Battery occasionally draining over night

[HarryHornby]

I had to push start the bike this morning.  Battery was flat as a pancake.  It happens about twice a year.


Once bumped it then charges fine during my 30 minute ride to work.


The bike isn't necessarily left for a long period of time, for example I rode it Monday, it was dead on Wednesday.


Got a chap at work who was a mechanic in a former life, sat there, pondered and came up with the regulator.  Sounds plausible.


I did wonder if I had locked it with the parking lights on but I don't think I did/have done.


Ideas?

[BBROWN1664]

My money is on the parking light being left on if you can leave it the same sort of time (or longer ) on other occasions without an issue.

[darrsi]

Alarm?

[bandit]

How old is the battery? charge up on a optimate type charger that accesses it's condition.

[HarryHornby]

no alarm.  Battery is about a year old, I bought a new one after it suddenly drained last year and I didn't know the age of the battery because I'd only had the bike 4 months previous.