mbilar1,

I think on your transmitter/receiver wall charger it says how many hours you should be charging them for. If its not there i know the receiver battery pack should say on it how many hours it should charge for. Funny to say actually..... but i discharge my reciever pack with a christmas tree light bulb (the small ones) till the bulb goes out/burns out. usually goes for a few hours. i do this after a day at the field. Then i recharge the pack the full charge time of 12-15 hours.

I think the only thing the extra charging might do is affect the memory of the nicad cells overtime. overcharging gradually overtime could possibly reduce the life of the battery and affect the voltage it can take, ability to hold charge, effectiveness, etc... Others will have to add to that question, im not 100% positive.

As for a thing to measure voltage, i just use one from the hardware store to check when i start charging, when its done charging, and when im done flying for the day. Just a standard digital voltage reader would work great for what you want.

-David