Am I going crazy?

Don't get discouraged, but I'm sure one or more people will stop by to tell you everything wrong with that last comment.

That aside. What are you trying to build with your servos?

You looked at the battery and threw it in the trash?

Wasn't really trying to build anything. I was just sharing my experiences and asking if anyone's was similar.

What do you do with a battery that outputs 10v, 30a? It was a Li-Capacitor battery from a broken RC car.

Use it?

What is the use case for that?

Recycle it if it's no good. Someone can use the Lithium.

It’s powerful battery if it can handle 30A, you can use it in the project that requires a lot of power

It's gone now!

It has a very low capacity.

EDIT - Had. It's gone now.

Now i’m curious, have you got a link to make/model?

Everyone is typing . . .

It came from an RC car by GP Toys. The S911 to be specific.

looks like a perfect battery for a project with a motor, it would also power Arduino alone for a week with 800mAh

Yeah but it did a number on my Arduino. Don't recommend it unless you have a way of lowering the amperage.

I’m sure someone in this thread already tried to tell you that amperage is irrelevant in this case

They did. But I swear it did something.

You need to lower the voltage, not the current.
The device will draw only the current it needs, but a 10V source into a 5V linear regulator means Your current draw times 5 is your necessary dissipation and that's just generally bad
I don't think that creates an unresponsive Arduino though, just a lot of heat and eventually a burned out regulator.
Might have programming issues too.

It did but it didn’t?

Yes. I can't really explain what happened.