How to tell if a (chargeable or not) battery is bad?

[swampwiz]

Somehow I've never really known how to tell if a battery is bad without simply using it and seeing if the device it is powering doesn't work, an experiment that can get tricky trying to isolate a singe battery in a device that uses multiple battery cells. I figure that it is some combination of voltage and internal impedance - i.e., which is an effect of the ability of a battery to deliver a current, which is why in that "The Mechanical Universe" episode, a lemon can be made into a "battery" that can generate a voltage but not much current.

I have a pretty good digital multimeter. The motivation for this question is that I'm trying to take pictures with a digital camera (i.e., a real camera, not a smartphone) that requires rechargeable batteries, but all my batteries like that don't seem to work (I'm charging them as I type.)

 

[Bystander]

Find resistors that match loads for the various gadgets, measure voltage(s) across just the battery, and then across the battery plus the "dummy load." Excessive drop is a bad battery.