Hitec and entry level Futaba radios have diodes in the charging circuit tha prevent using a voltmeter to check voltage. They can easily be bypassed to use chargers that detect charging activity by sampling what's in the battery. I use a Siruius charger and have "jumped" all the diodes in my transmitters. If you go to the Peak Electronics web site or do a search for Sirius Chargers, you can find a link to the diode sheets that explain in pictures how to do this. I am now using a futaba 9C that does not contain a diode.

DaRock-- in an earlier post, you mentioned using a volt meter to check the battery capacity. My voltmeter will put a load on the batteries but will only read the voltage, not how much is left. The only way I know how to do this is to discharge the battery and see how much has been used. I know some cyclers will do this, but i don't know how to check capacity with a volt meter. Am I missing something?