00986 Accuracy

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I Have just Set Up A New 00986 System, by the Manual, using Energiser Lithium Ultimate (although i See here You Reccomend Advanced Lithium, i Have Confirmed With Other Sites Advanced Lithium Has Lower Power And Shelf Life) Batteries In Both Sensors With Expiry Of 2035.
On The Bench Both Sensors Read 21 And 20 Degrees On The Display.
When Testing The Two Resulting Tempretures Displayed With Sensor One In The Fridge And Two In The Freezer I Get 2 Degrees C In The Fridge, And 4.5 Degrees C On The Accurate Multimeter. This Might Be within Spec, But Your Specs Page Does Not Mention The Tolerances For Your Fridge Thermonitors.
In The Freezer I Get -22 On Your Device On Sensor Two, And -15.5 degrees On Both My Multimeter (1 Degree Accuracy) an -15 Degrees On My Other Digital Thermonitor. I Am Enclined To Beleive Your Device May Be 5 Degrees C Out. This Cant Be Within Your Specs Can It.
I Could Do A Reset, but Then How Many Resets Would I Have To Do Everytime I Do A Battery Change To Ensure Accuracy? Resets Shouldnt Be required.
I Have Now Put Both Sensors In The Freezer To See What Happens.

But What Would You Suggest? I Expect The Sensor Is Out Of Spec Under 0 Degrees C.

Thanks

Also, I Cannot Find The Model 00986 Or Its Previous Model 00985 Refrigerator Thermometer In The Drop Down List On The Bottom Of This Page!
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Kym Sims

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Posted 2 years ago

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Kym Sims

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update.
After One Hour And 15 Minutes sebsor 1 Shows -16 Degrees C And Sensor Two Is Showing -21 Degrees C With Both Sensors Sitting Next To Each Other In The Freezer
Checked Inside Battery Bay Of Sensor 2. It Says QC3416
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George D. Nincehelser

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There generally isn't a high degree of linearity in the error curves for consumer devices like these.

They are often calibrated to room temperature, and the possible errors get larger as you head toward the extreme ends of the scale.

Acurite's stated error for digital weather products from -40 to 32F  is +/- 4 degrees F.  This would translate into +/- 7.2 degrees C.  I would not expect to the freezer thermometers to be much different.

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Kym Sims

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7 degrees? That's the difference between spoiled food and not spoiled.

The back of the user manual states "it's more than accurate, it's Acurite"

$80 is a lot of money to spend on something that is 5 degrees incorrect.

Weather sensors should never be seeing - 20 degrees like freezers do.
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George D. Nincehelser

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Note the chart I posted.  at 32F to 122F the tolerance is stated at +/- 2F.

That doesn't mean there is a huge discontinuity at 32F.  It's just a convenient point to break up the spectrum.

As for weather sensors never seeing -20 degrees, many would disagree with you.  For those on the F scale, that's only 4 below zero, which is not at all unusual for many in the northern US.  

Also as far as food preservation and freezer temps, you might want to read this:

https://www.reference.com/home-garden/temperature-should-deep-freezer-set-87eb4b330cb14632
(Edited)
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Kym Sims

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Agreed on the weather temps. But people are using these devices to prevent food spoilage, and stop people getting sick.
Ideal fridge temperature is below 5c. With this unit I could be at 4c on the display, but my food could be spoiling at 10c in the fridge. That's not why I spent $80 on the device, not to mention the blurb I mentioned about the manual saying how accurate these units are.

Also what would be the point of having a temperature scale showing .1 degrees if the unit could be 7c inaccurate?

Let's see what the manufacturer says I guess. But considering I do have one sensor that is within 1c accurate, and the other is 5c incorrect, I'd think I have a faulty sensor.
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George D. Nincehelser

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4C would be 39.2F.  That's in the +/- 2F error range, meaning it could be as warm as 41.2F according to the spec.

41.2F is would be about 5.1C, pretty far from 10C that you speculate.

A common reason to use tenths in Celsius is because the unit of 1 degree C is almost twice the size of 1 degree F.  (actually 1.8) 
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Kym Sims

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I currently read - 22c on sensor two. It is actually -16c.

That same sensor in the fridge reading at 4c would read 10c. That's correct isn't it?

George above stated that he thought spec said it could be up to 7.2c out of spec? That would have a 4c fridge showing up to 11.2c and still be just within spec? If so that's a fridge full of spoiled food... My $80 thermometer says the temperature is fine.
Im happy to be corrected if I've calculated that wrong.

Accurate to me is at least accurate to 1c, unless you only paid $10 for it.
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George D. Nincehelser

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Oh.  Yeah, it looks like I went the wrong direction on my first response and multiplied when I should have divided.

A +/- 4F should be a +/- 2.2C, not +/-7.2C

The math in my other response is correct, though.

So it looks like you could have a bad sensor.

Sorry.
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AcuRite Jennifer

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Hello Kym,

When comparing for accuracy you want to compare to a unit of known accuracy. Bring the display and 2 sensors together along with any other product you are comparing to. Sit them side by side for at least 1 hour when comparing temperature readings. The accuracy standard of our product is +/- 2 degrees Fahrenheit. This means that when you are comparing 2 AcuRite products together there can be a total of a 4 degree difference. Thank you. Enjoy your day!
(Edited)
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Kym Sims

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OK. So I have a difference of 5 degrees centigrade now on both sensors. Is that within spec? I can't work with fahrenheit.
My multimeter has an accuracy of 1 degree. Along with another digital fridge thermometer.
Both my multimeter and digital thermometer are showing - 14.5 degrees. Both of your sensors are reading -19 degrees Celsius.

I don't call 5 degrees Celsius accurate at all.

Thanks
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AcuRite Jennifer

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Hello Kym,

We have emailed you at the address on file for more personal information. Please check your inbox. Have a good day!