Author Topic: Davis reliablity?  (Read 1155 times)

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Offline NHSkierGolfer

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Davis reliablity?
« on: August 28, 2019, 11:28:01 AM »
I'm looking to upgrade a 6-yr old Ambient WS2080 fine offset that has worked very well.  I was considering a Davis VP2 until I read this: "Temperature and Humidity sensor in Davis are known to go bad on average every 18 months or so. Some people fair better some worse."  Wow, who would buy a station where two of the most important features go bad in 18-months?  Is this true? If so, it's off my list.  Does the Vue have the same issue?

I want a set-and-forget unit that doesn't need maintenance.  (One of the key reasons for replacing the Ambient is that it doesn't have solar batteries and I have to change them once a year and that's a big deal.)

My WS2080 console sits next to my PC connected via USB to Cumulus software that updates WU and through a chron job updates my website.  It's a nice simple, clean setup. 
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Offline sacreyweather

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Re: Davis reliablity?
« Reply #1 on: August 28, 2019, 11:41:34 AM »
Davis units are just fine. My VP2 Pro just now needs a new temp/hygrometer. It is 7 years old. I have not had any issues with it at all. I clean it several times a year, for leaves, debris, wipe out the spoons for the tipping gauge, etc. For the money, they are the best buy IMHO.

John

P.S. - There is a Davis unit that survived Hurricane Maria (this unit recorded a 199 mph wind gust in the right front quadrant of the eyewall. This unit is still in service). Another story is a unit that survived Hurricane Harvey and recorded a wind run of over 49,000 miles and measured 90 mph winds!!!! That story is on this forum.
« Last Edit: August 28, 2019, 11:48:58 AM by sacreyweather »
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Online johnd

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Re: Davis reliablity?
« Reply #2 on: August 28, 2019, 12:35:08 PM »
I was considering a Davis VP2 until I read this: "Temperature and Humidity sensor in Davis are known to go bad on average every 18 months or so. Some people fair better some worse."  Wow, who would buy a station where two of the most important features go bad in 18-months?  Is this true? If so, it's off my list.  Does the Vue have the same issue?

The 18 months is a rather irresponsible comment. What happens is that the sensor is at its most accurate when brand new and (inevitably) slowly but steadily drifts away from optimal readings over time. Certain users are very pernickety over the precise readings and may consider the humidity part of the sensor (which is usually more drift-prone than temperature) to be faulty once it differs by more than 3-4% from what they consider to be the true reading. This doesn't bother most users who will be happy to use the sensor for eg 5 years or more.

It does also depend on the purpose for the RH readings and on location. Near the ocean where there may be some salt spray in the air then inevitably the sensor will degrade more quickly. Or if you're especially keen on monitoring low RH values or values close to 100% then your attitude to the numbers may be more critical.

But most users seem to get say 4-5 years life out of the T/H sensor. Remember also that you can get a brand new VP2 T/H sensor for just $45 and it's reasonably easy to fit yourself.
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Online droiddk

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Re: Davis reliablity?
« Reply #3 on: August 28, 2019, 12:38:48 PM »
"Temperature and Humidity sensor in Davis are known to go bad on average every 18 months or so. Some people fair better some worse." 

Please!
Where did you find that?
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Offline galfert

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Re: Davis reliablity?
« Reply #4 on: August 28, 2019, 01:08:39 PM »
I am the source of that comment. Where did I get this information from? From many many sources.

- The Monster SHT31 thread in this forum
- The multitude of Davis users I've helped (on this forum and my neighbors)
- The multitude of Davis stations around me that I've monitored for years
- General consensus around this forum and others

You asked about the Vue if it fairs better. NO! The Vue is even worse because you can't replace the sensors and it suffers from the same problem in exactly the same way. On the Vue you can't replace the super capacitor either. At least not very easily because of potting so you can't desolder.

The Temperature sensor is not the one that goes bad. The problem is with the humidity sensor. But they are one and the same. In the latest Davis stations the temperature and humidity come from the SHT31 sensor made by Sensirion. Interesting observation though is that others manufactures also use Sensirion SHT30 and a different version of the SHT31 and they don't seem to be suffering from these problems.

This is one of the major reasons I myself don't have a Davis. I don't mind helping and playing around with all my neighbors Davis stations though. I even helped my kids local school get a Davis WeatherStem station. ...which has a broken SHT31 sensor right now after only about 2 years.

I don't feel my comment is irresponsible at all. It is true what johnd says that after some time the sensor starts to drift. The first sign of things going wrong is that it never reaches 100% humidity. You notice that the sensor tops out at 99% or maybe 98% and then it keeps getting worse. On average most RH readings are 94% I would say. Then it might hang there for yet more months or years. Then it gets worse...goes below 90% and here is where it gets bad...what you see then happen is that as it reaches it top of 86% or 90% and the real RH goes higher the Davis station will crash with like 60% or 50% RH and then if you ignore it even more it will crash to 0%.  It only recovers as the RH drops back down to the max point where ever that is 88% for example.

The other problem is wet bias in the RH sensor.

This isn't an issue just for those wanting to track accurate RH % because it affects everyone in the dew point calculation. The worst part is those stations that report to CWOP and then they mess up their neighbors. I recently am sporting a nice red X on Gladstone thanks to these new neighbors whose stations have crapped out. I've successfully ask one of them to take their station down...as it is a Vue and we will explorer options to replace it...probably not another Vue. The other person has not responded to my emails. I'm tempted to drive over and leave a friendly note and offer assistance.

« Last Edit: August 28, 2019, 01:39:49 PM by galfert »
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Offline galfert

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Re: Davis reliablity?
« Reply #5 on: August 28, 2019, 01:22:05 PM »
Please don't misunderstand my comments.

I'm a big Davis fan.  But facts are facts. I will probably buy a VP3 when one becomes available.

The matter at hand is just one of the issues with a Davis station. As mentioned before you can fix the problem for less than $50 on a VP2.  So don't buy a Vue. Go big with a VP2 or choose an Acurite or Ambient/Ecowitt. I wouldn't say that this issue should deter anyone from buy a VP2. Just be aware of it and be ready to pluck down $50 some months or years down the line.

To the OP ...if you want to replace your aging Fine Offset clone then pick your poison. There is no perfect station at any cost.

I'm not praising what I own either. Everything has a drawback. More info:
http://www.wxforum.net/index.php?topic=37425.0

This thread is going to stir some emotions...just like it does every time any brand is disparaged for its drawbacks. You are going to see the Davis fans jump in and defend their quality expensive purchase that lasts years. You are going to see the Ambient/Ecowitt/FineOffset defend their smart purchase for the price that is replaceable even if it only lasts 3 or 4 years. And you are going to see the Acurite fans jump in and defend their extra features and quality for much lower price than Davis. What you won't find many of are people that don't see the world through rose colored glasses and are unbiased and generally are willing to consider all the Pros and Cons and tell you all the crap they dislike about their current station. I do tell everyone about all the crap that I dislike about my station....and I equally share about the crap from all the others. Settle with what makes you happy. Decide what you want ...most accurate sensors and features at any price with plenty of replacement parts ...then the answer is Davis VP2 hands down.  Want to save some money and entertain different combinations features quality and capabilities then Ambient/Ecowitt/FineOffset or Acurite.

If you want to keep using that discontinued antiquated version of Cumulus 1 then your only option is a Davis. Because the new stuff from Ambient/Ecowitt/FineOffset does not support that USB connection any more and Acurite was never supported. Plenty of people are happy with Cumulus 1. If it ain't broke don't fix it right? But many people are also very happy with new options like Meteobridge NANO, WiFiLogger. Yet others are equally happy with Weather Display and original Meteobridge and Acuparse and WeeWx and Cumulus MX and WeatherSnoop...etc etc... Plenty of software options depending on hardware.
« Last Edit: August 29, 2019, 06:39:36 AM by galfert »
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Offline galfert

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Re: Davis reliablity?
« Reply #6 on: August 28, 2019, 02:58:59 PM »
Here is how to spot a bad Davis SHT31 humidity crash.

D70 and E42 are both Davis stations. One is a Vue and the other is a VP2.
Notice how each have a different crash point. This drifts over time. The two crash points are 88% for D70 and 80% for E42. They only recover once the humidity drops back down to their crash point. They continue to work fine as long as the RH is below their crash point. The crash point causes the RH reading to drop significantly when it should actually be going up much greater than the crash point.

FW3708 is my station
KSFB is local airport

 [ You are not allowed to view attachments ]

When the SHT31 crashes really bad as in does all the way down to zero on a crash as in this case with station AS6 below it cases my analysis to get all thrown out of wack. Notice AS6 stopped transmitting on this day after I contacted them. Immediately my analysis started working again. On CWOP I think it is bad etiquette to stay online if your sensors are bad as you all affect each other.

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« Last Edit: August 28, 2019, 07:20:44 PM by galfert »
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Offline waiukuweather

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Re: Davis reliablity?
« Reply #7 on: August 28, 2019, 03:32:36 PM »
to be fair, any weather station type has problems over time with the humidity sensor, yes?
so it comes down to the cost of replacing that

Offline CW2274

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Re: Davis reliablity?
« Reply #8 on: August 28, 2019, 03:44:28 PM »
My personal experience with the SHT31 is this; I bought one when they first came out and got 3 years from it before it started getting flaky below 8% humidity or so (doubt you'd ever see that). It would routinely hit 1% to 99%, not 100 though, and in between it was a good all around performer. Many will say that's due to the 31's apparent preference to a dry climate, and it's supposedly only meant for indoors as well, I cannot argue these points. However my new 31 (I installed the SF2 cap as well, and I would recommend this) has been in service for 2 months now and has been outstanding, so far... I'm still waiting on a good, saturated air mass to take over to see it's above 95% performance (only been to 94 so far) and also see how it recovers.
As far as the rest of the VP2, mines been in the Arizona sun, sunup to sundown for 12 years and doesn't skip a beat. Without getting into RM Young money, the VP2's durability and performance are unmatched.
« Last Edit: August 28, 2019, 03:56:58 PM by CW2274 »

Offline CW2274

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Re: Davis reliablity?
« Reply #9 on: August 28, 2019, 03:45:36 PM »
to be fair, any weather station type has problems over time with the humidity sensor, yes?
so it comes down to the cost of replacing that
All sensors will drift over time, temp as well as humidity.

Offline nincehelser

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Re: Davis reliablity?
« Reply #10 on: August 28, 2019, 04:10:33 PM »
to be fair, any weather station type has problems over time with the humidity sensor, yes?
so it comes down to the cost of replacing that

Yes.  The membrane in the humidity sensor can get contaminated with other chemicals over time reducing its effectiveness. 


Offline Papa

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Re: Davis reliablity?
« Reply #11 on: August 29, 2019, 09:17:16 PM »
I have a Vantage Pro that is going strong after 16 years. Was going to replace the humidity sensor last year but the plastic seemed too fragile. Lost anemometer to roofers replacing roof in January. Just installed an Ambient Weather WS2902a
 Leaving the Davis just too see how long it will go.

Offline Papa

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Re: Davis reliablity?
« Reply #12 on: August 29, 2019, 09:21:54 PM »
I might also add to my post referencing 16 years old Davis unit, all readings are within 1 to 2 percent on both units excepting humidity.

Offline NHSkierGolfer

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Re: Davis reliablity?
« Reply #13 on: August 30, 2019, 10:51:49 AM »
Thanks, all for an enlightening discussion.  For the record, I wasn't disparaging the VP2, simply repeating a comment from someone else and asking the question.  For me, I want reliability.  My unit is mounted on a pole on my roof so replacing something (you can fix the problem for less than $50 on a VP2) is much more than $50, it's climbing up onto the roof and getting to the unit, etc.

RH is meaningful to me only that it helps in calculating dew point which is something I am interested in.
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Offline galfert

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Re: Davis reliablity?
« Reply #14 on: August 30, 2019, 11:14:41 AM »
The VP2 has the advantage in that you can separate the ISS base from the anemometer with an extra transmitter. This way only the anemometer is on the roof. Then you can more appropriately site the ISS base where you can easily service not just for temp/hum sensor replacement but for cleaning out the rain gauge which is bound to collect debris and insects and spider webs. Besides the ISS base will provide better data if mounted closer to the ground.
« Last Edit: August 30, 2019, 11:42:33 AM by galfert »
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Offline Bushman

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Re: Davis reliablity?
« Reply #15 on: August 30, 2019, 12:36:28 PM »
The only thing I've had to do with mine other than the occasional rain bucket cleaning, is the super cap replacement.  Super cap issues seem to be non-existent now.
Need low cost IP monitoring?  http://wirelesstag.net/wta.aspx?link=NisJxz6FhUa4V67/cwCRWA or PM me for 50% off Wirelesstags!!

Offline Dennis Rogers

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Re: Davis reliablity?
« Reply #16 on: September 01, 2019, 08:43:12 PM »
As the guy said wants something with no or little maintaince and the weather flow smart station would have fit his needs.

No batteries need to be changed in the sky unit itself with solar panel used and all are now supplied with it.
« Last Edit: September 01, 2019, 08:47:14 PM by Dennis Rogers »

Online davidmc36

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Re: Davis reliablity?
« Reply #17 on: September 02, 2019, 04:16:25 AM »
Looks cool but +-20% on rainfall accumultion would be useless since the local conservation society pings our stations for localized rain data.

Offline fish-on

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Re: Davis reliablity?
« Reply #18 on: September 06, 2019, 10:33:28 AM »
I'm looking to upgrade a 6-yr old Ambient WS2080 fine offset that has worked very well.  I was considering a Davis VP2 until I read this: "Temperature and Humidity sensor in Davis are known to go bad on average every 18 months or so. Some people fair better some worse."  Wow, who would buy a station where two of the most important features go bad in 18-months?  Is this true? If so, it's off my list.  Does the Vue have the same issue?

I want a set-and-forget unit that doesn't need maintenance.  (One of the key reasons for replacing the Ambient is that it doesn't have solar batteries and I have to change them once a year and that's a big deal.)

My WS2080 console sits next to my PC connected via USB to Cumulus software that updates WU and through a chron job updates my website.  It's a nice simple, clean setup.


I BOUGHT THE DAVIS AND IT IS AN EXCELLANT PRODUST

Your lucky your Ambient weather station has lasted that long. Like a Davis unit, they use similar sensors and are constructed of plastic. I have had my VP2 for 5 years. Works great and it gets yearly maintenance. Just mounting and setting it up and forgetting it is something I personally do not believe is something I feel is good for a major investment. Would you run your car for 6 years and not change oil, air filters, tires, wash, clean inside, etc.

Davis makes a great product for buyers in this price point. Even if you speed more for a system NOAA uses, well they too have sensor failures and they must calibrate the units on a regular basis because of FAA rules and needs.

If you want to update/upgrade then do it. My recommendations is to do what the earlier poster said and invest in another wireless transmitter so you can separate wind unit from temp/rain unit. Well worth the extra cost if you do not like climbing on roof. I am no spring chicken myself and this is what I have done. Maintenance is a breeze and my VP2 is a pleasure to own and use. Separation allows you to easily maintain the ISS for temp and humidity.

Having worked in the electronics field all my life, I take component failure with a grain of salt. Yes most last for years, but semi-conductors are like a vacuum tube. They do change over time and eventually will fail. Maintenance will help extend sensor life. Yearly disassembly and screen cleaning will and does extend sensor life. Based on the  sensors dooms day post, your Ambient sensor should fail today.

So don`t get hung up on the post that says sensors are not going to last more than 18 months, when there are more units in service that have not had any issues. Ya sensors fail, but as with most instruments, the percentage of units failing is low.

Offline pabloako

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Re: Davis reliablity?
« Reply #19 on: September 14, 2019, 05:32:43 AM »
I have had my David Vantage Pro 2 (cabled) sitting on my roof in the full Australia sun for 10 years now and it hasn't skipped a beat with data recording (Except wind once).  I decided on the cabled version mainly because I have had issues with wireless devices over the years, so I stuck with the tried and tested physical cable.

In the 10 years the only think I have had to replace was the solar panels on the front for the fan and the anemometer failed after 8 years.    The UV sensor and Solar energy sensor seems to still be working very well and just have a wipe once a year to get the dust off.

It is looking a bit old now and I wish Davis would bring out a new version, but it is on my roof and I don't really see it much.  I hardly look at the LCD display now, apart to change the batteries as a backup for when we have power cuts.