Power supply or motherboard problem on Acer Travelmate 2702Wlmi?

Hi, I can not recharge the battery of this laptop when it is on, this is a known problem, I know, but everything should work perfectly only with power supply connected and no battery. Infact it is so on my laptop, but lately ( from last week ) when I connect the external power supply to the mains after about 8 hours that was disconnected and immediately connect to the laptop, this takes 3 attempts to start: lights for 1 second and immediately off, so the second time , third and finally turns on perfectly. I hope and believe that the external power supply needs little time to provide proper tension, but may persist (beyond the pin which prevents the battery charging) another component that blocks the input voltage for a bit '?

the LED of the external power supply is always green when connected to the mains (even after days it was disconnected), I can not understand his behavior.

Help please