Charger Control Box Limiting Current After Changing Plug Top

I got an electrician to change my level 1 charger from Japanese pins to 15amp Australian pins to make charging more convenient. It charges, but much slower than I expected. Eg, After a few hours charging I was expecting about 6% an hour from the 15 amp socket, and instead got about 3.8%. The EVSE control box's indicator lights start off normal, but a few seconds after starting to charge, all three start flashing. The manual says this means the control box thinks the plug top is overheating, or it just can't detect the temperature, and so is limiting current as a safety measure. Was there a temperature sensor in the Japanese plug top that was wired into the control box? Has anyone else had a problem like this?

Welcome. It sounds like the plug wiring is the issue, all right. BTW, what voltage is the circuit?

Yes there is a temperature sensor in the plug--did you just chop it off to add the local plug?

Thank you for your replies.
Talked to the electrician and he confirmed there was another wire and he didn't know what it was for so didn't do anything with it (he couldn't find a temperature sensor in the Japanese plug top, and he opened it up to look).

On further investigation, some people have had a similar problem:
https://www.speakev.com/threads/putting-a-new-plug-on-an-evse-and-the-thermal-sensor-question.57161/

According to the above link: Apparently there are two black cables (apart from the three power cables) that connect to a thermistor. A 22k Ohm resistor can be soldered to connect the two black cables and that will basically tell the control box that everything is fine always. Or you could actually connect a thermistor. If you manage to salvage the original part from the original plug top, that would be ideal.
I haven't done any of this, but I'm going to have to look into it.

LeftieBiker said:

Welcome. It sounds like the plug wiring is the issue, all right. BTW, what voltage is the circuit?

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The control box says it is 15A, 200V AC, 50/60Hz.
Australian voltage is apparently 240V, but others who imported Leafs from Japan who I've talked to haven't had any problems using the Japanese cables to charge in Australia.

Inicus said:

I got an electrician to change my level 1 charger from Japanese pins to 15amp Australian pins to make charging more convenient. It charges, but much slower than I expected. Eg, After a few hours charging I was expecting about 6% an hour from the 15 amp socket, and instead got about 3.8%. The EVSE control box's indicator lights start off normal, but a few seconds after starting to charge, all three start flashing. The manual says this means the control box thinks the plug top is overheating, or it just can't detect the temperature, and so is limiting current as a safety measure. Was there a temperature sensor in the Japanese plug top that was wired into the control box? Has anyone else had a problem like this?

Click to expand...

I don't think you said what year Leaf you had but with my 24kw Leafs @ 240v I get about a percent per amp. IOW @ 240v with a 12a EVSE I gain about 12%/hr, with a 20a EVSE it would be about 20%/hr, roughly. Now of course if you have a larger battery you won't gain as much %/hr.

You're better off installing a level 2 charging station. I've had my United Chargers of Canada Grizzl-E since January, and it has performed beautifully so far.

jjeff said:

I don't think you said what year Leaf you had but with my 24kw Leafs @ 240v I get about a percent per amp. IOW @ 240v with a 12a EVSE I gain about 12%/hr, with a 20a EVSE it would be about 20%/hr, roughly. Now of course if you have a larger battery you won't gain as much %/hr.

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Ah, sorry, you're right. It is a ZE1 made in 2018 with a 40kWh battery.

hbquikcomjamesl said:

You're better off installing a level 2 charging station. I've had my United Chargers of Canada Grizzl-E since January, and it has performed beautifully so far.

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We have been considering that. But we aren't sure how much longer we will be in this house, maybe two years. And by my calculations, we should be able to easily recharge the car with about two night charges every 5 days using only level 1 charging. So (in theory) a level 2 charger shouldn't be strictly necessary. Just nice to have. When we move into our forever home, we'll probably install one.

All you really need for a Level 2 charger, at least in North America, is a 240V power socket that can safely deliver at least 20A. Which is to say that the portable charger that comes with at least a North American Leaf is Level 2, if plugged into a 240V 50A power socket. (The rub is that the portable charger assumes that if it's fed 240V, it's on a 50A circuit, and so if you plug it into a 30A circuit, you'll blow the breaker the moment you plug in the car.)

Of course, I'm guessing that even at 240V, 15A is not enough capacity to qualify as Level 2. I just checked the Grizzl-E site, and the maximum current settings are 40A (for a 50A circuit), 32A (for a 40A circuit), 24A (for a 30A circuit, like mine), or 16A (for a 20A circuit). This is of course based on the usual rule-of-thumb of keeping continuous loads at or below 80% of a circuit's rated capacity.

(The rub is that the portable charger assumes that if it's fed 240V, it's on a 50A circuit, and so if you plug it into a 30A circuit, you'll blow the breaker the moment you plug in the car.)

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Not exactly. Plugging the Nissan dual voltage (without the 120 volt plug in place) will NOT trip the breaker on a 30 circuit - and that's part of the problem. The car will charge, but with the circuit maxed out, extended charging will tend to heat the wiring and/or breaker up, and isn't really safe. It also violates the National Electrical Code.

Reason being the Leaf just draws ~27.5a max which won't blow a 30a breaker but as Leftie said can make things very hot after an extended charge.

Also the 125% (or 80%) amperage rating adjustment for continuous loads isn't a rule of thumb. It's very explicitly stated in the NEC. Not that it's clear or concise, but it is explicit

Inicus said:

On further investigation, some people have had a similar problem:
https://www.speakev.com/threads/putting-a-new-plug-on-an-evse-and-the-thermal-sensor-question.57161/

According to the above link: Apparently there are two black cables (apart from the three power cables) that connect to a thermistor. A 22k Ohm resistor can be soldered to connect the two black cables and that will basically tell the control box that everything is fine always.

Click to expand...

Okay, I found the Japanese plug top in the bin and had to cut it apart (it is completely solid with rubbery plastic filling every void) but managed to find the thermistor. It was in the centre between the three pins, and as close to the face of the plug top as possible, which makes sense if it was intended to be as close to the wall socket as possible. It was actually two yellow cables, not black. Borrowed a multimeter and measured it as approx 18.25k Ohms. I don't know if it is an NCT or PCT.

If anyone else finds themselves in a similar situation to me, you may find this information useful.

Undecided if I will use the original thermistor, and whether I'll try to attach it at the plug top end or in the control box.

goldbrick said:

Also the 125% (or 80%) amperage rating adjustment for continuous loads isn't a rule of thumb. It's very explicitly stated in the NEC. Not that it's clear or concise, but it is explicit

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It's not just the code; it's a good idea.

(Which is to say that my new seat heater draws 5 amps, on "high." It does not blow the 5A fuse in the lighter plug to which I've jury-rigged the "kit" wiring harness. But I set 8A as the minimum acceptable rating for the power relays in the control mechanism I'm building.)