If your batteries are all mingled up and you do not know which are still good to use, there are battery testers in the market to help salvage them from the lot. This is what I have.
Here is another way for you to test your battery life without any gadgets. See if it works for you too.
Can we find ways that will help us reduce our reliance on "gadgets" and be more earth friendly? A great activity to start working on for earth month, don't you agree?