Rodney

I have never used the Voltmagic but it appears to be a device very similar to the Voltwatch. IMHO (as a retired EE with many years in the hobby) I believe that the Voltwatch is superior to the loaded voltmeter for most applications although, if used prior to every flight, the loaded voltmeter is nearly as good. The reason is that the Voltwatch (and I would assume the Voltmagic will as well) give you more information. It is using the actual load used in the previous flights so the voltage is quite settled plus when you cycle the sticks you can see if any problems are present due to voltage drop in a switch or wiring or binding servo as, if the lights are cycling or blinking in the yellow region, even momentarily. It is almost as good as having a scope on the battery voltage as it shows up those momentary voltage drops caused by the current surges as when a servo first starts to move. This is especially important if you are using one of the 2.4 GHz systems as they may reboot if you get a voltage drop for just a microsecond or two. Loaded voltmeters do not show up these type of problems which are much more possiable than just a low battery which is also caught by the Voltwatch.