Regarding the charging system:
My service manual indicates the alternator/regulator can provide 22 amps @ 1200 rpm, and 36 amps @ 3500 rpm. If we assume the low rpm case, and lets say 13 volts, we get (22 amps) x (13 volts) = 286 watts. At the higher 3600 rpm we get 468 watts. My quick check suggests the fans may be as high as 85 watts each (ouch). The tail/running lights should be less than 30 watts total (don't stand on the brake, and run the turn signals all day), and the ECM/TSSM/... is under 1 watt (mine measures 0.87 watts when the fuel pump is running). So if this is correct, we have:
65 watts (stock headlight high beam)
85 watts (fan 1)
85 watts (fan 2)
21 watts USA (tail/running lights), HDI model is different here
1 watt (ECM/TSSM/...)
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= 257 watts USA
Comparing this to the 286 watts output by the alternator/regulator at idle, it seems that the battery should stay charged, even at idle with the fans running. The HDI (international) model has different blinker and running lights, so this calculation does not apply there.
I'm probably a bit high on the fans, so in reality, it's probably even better than this. And, I'm guessing you would be in quite a unique situation if you leave your bike idling for a LONG time (tens of minutes or hours), and the fans are running the whole time (VERY hot day).
But, if you hold the brakes on (29 watts for brake light), and turn the blinker on (29 watts average for 50% duty cycle), then you might exceed the capability of the charging system. But that would really be an odd situation. So, I still say the charging system should keep the battery charged, even when idling.
Now, for a twist. The three wires coming out of the alternator on the left side cover of the motor have a screw clamp inside the case to hold down the wires. I have seen where that clamp and wire routing was not done perfectly, and metal wore through the insulation and shorted out (to ground) one wire from the alternator. If that happens, you will not loose 100% of the charging capability, but you will loose enough that the battery may not stay charged. To check for this condition, you only need an ohm meter to check for a short between each of the three wires, and ground. There should be no electrical connection between any of the three wires and ground. There are further more elaborate checks of the charging system that are explained in the electrical manual, but this simple check with an ohm meter is really easy to do.