Eco Wittboy rain comparisons

[TonyC]

After having problems with my 15 year old Davis VP, I thought I'd shell out a few dollars on a spare weather station as a backup. At $350 freight included I ordered a GW2001CA - 433mhz from AliExpress, which duly arrived 5 days later. The package includes a WS90 sensor and a GW2000 Lan hub. (No console) Both stations (VP and Wittboy) are installed on different PC's using Weather Display software

The Davis VP by this time had been restored to full operational fitness, so my interest has been in comparing the readings from both. Temperature and Humidity have been pretty close. Solar readings on the the Wittboy are slightly higher than the Davis sensor. The Wittboy has a UV sensor which is a plus for my website, I couldn't afford a Davis one!
Wind readings are pretty similar, though the last hour gusts are slightly higher on the Wittboy.

Rainfall:
The WS90 has no moving parts and uses a Haptic rain sensor which detects and quantifies rain using vibration signals - not directly by volume or weight.
We had our first rain storm over the last 24 hours so this was my first opportunity to do a direct comparison using a classic plastic rain gauge, The Davis tipping bucket and the new GS90.
Classic rain gauge:  28mm
Davis VP:  28.4mm
GS90 (Haptic) 30mm

Rain since midnight today on both the Davis and Ecowitt match each other at 6.5mm

Interestingly, the GS90 haptic picked up 0.4mm a few days previously whereas the Davis registered zero and I suspect over time the GS90 may accumulate more than the Davis over time. However at this time, my opinion of the Wittboy as an inexpensive hobby weather station is pretty high and accurate enough for general weather observation.  I'll come back to this post in a couple of months time and update the comparisons.
UPDATE: 13/2/2025
Both the Davis and Ecowitt Wittboy are on WeatherUnderground so anyone wanting to do their own comparison of records from both stations which are situated 5 metres apart.
https://www.wunderground.com/dashboard/pws/IDOMET1
https://www.wunderground.com/dashboard/pws/INORTHCA6#history


regards
TonyC

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[Wolfie33]

Hi Tony

I'm liking what I see !!
Have been doing a rough daily compare, I like the more immediate & maybe more responsive register of lower wind & rain while the rest looks pretty close.
From what I've read it will be interesting to compare readings from a concerted heavy rain & wind spell.

Good Stuff !!
Cheers

[TonyC]

I thought I'd do an update as over the last 12 hours as there has been a substantial amount of rain.
The accompanying graphic compares the two stations with data supplied from each to Weather Underground from midnight to midday today.
The amount of rain recorded from the Ecowitt shows about 9mm more than the Davis tip bucket in total for the 12 hour period. Between 3am and 6am they appear to assess similar quantities and there appears to have been a sudden peak at 9am (I've not been at the property during this time).
The wind comparisons are interesting too. The Davis is 16 years old, with the original vane having had no maintenance over that period so perhaps it's not as responsive as the electronic sensor in the Ecowitt.
Here are the comparisons for what they are worth and draw your own conclusions 

UPDATE @ 4:30pm
Go figure!!!  I've just checked the daily rain totals for both Stations and the Ecowitt is 44.4mls and the Davis 43.6mls.......

[TonyC]

Having been in possession of an Ecowitt WS90 weather station for about 3 months now I thought I’d quickly review my experience for anyone considering going down the same track.
If you don’t like reading manuals, you can install the Wittboy WS90 in a very short time to record temp/humidity/wind and whether it is raining or not. Built in software allows you to easily connect to publish your data to the internet. It is a relatively cheap way of starting off down the weather station journey.
By installing it next to a Davis VP2, I’ve been able to compare the readings, which have been fairly consistent in all but the rainfall.
If you are thinking of making a purchase, I’d recommend you read this first regarding rainfall. http://meshka.eu/Ecowitt/dokuwiki/doku.php?id=start#ws90_wittboy

The Haptic rain gauge has so many variables which can affect the accuracy of the readings. Wind can affect both Haptic and tipping bucket, but different intensity levels of the downpour affect the Haptic sensor solely. To compensate for this, the software in the WS90 has 5 settings to set a gain factor going from less than 4mm per hour, up to more than 60mm per hour. (I wasn’t aware of these settings until I did some research.  With the amount of rain we’ve been having lately, it’s been giving me the chance to have a play with different settings in an attempt to align rainfall to the Davis. I guess one could use an old fashioned plastic gauge to do the same thing.
I’ve included a graphic here to illustrate the settings in the software. At installation all the gains defaulted to 1.00  which tended to record higher rainfall than the Davis. Altering them to firmware 1.4.7 recommended settings, recorded somewhat less than the Davis.

Summing up……. I’m not convinced Haptic rain gauges are the way to go if you want accurate rainfall records without an awful lot of experimentation.