Neil, did you think about replacing your Bb battery with a LiFePo4 one?
I changed in both, XC300i and BMW R1100RS to this accus (other scoots as a XC 500i too).
No probs at all since 9/2023. Has the advantage to keep voltage around 13V DC and even over longer periods of no charge, nearly no discharge.
Price approximately the same, less weight but only half of amph, so you need a 14Ah as a substitute for a 7Ah which is usually mounted in our scoots.
No change at all (against voices of socalled experts) to scoots or motorcycles charging system neccessary.