How to Know When It’s Time to Replace Your Laptop Battery

Most laptop batteries would fail within 2-3 years after it has been bought. There are numerous signs that you may observe when it’s time to replace your laptop battery. The first and most obvious thing is the backup time. It will be considerably lower on weak battery. Even if you charge to full, it will warn you to recharge after half an hour usage.  Also another important point to note is that, the charging time would be surely reduces to less than 1 hour. The normal charging time for a healthy laptop battery from 15% to 100% is about 3 hours (It might vary according to capacity). This two symptoms can be taken as a sign of poor battery operation which can only be treated by battery replacement.

There are numerous ways to make sure your your battery is reaching death before you buy a new one. There are plenty of apps out there to check battery health. But here’s two methods that you may do to confirm your battery inefficiency.

1. Soft testing: Generate a detailed diagnosis report of your laptop’s power management system.

2. Hard testing: Testing your battery terminal voltage using a multi-meter and compare the results with rated/printed values.

After both these tests we can conclude whether the battery should be replaced or not.

Generate a diagnosis report of your battery charging:

Within Windows 7 or 8 we can create a detailed report of it. Follow these steps:

  1. Click Start button and type cmd in Search box. It will open the command prompt window.
  2. In the search results, right click on the cmd.exe and select Run as Administrator.
  3. To change the path to desktop where you generate the log file, type cd %userprofile%/Desktop and press Enter.
  4. Then type powercfg -energy in cmd and hit Enter key.

If you’ve done all as per instructions then it will display something like below after 60 seconds:

Batt1

Also there would be a log file named “energy-report.html” in the desktop. Opening it will show you like this:

Power Efficiency Diagnostics Report

Computer Name: DELL_XPS
Scan Time: 2014-04-11T13:29:07Z
Scan Duration: 60 seconds
System Manufacturer: Dell Inc.
System Product Name: Dell System XPS L502X
BIOS Date: 09/07/2012
BIOS Version: A12
OS Build: 7601
Platform Role: Mobile
Plugged In: true
Process Count: 95
Thread Count: 1044
Report GUID {81fa245e-a666-418a-b4e4-dc040790e503}
Analysis Results

Errors

Power Policy:Sleep timeout is disabled (Plugged In)
The computer is not configured to automatically sleep after a period of inactivity.
Battery:Last Full Charge (%)
The battery stored less than 40% of the Designed Capacity the last time the battery was fully charged.
Battery ID 379SANYODell
Design Capacity 57720
Last Full Charge 11500
Last Full Charge (%) 19

As evident from the Errors section the battery is storing less than 40% of its designed capacity on full charge which means it is currently backingup the laptop for less than fourty percent of the initial backup. This battery may last 3-4 months more but not more than this.

Test battery terminal voltage

For this you’ve to know how to use a voltmeter or multimeter.

BATTMM

1. First charge your laptop battery to full.

2. Turn off your laptop and take battery out. Note down the imprinted voltage rating. Normally they’ve a voltage rating of  9.6V, 10.8V, 11.1V, 14.4V . For a reference mine have a 11.1V battery.

3. Look for the battery connector. it will have copper leads that can be attached to laptop body while fixing. Refer the below diagram to find the positive(+) and negative (-) pins. They’re the two outermost prongs.

Battpin

4. Rotate the multimeter to DC voltage measurement mode in the 20 volt region. Connect the probes to positive and negative leads of the battery and read the voltage. A fully charged healthy battery will show a number which is very close to the rated voltage.

5.  Discharge the battery to 70 % and try measuring again. A fully drained laptop battery would never give a value near zero if it is healthy.  A few volts will be there. When the laptop battery voltage drops below a threshold, the protective circuitry in the battery will shut down the laptop to prevent battery damage.

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