2019 Drake Smith - Please do not use or reproduce this elsewhere.  Feel free to link to it though.

Inexpensive "On Demand" Voltmeter

Add a digital LED voltmeter that's activated by the turn signal cancel switch. This is an easy inexpensive mod that lets you quickly and easily check the battery voltage without even having to turn on the bike or have the key inserted. I just hit the turn signal cancel switch to know the battery voltage.

(If the bike is running then it shows the alternator voltage.)


Blue LED Voltmeter - K1100LT


Red LED Voltmeter - K75S

(This looks much better in real life. My camera doesn't like red LEDs.)


There's a variety of LED voltmeters available for this. My current favorite is this one that costs $2-3 shipped on Ali Express. Available in five colors: red, green, blue, yellow or white. (I've experimented with all of these colors and only buy the red ones now as they work best in sunlight.)

Width (w tabs) 40 1.575
Width (w/o tabs) 27 1.063
Height 15 0.591
Depth 17 0.669

Whatever LED voltmeter you decide to use, it's a good idea to get one that's waterproof.

Here's a link that works as of December, 2019: Ali Express. Or search Ebay or Ali Express for "mini led waterproof voltmeter."


The voltmeter wiring is obvious: red to positive, black to ground. Wiring to check the battery voltage quickly without needing a key or having the bike turned on:

Red Wire: Tap into the red/yellow wire (unswitched power from Fuse 5) of the white nylon alarm connector in the relay box.

Black Wire: Tap into the brown/white wire (turn signal cancel) from the right combination switch. You can do this under the tank at the right combination switch connector or at the flasher relay connector in the relay box.

(I recommend using Posi-tap connectors to tap into existing wires.)


I snip off the voltmeter's mounting tabs with holes and use 3M automotive molding tape to mount the voltmeter to the front bottom of the instrument cluster.

Voltmeter Accuracy:

It's a $2 voltmeter so don't expect Fluke accuracy.  In comparing these voltmeters to more accurate voltmeters I have these are usually within 0.2V of the true voltage - which is good enough for getting an order of magnitude reading of your battery's state of charge. It's not a bad idea to compare your LED voltmeter against a known good voltmeter to know how high or low it reads.


2019 Drake Smith - Please do not use or reproduce this elsewhere.  Feel free to link to it thou