If the charge in your VGN-FZ140N battery is dying out noticeably faster, you may need to replace it. Battery performance is affected by many factors like the environment, age and frequency of utilization.

Every battery has a certain number of charge cycles specified by the manufacturer and indicates the number of times you can charge it - this figure is around 400 - 1200 for a standard Lithium-ion laptop battery. Once this limit is crossed, the performance begins to deteriorate.

Depending on the devices available in the laptop and their usage, the battery might be able to power it for 2-3 hours before it needs to be recharged. Normal lifetime is in the range of 1.5 - 2 years. If you use the laptop continuously and recharge the battery several times a day; it may need to be replaced well before the time frame specified by the manufacturer.

These steps must be followed for battery replacement:

1. Buy a New VGN-FZ150E battery - Make sure you purchase a replacement that is compatible with your laptop.

2. Unpack the New VGN-FZ160E battery - Remove all packaging material and keep have the new battery ready to be popped in immediately.

3. Undock Laptop - If your laptop is connected to a docking device, you need to unlock it before attempting to replace the battery.

4. Turn Off Laptop - You may not want to lose any files you are working on or risk corruption of software, so it may be better to turn off the laptop.

5. Unplug AC Power/Internet Connection - It is a good practice to disconnect your laptop from the AC outlet, Internet and Telephone before replacing the battery.

6. Flip the Laptop Over - Most laptops have the battery release mechanism on the underside of the laptop. If you are not sure where you should look you can refer to the documentation of the laptop or have Technical support guide you.

7. Unlock and Remove Old PA3641U-1BRS Battery - Laptop batteries usually use a two-step locking mechanism, first there are latches that need to be released and then a sliding motion has to be performed to release it completely. Your documentation can be invaluable in this.

8. Position New VGN-FZ180E battery - Follow the reverse process for fixing the new battery. First slide and then latch the new battery. If the latches get stuck, you may need to adjust the positioning.

9. Charge Battery - Bring laptop to usual position; replace all the cables that you disconnected earlier, including the AC power. Charge your battery for the duration specified by the manufacturer before using it.