1996 ultra classic new battery fully charged it will start once then it won't battery shows 12.7,it will start then the voltage will drop below 7 radio stops working but then turn it off it just clicks put the battery on charge for 10 minutes it will start ,if you idle high voltage stays up let off of the gas it drops all the down to nothing.Help I need some advice please.thanks.

 

Fully charge it - overnight and have it load tested. Just because it has voltage doesn't mean it wasn't damaged or defective.

 

I'll bet your stator is toast and it's not recharging the system.

 

Battery is toast.
Replace it.

 

Put a voltmeter on the posts when running and watch it. If it's dropping fast it's probably not charging. Don't fully discharge the new battery you will kill it.

Edit: check the stator plug in the primary, is it burnt?

 

10 minutes should be 10 hours more the likely. That low voltage when you hit starter means hopefully the battery is highly sulfated from sitting. Do not use a full size charger on it. If you are still having problems and want me to, I will post a check list to run down with a simple volt/ohm meter to answer all your questions.

 

Sure sounds like a loose battery cable to me.I've seen this exact problem probably 100 times.Remove pos cable,clean post and cable ends.Remove neg cable,clean post and cable ends.Re-install cables and TIGHTEN the bolts.

 

By all means, start with the cheapest fix first, but I'm laying 2 to 1 odds is the stator.

 

Here is a way to check your charging system.
https://www.hdforums.com/forum/evo-c...ng-system.html

 

Possible a bad new battery or a short somewhere.