WXforum.net
Weather Station Hardware => Davis Instruments Weather Stations => Topic started by: ryan hothersall on July 27, 2008, 08:17:16 AM
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Although I have only had my Vantage Pro 2 set up for about a month. How do I know when the battery in the ISS needs replacing?
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It's best to just replace it every year just before winter. The batteries can last as long as 2 years though, so in your case, you could probably wait to replace it in the fall of 2009. Typically, people don't find out the battery is low until it's gone out completely and their data stops being transmitted from the ISS.
Steve
SoftWx
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WeatherDisplay has a status monitor that also checks the battery level and I believe weather Link does too. I am not sure how accurate it is though.
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Where do I look in Weatherlink for the battery level?.
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In WeatherLink you can check: Window -> Alarm and Battery Status.
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My experience is that the ISS battery indicator does not provide good warning that the battery is approaching failure.
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I can confirm that with my 2nd temp sensor (same board). Data was missing/reception in & out while the batt status showed "OK". After it went dark I changed the batt and all was good again.
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I understand this is an old topic but also a very good topic. I wish Davis would implement a way to see on your console how much ISS battery life is left, how much is used each day/night and such once the supercap is deprived of energy. Would be pretty cool and nice to see, and it wouldn't catch you off guard.
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I understand this is an old topic but also a very good topic. I wish Davis would implement a way to see on your console how much ISS battery life is left, how much is used each day/night and such once the supercap is deprived of energy. Would be pretty cool and nice to see, and it wouldn't catch you off guard.
Do you have Weatherlink? If so you can check battery status there, but it only says "OK", no voltages, except for the console. Nothing like what you're after, but something.
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I understand this is an old topic but also a very good topic. I wish Davis would implement a way to see on your console how much ISS battery life is left, how much is used each day/night and such once the supercap is deprived of energy. Would be pretty cool and nice to see, and it wouldn't catch you off guard.
Do you have Weatherlink? If so you can check battery status there, but it only says "OK", no voltages, except for the console. Nothing like what you're after, but something.
Yeah, I have weatherlink 6.0.3 and it says ok, just wish it would come with at least somewhat more information. To your knowledge, is there anywhere else that would give me a clue on how much more life is in the battery or will I have to be "ok" with the ok? lol You would think with all the technology in this station there would be something that would give a digital output on something like battery life.
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I understand this is an old topic but also a very good topic. I wish Davis would implement a way to see on your console how much ISS battery life is left, how much is used each day/night and such once the supercap is deprived of energy. Would be pretty cool and nice to see, and it wouldn't catch you off guard.
Do you have Weatherlink? If so you can check battery status there, but it only says "OK", no voltages, except for the console. Nothing like what you're after, but something.
Yeah, I have weatherlink 6.0.3 and it says ok, just wish it would come with at least somewhat more information. To your knowledge, is there anywhere else that would give me a clue on how much more life is in the battery or will I have to be "ok" with the ok? lol You would think with all the technology in this station there would be something that would give a digital output on something like battery life.
Well, it is what it is. The VP2 is long in the tooth, as many here will be happy to expound upon. I think voltage is completely acceptable to ask for, but "battery life" is way out of the purview of what a PWS should report, even nowadays. FWIW, my VP2 is 9 years old, and I've never replaced the battery or supercap.
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What is weird is that most devices I use report specific battery levels. But I have been through this a few times, and there is no easy way to get the ISS voltage.
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I understand this is an old topic but also a very good topic. I wish Davis would implement a way to see on your console how much ISS battery life is left, how much is used each day/night and such once the supercap is deprived of energy. Would be pretty cool and nice to see, and it wouldn't catch you off guard.
If you study the Davis Serial Communications Protocol, and the Loop command, you will see that the station battery indication is binary: OK or LOW. This is how almost every hardware or software product gets battery level info from the ISS and other stations.
Similarly, if you search the forum for those that have sniffed and decoded the wireless transmissions, I believe that you will find that the battery level sent from the station to the console is also binary (OK/LOW).
Now then, a quick survey on BatteryJunction.com shows CR123A capacities of 1300-1550 milliamp-hours, a difference of almost 20%. Since Davis can't control which CR123A you put in your ISS or how old they are, any life calculation is a crap shoot, especially adding in temperature considerations.
So, changing the data protocols to add the data you desire will probably break the data connection to almost every hardware device or software program currently getting data from a Davis station, and perhaps make new ISSes etc incompatible with existing hardware.
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Another byte or two and the could have supplied voltage. You could then make the life calc yourself.
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Another byte or two and the could have supplied voltage. You could then make the life calc yourself.
It would probably have required additional hardware to measure the voltage (rather than comparing it with a fixed value).
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Probably not since the ISS already has to know the voltage to compare whether it is OK or not (some arbitrary voltage cut-off is the baseline). I might have mentioned this in another post, but I have lots of battery devices that track the specific voltage and report that back to me to two decimal places.
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Another byte or two and the could have supplied voltage. You could then make the life calc yourself.
Remember that - in the first instance at least - you need to be thinking about how any voltage data would get from ISS to console. I suspect that there are already potential message packets that could contain this information, but whether or not they're enabled and in which ISS firmware version is a question for the packet decoders - it may be that the relevant packet types haven't been identified as yet. The schema for the 8X WDTU database is also potentially relevant.
But on a separate point, I'm really not sure how easy it is to read out the state of charge of a primary lithium battery from its voltage - isn't the discharge characteristic very flat, except when brand new or nearly flat, compared to eg a lead-acid battery?
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But on a separate point, I'm really not sure how easy it is to read out the state of charge of a primary lithium battery from its voltage - isn't the discharge characteristic very flat, except when brand new or nearly flat, compared to eg a lead-acid battery?
You are right, but it is even more complicated than that if what you are really interested in is battery 'health' (remaining charge capacity), rather than just a voltage number. The (positive) dependence of battery voltage on ambient temperature seems to be of at least the same order of magnitude as its decline as the battery discharges, so you would have to take account of the temperature, too. I am not surprised that Davis apparently doesn't want to attempt this.
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Tongue-in-cheek ANALOGY: It's just DAVIS's IDIOT LIGHT for the ISS battery voltage (wink,wink).
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Tongue-in-cheek ANALOGY: It's just DAVIS's IDIOT LIGHT for the ISS battery voltage (wink,wink).
Blonde jokes...
Seriously, I would happy with the voltage. I know how to calculate capacity remaining.