Good question. I test batteries daily at work but for the DIY guy at home there may be a way-
I will have to find out what the amperage draw is from the starter while its cranking the engine some day when my truck is at work.
Knowing that may put us on track to a quick test procedure.
Maybe someone here already knows what the starter draws??
If so I can give you the test to do as long as you have a volt meter.
I tested my sons batteries (04. 5 original) the other day, they are 750CCA each and one tested bad yet the truck starts fine. This condition puts added load on the alternator and you wouldn't know it. he will replace the pair not just the bad one.