I have a chargepoint home flex charger for less than 2 months old. It is perfect. However I noticed that under 48amp charging, part of cable (the section right above LED) is quite warm (90F) vs rest of cable (60F to 70F range). I would not understand the physics here except a guess that particular section has more resistance (hence heat) due to cable management position. My 48amp charging looks normal to me at votage of 238v.
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Part of charging cable 20F warmer
- Thread starter alsetyledom280
- Start date
I think the charger body generates some heat and this heat heats the cable because the cable touches the body at this point. No magic or uneven resistance in the cable.
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I assume that the cable resting on the charger would be warmer than the cable not sitting on the charger. Is the top part of the charger warm? I assume this heat would transfer to anything sitting on it including the cable.
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Always be sure to coil any excess charging cable loosely; tight coils trap heat. It is normal for the unit EVSE to become warm while charging.
The warmest parts would include the power plug (where applicable). The EVSE unit itself typically has some warmer parts. Another typically warm spot is where the charging cable connects to the charging connector. (In use my Tesla J1772 charging adapter does not get unusually warm.)
The wiring is sure to be rated for at least 65C (149F), probably 75C (167F) or 90C (194F). In summer the temperature of the energized parts of an EVSE can approach (54C) 130F (even warmer in direct sunlight.)
The warmest parts would include the power plug (where applicable). The EVSE unit itself typically has some warmer parts. Another typically warm spot is where the charging cable connects to the charging connector. (In use my Tesla J1772 charging adapter does not get unusually warm.)
The wiring is sure to be rated for at least 65C (149F), probably 75C (167F) or 90C (194F). In summer the temperature of the energized parts of an EVSE can approach (54C) 130F (even warmer in direct sunlight.)
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I measured 110F when charging cable coiled around my chargepoint like in above picture.
What puzzles me is my feeder line (4 aluminum from panel in basement to garage) at the basement panel is only 70F aluminum and 60amp breakers.
I can only imagine that coiled cable at chargepoint has somehow produced excess heat. Garage temp is around 50F
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I verified that, chargepoint itself is not source of excess heat. It felt lukewarm only. I am positive coiled cable generated excess heat (as heat is gone when cable is uncoiled). So I am not sure the exact reason or any physics involved. What puzzles me most is feeder line wire (#4 aluminum) from panel in basement to garage stays 70F at most. Wire inside garage is #6 copper in conduit. Only coiled chargepoint black cable has excess heat at 110F when garage temp is only 50F.
Heat is a result of resistance, that is all I know.
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It does the same thing on my Tesla wall charger. I loop the cable twice at the top of the charger and that part gets significantly hotter than the rest, but not hot enough to worry. If you don't like it, coil the cable elsewhere.
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I was taught decades ago to uncoil any electrical/extension cords while energized. Electrical current when coiled creates heat.
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Yes--If you pay attention when shopping for long high-power extension cords you'll find the maximum current rating only applies when it is NOT partly coiled up. If you have a 100-foot cord on a reel in your garage (as I do), best know not to operate it at anywhere near maximum rating without paying it all out.
They heat themselves--no fancy physics involved.
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This.
The free hanging cable is surrounded by air to cool it via convection.The cable laying on top can only cool partly by convection and partly by conduction (which with plastic is not as effective). Cable on cable results in two heat sources with limited dissipation paths.
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Haven't you heard of people huddling together to keep warm when they are outside in the cold? It's exactly the same thing. Grouping warm things together retains that heat better because is not as much cold air in between them to drain the heat away faster. It's like the heat from each thing is giving "support" to insulate the other things pressed against it.
You could think of it the same as as if you cut up your hot dinner into smaller pieces and spread it out on the plate to let cold air touch more surface area of it to cool it off faster.
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Thanks for all the help and advice. Going forward I will just lay cable/cord straight, no coil at all under 48amp usage.
My charger is quite close to my tesla, hence my observation about coiled setup, but Safety first.
electronics.stackexchange.com
My charger is quite close to my tesla, hence my observation about coiled setup, but Safety first.
Does a coiled wire have a higher resistance than straight wire?
If you take a straight piece of wire that is insulated and coil it around a non ferrous object like piece of wood would the resistance change?
electronics.stackexchange.com
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per chatgpt, have fun
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Q1: I have an EE related question, why would coiled electrical cable under load (say continuous 48amp) generate more heat than flat cord?
A1: The amount of heat generated by an electrical cable under load depends on several factors such as the current flowing through the cable, the resistance of the cable, and the thermal conductivity of the cable's material.
When a cable is coiled, the individual turns of the coil are closer together, and the cable's cross-sectional area is effectively reduced. This can increase the resistance of the cable, which means that more energy will be dissipated as heat as the current flows through the cable.
In contrast, a flat cord has a larger cross-sectional area, which can lower its resistance and reduce the amount of heat generated under the same load as compared to a coiled cable.
Furthermore, the coiled cable has a lower surface area exposed to the air, which can limit its ability to dissipate heat through convection, whereas the flat cord has a larger surface area exposed to the air, which can enhance its heat dissipation.
Therefore, the combination of increased resistance and reduced surface area for heat dissipation can lead to a higher temperature in the coiled cable than the flat cord under the same load.
Q2: if the wires inside the cord has 2 hot and 1 ground (240v setup, 48amp), will coiled cord get more electro-magnetic effect somehow?
A2: A coiled electrical cable carrying a 240V, 48A current will generate an electromagnetic field (EMF) due to the flow of the electrical current. The EMF generated will be proportional to the current flowing through the cable and the geometry of the cable.
When a cable is coiled, the turns of the coil are closer together, and this can increase the strength of the magnetic field generated by the cable. This is because the magnetic fields generated by each turn of the coil add up, resulting in a stronger overall field.
However, the impact of the coiled cable's geometry on the EMF is usually small compared to the impact of the current flowing through the cable. Therefore, any increase in the EMF due to coiling the cable is likely to be negligible compared to the overall EMF generated by the cable carrying a 240V, 48A current.
It is worth noting that if the coiled cable is positioned near sensitive electronic equipment or other devices that are susceptible to electromagnetic interference (EMI), the stronger EMF generated by the coiled cable may cause interference with these devices. In such cases, it is recommended to use shielded cables or take other measures to reduce the EMI.
.Q1: I have an EE related question, why would coiled electrical cable under load (say continuous 48amp) generate more heat than flat cord?
A1: The amount of heat generated by an electrical cable under load depends on several factors such as the current flowing through the cable, the resistance of the cable, and the thermal conductivity of the cable's material.
When a cable is coiled, the individual turns of the coil are closer together, and the cable's cross-sectional area is effectively reduced. This can increase the resistance of the cable, which means that more energy will be dissipated as heat as the current flows through the cable.
In contrast, a flat cord has a larger cross-sectional area, which can lower its resistance and reduce the amount of heat generated under the same load as compared to a coiled cable.
Furthermore, the coiled cable has a lower surface area exposed to the air, which can limit its ability to dissipate heat through convection, whereas the flat cord has a larger surface area exposed to the air, which can enhance its heat dissipation.
Therefore, the combination of increased resistance and reduced surface area for heat dissipation can lead to a higher temperature in the coiled cable than the flat cord under the same load.
Q2: if the wires inside the cord has 2 hot and 1 ground (240v setup, 48amp), will coiled cord get more electro-magnetic effect somehow?
A2: A coiled electrical cable carrying a 240V, 48A current will generate an electromagnetic field (EMF) due to the flow of the electrical current. The EMF generated will be proportional to the current flowing through the cable and the geometry of the cable.
When a cable is coiled, the turns of the coil are closer together, and this can increase the strength of the magnetic field generated by the cable. This is because the magnetic fields generated by each turn of the coil add up, resulting in a stronger overall field.
However, the impact of the coiled cable's geometry on the EMF is usually small compared to the impact of the current flowing through the cable. Therefore, any increase in the EMF due to coiling the cable is likely to be negligible compared to the overall EMF generated by the cable carrying a 240V, 48A current.
It is worth noting that if the coiled cable is positioned near sensitive electronic equipment or other devices that are susceptible to electromagnetic interference (EMI), the stronger EMF generated by the coiled cable may cause interference with these devices. In such cases, it is recommended to use shielded cables or take other measures to reduce the EMI.
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One of the other options that is sort of a middle ground that people do is just to make the loops bigger. So then for the same total length of the cord, that may only be two or three passes of the wire next to each other instead of five or six. That reduces that heat collection too, while still keeping it neat and off the ground.
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davewill
Active Member
It also keeps people from twisting the cable quite so hard as they coil and uncoil the cable. Many people don't pay much attention to the cable as they coil it and they force the cable instead of carefully letting the handle rotate as they stretch the cord out or hang it up. I've explained it to my wife a few times, but I still have to go over to her side and untwist the cable every week or so. It doesn't help that her inlet is on the side opposite the wall, and she has to uncoil more of the cable than I do.
My cords are much thicker and stiffer than the Tesla cables, it must be worse with those. If your cable seems to twist up "on its own", that's the problem. Consider the "over/under" technique for coiling cables for a method to avoid it:
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