Digital Voltmeter, Clock and Temperature module

Another inexpensive voltmeter, now with clock and temperature probe!

This is the original thread:

Inexpensive voltmeter, monitor voltage while riding

I've had my eye on these newer Volt/Time/Temp displays for quite awhile now, and finally decided to get some to see how well they work. They run as low as $12 on eBay.

There's a large version that displays Voltage, Time, and Temperature in degrees Fahrenheit, with a remote probe.



There's also a smaller version, about half that size, identical features, but the temperature display is in degrees Celsius.

 

Both versions tested fine on the bench, voltage and temperature readings were fairly accurate.



But, I don't care for the appearance of the unlit LED segments, makes it hard to read.
A translucent green diffuser lens really cleans that up.

 

The mount plate uses the old ignition switch location, with 50mm screw centers. The larger unit is too big to fit in there. And, being a hard-headed American, I wanted the temperature display in Fahrenheit.

The pin-outs of the digital displays are identical, so I removed both digital displays.



And soldered the smaller display onto the Fahrenheit module.
Now I've got a smaller unit with Fahrenheit display.



Much better with the green diffuser.

 

Made up a new mount plate, with green diffuser lens, and better mini/micro pushbuttons.

 

Now, the 2nd half of the challenge: Where to fit the temperature probe?
The temperature limit for the display is 125°C (257°F), but the sensor is rated to handle up to 300°F.
I want to monitor sump oil temp, but don't want to irreversibly modify any rare/antique engine parts.

But, the non-rare sump filter plate is fair game. Got a spare unit off eBay.
Found a suitable, but cramped, location alongside the sump filter.



The hollow stainless-steel 6mm probe measures about 0.236" diameter.
A 15/65" (0.234") drillbit makes for a snug press-fit mounting hole.
Also, wanted the probe hole to be between sump cover fins.

 

Youze guyz crack me up. I guess that I should've continued posting, showing the probe fitment, but I ran outta steam. But, yes, thinking on how to fit and seal the probe did consume some grey matter.

I would've preferred to use a typical automotive type screw-in temp sensor, but this gadget uses a Dallas Semiconductor DS18b20 temperature sensor, in a TO-92 case. Looks like a transistor, but it's really a network-addressable microprocessor with its own temperature sensor (I suspect using a diode's Vf temperature slew). It communicates thru a single-wire bus topology to a master processor, and delivers temperature info in a 9 or 12 bit data block. Very accurate, no analog temp-varister inconsistancies. A popular item in the Arduino cult. But not in cars yet.

So, in the next couple posts is the probe fitment. Press-fitted with a thin coat of JB-weld. Kinda similar to the press-fitted oil gallery plugs found everywhere on aluminum bike engines.

 

The probe is too long, so it's shortened to 1.300" max.



I had ordered some sealed 3-pin flat micro connectors for this project, but what was delivered some 4-pin large Molex connectors.
Oh, well. Digging thru the junkboxes yielded some suitable WW-2 era Winchester connectors that should work.

Shortened probe and connectors ready for fitment.

 

A ring of JB-weld is applied around the probe base, then press-fitted, wires first, downward into the hole. The excess epoxy forms a sealing ring at the base of the probe.

Connector and wiring is soldered, then epoxied to the sump plate.



Testing the system.
You can see the little ring of epoxy at the base of the probe.



Then seal it all up with a blob of epoxy.

 

Sump filter mounted, gasket greased up, ready to mount.



Sump cover with filter and probe mounted.
Cable tucked away, and routes alongside the alternator harness.



Yes. That's 44 year old grunge in there...

 

Not a problem, TLCbobber. In fact, the interaction is quite helpful. All this bike stuff can be difficult to solve and explain, and community involvement adds to, and helps clear-up, the thread. Keep it coming.

Been doing other maintenance and nit-pic things on the bike, ran outta steam again. Will post final fitment and testing later...

 

Yeah, he won't miss it.

Besides, he's constantly complaining about how hot it is out there...

 

Here's the unit mounted in the old ignition switch location.
It can be set to cycle thru the 3 displays, 5 seconds per display.

Voltage ---> Temperature ---> Time

 

Thanx, Skull.

Eeeeoooowww, a new wrinkle. Yep, that'll take a little gettin' used-to.

We're into the Hot-Dawg-Days of summer now.
Ride report with boiling oil and rider meltdown a-coming...

 

Well, it's around 100°F out there. I was planning on riding and testing the Volt/Time/Oil-Temp display, but this little one said "Don't go out there!".


So, I waited until just before sundown, when it cooled down to about 93°F.

Here's the display unit during bike warm-up:



And, after a short 6-mile run. Oil temperature got up to 214°F.


I'll try for a "Peak heat of the day" later. Curious to see how hot the oil gets...