Pages: [1]   Go Down
Author Topic: 18B20 as an automotive fluid temp sensor?  (Read 2187 times)
0 Members and 1 Guest are viewing this topic.
Florida USA
Offline Offline
Newbie
*
Karma: 0
Posts: 38
Modernizing old motorcycles
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

I'm working on adapting an LCD panel to replace the broken gauges on my motorcycle. In the process of doing so, I've been learning about the Arduino stuff, and related sensors.

I want to monitor the oil and coolant temps on my engine as well as the ambient air temp. I found the 18B20 chip is a really neat one, it can be daisy chained together since each has a unique 64 bit serial #. This would minimize wiring. I know I can use it as-is for ambient temp, but I got to thinking it could also be used as a fluid temp sensor if properly prepared and protected.

I have a few of these on order. My plan is to get some brass pipe plugs and drill out the tops, insert the 18B20, and then use some high temp epoxy to seal them in. This is similar to existing automotive sensors I've seen, and perhaps a little more compact.

The 18B20 is rated as working from -55C to +125C (-67F to +257F). This would work for all coolant systems, and most oil systems.

Are there any drawbacks to this idea based on anyone that has used the 18B20? I don't have them in hand yet, but thought about this & wanted to get some feedback.
Logged

Global Moderator
Netherlands
Online Online
Shannon Member
*****
Karma: 227
Posts: 14048
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I know I can use it as-is for ambient temp, but I got to thinking it could also be used as a fluid temp sensor if properly prepared and protected.

Saw this lately - http://arduino-direct.com/sunshop/index.php?l=product_detail&p=151 -
might be usefull,
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

Offline Offline
Jr. Member
**
Karma: 0
Posts: 71
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Check that your LCD panel still works under typical summer and winter conditions' for your location.
Some of them turn black if they get too hot and suffer from slow refresh if too cold.
An LED display may be more robust. See http://octanereport.com/upload/image/2010/06/formula-one-steering-wheel-000.jpg
LEDs also give you colour options.



Logged

USA
Offline Offline
Jr. Member
**
Karma: 0
Posts: 90
I’m no expert, but I play one on the Internet…
View Profile
WWW
 Bigger Bigger  Smaller Smaller  Reset Reset

If you want to build one yourself you can check out my DS18B20 Temperature Probe article at:
http://nuewire.com/2011/06/ds18b20-temperature-probe/

As robtillaart pointed out you can buy them from the Arduino Direct store in China and just this week Adafruit (based in NYC) added them to their store as well:

Waterproof DS18B20 Digital temperature sensor + extras
http://www.adafruit.com/products/381

As far as gotchas go I would test a few to see if the reaction time is OK for your needs, the DS18B20 tends to be slow to adjust to a change in temperature. I would also watch the cable insulation as Adadfruit points out:
Quote
While the sensor is good up to 125°C the cable is jacketed in PVC so we suggest keeping it under 100°C.

willnue
Logged

Florida USA
Offline Offline
Newbie
*
Karma: 0
Posts: 38
Modernizing old motorcycles
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Those waterproof sensors are great, but there's no way to mount them in a fluid line. I think what I want to do will work- just drill out a 1/8 pipe plug, seat the 18B20 in it, fill with epoxy, and wire in a connector.
Logged

Global Moderator
Netherlands
Online Online
Shannon Member
*****
Karma: 227
Posts: 14048
In theory there is no difference between theory and practice, however in practice there are many...
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Can you post some pictures (2-4) how you fixed it?
Logged

Rob Tillaart

Nederlandse sectie - http://arduino.cc/forum/index.php/board,77.0.html -
(Please do not PM for private consultancy)

Swannanoa, New Zealand
Offline Offline
Full Member
***
Karma: 1
Posts: 202
New To Arduino (and C)
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

You've hit the nail on the head about sealing it.

You could buy a normal sensor and drill that out. You need to measure the fluid temperature, not the surrounding metal, or surface temperature, which is why drilling out a 1/8 plug might not work.

The other option is mapping the existing sensor and read it with an analogue input.

I'm going down this path to replace the existing idiot light in an american classic with a more intelligent offering.

Mark
Logged

Pages: [1]   Go Up
Jump to: