Topic: VP2 anemometer reading crazy high (or zero)

[vinceskahan]

I have an almost 10-year old VP2 and recently I'm not believing the wind speeds it's reporting.   I had a couple days where it read 'zero' although the cups seemed to be spinning ok.  More often it reports wind speeds that are far higher than reality almost certainly, sometimes as high as 60 mph or greater.  No way.

I worked with Davis to get their test cable which tests out ok, and I verified the bottom 2/3 of the actual cable is ok (didn't haul the pole down to check the top 10 feet though), so I'm wondering if it's time to replace the anemometer.  Is it possible for those things to have the bearings get loose and spin much faster than reality ?

[dalecoy]

What do the console disgnostics show, when it's not doing what you think it should be doing?

There are indicators for that specific situation.

[johnd]

Is it possible for those things to have the bearings get loose and spin much faster than reality ?

Not really. Far more likely that it's an old anemometer with reed switch that's gone faulty and the contacts are bouncing. Or that moisture is getting into a cable plug/joint  and shorting across the speed connector.

If you rule out the possibility of moisture as a cause then a new anemometer should fix the problem.

[vinceskahan]

Ordered a replacement from Ryan at Scaled.   Fingers crossed that's indeed the fix (guessing it will be).

[EA1EF]

We are seem that new models wind speed units have any problem on bearings that blocked meter at low speeds. It seems on all four wind speeds meters new model and never in other 15 units old models.

Nest days try dismount and we plain get silicone oil and unblock.....

[havtrail]

EA1EF, I'm not clear on what you are trying to say. Is there a known issue with newer Davis anemometers physically getting stuck at low wind speeds? I have not read this on this forum, but maybe I didn't go back far enough.

I have had that situation happen one time, with a new Davis unit bought six months ago. The wind speed graph on the station's webpage stayed absolutely on 0 for over 12 hours. When I went to inspect the station, I could gently rotate the cups backward and let them go, and they would stop abruptly at the same place, again and again. (I could verify by the location of the set screw.) Rotation was smooth and easy, but it just stopped when it reached that point.

I finally gave the cups a good spin in each direction, and then they went back to their normal slow speed rotation, without stopping at that spot.

Rich K.

[johnd]

EA1EF, I'm not clear on what you are trying to say. Is there a known issue with newer Davis anemometers physically getting stuck at low wind speeds? I have not read this on this forum, but maybe I didn't go back far enough.

There was a limited period 3-4 years back when the new design anemometer was first introduced when the wind cartridge had no upper seal on the bearing. But that issue was rectified with a production tweak after about a year or so and IME all the more recent ones seem to be lasting well. Of course, after a period of years the bearings inevitably still wear and benefit from a new wind cartridge and also, just like anything else, it's always possible to get the odd unit that escaped proper QC. But in general the 6410 anemometers are pretty good now IME.

[wxtech]

I hope that you will advise us of what failed.  Here is another more in-depth method of testing the anemometer while it is still mounted atop the mast.  You'll need an Ohmmeter and a 6 pin telephone jack.  Use the attached chart to compare your meter readings.