Loud thump/vibration when DC fast charging

[Astral]

Hi all, just wondering if this has been discussed already, I was not able to find any info. Most of the time when I am DC charging I am waiting in the car doing some work on my laptop. And without exception, at basically any battery %, I hear and feel a hard quick thump or kick from beneath the car, for the lack of a better word. It happens once per charge and it does not seemingly affect anything. Charging continues normally, all looks normal. But I asked other MG4 drivers and they don't hear this. I have the base model with LFP battery. What could cause this sound, any ideas? Could it be dangerous?

Currently I have 12k kilometers on the clock, 8 months old. I think this happened from the beginning but before I would leave the car unattended and not sit in it. So I was not aware of this.

 

[siteguru]

Are you simply hearing the contactors making/breaking as charging starts/stops?

 

[Astral]

This happens out of nowhere, sometimes 5min after charging started, sometimes 20min after charging started, at any % level. The noise could be characterized as similar to the contactors but much harder as I can basically feel the vibration of it.

 

[Astral]

Hi Pryde, something you wanted to say other than quote me?

 

[siteguru]

Some people seem to struggle with this forum ... maybe it's mainly those who use mobile devices to use the forum?

 

[GaryMG4]

Could it be battery cooling/heating kicking in?

 

[Everest]

Some people seem to struggle with this forum ... maybe it's mainly those who use mobile devices to use the forum?

Definitely. Fails every time I try and use one...

 

[Astral]

Could it be battery cooling/heating kicking in?

I was connected to OBD, 16°C batt temp. It could be when heating stopped. But why would that cause any noise? I will check that again next time.

 

[Macadoodle]

Pretty sure i remember Tesla owners commenting about a similar noise a few years back, was traced to the battery casing flexing due to the heat from rapid charging

 

[Coulomb]

It could be when heating stopped. But why would that cause any noise?

There will be a DC rated contactor turning on and off the battery heater. Contactors make a noise when turning off as well as on. But I'd expect that contactor to be smaller than the main ones, and the main contactors are amazingly quiet in MGs.

 

[HammerDave]

I have the same noise when DC charging in my Xpower. As you say it happens only once at any percentage. I have no idea what it is either. Had my car 8 months and I never used to hear it until about a month ago.

 

[Astral]

Tomorrow my MG is going in for a service not related to this but I will mention it, hopefully they will be able to check something. I will report back if I get more info.

 

[Astral]

Ok so, I've received all the module updates on todays service, but they have not really checked my remark abut this problem. They just charged my car to 100% and said it charges normally So I don't know what to do next...

@HammerDave - is it possible that you contact your dealer and explain the issue, UK is a much larger market, maybe they have come across this problem already so you can let me know what it might be?

 

[HammerDave]

Yes if I find out anything I will update the thread (My car is due for a service soon)

 

[Coulomb]

... was traced to the battery casing flexing due to the heat from rapid charging

That sounds the most plausible to me.