Topic: Davis VP-2 sensor(s) apparently drawing too much current - ideas?

[elagache]

Dear WXForum Davis station troubleshooters,

I have been troubling all of you with a very strange scenario over the past two months.  My Davis VP-2  (6152) started to produce sensor errors, usually from both my temperature/humidity probe and my anemometer early in the morning.  If I did nothing these errors would become worse and worse.  However, replacing the 123 battery would cause the problem to stop, but only for about 6 days.  I started this thread about the problem:

http://www.wxforum.net/index.php?topic=24235.msg232831#msg232831

The consensus was that the super capacitor on my ISS circuit board had failed.  I purchased a new ISS board from Scaled Instruments and the same problem happened again.  Kindly, Ryan Wilhour of Scaled Instruments allowed me to exchange the ISS board and it appeared I was finally back in business.  Alas, it took 12 days instead of 6, but this morning once more I had temperature/humidity and anemometer errors.  Each instrument generated exactly the same number of errors: 422.  The sensors errors were reported from roughly 1am to 1:30 and since then everything has been working normally.  We are getting some much needed rain here in Northern California, so I can't open up the station to check the battery, but I fear I'll find a once more partially discharged 123 battery when I installed a brand new battery 12 days ago.

Since I now have tried 3 different ISS circuit boards, that component cannot be the cause of the failure.  Since the station reports errors from more than one sensor, there isn't an obvious which sensor is to blame.  I have configured this weather station in an odd manner.  Since the FARS system was new when I purchased it, I opted instead to move the temperature/humidity sensor under a large deck to serve as the radiation shield.  In order to do that, I spliced the temperature/humidity sensor cable to about 100 feet of 6-conductor phone cable so I could reach that deck.  Nonetheless, I've never had any problems until now, and the station has been operating for over 5 years.  I inspected the temperature/humidity sensor and it looks brand new.  The cable shows no signs of any damage.  I haven't brought down the anemometer, but it also looks okay at least from a distance.

It sure looks like I'm beaten and will have to contact Davis support to see if they have any experience with problems like this.  However, if any of you have some troubleshooting tips or other advice I sure would appreciate it!! 

Thanks for all the help already provided! 

Cheers, Edouard

P.S. The rain stopped long enough for me to check the battery.  The voltage under load was 3.03 Volts.  That is also what the 123 battery registered after being removed from the station.  New 123 batteries are typically 3.23 Volts.  I swapped in a new battery for now.

[moehoward4]

Somewhere on this board I think I read something about cable length on the T/H sensor, it is better if you don't increase the cable length. You should do a search for the thread, and read what was posted. When you spliced in the 100', did you MATCH color for color? That could also be a problem. Just my .02......

[kobuki]

Sorry if you have already checked it, but isn't it possible that the solar cell is failing? Did you try measuring its open circuit voltage? IIRC it should be about 2.5V in brignt light. Plugged in it depends on the load, but should be around 2V.

[dalecoy]

.... this morning once more I had temperature/humidity and anemometer errors.  Each instrument generated exactly the same number of errors: 422. 

.....  I have configured this weather station in an odd manner.  Since the FARS system was new when I purchased it, I opted instead to move the temperature/humidity sensor under a large deck to serve as the radiation shield.  In order to do that, I spliced the temperature/humidity sensor cable to about 100 feet of 6-conductor phone cable so I could reach that deck.  Nonetheless, I've never had any problems until now,

.....  I haven't brought down the anemometer, but it also looks okay at least from a distance.

Exactly where in your previous posts did you mention that you "configured this weather station in an odd manner"?

Exactly what were the "temperature/humidity and anemometer errors" you experienced?  Is the data visible to us anywhere?  In particular, what were the anemometer errors?  Was this only wind speed?  Or also wind direction?

Note that I said to tell us the readings - what numbers, were they constant, etc.

You said it's raining.  Is the rain sensor working correctly?  [If you have solar and/or UV, are they working correctly?)

Did you configure the anemometer assembly "in an odd manner" also?

What are the reception diagnostics? (see the console manual for how to do that).

How to troubleshoot:

1.  If you kept the temperature/humidity assembly wiring and connector exactly like it originally was, and just fabricated an extension cable, then move the temperature/humidity assembly back where it originally was mounted, eliminating the cable.

1a.  If you didn't do that (i.e., cut off the connector and spliced in the cable), then just unplug the cable from the ISS.  You won't get any temperature/humidity readings for perhaps 2 weeks, but that will confirm whether the problem is with that sensor setup or not.

[dalecoy]

Just for the record, did you ever change the transmit/receive channel as suggested in the previous topic that you started?

http://www.wxforum.net/index.php?topic=24010.msg230480#msg230480

Also, what is your Weather Underground ID?  And/or the URL of where your weather data is uploaded?

[elagache]

Dear WXForum Davis experts,

Thanks for your suggestions.  Sorry, it is a very strange problem.

Somewhere on this board I think I read something about cable length on the T/H sensor, it is better if you don't increase the cable length. You should do a search for the thread, and read what was posted. When you spliced in the 100', did you MATCH color for color? That could also be a problem. Just my .02......

The splice was less than 100 feet, but close to that.  Yes, I did match the wires carefully color for color.  I used the Davis waterproof coupler kits to make the connection.  They don't seem available separately now but here is the 4-conductor version documentation:

http://www.davisnet.com/product_documents/weather/manuals/07395-010_IM_07957.pdf

Obviously I used the 6 conductor version.  As I reported, these splices have worked perfectly for over 5 years.  I inspected the housings and they look perfect.

Exactly what were the "temperature/humidity and anemometer errors" you experienced?  Is the data visible to us anywhere?  In particular, what were the anemometer errors?  Was this only wind speed?  Or also wind direction?

Unfortunately, these were errors reported by the WeatherCat Mac weather station software.  There is nothing more than the number of errors encountered.  Since the errors occurred while I was sleep I didn't check the console to see what was going on there.

You said it's raining.  Is the rain sensor working correctly?  [If you have solar and/or UV, are they working correctly?)

All other sensors had no errors during the 30 minutes episode and after about 1:30AM everything was working as normal. 

Did you configure the anemometer assembly "in an odd manner" also?

No, the anemometer has the standard Davis cable, no splices.

1.  If you kept the temperature/humidity assembly wiring and connector exactly like it originally was, and just fabricated an extension cable, then move the temperature/humidity assembly back where it originally was mounted, eliminating the cable.

I didn't move the temperature/humidity assembly.  Instead I had bought a Davis temperature/humidity station (6382).  My original plan was to use that second station as the primary temperature.  When I realized I couldn't I effectively "crossed" the two probes.  Using the extension I ran the cable from under the deck all the way to my ISS and then I ran the standard ISS temperature/humidity probe to the transmitter that comes with the 6382 kit.  This afternoon I did essentially what you suggest.  The probe under the deck now goes to the 6382 kit and the original ISS temperature/humidity probe is once more connected to the iSS transmitter.  Now I'll see what happens.

Thanks again,

Cheers, Edouard

[dalecoy]

Just for the record, did you ever change the transmit/receive channel as suggested in the previous topic that you started?

http://www.wxforum.net/index.php?topic=24010.msg230480#msg230480

Also, what is your Weather Underground ID?  And/or the URL of where your weather data is uploaded?

Being able to see the data might be helpful.  Where is it posted online?

[PaulMy]

I presume this is the WU site http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KCAORIND10

Paul

[Aardvark]

to throw you a curve ball, could the error be in your receiver instead of the ISS?

[dalecoy]

I presume this is the WU site http://www.wunderground.com/weatherstation/WXDailyHistory.asp?ID=KCAORIND10

Paul

Perhaps - but that doesn't match very well to the position reported in his profile on this forum.

http://www.wxforum.net/index.php?action=profile;u=10081

[dalecoy]

to throw you a curve ball, could the error be in your receiver instead of the ISS?

Receiver problem would be unlikely to cause the transmitter battery to be quickly drained.  (Which is the reported problem).

[elagache]

Dear WXForum Davis troubleshooting experts,

Sorry, I wrote my reply very quickly and late last night, I missed a few points,

Sorry if you have already checked it, but isn't it possible that the solar cell is failing? Did you try measuring its open circuit voltage? IIRC it should be about 2.5V in brignt light. Plugged in it depends on the load, but should be around 2V.

Yes, I did check the solar panel and indeed in sunlight it is at about 2.5 Volts.

Just for the record, did you ever change the transmit/receive channel as suggested in the previous topic that you started?

Yes I did both transmitters are at new IDs.  The ISS is at 3 and the temperature/humidity transmitter is at ID 4.

Also, what is your Weather Underground ID?  And/or the URL of where your weather data is uploaded?

Yes, there are quite a few actually, but the Weather Underground is the most familiar:

http://www.wunderground.com/personal-weather-station/dashboard?ID=KCAORIND10

There is also a humble weather website:

http://www.canebas.org/Weather/

to throw you a curve ball, could the error be in your receiver instead of the ISS?

I can rule this one out as well because I have redundant equipment.  I have a Weather Envoy containing the data logger with the VP-2 console in another part of the house.  When these problems first started I moved the data logger to the console to see if that was the problem.  Not surprisingly the console also started to report the same errors.

Thanks for all your thoughts.  Alas, this is indeed a very strange problem . . . . 

Cheers, Edouard

[elagache]

Dear Aardvark and WXForum Davis troubleshooting experts,

Yes I did both transmitters are at new IDs.  The ISS is at 3 and the temperature/humidity transmitter is at ID 4.

How about setting the ISS at 1, as that is the recommended default,  what do you have at station 1 now?

Alas, that is another sub-plot of my current station nightmare.  For a while it appears that my Weather Envoy was picking up another local Davis station.  Here is the thread where I found this out:

http://www.wxforum.net/index.php?topic=24010.msg230480#msg230480

Checking around the neighborhood there are apparently 2 other stations not to far away.  The stations should be far enough away to eliminate this problem, but since I have had this happen once, it seems prudent to choose another ID.

Thanks for the suggestion though.

Cheers, Edouard

[Aardvark]

Then let me leave you on this,  it is often something simple, something overlooked that when looked closely at, looks perfectly fine.  Perhaps you were fine to begin with and picking up readings from those other two stations, which might be off a bit to start with.

For me, the only thing I worried initially about was a new HAM radio station operator , a block away trying to trim his frequencies close to the VP station and not realizing it was messing with me. What cured him was that the electrical, gas, water meters are also radio data senders, close to my frequency and he was messing with that as well, that he did move way away from.  All is good, other than a few weeks ago I had my reception drop to zero on my three Envoys and 2 consoles, so it did worry me,  not sure what happened,but I am it hasn't  happened again, so far.

I wish you the best of success in your future endeavors, and now I am going to work on my hooked  rug project and then go to a book signing for one of those interesting people I worked with for over 10 years.  Peace and tons of interesting weather situations.

[dalecoy]

Observations:

Regarding the data problems around 1:10 on November 22nd:

Your every-5-minutes reports to WU were OK at 1:06 and 1:26 AM.  The three uploaded reports in between those times showed missing data for temperature, humidity, wind speed, wind direction, and solar.  Barometer was OK.

I didn't move the temperature/humidity assembly.  Instead I had bought a Davis temperature/humidity station (6382).  My original plan was to use that second station as the primary temperature.  When I realized I couldn't I effectively "crossed" the two probes.  Using the extension I ran the cable from under the deck all the way to my ISS and then I ran the standard ISS temperature/humidity probe to the transmitter that comes with the 6382 kit.  This afternoon I did essentially what you suggest.  The probe under the deck now goes to the 6382 kit and the original ISS temperature/humidity probe is once more connected to the iSS transmitter.  Now I'll see what happens.

I'm guessing that you did that (as indicated by data anomalies) around 1:25-1:30 PM.

So, you switched which temp/humidity sensor was being reported:

                Temp        Dew Pt      Humidity
1:20 PM    61.4 °F    59.4 °F    93 %
1:35 PM    61.4 °F    58.8 °F    91 %
That's a surprisingly small difference between two sets of temperature/humidity sensors in different locations. (I almost said "unbelievable")

[For some reason, your software reported zero accumulated precipitation between 1:10 and 1:56, with 0.69 inches before and after]

Another observation: no apparent problems in the last 20 hours.

And a suggestion: please turn off your 6382 wireless additional temp/humidity system.

[elagache]

Dear dalecoy and WXForum Davis station experts,

Regarding the data problems around 1:10 on November 22nd:

Your every-5-minutes reports to WU were OK at 1:06 and 1:26 AM.  The three uploaded reports in between those times showed missing data for temperature, humidity, wind speed, wind direction, and solar.  Barometer was OK.

As I said I was asleep when this happened so the event was handled by the WeatherCat software.  It does seem to be inconsistent in reporting problems via email.  If data was missing for all the external sensors that would indicate that WeatherCat detected that the data was invalid for all of them.  That is consistent with what I have seen when this problem has occurred while I'm up.  Every ISS sensor stops transmitting valid data.  As I have said before, replacing the battery resolves the problem for a while.

. . . . . .
The probe under the deck now goes to the 6382 kit and the original ISS temperature/humidity probe is once more connected to the iSS transmitter.  Now I'll see what happens.

I'm guessing that you did that (as indicated by data anomalies) around 1:25-1:30 PM.

Correct.

So, you switched which temp/humidity sensor was being reported:

                Temp        Dew Pt      Humidity
1:20 PM    61.4 °F    59.4 °F    93 %
1:35 PM    61.4 °F    58.8 °F    91 %
That's a surprisingly small difference between two sets of temperature/humidity sensors in different locations. (I almost said "unbelievable")

Perhaps you find it surprising, but that has always been the case for 5 years.  The thermometers are only 100 feet apart and on a cloudy day, both are measuring air temperature.  Honestly what would you expect in that case?

[For some reason, your software reported zero accumulated precipitation between 1:10 and 1:56, with 0.69 inches before and after]

Yes, somehow I managed to cause the rain buckets to tip twice while moving the ISS so I could service it.  Life is tough. 

Another observation: no apparent problems in the last 20 hours.

As I have stated, the symptoms always go away for a while with a new battery.

And a suggestion: please turn off your 6382 wireless additional temp/humidity system.

Sorry but I don't understand your suggestion.  If it turns out that the temperature/humidity probe under the deck is the cause, then I should get confirmation by killing the battery in the 6382 transmitter.  Isn't that additional diagnostic data worth obtaining?

Cheers, Edouard

[dalecoy]

If the temp/hum sensor under the deck is not connected to the ISS in any way, then there is no way it can be affecting the battery in the ISS.

I simply suggested turning off that sensor/system, to eliminate any chance of confusion.  Just a temporary suggestion.

Regarding my comment about the sensors:
                Temp        Dew Pt      Humidity
1:20 PM    61.4 °F    59.4 °F    93 %
1:35 PM    61.4 °F    58.8 °F    91 %
That's a surprisingly small difference between two sets of temperature/humidity sensors in different locations. (I almost said "unbelievable")

...Accuracy of those sensors is such that I was just surprised at the tiny disagreement.

[dalecoy]

No errors in approx. 2 days - now wait to see if the battery is being drained.  From the site data:

Metrics of weather station connection reliability and instrument accuracy
Good data elements received from weather station:
   70658
Data link timeout errors:
   0
Data link invalid data errors:
   0
Weather station sensor errors:
   0

[elagache]

Dear WXForum Davis troubleshooters,

I just got off the phone with Jerry at Davis Tech support.  He made most of the suggestions you all had already given me, so all the alternatives were ruled out.  According to him, there is exactly one way for a Davis ISS to exhibit these symptoms: another failed super-capacitor.  Could I be so unlucky as to have gotten 2 replacement ISS circuit boards with bad super-capacitors?

I just sent an email to Ryan Wilhour at Scaled Instruments.  I'll be interested to learn what he thinks about this possible scenario!

Cheers, Edouard

[moehoward4]

Call Jerry back and ask him about problems with the 'power switching circuit' that Davis likes to call a 'bad' supercap. I HAVE HAD that problem twice, Davis has a tough time admitting to that one. I've got two more stations showing the same thing now.

[elagache]

Dear moehoward4 and WXForum Davis troubleshooters,

Call Jerry back and ask him about problems with the 'power switching circuit' that Davis likes to call a 'bad' supercap. I HAVE HAD that problem twice, Davis has a tough time admitting to that one. I've got two more stations showing the same thing now.

Could you explain exactly what is the problem with the 'power switching circuit'?  Is this another failure mode that would cause excessive battery drain and is it something that is more common than Davis would prefer to admit?

I just got my reply from Ryan Wilhour and he cannot believe that two new ISS boards could have failed in a row.  So he thinks I should try to get a complete sensor suite and replace everything.  However, if Davis is correct and the sensors cannot cause that sort of battery drain, that would put me through an awful lot of work for nothing.  The National Weather Service is starting to get excited about a potentially strong set of storms coming through Northern California starting on Friday and i sure would hate to miss out on that data.

Cheers, Edouard

[kobuki]

You could try to confirm a bad supercap. Unplug the solar panel, remove the battery. Start measuring the voltage across the supercap leads periodically, like in every 15..30 minutes. If it's indeed failing, you should see it drop its voltage rapidly in a few hours. In normal circumstances the supercap is able store the necessary energy for about a day (an educated assumption; it does hold it at least for a night), that means the voltage shouldn't drop significantly in a few hours.

EDIT: thinking it a little further, obviously it can't rule out other failures somehow draining the supercap (like that misterious power switch). But, if you repeat the experiment above with all sensors unplugged, possibly you can at least rule out other factors.

[dalecoy]

  According to him, there is exactly one way for a Davis ISS to exhibit these symptoms: another failed super-capacitor. 

I disagree.  Call that possiblity #1.

Symptom: battery being discharged rapidly.

#2.  Solar cell not charging the supercap (i.e., the only power source is the battery).  Or only partly charging the supercap.  [I note that you have a lot of shading]

#3.  A "sneak connection" in the set of sensors that is draining the battery (and/or draining the supercap). 

Note that #2 has not been tested (by anything suggested here).  To test that - remove the battery and see if (and/or how long) the system continues to transmit. 

And we have only partially investigated #3 - although returning the system to "original configuration" (of the temp/humidity sensor) was the start.

===================
Footnote: you could always consider returning the whole VP2 setup and both consoles to Davis, for refurbishment.

[elagache]

Dear dalecoy and WXForum Davis troubleshooters,

  According to him, there is exactly one way for a Davis ISS to exhibit these symptoms: another failed super-capacitor. 

I disagree.  Call that possiblity #1.

Look, if a Davis tech says something - we ought to assume he understands something about the way the instruments are wired that explains his statement.  I'll call tomorrow anyway to double-check, but don't shoot the messenger.

#2.  Solar cell not charging the supercap (i.e., the only power source is the battery).  Or only partly charging the supercap.  [I note that you have a lot of shading]

It isn't a foolproof test, but the solar panel voltage on a winter day and late in the day was 2.5 Volts.  According to other folks on WXForum 2 Volts or more was a sign of health.  So there is some reason to suppose the solar panel isn't at fault.

#3.  A "sneak connection" in the set of sensors that is draining the battery (and/or draining the supercap). 

That's an interesting hypothesis, however, explain to me how instruments that haven't been touched could spontaneously start shorting out?  The Davis tech had never heard such a thing.  I'll call tomorrow to get that second opinion, but if Davis has never never encountered such a thing - does that seem like a likely explanation?

Cheers, Edouard

[moehoward4]

Somewhere on the PCBA is something (circuit(s)) that tells the board where to get power. It doesn't decide magically to use the solar panel, the supercap, or the battery. Something has to tell it the BEST location to draw from or to charge the supercap. I have had that problem on two ISS boards and on one leaf/soil station board. One more thing....how many times did Jerry put you on hold while he went to ask someone else????? Davis tech support is nothing like it was 8 to 10 years ago, the ones that knew their stuff then are retired or dead now.