Mike, you are a little off on your assesment of voltage indicators. They do much more than indicate no load situations. They indicate everything from neutral position idle loads to dragging and binding loads on control surfaces.
Granted that they are far from an absolute necessity but they are also far from being just another interesting trinket.
Also all onboard indicators are not created equal either for accuracy or the usefull informatiion that they can furnish. A good one can give a fair idea of the non flying system load where a ESV gives only a response to the fixed load in in the ESV.
ORIGINAL: mglavin
ORIGINAL: Bosch232
Is it advisable to also use one for the pack that powers the electronic ignition?
I have a new 1400 mah pack for the E.I.
I don't think these devices are very useful, they simply indicate the NO-LOAD voltage. Pretty much worthless information IMO (albeit you can stir the sticks and observe the voltage reading). An expanded scale LOADED volt meter (.5 to 1.5 Amp load) on the other hand is a must again IMO. The ignition system cannot load the battery dynamically like a flight system accordingly the information is of little value with regard to the reserve of the battery under test.
Anywho even ESV dynamic battery loading only offers a kinda-sorta-maybe feel for what’s left in the battery. A poor mans fuel gauge so to speak. One can garner information of the specific battery pack and develop a relationship with regard to expected discharge time intervals, characteristics and the like. This allows you to form an educated “feel” for the batteries well being and expected flight times.