Can I plug my battery tender into the heater plug
 

Will it work

Why wouldn't it? Make sure polarity is correct!

whats a heater plug? would polarity even matter if its AC?

I have a YUASA battery tender. The connector is un-marked as to polarity. Last night I hooked it up to charge a Gel Cell battery on my workbench. The first try, I had polarity reversed. I just touched the lead briefly... and noticed the charge LED lit RED (instead of the normal green) to alert me that I had to reverse the polarity of the lead extensions. I swapped them, and it started charging the battery. :-)

If your battery tender is as smart as my YUASA unit - it should tell you if polarity is incorrect.

Red usually means its charging or that it needs charging and green means its done.

I know charge is DC, but I simply do not know what a heater plug is...

Acualy I'm not sure what the plug is for that sticks out beside the seat. I assumed it was for a heated vest or something

o ok, now i got a much better idea about what ur saying... yea keep polarity correct and ur good, assuming the funky thing is hooked up right n such, i know my bike doesn't have a plug hanging off stock lol.

The thing that sticks out under the seat is for a battery tender. Lucky you someone pre-wired the bike for ya.

So all 09's don't have that? :o
I got the bike with 200kms without a scratch on it in what I thought was completely stock form.
It works with my heated vest also but that kills the battery.