I have an HP ProBook 450 G3, it's about 3-4 yrs old. I recently bought a new battery for it becuase I was having a problem with the old battery being completely dead after I let the laptop sit unused for a couple of days (I figured the battery was just degraded after having it for so long). Well now I am having the same exact problem with the brand new battery I just purchased 2 months ago. The battery was fully charged when I put my laptop aside for a couple of weeks, now as i was about to use it I tried to power it on and it does not turn on because the battery is completely dead. At this point it can't be the battery it has to be the laptop that is causing the power drain. I went into control panel>power options and set it to balanced. I also made sure that it was set to turn power off when lid is closed. Intially I had it set to power on when lid is opened but I thought maybe the lid was opening when I put the laptop in my laptop bag and maybe it was turning back on, but that can't be the case anymore. If anyone knows what the heck is going on and can provide me with some insight it would be greatly appreciated because this has me stumped.