Consider the Futaba voltmeter as well. I think it loads the pack with 3 Amps for a couple of seconds and display the voltage.
It showed me that my switch was getting bad as the voltage drop before and after the switch was substential.
It takes a while to get adjusted to using it because the reading is lower than with the traditional 300mA, but once you stop freaking out when you read 5.8V after just one flight (on a 6V battery), you know that you're OK.