What are the 5 slots on an Aventon battery?

[stompandgo]

You shouldn't need additional flux 99% of the time if you are using flux core solder.

All it does is make a big mess. Extra flux is handy for dirty, large conductor applications.

 

[spokewrench]

I've used gallons of Penetrox... and correctly.

You started by saying metal to metal contacts must be kept clean:

"So am I, but as an electrician we were always taught to keep metal to metal contacts clean and free of any contaminants."

On that doctrine, you said anyone who greased before connecting was a fool.

Doubletalk. You should practice what you preach or preach what you practice.