Elitebook 8540w replacement HP battery?

[BigNich]

As far as battery life goes, there is a host of factors that can determine this, and many things you can do to help preserve or prolong the life.  I believe that is an 8-cell LIO (Lithium Ion) pack.  with LIO battery packs, the two most important things to remember is don't let 'em get hot if you can avoid it, and they generally do better with partial charges rather than the deep-cycle charging recommended for NiCads.  there are several articales out there, suggest

http://www.techrepublic.com/blog/five-apps/five-tips-for-extending-lithium-ion-battery-life/

Also, you might see if you can get Amazon to ship overseas, I really don't know if they support that or not, but you can probably get battery packs for as little as 20 USD if you can stomach the shipping cost.

What i would recommend is looking in your manual to see if you can find any power consumption numbers, then determining the longest time you would need to be on battery power, and doing the math.  most batteries i see are rated in mAh, or milli amp hours.  to convert to Wh multiply the voltage by the mAh rating and dive by 1000.  so a 14.8V battery rated at 5200 mAh would nominally be rated at 76 Wh.  Divide by your power consumption to get expected hours on a charge, so if your laptop consumed about 7.6W, you could expect to get about 10 hours of charge.  Remember, though, the while the math is an exact science, the reality is not.  Heat, more apps, more disk access, running the DVD, brightness, are all factors