I have a 2001 sundancer 260 and...

[jrad]

I have a 2001 sundancer 260 and experiencing draining power even when the shore power is plugged in. 2 brand new marine deep cycle batteries installed. Any idea what could cause this? 

[gregk]

I would try putting a volt meter on your batteries to confirm your battery chargers are working when plugged into shore power. I assume you can see the charging lights are on?

[Brite_Idea]

Start with a multimeter hooked up to the battery directly and turn everything off. First see if you have a voltage drain without anything on. Next one by one power up your systems until you find the source of your problem. Shower sump float switch is a suspect.