Haven't managed to record this but I'll try to explain.
When driving uphill on steep roads at low RPMs and sometimes even when idling there is this loud noise that I don't think is the engine noise, as it sounds more like a loud fridge compressor or a petrol generator. Seems to overlap the regular engine noise and it's a bit higher pitched and sounds... Hmmm. A lot less refined, let's put it like that.
What's interesting is that during idling, it says it's charging the Battery, but the