I was out on my R80 this evening and the dipped beam blew, I was about 1/2 mile away from home so I switched to the main beam and the cars would have to live with it. It lasted about 2 seconds. Literally. I pulled over and found that the side light had also gone (I don’t know when in the sequence it had failed) but the rear lights were OK. I carried on as there was little traffic apart a van that I followed. Ahem, sorry officer. The bulb is a standard power of Osram parentage - they have been in for about 20 miles after the last one failed.

So clearly there is an electrical issue. Other symptoms are that the battery doesn’t seem to be holding its charge too well evidenced by a sluggish turn over when starting.

OK, so my assessment is as follows.
1. The battery needs to be replaced (it is a gel battery and about 3 years old but didn’t get used enough for 2 years as it was off the road) - this change is planned anyway
2. The bulbs blew due to high voltage as I think the voltage regulator may have fried as a result of the battery being half dead so would need to be replaced.

Firstly question - do my assessments make sense and / or are there any other things that I should look at?

Second question - as it is a standard alternator and I am intending to replace it at some point for a 400W Endurolast system do I bite the bullet and replace the alternator now (as well as the battery) or just the voltage regulator (assuming it is fried)? I am not fixated on the Endurolast system but I am not after vast amount of power either as I am not planning on running anything with that draws much power but could do with a little more than the standard 280W (having said that is the 600W on sale at Motorworks worth looking at?).

For the record the bike is an R80 Mono from 1986.

Thanks for any advice.