Hi all,
I have a 6S li-ion 18650 battery pack connected to a 6S-20A BMS (blue block in photo)
As you can see, there is an AC jack as output for charging the battery pack. Since the battery pack is made by a manufacturer, I have not disassemble it to look at the connection inside.


However, I want to test the size of the DC output to buy according DC plug. I have a 5V-4A DC adapter at home (used for Jetson Nano) and want to try if it's the same size plug. As I moved the plug near to the output of my battery pack, there is spark at their contact, my adapter popped and later exhaust burnt smell.

Nothing serious happened, but my adapter is toasted. My question is, how can my adapter explode since I don't plug it into any AC power source or anything at all at the AC plug end??


Please help me out since I need to charge 3 of these packs for my project.
Photo below shows the set up when my adapter popped.

 

The polarity of Power-Plugs is seldom the same ..........
They don't necessarily follow any standard conventions,
and the one You have IS ALWAYS WRONG.

You had a reversed Polarity between the Battery and the Charger,
the Circuit inside the Charger tried to protect its self, but failed to achieve that end.
The Batteries can supply a lot of Current,
when the Polarity is reversed,
something is going to let out the "Magic-Blue-Smoke".
.
.
.

 

The polarity of Power-Plugs is seldom the same ..........
They don't necessarily follow any standard conventions,
and the one You have IS ALWAYS WRONG.

You had a reversed Polarity between the Battery and the Charger,
the Circuit inside the Charger tried to protect its self, but failed to achieve that end.
The Batteries can supply a lot of Current,
when the Polarity is reversed,
something is going to let out the "Magic-Blue-Smoke".
.
.
.

Hi there,
Thank you for your reply.

Could you give more clarity to your answer? What do you mean "ALWAYS WRONG"?

On another note, how can I make sure the charger can work with the battery? Do I have to disassemble the battery pack and reverse the wire connection?