Modern Vespa

Hi everyone,
I changed the front bulbs on my Vespa ET 4 (150 Leader). The procedure was that I disconnected the entire light cable. I may have made a mistake, that after connecting the light and cable and having the keys in the starter lock, it was in the on position .

After about 8 starts, my battery ran out and after recharging it, after another 8 starts it ran out again (no problems with battery before changing bulbs)

I bought a new battery because the original one was older.

I rode on this battery for a whole week but with the front light off (20 +starts). The battery held up just fine until I turned the front lights back on. The battery then didn't last a few starts.

Is it possible that I caused an electrical short circuit in the lights (conectors?) that drains the battery when they are on?

Please do you have any recommendations on what to do and what to measure??

Thanks in advance for any advice

The headlights work on AC, not DC, so can only have any power when the engine is running.

However, have you checked the fuses? If the fuse between the stator and the battery has blown, you won't charge the battery.

Even if the fuses are OK, check the voltage at the battery, as the regulator may not be functioning as expected:
Off: 12.6V
On, idling: >12.6V
On, revving: >13V, <15V.