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Refrigerator monitor

Discussion in 'Living Life in a Prius' started by ChapmanF, Jun 14, 2022.

  1. ChapmanF

    ChapmanF Senior Member

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    I'd like to know if my fridge has gone above the safe temperature range while I was away. I'd like to know that even if it is back in the safe temperature range when I come back and look, and ideally I'd like to know what max temperature was reached and for how long.

    I don't want any overdesigned gadget that has an IP address and demands wireless coverage and sends singing movie clips to an app on my smartphone, thankyouverymuch. Just something I can put in my fridge and look at, and know what happened.

    For a freezer, you can lay a penny on top of an ice cube. If you come back one day and open the freezer and the penny is in the ice cube, you know stuff got thawed. But I have only a fridge.

    I suppose I could lay a penny on some frozen benzene in a jar, which has close to the right melting point for fridge purposes (about one kelvin too high though). Only I don't really know where to go get some benzene, and I'm not really excited about a jar of benzene in my fridge.

    Anybody know of some simple, non-overbuilt, monitor product for doing this?
     
  2. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I bought pretty much that, in a package of two for about $16 from amazon. It's a little plastic thingy the size of certain packs of gum, runs on a coin cell, shows current temp, min/max since clear, reset key & c/f swap key on the face. Hook/easel stand and magnet integrated on the back.

    Seach for "KeeKit refrigerator thermometer."
     
  3. PriusCamper

    PriusCamper Senior Member

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    You basically want temperature data logging without the standard method for data logging. All the products that do this are bluetooth and wifi based. If you were in my shoes you'd simply spend $30 on another temperature sensor for your lacrosse weather station... I bought one of these sensors for a sauna I restored on the property. I can view the whole history of temperatures on a chart on the La Crosse view app. Not wanting a system that's as easy as that to use makes me think you're asking for something that's super cheap and will fail at data logging. Of course if you were an Arduino micro-controller guy or owned a wifi connected fridge, you'd be done by now and it wouldn't be a question.
     
  4. Salamander_King

    Salamander_King Senior Member

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    Any cheap thermometer with min/max will let you know if the temperature has risen to the danger zone, but will not tell you how long. Also, most min/max functionality on those thermometers records the min and max within 24 hours from the reset time, so if you are away for longer than 24 hours since the last reset, it will not tell you when it happened.

    Of course, if you pay more, you can get a Bluetooth version of the smart thermometer that can record the temperature data. It's not WiFi, so there is no IP address... but you may not want that option.

    I have this device inside of my Prius Prime traction battery compartment to monitor and record the temperature and humidity changes.

    upload_2022-6-14_18-37-0.png

    upload_2022-6-14_18-38-48.png
     
  5. ChapmanF

    ChapmanF Senior Member

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    I stopped at two RV places today to ask if any of their customers have asked them for pretty much this same exact thing, and oddly enough, nobody had. Max temperature and duration of excursion would be the sort of minimal reasonable features, or something like a (weighted?) time integral of degrees above normal.

    I'm now thinking I've got enough old retired smartphones, with temperature sensors in them, that I should just write a bespoke Android app, load it on one of those, and toss it in the fridge. But I'll have to refamiliarize myself with that Android SDK that I haven't played with in some time.
     
  6. PriusCamper

    PriusCamper Senior Member

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    Can you show us some charts of your temperature data in your battery pack? Have you compared them to the temp data you can view on Dr. Prius App?
     
  7. Salamander_King

    Salamander_King Senior Member

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    I have never compared it to the temp data from OBD2 apps. Since the probe is not inside the battery case, it is probably not accurate in measuring the actual battery core temp. I have no idea where the OEM temp probe is located.

    I was more interested in using this probe to check the ambient temp surrounding the battery pack to monitor the cold-soaked battery before attempting to charge it. Here is an example of the temp data display for the current Month. The highest temp recorded corresponds to the hottest day we had so far this summer, not necessarily correspond to during charging or driving.

    I can try next time I do a long drive to see how well the temps from OBD2 correspond to the surrounding ambient temp outside of the casing.


    upload_2022-6-14_23-15-35.png
     
    #7 Salamander_King, Jun 14, 2022
    Last edited: Jun 14, 2022
  8. PriusCamper

    PriusCamper Senior Member

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    Thanks for sharing... There's multiple temp sensors in your battery pack and when your car gets older it'd be wise to keep an OBD2 in your glove box so an app like Dr. Prius can allow you to quickly see what those temp codes are saying because if you don't want to get stuck on the side of the road you can keep clearing error codes until you get home, but only if those temp sensor readings don't get too hot.
     
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  9. Salamander_King

    Salamander_King Senior Member

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    Do you know what is the "normal" range of the traction battery temp? Or, I should ask, what are the "out of range" traction battery temp that will be reported as abnormal by the ECU?

    I have not really looked at OBD2 temperature data carefully. One thing is that Dr. Prius or Hybrid Assistant reports the battery temp only when the car is in Ready (or maybe also on ACC?). So, I really can't check the temp of the battery pack when the car is parked in OFF. Looks like a PP has 3 battery temp probes. Or is the app showing only three and there are more?

    upload_2022-6-15_6-34-11.png
     
  10. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    Just here to award points for a fast pivot. That went from "no ip address" to "let's support a legacy SDK for fun" in record time!
     
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  11. smitbret

    smitbret New Member

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    You can place this thermometer inside your fridge before leaving, and when you return, you can check the min/max temperature readings to see if it went above the safe range. You won't need any wireless coverage or apps, just a quick glance at the thermometer's display.
     
  12. ChapmanF

    ChapmanF Senior Member

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    What thermometer is that? And will it show not just what the max reading was, but for how long the reading was above a certain level?
     
  13. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I sort of forgot about this thread. Since then I discovered the Taylor 1445. It would appear to fit the bill for
    @ChapmanF - it starts a stopwatch when the temp goes over 45°F (5°F in freezer mode)
     
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  14. ChapmanF

    ChapmanF Senior Member

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    Great find, thanks!
     
  15. PriusCamper

    PriusCamper Senior Member

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    I bought a cheap refurbished La Crosse weather station a few years ago for $50. I also bought a temp/humidity sensor for $22 for a small sauna I restored just before it was about to go to the dump. The La Crosse app allows you to set up alerts for when temp, wind, rain, humidity hits a specific number. It also presents your data in charts and graphs so you can see how things have changed over time... It's too cheap to have lots of features, but it has what I need.

    As in way smarter to invest in a system with an app for all these types of monitoring needs then to do each one separately with a stand alone device.

    But I know you don't want that... You just want to keep an eye on your frozen penny...

    Screenshot_20240326-130315.png
     
    #15 PriusCamper, Mar 26, 2024
    Last edited: Mar 26, 2024
  16. ChapmanF

    ChapmanF Senior Member

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    Where am I gonna put all that stuff while I'm camping in the car? Your Prius might be capacious as a TARDIS inside, but mine isn't.