When your current battery finally quits, I would suggest an AGM type battery .
If the bike doesn't get ridden frequently, a battery 'tender' is a good way to keep the battery at full charge .
Two mods that I did recently on my R65's, was to replace the negative cable from the battery to the vent bolt on the transmission .
I used a pre made cable from an auto-parts store and moved the grounding point from the trans vent bolt, to the forward side of the lower right engine to transmission bolt .
The other was, I made up a heavy gauge wire (10 ga US wire size, 3 sq mm) and ran it from the main grounding point for the bikes electrical systems (on the '81 and later bikes) the voltage regulator attach screw/bolt, back to the negative post of the battery .
A 330 ohm resistor placed in between the two wires for the 'GEN' light in the tachometer, will prevent the loss of your charging system, if the light bulb for the 'GEN' light burns out, (yes, it's that important!!!!!!)
One thing you may want to do, is to go through all of the electrical connections on the bike and make sure they are clean and secure .
The two most common charging system failures are the diode board and alternator rotor .
There are aftermarket replacements for the diode board that are a heavy duty part that can handle the job better than the OEM part and are in the same price range as the OEM part .
The after market charging systems are a bit pricey, the Omega from Motorrad Elektrik is $575US, the Enduralast from Eutomoto Electrics is  $500US .
A comparison test was done of both charging systems by Snowbum, an engineer turned BMW enthusiast .
The test showed the Enduralast system was not putting out anywhere  near the rated wattage, don't know if that was just an issue with the system they tested , or if it is what the system really puts out .
http://bmwmotorcycletech.info/AftrMrktAlt.htm