sounds like a "super cap issue" with the VP ISS?
I did find a good home for the VP to a gentleman a few miles north of me. It just happens that we both report through muc.appriss.com (local ABC affiliate). He is "old school" and still gets out there with his rain gauge and thermometer to do his reports. Once I get the MK-III up and running I will take the VP-III down and make a gift of it to him (it really needs tender loving care).
When Davis replaced the motherboard the supercap was replaced as well. The triple AA battery (like a cordless phone battery) was also replaced. I think the problem has to be with where the station was mounted. At the most it would get sunlight from 9 am until about 2 pm (during the summertime) due to the way the trees and terrain are in this area. Trying to squeeze a full charge with at the most, 5 hours of sunlight a day was just not cutting it.
Learning a lesson I am relocating the MK-III to what I call "my helicopter landing field" (that actually is big enough to land a Huey in, my former spouse was a Vietnam 1/9th aviator and said he could easily put a bird in that spot, using the main blades to do a little bit of weed whacking). From that spot I will get more consistent temperature, wind speed and direction readings . Where I am located at before I think my precipitation was under-reporting (rain bucket on the side of a power pole) and wind was obstructed by other issues. I have been half-tempted to put an orange wind sock up out there and a white tire to mark a landing field.
One of the things I noticed about the plastic rain buckets and this has applied to every one I ever had, going back to one of the transparent plastic gauges is that for trace precipitation I really need to keep that plastic clean. On the Davis what I resorted to was a buffing wheel with a high quality carnuba automotive wax to polish up the funnel. Water, instead of wetting the funnel would drop straight down into the little tipping buckets that rocked back and forth. Periodically I had to open up the davis to gently clean and polish those plastic-chromed buckets as sediment would build up in them. Surprise-surprise when one time the rain gauge stopped working and I pulled the gauge top off to find a wasps nest in the bucket (they made their way in along where the cable entered the Vantage Pro's bucket.