Laptop shutting down when the battery reaches 25-30% without warning

It seems that it considers this a “critically low voltage”.

Rather than run until it just dies, At some voltage, your laptop decides to give up. To Take its remaining energy and gracefully shut down.

1. Click on the battery meter on taskbar & click more power option.
2. On your current power plan click change plan settings.
3. Click on Change Advance power Settings.
4. Scroll to botton and click the + sign of the battery, a list will appear at bottom.
5. Click on low battery level and change the following setting:

on battery to: 40 % (if ur system shut downs at 30% this will warn you battery low at 40%)

now click on Critical battery level and change the setting to 35%.

now click on critical battery action and change the setting to hibernate.

This will hibernate you system before the battery is over and prevent it from sudden shutdown. If possible set the battery %age to little more less as the sudden shutdowns differs everytime.

Charge to 100% then let it work until it dies then recharge. If same thing happens, buy a new battery.

Also do the following steps and see if it helps.

Switch of everything and unplug the charger from the laptop.
Take the battery out.
Plug the charger to the laptop and the power supply and switch your laptop on.
If it switches on, your laptop is OK, the battery is probably the problem part.
If it switches on, again turn it off, unplug, put the battery back and give it around 10 minutes charge and then switch it on.
Give it full charge.
Then try it again on battery power only.