It's odd that riders who are otherwise anal compulsive about preventive maintenance never give a thought to the electrical system beyond changing spark plugs at tune-up time. Here are some thoughts from my friend Eddy who is a really smart engineer in California:
I was able to fix or at least very much improve the battery overcharging problem. I found that bad contacts in connectors were causing the regulator to sense a lower system voltage so it was regulating the voltage on the battery too high and it would boil off fluid. Cleaning connectors around the battery and regulator and filling them with lithium grease solved the high system voltage problem. I remember being surprised about the difference when I measured the battery voltage before and after the cleaning effort (with engine rev'ing at about 3000 rpm).I am a big fan of CRC Di-Electric Grease for this purpose. Take the connectors apart, clean off the corrosion, coat everything with goo, and put it back together. SOS or Brillo pads are good for this and less aggressive than sand paper. The CRC can has a snout that makes it especially good for shooting grease into the female side of the bullet connectors. Do it now unless you really have the urge to study the stars at night on some lonely road in the middle of nowhere. You know the one, it's unencumbered with cel phone coverage. BTW, this also makes a great points cam lubricant for vintage bikes.
I understand that the part of the battery plates that becomes dry will be useless when it is exposed too long to air. It oxidizes or something and this prevents the usual lead-acid interaction. So keep an eye on those plates and keep 'm submerged!
Speaking of things CRC, let me also recommend CRC Power Lube. It's everything WD-40 wishes it was. It is a real lubricant. It used to be called CRC 5-56 but I guess they thought the name was too geeky. Whatever... I buy the stuff by the case to use for everything that needs light lubrication. Great for freeing sticky cables, levers, and parts too.