# Nest Protect Wired version detection

First post for me, although have had Sense for 3 years or so now. Have made good progress with my “Always On” but realized that I have 7 or 8 wired Nest Protects and am hoping that someone can tell me what amount of power they use? And if Sense will be able to detect down the road or if this type of device will be tough for Sense to detect at any point? Thanks.

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Here’s a swag based on the Gen 2 non-wired version, which has 95% the same circuitry as the wired version.

6 x capacity of AA lithium batteries (1150 mAh) = about 7 Wh of total battery capacity. Bump to 25Wh to account for added wired circuitry and AC/DC conversion loss. The non-wired model is speced to run 5 years on those 6 batteries, so power consumption should be roughly 25Wh / 43,800 hours = 1mW. That’s not even going to register on your Sense, even with 7-8 of them. Maybe someone can check my math and guesstimate for the wired versions power supply and associated losses.

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A side point inspired by your comment: a regular AA battery costs ~30 cents and has ~3 Wh of energy to give, so \$100 per kWh. Compare to the grid, \$0.12 per kWh in our case. So battery energy is x1000 more expensive.

I’ve been wondering whether I should get small devices in battery or wired version, clearly wired wins from this angle.

For devices that don’t need to be portable, wired wins for sure…not to mention the horrible environmental contamination batteries create. The downside is needing a power line to the device, sometimes challenging/costly.

Your comment helped me find a mistake in my calculations. I based the 1150mAh on a quick Google of “AA lithium capacity”, but that was for a rechargeable. Looking at the product used in the Nest Protect, the Energizer e² AA Ultimate Lithium Batteries, shows essentially the number you are using, 3Wh. So I should bump my number by about a factor of 3, to 3mWh of consumption per wired Nest Protect. Still not much.

ps: the OEM battery, the Energizer e² AA Ultimate Lithium Battery, costs about \$1.50 best price retail, so the wired version is even cheaper, though the numbers over 5 years remain fairly small.

When I mentioned this to my wife, she said that she thought the factor of x1000 also applies to bottled vs. tap water. So the calculation for our place is:

• Tap water: \$3.41 per 1000 gallons for water, plus \$6.00 per 1000 gallons for sewer, total \$9.41 per 1000 gallons

• Typical bottled water: \$2 for 750 ml, or \$10,130 per 1000 gallons

So indeed bottled water, like “bottled electricity” has a premium of x1000! I always try to avoid bottling water, but this gives me more motivation to bring tap water along at all times.

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Thanks for the comments. Seems pretty clear these devices are not a big contributor to my “Always On” power. Will keep hunting for the missing watts

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seems like it would be in the “Always On” category since it is always on? For Sense to detect, it would have to cycle.

Kind of like how you get used to smells that are always present. you go into someone’s house and it stinks really bad, but they can’t smell it because they live there. because the smell is omnipresent for them, their brain filters it out and they no longer notice it. If you are there long enough you get used to it, until you leave for a few hours or more and come back.
Always on devices are like that. unless there is fluctuation in their presence, Sense can’t distinguish them.

As for how big a contributor it is to your usage… I have one that I need to install, but never got around to it.

Interestingly it did come out of “unknown” category which must have been from fluctuations in power given compressor but not my area of expertise. Only issue is that refrigerator temperature seems to have gone up from standard 37 degrees to 57 degrees while freezer temp has stayed at 0 degrees F. May be an issue with frig and HS110. Hopefully it gets back on track.

Sorry I changed topic mid-stream as I was putting in some smart plugs today

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