Got some Nikon D5000 doubts and queries?

I have a new Nikon D5000 and i forgot my battery charger back home and i'm on a holiday now. I went to a shop and asked for the charger. After that i did the stupidest thing ever by giving the lady my camera battery. She took it somewhere inside and brought "it" back with the charger for the battery. Now the charger doesn't blink while charging like an ordinary charger does but it charges the battery. Also, the battery drains out pretty fast. I wanted to know if I'm using a duplicate battery or something like that and will it have very bad effects on the camera.
Also, I wanted some tips on taking care of the camera!

Your issue is with the way you have used your Li-ion battery. And has nothing to do with the D5000

* One thing that can really damage Li-ion batteries is to let them sit for days fully discharged
* generic battery charges do NOT have the safeguards that prevent overheating or overcharging, both contributors to damaging Li-ion batteries.

Generic batteries are also a bad idea.

There's a proprietary communication that goes on between the Nikon Li-ion battery and your camera as well as between it and the Nikon battery charger missing in generics

Try to find a camera store with a reputation for being honest, and get a new Nikon battery and charger.