flagged in the instructions.

 

[Everest]

I read that the size of the cable is large enough to prevent a build up of heat at 32amps. If it was going to be a major issue, I think it would be flagged in the instructions.

- agree

Assuming the type 2 cable has 6mm^2 cross-sectional copper conductors, the power loss should be less than 50W (see below). Assuming that (worst case) half of the cable is coiled, then the coiled part (4m length) will be dissipating less than 25W. I wouldn't want multiple tight coils of say an extension cable dissipating that much close to each other, but a thick EV cable would be maybe just 6 or so turns for 4m Gut feel is that wouldn't overheat outside with free-air around it - though that will depend on the exact design of the charge point.