The voltage indicator that I fitted to my “Wee” is a tiny single indicator that is about 4mm across.It changes colour with different voltages, green OK, orange a little low and red very low, and only operates with the ignition on.I used to have one on my Honda PC800 many moons ago and it works perfectly.It even dims at night, very clever.I paralleled it with the satnav feed off the Suzuki grips connector.