E-bike battery charger making horrible noises, only works certain outlets? I had posted on endless sphere but since then I have possibly made a little discovery. 

Tldr; I have a fresh 48v battery and charger around less than 3 months old. Very intermittently when trying to charge the battery the charger will power up, the fan spins up and then it starts to make a nasty buzzing / whirring sound. Its pretty loud normally but this is something else.

My discovery since the last post is that I no longer believe this is a broken fan issue, as I know that can make a lot of noise. I will not dismiss the possibility by any means though. Main reason for believing this is that when I charge at home it boots up fine and lightly whirrs. But more often than not I have noticed when I am charging in my place of work, this weird sound starts like clockwork almost as soon as I turn it on. 

I can be entirely sure of this but id say i cant remember it once doing it at home, but its happened around 10 times now in work. Sometimes it can charge fine even on the supply, it is kind of odd. 

I have attached a picture of the charger and a video sample of the noise it makes.

It is a generic style chinese brand charger so criticise if you wish but this is brand new, CE and RoHS tested. 

Any help or SUGGESTIONS FOR A NEW CHARGER using the bespoke connector it has would be GREATLY appreciated. 

The charger is a generic-style C300 model battery charger, similar to the one shown below:
https://i.imgur.com/a1vYr7K.png

[Charger noise video]
https://streamable.com/1kmpr

[3 Pin DIN style connector, not XLR]
https://imgur.com/a/4oqjeRB
Even though the design may be CE compliant, the unfortunate reality is that cheap manufacturers will still leave out "unnecessary" circuit components or replace them with fake ones when actually building it.  (RoHS just means it's free of lead and mercury etc etc, nothing to do with quality or usability of the electrical design.)

The components that are supposed to filter and reject electromagnetic noise are common victims since they're both expensive and it "normally" works just fine without them.

So if it works fine at home but makes weird noises at work, it seems more likely there's a failing connection in the electrical power system at your work putting a lot of noise on the line, rather than a problem with your charger.  (Other than potentially failing to reject an amount of noise that other DC supplies in the building seem to be handling, whether due to a lazy design or corners being cut in assembly.)