Join Date: Aug 2010
Location: Grand Rapids-ish, MI
The Heads-Up LED voltmeter that dariv linked to is similar to the BackOFF LED voltmeter that I've seen around (though the lack of info on that page makes it hard to say if it's the exact same thing).
It won't tell you exactly what your voltage is down to a tenth of a volt like some digital meters will, but it will tell you the condition of your electrical system at a glance:
Flashing Green (Above 15.25V)
Steady Green (12.9V-15.24V)
Steady Amber (12.6V-12.8V)
Steady Red (12V-12.5V)
Flashing Red (Below 12V)
I usually don't really care if my voltage is 12.6V or 12.7V. I do care if it's ~11V vs. ~14V, and the multi-color LED tells me if the voltage is "good", "a little off", or "really bad". If I do need to know the exact voltage for some precise troubleshooting, I've got a multimeter.
You can tuck the control box away somewhere, and only have to mount a single LED somewhere visible. It's a minimalist solution that I feel provides "good enough" feedback on the status of your electrical system. Especially compared to buying a full analog gauge that matches the stock gauges and fabbing up some sort of mount for it.
It can even be better than a digital gauge in some situations. On a standard LCD display, there's only a couple segments different between 11.0 and 14.0. With this LED voltmeter, the difference would be a flashing red LED vs. a solid green LED. Your brain doesn't have to take the (tiny bit of) time to see and process the numbers, you just know instantly that green is good and flashing red is bad.
1985 VN700 A1 (Sold) | 2009 Ninja 500R EX500D9F