Batteries, batteries, batteries oh dear lord batteries

[Matador]

What end is it made the POS only ?

In theory, it doesnt matter if pos or neg, so as long as it breaks the circuit.
In practice however, for the fuse layout from the link you provided, i would put them on the negative. Cause if the fuses burn on the positive, it could melt the wrapper an touch the negative rim of the can.

 

[999zip999]

Good thinking. The POS end always scares me.