The voltmeters that are sold for rc applications are loaded for the proper loads consistant with rx's and tx's and will give readings more usfull for rc use. A standard multi=meter will do the same thing but needs to have the load built in to the probs.
I have had a bad experience with a field box bat powered glo=igniter. The bat was low and when the engine started the batt gave a voltage spike that burned the plug out every time. I used a whole card of plugs before I figured out what was wrong. Also using the power supply for the starter and glo=plug made for sometimes having low voltage to the plug and hard starting. I like to keep the power source separate for the plug and the starter