Solar charger blowing fuse?

[AldeanFan]

I have a 40w solar charger that I mounted on my travel trailer to keep the battery charged. I've been using it for about 2 years with no issues.
Last week I put in a new battery and now the fuse in the line from the charge controller to the battery blows.
Electrical isn't my strongest skill, where do I start?

 

[Rookie2]

Was the battery fully charged before you installed it ? might be the problem. Or global warming is producing too much sun ! My Bad !

 

[AldeanFan]

Was the battery fully charged before you installed it ? might be the problem. Or global warming is producing too much sun ! My Bad !

I didn't measure the voltage when I bought the battery but it was brand new. As of last night it was at 12.8V after i had the trailer plugged in to the house for an hour.
The panel didn't have a problem charging the old battery from almost dead.

Maybe it's just too sunny!

 

[Rookie2]

Odd, look for a wire worn thru or a wiring problem, i think the panel go's through its own regulator and diodes to prevent back feeding.