Battery tester?

[accordeur]

I wonder if I use a universal battery tester, where would I connect the terminals? One on the rim and the other at the center? Thanks

 

[Meltrex]

the threaded part /rim as you call it, is your ground... the center area where the hole is, will be your positive... you must activate the battery by air flow in order to get voltage to measure with. You can blow thru the led side to activate.

 

[accordeur]

Thanks, I'll give it a try.