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Archibald Tuttle
Sep 22, 2015, 8:47:11 AM9/22/15
to Wireless Sensor Tags
The explanation of battery voltage drop off depending on ambient temperature of tag says that the X axis is the power consumed but it appears that the x axis is simply time with a constant load assumed.
all of the tags seem to run out of batteries at 10 days regardless of temp. which confuses me compared to all the talk about tags that can last 3 years and stuff, but maybe this is because the assumed consumption is high compared to tags that have been optimized.
i'm only a little concerned because my first application is monitoring refrigeration temps. and you speak about dropping a tag in the freezer although you seem to be talking about keeping track of how often the door is open. maybe if you're concerned about who is stealing the ben and jerrys that matters but i'm concerned with temperature readings.
it appears that one power conservation tool is to let the tag monitor temp but only send temps when a change of a certain threshold is experienced.
in any event, without regard to temperature that chart illustrates only a ten day working life for a tag before it drops below the requisite 2.2 volts. Can anyone explain to me results they have had for this kind of work. i really could use them for fridge systems that appear to work fine but a day later fail but by the time i get there are working again. i need to get a signal when the temperature starts to rise.
i could live with 10 days of battery life and that would still be helpful but longer would be better if it takes me longer to catch a problem.
thanks,
brian
all of the tags seem to run out of batteries at 10 days regardless of temp. which confuses me compared to all the talk about tags that can last 3 years and stuff, but maybe this is because the assumed consumption is high compared to tags that have been optimized.
i'm only a little concerned because my first application is monitoring refrigeration temps. and you speak about dropping a tag in the freezer although you seem to be talking about keeping track of how often the door is open. maybe if you're concerned about who is stealing the ben and jerrys that matters but i'm concerned with temperature readings.
it appears that one power conservation tool is to let the tag monitor temp but only send temps when a change of a certain threshold is experienced.
in any event, without regard to temperature that chart illustrates only a ten day working life for a tag before it drops below the requisite 2.2 volts. Can anyone explain to me results they have had for this kind of work. i really could use them for fridge systems that appear to work fine but a day later fail but by the time i get there are working again. i need to get a signal when the temperature starts to rise.
i could live with 10 days of battery life and that would still be helpful but longer would be better if it takes me longer to catch a problem.
thanks,
brian
Heinz Wittenbecher
Sep 23, 2015, 1:28:11 AM9/23/15
to Wireless Sensor Tags
I'm running a temp tag in the freezer drawer of our fridge. Update interval is 15 minutes. Temp is approx. -20 C. Approx. because it does vary some degrees up/down as drawer is opened, etc.
Temp range is set to -25 and 0.5 with a threshold of 1.4
Email and push notification on Temp going out of range.
Using battery that came with the tag. I'm on day 22 and battery shows 23% left, 2.7 Volts. Battery voltage does vary a bit as temp varies.
I'm hoping for 30 days on the battery.
Optimistic that I have another week of juice left.
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