13A fuse blowing on MG4 Trophy granny charger plug.

[Suilven]

I have an intermittent problem with a 13A fuse blowing in the 3 pin plug of a granny charger for an MG4 Trophy. The RCD on the mains supply circuit also trips on occasion.

The charger plug is connected directly (no extension lead) to a standard UK 3 pin 240V socket.

The charger has always used been indoors and is visually in new condition with no sign of physical damage.

The dealer's solution was to install a software upgrade on the car but this hasn't resolved the problem.

 

[Ian Key]

Can you borrow another granny charger and let them try yours? If you have the same problem then its your house wiring, if not its your granny charger.

 

[Suilven]

Hi Ian. That was my first suggestion to the garage but they were convinced the software update would resolve the problem. I'll try the garage again with your idea.. It's unlikely that the house wiring (it's fairly new) would cause an appliance fuse to blow though. Thanks for your advice

 

[Martinonline]

Is your granny charger an official MG one?

Have you tried reducing the current draw in the car?

Do you have access to a power meter to see what power is being taken by the granny charger?

 

[DBedford]

I'd be questioning the quality of the wiring to the outlet you are using.

 

[EvTek23]

If the fuse is blowing then there is excess current being drawn. This will either be because as @Martinonline has suggested that the car is requesting more power than the fuse can support i.e 13A, or there is a fault with the granny charger with an internal fault when on load.
The fact that the RCD also trips suggests an imbalance between live and neutral, or potentially a leakage to earth of 30mA or more.
Have you got access to another granny charger to try out?
Does the granny charger have the same problem when just plugged in and not charging or only when charging?
Also does the RCD trip if any other high current device is plugged in like a kettle, air fryer, or electric room heater?

 

[Suilven]

If the fuse is blowing then there is excess current being drawn. This will either be because as @Martinonline has suggested that the car is requesting more power than the fuse can support i.e 13A, or there is a fault with the granny charger with an internal fault when on load.
The fact that the RCD also trips suggests an imbalance between live and neutral, or potentially a leakage to earth of 30mA or more.
Have you got access to another granny charger to try out?
Does the granny charger have the same problem when just plugged in and not charging or only when charging?
Also does the RCD trip if any other high current device is plugged in like a kettle, air fryer, or electric room heater?

Thanks for your logical reasoning. I swapped the charger with the one the dealer was using in store and problem is now resolved.

 

[Suilven]

Is your granny charger an official MG one?

Have you tried reducing the current draw in the car?

Do you have access to a power meter to see what power is being taken by the granny charger?

Thanks for your suggestions. Yes it is a factory original. I have now received a replacement from the dealer and the problem is resolved.
Out of interest, how can I control the charging current?

 

[Martinonline]

@Suilven, you can control it in the car. Tap the battery section of the infotainment screen home page. That will take you to the charging page. At the bottom of the page you will see a listbox that allows you to limit the current. AC in the box means max current that the car can take, the other items are numbered limits.