I pulled out the 2006 Harley "Parts & Accessories Wish Book" and found some information that might help.

They sell the Battery Charging Harness, Part Number 94624-97B, and has a retail list price of $7.95.

Works with HD chargers, Deltran chargers, and probably everything else.

Not sure about the HD Chargers, but I prefer to use the Deltran Waterproof Battery Tender, as it can be used outside in the elements/rain/snow/whatever....

Here is the description:

"Heavy duty battery charging harness with ring terminals and in line 7.5 amp fuse protection for attachment to a Harley Davidson 12-volt battery. The wiring harness utilizes a plug connector that is compatible with all Harley Davidson battery chargers equipped with black connectors. The ring terminals are attached to the battery with the harness routed to allow access for the plug connector attachment to a HD battery charger. The harness plug connector is protected with an attached weather shield cap when not in use."

Not a good picture, but this is the HD harness.

 

I ride 'year round', but within limits..

We sometimes hit minus 10 (or lower) during the winter months, and that's the time to break out the ole Jeep Grand Cherokee.

 

Hell, I think the world would stop if it hit that low down here. I know I'd be holed up in the house crying like a little girl. That's why I left Ohio...well, that and a LOT of other reasons.

 

Like the others have said it is the battery tender/maintainer plug-in. I have one and it's great for keeping the battery up-to-charge while the bike is sitting.