Let the battery completely die while letting it play video. Then when the button flashes red indicating its low on charge like 1% hold the button till it dies completely and then charge the battery again. That should get some extra electricity out of it.

Dell laptops use Li-ion batteries which have high performance with a short lifespan and their swelling can damage your laptop. Dell recommends buying a new Dell laptop battery when the battery run time does not meet your needs (Here). Create a Win10 Battery Report and go to bottom of report to see Battery life estimates. 

When I said drain the battery. It’s supposed to clear any excess voltage in the system and he should try powering it on when it dies and then replugging it in and checking if it fixed the issue.

For the typical user, noticeable reduction in run time generally will be observed after 18 to 24 months. For a power user, reduction in run time generally may be experienced within 18 months. We created a Win10 Battery Report (Here) and note that our 17 R5 main battery fully charged life is now 1:49:02. If your 15 R4 main battery life is very low and continues to drain after complete shutdown, you should consider getting a new main battery.  

new Battery:

https://www.amazon.com/Tinkerpal-ALW17C-D2738-ALW17C-D1738-ALW17C-D2748-ALW17C-D2758/dp/B07Z32BY4R/ref=sr_1_1_sspa?dchild=1&keywords=alienware+15+battery&qid=1594630290&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFBN09XV1pROThXUjgmZW5jcnlwdGVkSWQ9QTA2MjY5OTRYNEdGUkdJTDhLV0UmZW5jcnlwdGVkQWRJZD1BMDMxOTQ4NTJONDZXRU1GR01GUlQmd2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl

Hey, thanks for the suggestion.

I tried it and actually my laptop didn't shut down even after battery showed 0% and it ran for about 40mins with screen brightness and a video running in the background with google chrome open.

Now my battery life is better than it was before.

Hello @Aravind_Korada thank you for the update that your laptop is working. It should be possible to run the laptop on the mains when the main battery run time status is 0%.

Did you create a Win10 Battery Report to look at the main battery run time history? If the main battery is ok and battery report says charging suddenly stopped, further investigation should be conducted to determine the problem. 

If the old battery is unserviceable, it should be removed so that it does not damage the laptop at some future date. 

These are the limitations of your Alienware laptop. I am sorry but the battery drainage issue that you face after shutdown is a consequence of the Alienware limitation:

This is working as designed due to the hybrid power design on the Alienware 15 R3/15 R4 and 17 R4/17 R5 systems.   Under heavy loading environment, the system may require more power besides of AC adapter as to meet the system power requirement, and the battery would be triggered to provide the system a certain amount of power in this case. Therefore you may experience that the battery capacity keeps dropping even when the AC adapter is connected. If the remaining capacity is lower than 20%, the battery would stop supporting the extra power requirement and cause system throttling (stuttering/lagging/throttling).

Hello @RuskinF thank you for the clarification that the laptop requires a fully functional main battery to meet all power requirements. Do not know why @Aravind_Korada is seemingly reluctant to create a Win10 Battery Report when it is not difficult. 

Hey @crimsom 

I did create one before following your suggestion and after discharging the full battery. After following your suggestion battery time increased from 1:44:51 to 02:03:18.

Hello @Aravind_Korada thank you for the update. Although the images do not display, the text reveals that your laptop is now fully functional. This is an excellent outcome for your thread. Kind regards.  

glad my suggestion worked for you @Aravind_Korada.

Does it charge to 100% again aswell as the draining issue gone?

Yup and now even after shutdown my laptop runs normally when turned on again.

Well that’s Amazing!

Hopefully you can accept my solution to this question as answered so people don’t get confused if the question still hasn’t been answered.