I have an 03 Deuce CVO and just put a new battery in it. Rode it for one day and now both terminals melted on the battery. Any ideas what the problem could be? Thanks for any help

 

Why did you replace the battery to begin with? Might be just continuing issue.

 

Usually means your terminals were loose.

 

Have there been any resent mods?

 

I have found that newer batteries have some type of coating
on the lead terminals. Maybe they are not lead??
I found a couple of grounding problems with these newer batteries
at the terminal that was corrected by a wire wheel brush/dremal tool.
A car mechanic friend said to take a wire wheel or file to the terminals before installing.

 

bad connections (loose, coating, etc.) to battery terminals or a dead ground to something on positive side.

 

^^^Agree w/all above^^^

You're cook'n something...bad connections.