What does a EV charging point actually do?

I have bought a 2nd hand Nissan leaf and have been happily charging it slowly from a 13A socket (fed by solar panels) for 6 months using the "granny lead" that comes with the car.

Yesterday, when I turned it on, the READY and CHARGE light flashed about once per second, as did the lights on the dashboard, and there was a click each time from the unit. The manual does not list this combination as indicative of anything.

This lead me to wonder what the "charging unit" actually does, It lists its input and output as 250V ac so it clearly is not a transformer/ rectifier. If it is a protective relay measuring neutral earth voltage, then maybe the ON / OFF is caused by something happening to the voltage in the house?

I have not found any information on the internet as to what is inside these units.

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  • This is a really helpful answer, but it doesn't answer the original question which is why my granny lead switches itself on and off at about 1 cycle per second. This seems far too fast for a thermal cycling issue.

    Also, it seems that it only does this when I plug in a car that has just been driven. If I wait an hour before plugging in, it is happy.

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  • Also, it seems that it only does this when I plug in a car that has just been driven. If I wait an hour before plugging in, it is happy.

    Sounds like an issue inside the car then (or possibly with the connecting lead). As above, the granny lead (just like a mode 3 box on the wall) will disconnect if any of the basic correct "all-OK" signals no longer arrive).

       - Andy.

  • Then I wonder whether the battery is getting a little warm. So you plug it in, it warms just a little and then it cuts out. Then is cools just a little and it connects again, and so on.

    When you wait an hour, the battery may have cooled down enough not to affect charging.

    Or maybe the temperature sensor in the battery is defective.