I have a 4 year old rebel t3, and I've been using the same genuine Canon battery up until a month ago, about. And normally, one full charge can last a few months worth of sessions. But the battery would die after a few days of not even having the canon on, so I figured the battery was old, and losing its ability to hold a charge.
But this is why I'm writing this post. I was low on funds, and about to go on a huge vacation, so I desperately bought an offbrand $10 battery off Amazon, fully understanding the potential consequences. But I'm having the same issue with it. I'll charge it fully, place it in the canon, have turn it on for a few minutes a day, and then it stops powering on after a week, give or take. This battery even has double the capacity, allegedly. What am I doing wrong? Should I replace my canon charger, too? Maybe this battery I just bought is also old? Is something wrong with my canon itself? (I don't know the life expectancy of these things.)
