5100 or 5100r

[Caldwell 3]

Ok, what's with the reverse polarity deal here? What is the benefit? I'm guessing I would have to wire the 5100r different from the 5100 when running it as a second battery? So the black is actually the +, and the red is actually - ? Is the point in this so you can wire it in series?

[gss 11]

positive is still positive and negative is still negative, the terminals are just reversed to fit specific applications. For instance a 92-00 civic uses a 51R and a 01-05 civic uses a 51, same battery just with the terminals on opposite sides.

[Caldwell 3]

Ahhhh ok, makes sense