My Car maybe tripping fuses

[davidmc]

Hi All

Further to a post I made regards my Type 2 cable pin that was blown I have now a slightly different problem and I’m trying to identify the problem by eliminating each bit at a time and to find out what’s causing it.

Charging Situation

My work has a Car Mechanics garage next door to our office and this has 2nr 7kw (32amp) chargers (Both Single phase versions). These are cabled back and fused separately to the main fuse board independently so don’t effect each other. Both are earthed via a Earthing rods. I believe the Garage has 3 phase incoming main supply.

1 of the chargers is a Rolec (Green and white one that you get for home) and the other is a SCAME Wall box type 2 with RFID Card.

Problem

I plugged my car in this morning at work on the SCAME charger (7kw). I used this last Friday with no problem and completed a 35-90% charge. However today this chargers fuse blew after about 27mins causing the Buildings (Its our company garage) Fire alarm to go off!

At the time a Range Rover PHEV was using the Rolec and this did not trip and carried on charging.

We then decided to plug mine into the Rolec and monitor and leave the RR unplugged to make sure it was not over loading somewhere.

22mins after this the fuse popped inside (Not the fuse in the Rolec but the one inside the building popped).

After this we then decided to use the RR Type 2 cable (Single Phase version Rated at 32amps) on my M3

Again after about 36mins the Rolec popped again.

Question

I have used both these chargers prior to Christmas no problems so could it be the car? Has anyone else had a similar situation?

I am getting my new 3p 32amp Mennekes cable tomorrow and will try that on both these chargers to see if that does the same to eliminate both the cables and the chargers.


Note: I have looked in all the socket holes for any signs of debris/burnt/broken bits and they all look very clean.

 

[Glan gluaisne]

It's not very likely to be the car drawing more current than it should (you can see this from the screen, it's the first current shown of the two, so 32 / 32A indicates that the car is drawing 32 A from a charge point that's advertising a maximum of 32 A), so the first thing to check is whether the tripping that's happening is from over-current, or from earth leakage.

When you say that the "fuse popped" I'm guessing that you mean a circuit protection device opened, one that can be reset with a lever. Did that device have a "push to test" button on it?

If so, then there are two possible causes for it tripping out, either a current overload on that circuit, or an earth leakage fault somewhere downstream of that protection device.

If I had to guess, I say that an earth leakage fault is most likely. The cause could be anything from a bit of water that's got into the cable/charge point/charge point wiring, to a fault in the car.

Because you tried the RR cable and still had the problem, I suspect that your cable is unlikely to be the cause.

From your description it sounds as if the two charge points are on different circuits, perhaps even different phases, hence the reason the RR kept charging after the circuit you were using tripped.

Is it possible to get the charge points tested to ensure they are free from potential earth leakage faults? There is a very small earth leakage from the car onboard charger normally, nowhere near enough to cause a trip, but can be enough to trip a circuit that is already right on the edge of tripping because of other accumulated earth leakages. Water getting into outdoor stuff is a common reason for earth leakage faults.

 

[davidmc]

Hi Jeremy

Many thanks for the response and my little answers to them below:

It's not very likely to be the car drawing more current than it should (you can see this from the screen, it's the first current shown of the two, so 32 / 32A indicates that the car is drawing 32 A from a charge point that's advertising a maximum of 32 A), so the first thing to check is whether the tripping that's happening is from over-current, or from earth leakage..

My Car showed 32/32 on both chargers - its did show 16/32 but i did up this to 32/32 as i knew these chargers can do this and did previously with no problem.

When you say that the "fuse popped" I'm guessing that you mean a circuit protection device opened, one that can be reset with a lever. Did that device have a "push to test" button on it?

Correct, it was the RCD tripping and our mechanic switched it back on after this tripping.

From your description it sounds as if the two charge points are on different circuits, perhaps even different phases, hence the reason the RR kept charging after the circuit you were using tripped.

Correct, both chargers are on different circuits - Not sure about different phases.

If I had to guess, I say that an earth leakage fault is most likely. The cause could be anything from a bit of water that's got into the cable/charge point/charge point wiring, to a fault in the car.

Because you tried the RR cable and still had the problem, I suspect that your cable is unlikely to be the cause.

Interesting - Your right about the RR cable not being the fault as the RR has been fine with its cable.

Hoping its not the car! will test with new cable tomorrow and then if it does trip will have to see if work will get the chargers tested somehow. If they pass then its the car.

WIll double check all ports for water to also make sure no probelms there -

SAFETY QUESTION - Is it safe to shove a cotton bud in the M3 charge port pins to see if its dry in there?

 

[Glan gluaisne]

Sounds very much like an earth leakage fault to me, which may be a real fault, or may be a fault with the RCD/RCBO.

Testing the charge point is reasonably easy if the person doing it has access to a charge point test box, like my home-made one, below:

This allows the charge point to be turned on and off, faults to be simulated and the earth leakage protection to be tested, by providing a way to both turn on the charge point (simulating a vehicle on charge) and allowing a standard electricians multifunctional tester (MFT) to be plugged in, and standard RCD tests conducted. It's possible to test the installation between the charge point and the protection device that's tripping without one of these boxes, but it's not easy to test the charge point itself without one.

Checking the car plug for damp with a cotton bud is safe enough, as there's no way for AC to feed to the car connector. Don't do the same with the socket on the charge point, though, as although it should not be powered on with no car connected, you cannot be sure without proving the circuit to be dead.

 

[davidmc]

Appreciate your response Jeremy

Will see if work can get an Electrician with a similar testing unit to see if any problems. Will also see if my new cable does the same before and will check for any moisture in the sockets before this.

 

[Glan gluaisne]

Happy to chat through how EV's turn charge points turn on and off with your electrician if that may help, as unless he/she is familiar with how they work it might not be clear as to how power is switched to the car. If he/she would like to chat this through I can DM you my 'phone number.

Also, there is a Heath Robinson way to get any AC charge point to turn on, just by poking a resistor between the control pilot and earth and another one between the proximity pilot and earth (these are low voltage terminals). This can get around the need to use a test box to get the charge point to power up for testing, but is not something that's advisable to do for anyone who doesn't know exactly what they are doing !

Pity you're a bit far away, if you were closer I'd either lend out my test box or pop over and have a look. However, often the cause of problems like this may be visible, if it's something like water that's got in where it shouldn't.

Have you had any other instances of earth leakage trips when charging anywhere else? If not, then the chances are that it's not a problem with the car.

 

[davidmc]

Happy to chat through how EV's turn charge points turn on and off with your electrician if that may help, as unless he/she is familiar with how they work it might not be clear as to how power is switched to the car. If he/she would like to chat this through I can DM you my 'phone number.

Also, there is a Heath Robinson way to get any AC charge point to turn on, just by poking a resistor between the control pilot and earth and another one between the proximity pilot and earth (these are low voltage terminals). This can get around the need to use a test box to get the charge point to power up for testing, but is not something that's advisable to do for anyone who doesn't know exactly what they are doing !

Pity you're a bit far away, if you were closer I'd either lend out my test box or pop over and have a look. However, often the cause of problems like this may be visible, if it's something like water that's got in where it shouldn't.

Have you had any other instances of earth leakage trips when charging anywhere else? If not, then the chances are that it's not a problem with the car.

Really appreciate this. Will let my work place do the testing etc first, this has only happened today so early stages yet and don’t want to upset the Big Bosses at work yet!

No earth leakages that they know of and first time its done it today.

Will see if it occurs tomorrow with new cable and a good clean/dry out of the ports and double check no water ingress in there (if visible)

Will do all above first then take it from there.

If all else fails and the electrician is standing there scratching his head i may give you a DM - Also i do not want to waste your time for my works problem and rather they ask a qualified person who deals with EV chargers and not our usual Commercial Electricians - (Unless its my car thats causing it!)

 

[Markblox]

A similar thing happened on a friends model 3 and I put that down to cumalative earth leakage, with the car providing a part of it. In his house he had a lot of sub mains but only one RCD and I think the car was the car was the straw that broke the camels back. A common problem.