Tech question: When are batteries 'toast'?

Can someone help me out here? I don't do this often enough to remember.

When measuring my BP-511 batteries with a meter, how do I tell when it is still good to hold a charge? Is there is definitive over/under number I should be aware of?

I have a couple batteries that can't seem to hold a charge anymore, so I'd like to verify they are toast before I get rid of them.

Thanks.

Simply testing a battery with a volt meter generally isn't enough to tell if the battery is bad or not. You need to test the battery under a load to determine if it is good or not. If they crap out in your camera after a few shots, they are toast. That's the only definitive way I know of telling.

I agree with CRN3371. Makes no sense to keep data on your batteries.

When I get less than 200 shots off a full charge, I toss (or rather, recycle) the battery.
Also, if you see any sign of corrosion on the battery, get rid of it asap.