Battery cut-out thresholds (Solved)

Your AIR and SKY devices will report their battery levels with each observation. Users can enable a battery “card” on their dashboard to monitor. App > Settings > Stations > select station > Advanced > ‘Show Battery Card’.


If you use the recommended Energizer Ultimate Lithium batteries (and insert in the correct orientation!), the starting voltage will be in 3.4-3.5v range. Here’s a battery power curve for an AIR in use for over 9.5 months: . And a battery power curve for a SKY in use for ~4months. (As of mid-July 2018) .

AIR voltage will remain sufficient until ~2.4v, then the lightning sensor will not have enough juice to function. However, the other sensors will continue to report until ~1.9v.

SKY voltage will remain sufficient and all sensor will function until ~2.0v. (Note: at ~2.2v the lithium batteries are approximately 90% drained.) Users who wish to get more battery life from the SKY should enable the ‘power save’ mode which samples wind every 15sec instead of every 3sec…with an expected life of 2+ years.

We strongly recommend Energizer Ultimate Lithium batteries as they perform much better in fluctuating temps. Alkaline batteries will work, but will not last nearly as long. Rechargeable lithium-ion batteries are not recommended. (We do not have any affiliation with Energizer or receive any reciprocal compensation to recommend. We tested lots of batteries, and those are the best we’ve found.)


Any idea on what I might be able to expect for battery life ?

I have an early Air that has been running for 462 days on the recommended batteries, and still reads 3.50 volts per the battery card.

I have a Sky that has been running for 133 days (in non-power-save mode) on the recommended batteries, and it is reading 3.43 volts.

As with any battery, the voltages will drop when it gets cold, and recover when it gets warm. Murphy’s Law in action…you’ll have to change the batteries on the coldest day of the winter! Given the wild variability of battery life depending on local climate, I don’t think that WF can give a more precise answer than they provided above. If you live in an area where it snows, I would change the Sky batteries every autumn just as preventative maintenance so that I will never have to go outside and take down the mast AGAIN at -5 F during a nor’easter.

My suggestion is to leave your battery cards enabled in the app, and watch the voltage graph as the temperature changes. Maybe I’m just a geek, but the graph on the battery card is one of the most interesting things to me in the WF system during winter months…


Are there any IFTT (or the like) alarms we can set for triggering a tweet or email etc. when battery voltages go below a certain threshold ? An occasional heads-up nagging message that we could configure on/off would be certainly nice to have…


The WeatherFlow app will alert you. And, WeatherFlow will send an alert email when voltage gets low.


I used the batteries and installations as recommended (except power save mode) and Sky only lasted 44 days. When I get new batteries I’ll replace them and set power save. Any other suggestions? I’m like 40 miles away from WF in east Orlando, so we’re getting about the same weather.



Did you use the recommended batteries as they really last way longer in the devices.



Yep, exactly those, but the 8 pack… Which I just ordered again last night from Amazon.

contact WF support as this is not normal for a normal production unit. It should last +/- 1 year. Some models are known to have a small ‘leakage’ and can drain the unit way to quick. They will investigate.

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Hi @rhoadrunner Thanks for the detailed report with the included power curve graph. This is definitely not the expected behavior. A normal power curve for SKY looks more like this:

Never fear, we’re happy to send you a fresh set of batteries free of charge. Run the new batteries for a few months. If you still experience a similar faster-than-expected power drain, we’ll send you a new SKY. (And retrieve your SKY for our engineers to inspect and learn from.).

Thanks for experimenting. Our goal is to make all owners stoked they chose WeatherFlow. :wink:


Did anyone verify that all of the batteries were inserted properly (all 8 facing the same way)???

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@vreihen Probably would not have operated for 44 days if inserted the wrong way. Entirely plausible that one bad battery can cause drain on all 8…we’ve seen this even with Energizer Ultimates. Aside from electrical engineers, no one tests each battery before insertion — but you’d be surprised what we’ve found from trusted brands. Then again, it’s also plausible there is a electrical drain somewhere in the circuit board on the SKY. A diligent way to test is to run known good batteries and see what happens. Onward!

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Yep, double checked when I re-seated the batteries.

I replaced the batteries with the ones sent by WF, and put it on battery saver and it seems to be staying flat at 3.39 volts, though it looks like it has gone down very slightly since I installed. I’ll keep an eye on it.
Let me know if you would like me to turn off the battery saver as a test.

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What could this be?


It was for a duration of 10 minutes.

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yeah it happens occasionally…

Funny… Nothing strange in the records of windspeed and direction. It still recorded everything at that moment.

Several have experienced this anomaly and some have actually recorded that data. WeatherFlow is aware and has it marked to fix.


Alright. :blush:

Thnx Gary.

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