OKay, so no click at all when you hit key, about right?? Would still suspect the battery. You can charge a battery and the meter will say it is fully charged but if you take a load tester and do that test you might discover that the needle is sitting either in yellow or in the red. Means that, internally, the plates are getting old and losing their ability to take care of business. Possibility one of the plates has shorted out against another. After that, you need a helper because you will have to lift the car and put it on jack stands high enough that you can slide under the front end and gain access to the starter. First would be a visual check of the solenoid to see if all the terminals and studs are in good shape. Then what I would personally do is be under the car with a multimeter that has the audio feature, set it to volts in the 50V range, attach pos to the large battery stud on the solenoid and neg to ground and then have your helper, VERY CAREFULLY turn the key to on. Read the meter or listen for the tone. If the needle swings to "12" or higher on the meter or the tone is correct then you have power to the solenoid. If nada, then start checking your battery circuit for that buggered fusible link that was mentioned above. If you get the needle swing or the tone, then it is something in the solenoid to the starter switch; start with the fusible link again and look from there. Corrosion and broken connections could be the enemy here.