a NORMAL 4 cell pack can be used down to 4.5 volts with no problem. Right after charge, it will be high like you read but that peak charge comes down very rapidly to a plateau of approximately 4.8 volts and will hold within a few tenths of a volt for a long time. It is easy to make your voltmeter provide a load to the battery when you check it, just parallel a 22 ohm one watt resistor across the leads while you are measuring the voltage. do be little Leary of the accuracy o your voltmeter. If you have a friend with a known calibrated one, compare them. Some of the cheaper ones do not have real good accuracy. Even if they don't compare, as long as you know the offset, you will be safe.