I finally got around to investigating what went wrong with the my Ariel NH last time out – very weak spark and general loss of electrical power. The Boyer Bransden unit really is not happy with low voltage. After a lot of low speed puttering I did get home. I assumed that my rewired (again) alternator system had died (again), with the alternator brushes being the prime suspect. Turns out I was wrong. The new battery had died – shorted out a cell by the look of it – which pretty much pulled the system down to 10 volts. Probable reason for the battery death was loose screws on the battery platform resulting in excessive battery shoogling. These batteries were suspiciously cheap, and shipping expensive,  so I did get two of them. Filled up the spare and all is well. They are Power Sonic brand equivalents to the original Yuasa 12N5.5A-3B. I selected this size long ago and made my battery box to fit it using leftover Sun server rack panels and a offcut piece of teak from Tantallon Castle bridge (wot Dad made). This is a hard battery to find as it was only used on mid-70s Yamaha RD400 machines.

So it is time to sign up for the BSA club annual gig in San Jose. Maybe I will brave the run this year.

In the meantime the kickstartless New Bonnie’s battery is now too weak to turn it over, so I need one of those too – and those are not cheap.