You can try hooking up an ammeter to the battery to see if it is leaking current when it is Off. If it is, start pulling fuses until the leak goes away to find what area is causing the problem.
Did the battery tender go bad? I’ve not had one go, but have read of others that had one fail. Does it go dead in 2-3 days with or without the tender on? Triggerman is right about testing for parasitic voltage drain.2000 1500 SE model. I don't run extra lights or anything to drain the battery except a GPS and charging my phone while I ride. I routinely use a battery tender (which I also use on another bike and jetski alternating them). I had to replace the battery last July (after purchasing the bike in April). The battery is now dead and I had to replace it again.
The bike is ridden regularly. never sits for more than 2 or 3 days in the warm months and perhaps 2 weeks during winter (location is NC), and then the tender is used.
Suggestions on what to check to determine if the charging system is doing it's job...or perhaps overcharging?
+1 on the Compufire. That's what I put on my '89 3 years ago.Are you using a stock Honda alternator, or aftermarket of some type? I had the best luck with a Compufire alternator with my 1500s.