I need a power calculator for my laptop

Hello techyv.com!
I was kind of pissed on my laptop because I've already bought two power supply, and it drains power so quickly for like 1 hr only. It wasn't like this before, I thought that if I bought new power supply, it will be good as new in terms of power, but it wasn't. So I want to know why it drains so much power, please teach me on how can I have a power calculator for laptop. Is it a hard ware that I would insert via USB port? or is a software that I need to download. Please teach me, thanks!
