So, I bought a new handset which is great (Huawei). However i still use my old SE handset for my emails. It normally loses charge within 4 hours of full charge, so I pop it on recharge overnight every night. This has been going on every day for over 2 months, charge, 3-4 hours use, dies, charge etc etc. Something weird has happened, for the past 2 days, it has gone back to normal, and having been on all day I still have around 91% left each night as I only use it for emails now. What would make the battery start working normally again? I haven't done anything different, but it just works again.