My phone came with two 2500 mah batteries. its called a cubot a8809. its not very well known. Anyway, I've had it for at most 3.5 weeks and It started to tweak with the charging. First of all it has a lot of trouble charging. And when it does charge it takes FOREVER. it takes 2 hours to get it to 60%. and the highest it's ever been charged to since this problem started arising is like 70%. this has been going on for 4 days now. Also it loses battery really quickly. The other battery just won't charge