I am working on converting my Garelli SSXL from 6VAC to a 12VDC setup, replacing the horn with a 12 VDC version and the bulbs with LEDs.
I also want to be able to charge a phone/tablet.
With the stock lighting coil the voltage can be as low as 3.5V at idle under load to higher than 55V at full rev with no load.
So to covert to DC and prevent over voltage I am using a rectifier / regulator from a 85 Honda motorcycle. It keeps the voltage at 14.5v max at full rev with no load vs the crazy 55v+ without it.
Then to fix the low voltage at idle and / or under high loads, ex. using the horn / charging a tablet... I ordered a DC-DC step up board from china off ebay. Rated for 3.5-30V, 6A - 10A max.
I also just ordered a 10000uf capacitor to replace the 2x 560uf capacitors I am currently using, as they are a bit to small.
After replacing the capacitors I should have a stable 13.5-14.5 VDC output at any rev and hopefully with enough current to run the LEDs, charge a tablet, and sound the 12V 2.5A horn if needed.
All without adding battery or replacing the stock coil.