Originally Posted by tmex
I have a 2005 12GS and a 2006 HP2. Both are hard on batteries. It is not a software upgrade issue or an accessory issue. With the ignition switched off I carefully measured the current drain on the battery by putting an amp meter in series with the battery cables. Both bikes showed an off current drain of about 5 milliamps. The stock battery will lose enough capacity with this current drain to not be able to start the bike after about three weeks time (at normal temperature - less than three weeks at low temperatures). It is an unavoidable fact of life that you need a battery tender if these bikes are not used regularly (every week or so).
Seems you have confirmed what I implicitly knew as true. Thanks. Amazon sells the Battery Tender as low as 25 bucks, and the Battery Tender Jr. as low as 19 bucks. Surely a wise investment. DON'T FORGET, can't use CAN-Bus.
BTW, I also have a 'pig-tail/SAE plug' going directly to my Jeep Wrangler. Was surprised, left Jeep with GARMIN 478 and GXM-30 on for two days without running. Dropped the starting voltage on the Jeep to below starting level.