Got a HP Pavilion dv5-2130us two years ago, now the battery not working properly, how can I fix it? 

We all know that a battery have certain life span, after a long time usage, the battery will not be satisfying as good as the first time you got it. This article tells you some way to get your battery back to track,(if possible). I'd like to take HP Pavilion dv5-2130us as example.

The technicians generally would recommend you to calibrate the battery first. Try this:

• Plug in the AC adapter and charge the battery until it reaches 100%.
• Disconnect the AC adapter than open the Power option and create a new Power Plane and name it Calibrate and click on next. In the On Battery choose "Never" for all topics.
• Click create. Than let the battery discharge completely until the Laptop shuts down (save your work)

Now the battery is calibrated connect the AC and restart. Now you can change the Power Plane back to your usual Power Plan.
 

You could try updating your BIOS, which is the second advice.Be careful when updating your BIOS, make sure you are using the correct version and do not interrupt the process.  When the update is complete the computer will shut down (not restart).

If these don't work, then you may actually have a dieing battery.You may considering buying a new battery in storebattery.co.nz.