I would not use any Android smartphone without an extended battery cuz hardcore high-end gaming, heavy internet browsing, constantly syncing and heavy use of streaming audio would simply make me recharge it every 10 hrs with the stock. 2 days on my S3 with 6000mAh battery out of mpj really changed my world, but as much as I'd love to slap on the extended battery, I still don't like the extra bulk and the fact that it stop being compatible with my case.
So... I like extd. battery rather than keep swapping backup batteries. I know there are tons of cheap batteries which i assume they were removed the original label from expired batteries, put a fake and sell on eBay for really cheap money. Only trust those with brands that highest quality cells are used to produce these batteries, more capacity is achieved than OEM, and at least one year warranty. I just want to figure out why is these stuff in some sort of underground when it comes to friends around me