Chargers aren’t usually meant to make noise when you use them. Despite that, lots of Milwaukee users have complained about their charger making a hissing noise.
That noise isn’t intentional, but there IS a reason for it. Keep reading to find out more about why you hear it, and whether or not it’s something you should be worrying about.
I have also made a short video about this topic and you can watch it below.
The hissing sound mostly happen on the Milwaukee rapid charger and it is completely normal. The hissing sound is from the fan cooler of the rapid charger.
Why Your Milwaukee Charger Is Making A Hissing Noise
I want to start by saying that most reports you’ll see about this issue will have to do with Milwaukee rapid chargers specifically. That’s not just a coincidence.
This is a common complaint about those particular chargers and that’s because it only happens with them. Normal Milwaukee chargers don’t get that hissing sound when in use.
Related: Common Milwaukee M18 Battery Charger Problems
That brings up the question; why does the hissing sound come up on the rapid chargers specifically? The answer to that is their power consumption.
Rapid chargers require a lot more power than regular chargers. That’s how they’re able to power large batteries (like the Milwaukee M18 8.0 I’m charging below) so quickly.
When I put on a big battery like that one on my Milwaukee rapid charger, it starts making a hissing noise. It kind of sounds like small fans spinning super fast, doesn’t it?
If that’s the kind of sound you hear from your charger too, don’t worry. There’s nothing to worry about. You can rest assured that this “problem” isn’t much of a problem at all.
Sure, the hissing is a little annoying. But, it’s a minor drawback that comes as a result of the rapid charging.
Where Is The Noise Coming From?
We all know the hissing is coming from inside the Milwaukee charger. What exactly is producing that sound in the first place though? What’s inside a charger that can cause that?
The answer to all those questions is a fan. There’s a fan inside the charger, and that’s what makes the hissing sound you hear whenever the charger is in use.
Rapid chargers have fans inside of them to help with cooling. If you put your ear next to the part of the rapid charger from this image, you’ll notice the hissing is loudest there.
That’s because this is where the fans are, and the stilts on the side of the charger are vents that the fans can blow air out of.
The reason why there are fans inside these rapid chargers is due to how much power they consume. That power generates a lot of heat while charging batteries.
Related: Reasons Why Your Milwaukee M18 Battery Charger Blinking Red Only
Without the fans inside, the charger and battery would easily overheat as a result of that. You hear the noise since those fans are actively pushing that heat out during charging.
Charging Smaller Batteries Won’t Make The Same Noise
Like I said, all this happens due to the high power requirement of rapid chargers and the heat that’s produced. That’s also why you won’t hear the same noise when charging smaller batteries.
Take this small 2.0 Milwaukee M18 battery I put on my Milwaukee rapid charger as an example. It’s charging fine and not making any noise at the same time!
Since it needs less power, there’s less heat. Since there’s less heat, the fans don’t need to go full power, which is why they don’t produce any hissing.
Why Am I Hearing Hissing On Normal Chargers?
If your Milwaukee charger is hissing even though it isn’t a rapid charger, it could be because the battery is loose. Push down hard on the battery to see if it stops the noise.
If you still hear hissing after that, your charger could either be overheating/overcooling or have an electric current problem. It’s best to stop using the charger for now and try again later.
