Coil whine on idle with full battery

[King-Chris]

Hello,

when my lapptop is fully charged, either 80% on battery health mode or 100% without, the laptop starts to have a strange coil whine when plugged in. This happens just on low load and gets louder when the display brigthness is reduced.

I read about a Burst mode to increase power efficiency under low load. I had it on my device and also on one more I returned due to the annoying issue. 
Does anyone have more clues or a workaround how to reduce it?

[A-09]

Hi, 

I had exactly the same issue with a new EliteBook 845 G10 and was so annoyed that I was about to return it, when I suddenly found a workable solution to the problem by using a charger with lower output. The chirping noise in idle is now barely audible and at the same time 30 watts is perfectly sufficient to maintain the battery at full capacity while working.

[King-Chris]

I also tried with my Smartphone charger and it seems to work within the given limits that in my case 25 W was mostly enough but the battery discharges slowly due to CPU peaks while doing Office stuff.

Does your charger provide a Voltage output up to 20 Volts? Does it say 20 V - 1.5 A on it beside other output voltages?

I guess there is no noise when using a charger with less output voltage. Anyhow it is difficult to find a more powerful USB-C charger not outputting up to 20 V.

[A-09]

Yes, among other outputs it delivers 20V / 1,5A / 33W, which is enough to keep the battery full and even to slowly top it up while working. However, using this charger the laptop stays quiet even once the battery is full. 

[King-Chris]

That is a great information but from an electrical point of view very strange. I guessed it must have to do with the provided voltage. I will try a 45 W Lenovo charger, the 100 W Lenovo I tried had exactly the same behaviour as with the original HP charger with 65 W.

[A-09]

Maybe it‘s related not only to the overall output but also to the type of coils, filters, etc. used in any specific device. For example, I noticed that with an iPhone charger there was slightly more noise although it‘s max. output is just 20 W. The quietest behavior so far is with the Anker 323.