Need info on extended life or ULtra XL battery

I have an Ultra XL battery for my HP 6910p which theoretically should give me (with my INTEL graphics card) 15 hours.
This morning my main battery was 12% and I hooked up the Ultra travel battery which was fully charged.

In XP the battery Icon in the taskbar showed only 68% full and a life time of 5 hours and 48 minutes. When I double click the icon I get to see the status of the 2 batteries I have where the primary is 12% full and the travel is 99% full.

I am not getting why I don't see a lifetime of approx 10 - 15 hours but just the 5 hours and 48 minutes - currently even 2:35.

Are there any users of extended life batteries or Ultra XL batteries that can confirm that they have the same or let me know what reading they get.

I tried to talk to HP but was unlucky enough to get someone that did not have a clue and which told me you will never see more life time than that of the main battery, i.e. 5 hours 45 minutes ?????

Hope some of you users can clear this up for me

 

You can get some serious battery life with the Ultra XL battery! Have you contacted the manufacturer?

 

I already open a support case at HP but wanted to do some further testing

Do you know if when using an additional battery like the ultra you would have to see the full life time in your system tray ???

 

Try with the fully charged primary battery and travel battery. The travel battery alone will not give you 15 hours, but combined you should be able to push the 12 hour mark, depending on brightness etc.
Also allow the fact that the battery needs to be used a bit before it actually holds it charge (like running in a car to get the drivetrain etc smooth so you can boot it later )
Also the read out that Windows gives is dependent on instantaneous load, so it varies all the time.
If you're really paranoid, download HP's battery health check software, which determines the status of the batteries installed, and the condition of the cells.