I picked up an Asus L402WA for less than $200 for use as a basic home laptop. Watching YouTube, social media, surfing the web. Basic tasks. It's great aside from the battery life. I'm only getting like three hours on a full charge. If that. I did update it from Windows 10 S to Windows 10 Pro. I've usually used Mac's in the past, so PC's are semi-new to me. Question is, would updating the BIOS or anything else fix the issue? I did find the below page on the Asus website. Would downloading any of those updates likely fix my battery issue? I read online that messing with the BIOS can brick the machine, and I don't want to do that. Thanks for any help.
its likely because you upgrade it to Windows 10 Pro. In Windows 10 S you can only have limited apps (only that available in windows store) it means less power and also it because you have 32WHrs batterywith 6h 27mins battery life running in windows 10 S (Reference: here). FYI, 2018 Macbook has 41.4 WHrs battery but it has one of best battery life with upto 10 hrs (Reference: here).
maybe you can get better performance if you update your bios but it wont give significant impact in battery life and I'm not recommend you to update BIOS without any expert guidance