The batteries can be checked if its original or fake by looking for signs of poor quality on battery placement such as: inaccurate printing, misspelled wording, crooked label placement and signs of defective workmanship. Some mobile phone manufacturers also place hologram stickers on their batteries, which are difficult to replicate by counterfeiters – although they do try.
Also other points to be noted are the battery life or power of the phone, how fast the phone charge is draining and check if the phone has been repaired or not previously.