Strange noise while charging

[tanka]

I've had my M3 for 3 months so I am accustomed to the muted sound that the car usually makes when charging, heating and cooling down the battery. But yesterday morning, I found my car making a concerning noise.

Here's a video:

It sounded like a bee, and could be heard 50 ft away. The car was charging at 24A / 240V but only showing 10mph in the charge speed (heat/ac/seat warmers all disabled), where it usually displays 25mph. I stopped the charge, started it again: noise gone, 25mph.

What could it have been? Slightly concerned to let my car charge alone at night now.

 

[dmurphy]

I've had my M3 for 3 months so I am accustomed to the muted sound that the car usually makes when charging, heating and cooling down the battery. But yesterday morning, I found my car making a concerning noise.

Here's a video:

It sounded like a bee, and could be heard 50 ft away. The car was charging at 24A / 240V but only showing 10mph in the charge speed (heat/ac/seat warmers all disabled), where it usually displays 25mph. I stopped the charge, started it again: noise gone, 25mph.

What could it have been? Slightly concerned to let my car charge alone at night now.

Totally, totally normal. Was it a little cool in the morning?

It pumps coolant through the battery to either warm or cool the battery so it can charge most efficiently. Totally normal what you were seeing - the battery was probably cold soaked and it was warming up to achieve maximum charging speeds.

100% normal - absolutely nothing to worry about!

 

[camalaio]

Normal, and I'm guessing you have a RWD version?

The sounds you're hearing correspond to it heating the battery. The reason only 10mph is being displayed is because it's using a decent chunk of the available power to heat the battery, probably 3-4kW (which is why I'm assuming it's RWD, it would normally be higher with AWD).

You don't hear this more often due to a few factors, but basically it will only heat once the battery is "too cold", then it heats for a while until "warm enough" (and eventually repeat if necessary). Usually due to scheduled charging or charging immediately after a drive (which would've heated the battery a bit), you don't usually witness the battery being actively heated.

 

[tanka]

Ok that makes sense, it was indeed probably the first time I manually plugged it in in the morning since it got cold. I usually plug right after driving, and leave it on a schedule. Thank you both. Now I feel like a typical Californian, losing it below 50F.

 

[camalaio]

Ok that makes sense, it was indeed probably the first time I manually plugged it in in the morning since it got cold. I usually plug right after driving, and leave it on a schedule. Thank you both. Now I feel like a typical Californian, losing it below 50F.

To be fair, the car is being a typical Californian too in this case

 

[Kimmi]

This is California? It was 37 degrees in West Covina last night!