JR batteries are NOT reversed polarity from all the other They are also centerpin positive just like Hitec, Futaba and Airtronics (not the old style Airtronics).

What you are confused about is the fact that JR chooses to wire the JR wall charger on the TX lead and the JR Tx charge jack with reversed polarity of everyone eles. The Battery agine is not reversed from the industry standard but the charge jack on the JR Tx's is.