Trixology
Weather => Weather Hardware/Measurement => Topic started by: elagache on September 28, 2014, 10:13:31 PM
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Dear WeatherCat fastidious weather station maintainers,
Okay, I "walked the walk" and did the annual maintenance of my station this morning. I always replace all batteries once a year, and decided to check the voltage just to know how far down the batteries had gone. I was surprised by one result. Here is what I found:
Davis ISS station Lithium 123 battery: 3.55 volts
Davis Console "C" battery: 1.55 volts
Davis Weather Envoy "AA" battery: 1.55 volts.
Now both the Console and Envoy receive household current 24/7, so those batteries only work during power outages and we haven't any long power outages. However, I was surprised at how little voltage drop I observed in the ISS battery. I don't have any way to test a 3 volt battery under load, so this is a bit of a deceiving measurement. Still I have the Davis Wireless Temperature/Humidity Station (#6382) and I have to replace that battery every 4 months. The Davis Vantage Pro-2 abandoned having a battery that can be recharged, so the solar panel only provides power for daytime operation. Since that is less than 50% of the time, you would expect that the 123 battery would be significantly used up if the power used was comparable to the 6382 station. I suppose the Davis ISS is more efficient than the 6382 and that explains the longer battery life.
It certainly seems that you could wait 2 years or more before replacing this battery. However, it is too much of a hassle to keep track of that for me. Also, I think it is a good idea to replace the batteries every year to reduce the risk of a battery going bad and leaking.
However, it is a free country!!
Cheers, Edouard [cheers1]
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I have had my VP for 9 years and only replaced the battery 2 times. They last and last.
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Davis Tech Support told me that the ISS battery does NOT run constant all night. It is only used during the actual time it takes to transmit the readings and is not providing power between transmissions. Apparently the power requirement for transmitting data is quite small. Davis says the ISS battery on average should last at least 2 years. My first one lasted 7 years.
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Davis Tech Support told me that the ISS battery does NOT run constant all night. It is only used during the actual time it takes to transmit the readings and is not providing power between transmissions. Apparently the power requirement for transmitting data is quite small. Davis says the ISS battery on average should last at least 2 years. My first one lasted 7 years.
Wouldn't nighttime battery life (after the capacitor charge has been depleted) depend, in part, on how often you have WeatherCat set to query the ISS (and how many sites you upload data to)? When I look at my WeatherCat log, I see entries that it's "Fetching data from weather station..." at intervals under one minute. I'm on my second Davis station and sure haven't gotten battery life anywhere near seven years.
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Wouldn't nighttime battery life (after the capacitor charge has been depleted) depend, in part, on how often you have WeatherCat set to query the ISS (and how many sites you upload data to)?
Nope the querys are to the base station, the ISS transmits data every 2.5 seconds(ish) regardless. But the key is the capacitor, the ISS runs off the solar panel during the day, and also charges the super capacitor. it then runs off the super capacitor at night, only if teh charge runs out during the night will the battery be used. The capacitor should last all night unless you have dull short days and/or long nights, or its capacity is depleting.
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Nope the querys are to the base station, the ISS transmits data every 2.5 seconds(ish) regardless. But the key is the capacitor, the ISS runs off the solar panel during the day, and also charges the super capacitor. it then runs off the super capacitor at night, only if teh charge runs out during the night will the battery be used. The capacitor should last all night unless you have dull short days and/or long nights, or its capacity is depleting.
Thx. Guess I misinterpreted the log info "Fetching data from weather station... ." Would never have thought the "weather station" was actually the console. So I guess I can turn on Wunderground's RapidFire mode without being concerned that capacitor depletion will be accelerated (thus forcing the ISS transmitter to run on battery) since you said it transmits back to the console on a fast fixed schedule.
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Dear Jeff, Blick, Felix, Mark, and WeatherCat Davis fans,
But the key is the capacitor, the ISS runs off the solar panel during the day, and also charges the super capacitor. it then runs off the super capacitor at night, only if teh charge runs out during the night will the battery be used. The capacitor should last all night unless you have dull short days and/or long nights, or its capacity is depleting.
Okay, that's the ingredient that I wasn't aware of. I had heard that one key difference between the Vantage Pro and Vantage Pro-2 was that Davis had ditched the rechargeable battery. I wasn't aware that they had provided a capacitor based "substitute." That now explains the huge difference between ISS power use and the Wireless Temperature/Humidity Station (#6382).
Thanks for educating us on this one!! (http://www.canebas.org/Weather/LWC_forum/Custom_emoticons/scholarly_teacher.gif)
Cheers, Edouard [cheers1]
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So, Edouard. Are you going to put that battery back in the ISS? You live in 3 seasons a year, Sunny California.
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Howdy Herb and WeatherCat Davis owners,
So, Edouard. Are you going to put that battery back in the ISS? You live in 3 seasons a year, Sunny California.
I suppose I'm being silly, but I think I'll continue my current maintenance routine and replace the battery every year. I would like to remove the cover every year anyway to inspect the seals and add a little more silicone grease. If I've got the cover open anyway, it is just extra insurance to replace the battery instead of taking a risk that in the following year it leaks. Batteries are dirt cheap, replacing the circuit board isn't.
Cheers, Edouard [cheers1]