Installing a voltmeter
A modification that will give you instant feedback on the status of your battery and charging system is a voltmeter. This is especially handy if you are running any accessories, as the EX250 doesn't have a lot of electrical headroom.
There are many different kinds of gauges available, but if you ask anyone who ever drove an old American car, the digital ones are much easier to use. Your local auto parts store may have what you need. You can also look at JC Whitney, or search the internet. The first part of this article shows a Datel voltmeter. Later we'll show one from CA Sport Touring, which doesn't require you to cut into your fairings and is about half the cost.
The first step with the installation of your meter is to find a suitable location. Put everything on your bike that you usually carry, such as a tank bag, and find a good place. Take careful measurements, because you only get one chance to not screw up your fairing. Ensure that you can see the voltmeter with a quick glance. On this Ninja 650R the meter was mounted low and to the left, but on the 250, due to a different tank bag, it was determined that up near the windscreen was better.
The first step is to place masking tape over the fairing and outline the necessary rectangular hole. The masking tape helps keep the fairing paint from splintering when drilled.
Four corner holes are drilled just inside the corners, with a small drill bit of your choice. Then, holes are drilled around the perimeter.
Note that this is only a procedural guide; you may have tools that you find will work better for you.
We take this opportunity to again stress the importance of taking your time and not rushing the drilling. Fairings are expensive expensive expensive!!
The next step in this installation was to attempt to use a heated and sharp razor blade to cut through the holes. Unfortunately, the fairing was flexing too much, and this effort was abandoned. Instead, a new, sharp drill bit was used as a saw. This works well, though slowly.
With the interior gone, it's time to smooth out the edges. Break out the file.
After one round of filing, there's still a ways to go.
The Datel voltmeter is constantly checked against the hole to determine where the hole needs to be enlarged. Then, you keep on filing.
The display has a 2-3mm lip that is wider than the body. This holds it in place from above. On the backside there is a metal rectangular retaining clip that holds the body against the mounting surface. There is also a trim piece held by four screws, but it's doubtful that most people would choose to use it with a sportbike.
The wiring on the unit is quite simple. You run two wires; one to positive and one for ground. Add a 3A or 5A inline fuse. Use a power source that is hot only when the key is on. The aux/accessory wires get power ALL of the time, even when there is no key in the ignition. Don't use them. A good location to tap into is the battery side of the horn button. (If you put it on the other side, it'll only work when you honk your horn.) Another option is to get your power from an electrical distribution block. Whatever you do, running the new wires along OEM wires will usually keep them out of the way.
The connections to the meter should be well protected from the weather by the fairings, but if you're concerned you can coat them with dielectric grease.
The finished product is shown here.
Show Chrome 5-function meter
The five-function meter from CA Sport Touring (and many other places - search) is larger than the Datel one. This unit mounts with Velcro. It gives you not only the voltage, but also the time and temperature. It has settings for temp readings in F or C. It also has a max temperature hold feature with a reset button. The voltmeter display is pretty straightforward and has a 3-color LED low battery alarm. The clock can be set to 12 or 24-hour format. You can also switch to a stopwatch/lap timer.
There are two temperature sensors. One of them is internal to the unit and (think car/truck) is expected to be your inside vehicle temperature reading. The other sensor is on the end of a long wire and intended to be your outside vehicle temperature reading.
You can mount this between the gauge cluster and the windscreen using a couple of small L-brackets and double-stick tape, although you might want to use 3M Dual Lock instead. You don't need to drill anything. If you like, put tape around the corners so it won't scratch the inside of the windscreen.
The example below uses one piece to hold the unit. Cut out a spot for reaching the buttons on the back. Then, take a second piece of metal, bend it to the shape of the dash, and JB Weld the two pieces together. File off the rough edges and paint.
Cover the bracket's mounting face in 3M Dual Lock material. You should only need two small pads of it on the meter itself. Dual Lock is strong enough that you only need small mounting points. Too large and you can't remove it easily. The small pads on the meter with the large pads on the bracket leave lots of movement for fine tuning the position.
The meter has 3 wires. Two are for a connection to constant 12V, which maintains the clock and runs the display with no backlighting. This is on all the time. The 3rd wire is tied to the ignition for the LCD backlighting. It’s wired this way so the unit does not draw much power while the ignition is off. Route the wires under the dash and back to the battery. Connection directly to the battery gives the most accuracy. The wires are plenty long enough.
For the third connection (comes on with the ignition switch), tap into the battery side of the horn or the instrument lighting wiring.
You can zip tie the temperature probe to the cross bar, or anywhere else that keeps it out of direct sunlight.
Reading the gauges
One reviewer said that the lighting was hard to read at night, but most have found that it works 'well enough'. It’s not super bright; you shouldn't have to stare at it to read it, but it takes slightly more than a glance when it's dark. Not enough to make for dangerous riding, but the readout is slightly dimmer than the dash.
The three LEDs are red, amber, and green, to indicate less than 12.3v, between 12.3 and 12.7v, and over 12.7. You typically get all three when moving, two when stopped without the heaters or brake on, and only the red with either load added. If you're running down the road and get anything other than green, it's time to start shutting electrical stuff off or finding out what your problem is. The voltmeter readout is more important than the LEDs.
This meter is not waterproof, but one of our members from the Pacific Northwest has had one on his Concours for years, riding year-round, rain and all. You just need to mount it somewhat out of the way and under cover, not out in the direct rain. You’ll probably want to cover it if you wash your bike.