Recommend a Temperature Logger?

Any recommendations for a battery-operated two-channel standalone temperature logger that collects data for a while in the field, then uploads via USB or serial to a computer? If proprietary software is required for the upload, then it’s provided? The whole works for under $150?

Insulating Paint for Bus Roofs

I’ve seen a couple of descriptions of mixing ceramic and glass microspheres into paint for repainting bus roofs, with the claim that it’s supposed to have thermal insulating value. One person actually took temperature measurements before and after — but acknowledged that he was going from a schoolbus-yellow roof to white, and the increased albedo obviously helped slow heat absorption into the bus as well.

I have a hard time imagining how — in the paint thickness and mixture proportions described — the microspheres could have much of an insulating effect. It seems as though there must be a whole lot more brittle than peanut, and the heat would go right through the brittle. But I’m willing to be convinced.

The Proposal

Converted schoolbus, front

Let’s do the empirical test of insulating microspheres on a bus roof. Half of my bus roof is already an extremely light grey that looks white. I want to paint it white. I’ll even pre-paint the purple roof edges white for the sake of the test. The magic spheres are relatively inexpensive and I’m willing to try them in the “real” roof paint job.

Help me find a two-channel temperature sensor — or two one-channel sensors — for under $150 and I’ll put one inside and one outside the bus for a month, taking readings every five minutes so we can graph outside and inside temperature. Then I’ll paint the roof with magic spheres mixed in and graph the inside and outside bus temperature for another month and we can compare the two.

Is this a proper test? Care to change the methodology and/or add constraints?

Of Course I Could Build One …

But I have enough things to build right now, I’d rather buy this. ‘Kay?

26 Responses to “Recommend a Temperature Logger?”

  1. whackpak says:

    I’m also searching for a such a temperature logger. I can’t find one for a reasonable price. If you find one plz let us know. If you build one. Would you share the schematics so I can build one to?

  2. Matti Airas says:

    You could try Maxim’s 1-wire family iButtons. They’re cheap and easy to interface with computers, and you might actually be able to get the buttons as samples from Maxim. You still need to buy the 1-wire USB dongle, but that’s inexpensive.

  3. Alex Marcy says:

    This would meet your $150 requirement for 2 one channel loggers.

    Omega is good for low cost stuff.

  4. robert says:


    glad you got that shifter working.

    Here’s a link to some battery powered data loggers. Maybe you’ll find it useful.

  5. Keith Neufeld says:

    Matti, the Dallas/Maxim DS1321 looks perfect! But I can’t figure out where to buy it — their direct sales says it has a four-week lead time, and at Digi-Key it’s a non-stock item with minimum quantity of 24.

    Still, at $15-20, they’re cheap enough I could buy three. At the size of a coin cell, they’re small enough I could dangle one unobtrusively on each side of the bus to correlate sun and shade temperature. I would really like to use this!

    Hey, Embedded Data Systems has a 15-46°C button for $22 and a USB reader for $28. I’ll put in an email to their support contact to make sure the USB reader is all I need to program the buttons for duty and read the results.

    Anyone else have experience with these? Any reason I shouldn’t get this?

  6. Keith Neufeld says:

    Alex, have you used that Omega sensor before? I’m very interested in the iButton but would be happy to hear about direct experience with something else.

  7. Evan says:

    if you find something that works well and is cheap enough for you great, but I offer a back up suggestion that’s probably adaptable to your situation.

  8. Arun says:

    On my rv i installed a gps-gprs logger, you could build a temperature logger(Arduino) and interface it with the modem. These things cost a fortune, but not on ebay :)

  9. Alex Marcy says:

    I have not used it before, but I have experience with other Omega products. Their stuff is good for the kind of stuff you would be using it for, although I would not put their products in a critical application.

    Cost wise it looks like the Maxim would be better and you could get more robust data with multiple of those.

  10. Brad Gilbert says:

    I think the paint additive has more to do with infrared light reflection, than insulating value.

  11. Keith Neufeld says:

    Evan, your Tweeter has potential. But do I understand correctly that it needs a 5V (or 3.3V) power supply and needs to be within wireless range of a computer? I’m really looking for something that’s self-contained and untethered — the bus will be parked 1/4 mile from home most of the time, and I’d like something that can log temperature without relying on being able to “see” a PC.

  12. Keith Neufeld says:

    Bryon, that looks very promising! If not for my interest in iButtons (I think they may be more flexible and reusable for other temperature-monitoring projects I have in the back of my mind), I’d have it ordered already. Thanks!

  13. Keith Neufeld says:

    Brad, you make a good point, and I just reread one of the sales sheets. You’re right that their major claim appears to be reflection of IR (and UV) radiation; but they do also claim to block conduction. Their drawing does make it look as though the paint contains enough microspheres to make a fairly solid boundary of them between the object and the surface.

    Regardless, I’m willing to test the claims and impressions about efficacy on a bus roof!

  14. Matti Airas says:


    I’ve got to give a disclaimer that I haven’t been using iButtons – although I can’t see why they wouldn’t work as promised. However, I have been playing with 1-wire setups, and they’re really fun to work with.

    I believe you’d just need the reader, DS9490B, or (maybe preferably) DS9490R together with DS1402D-DR8. With the latter you get the adapter with which you can begin fooling around with 1-wire setups. :-)

    The availability was indeed a bit of a bummer. Let’s hope you find a suitable reseller.

  15. jeanyves says:

    I’m also for the maxim ibutton solution.
    why dont you get two of them as samples ? cost = zero …
    but dont know the delay…

  16. Bryon says:

    This place says they have most items in stock:

  17. Keith Neufeld says:

    Jean, I don’t find them available to sample. Also this is my end use, so I don’t feel good about sampling them as I do with parts for circuits I hope to turn into kits.

  18. Slavo T. says:

    this not meet 2 channels, but 2 pcs will be below 120$.

  19. Bryan says:

    1wire + microchip

  20. Joe Zimmerman says:

    I agree 100% on the iButton 1wire solution…

    I’ve used mine for some interesting things in the past, and they are great.. You create a mission for them and tell them how often to log the temp, and they’ll do that for years if you want…

    Downloading the data is quick.

    You can interface with arduino if you want.

  21. Bill says:

    iButton’s are great. I have used them for the normal stuff but they are really fun for off the wall things like: Throw it under the hood of your car and watch the temperature spike after you park. Place one on the back of your TV and see how much time you are wasting (and who’s watching when you are away). Put a piece of black tape on one and throw 2 outside for an instant sunlight meter. Tape one to the cold water pipe coming in from the street and see when you using water….on and on…


  22. Keith Neufeld says:

    Bill, that all sounds great!

    For my first batch, I really want to hang them from fishing line so they’re measuring air temperature, not bus frame temperature.

    But assuming you want thermal conduction, is there any reason not to epoxy a magnet to them? Is there a surface where you could glue a magnet and still leave them able to go into the reader? Or is there enough ferrous material in them that a magnet will stick?

  23. Roughage says:

    These guys have been around for a number of years. I haven’t tried them, but they’ve managed to stay in business AND expand their product offerings:

  24. UncleTomCobbly says:

    iButtons are the way to do it, I’ve used them on and off for a number of years.
    They are (almost) hermetically sealed I’ve thrown one into the washing machine before when it started playing up just to monitor the wash cyce.
    There is also a humidity and temperature version it’s expensive, but actually very cheap when you compare it to other loggers.

    Try carrying one on a keychain and you can monitor your movements during the day, it’s amazing what you can tell from variations in temperature provided you have a little extra data to correlate with. had a article on reading 1-wire DS1821 temperature ICs using an Arduino a few weeks ago, these are also a handy little sensor.

    Search around for 1-wire interfaces you can make your own from simple parts or for development one-offs Maxim/Dallas samples several 1-wire interface parts. The free 1-wire software from Dallas will graph and setup the loggers using a simple UI.

  25. MARK P says:


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