WXforum.net
Weather Station Hardware => Davis Instruments Weather Stations => Topic started by: hasbo60 on February 04, 2009, 08:06:36 AM
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Hi,
I have a wireless vantage pro 2 which I bought 3 years ago. I now have a problem that I have replaced the battery in the station twice within a couple of days after being completely discharged within a matter of hours. The station is transmiting ok using the solar power cell although the wind speed is staying at 0 but the direction works ok. Is this 2 separate problems or are they linked together. It's a shame I can't use the station properley at the moment as we have all this severe weather over here in england but I can only record any of it when its sunny.!
Hope someone can help,
Thanks, hasbo
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The super capacitor in the SIM has failed. It probably looks like this.
(http://tobaccovilleweather.com/Super%20Capacitor009_640x480.jpg)
Digi-Key has the exact replacement.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=589-1002-ND
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Call Davis; have all info on your station and do a visual to see if your Cap looks like Tom's picture. My Davis is similar to yours and my cap failed out of warranty (slightly) and Davis replaced the board no charge. In the good old days I would have changed the cap myself but now I look hard at risk/reward and usually opt to spend a little money. My guess is you could send the unit back to Davis and have it "reconditioned" for $75.
Summary;
Known problem. Don't know present Davis policy. Could fix yourself if comfortable. I would at least ask how a do it yourself fix mistake would affect your options.
Good Luck
George
There is a video on the replacement of this board. It isn't hard but I would have been uncomfortable applying sufficient force if I hadn't seen it done.
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The down time for repairs might be a while when you factor in the round trip shipping time. I understand that the Davis repair time portion is pretty short though. If that down time is too long for you and you have the money, you could buy a replacement PCBA for the ISS: http://www.davisnet.com/weather/products/weather_product.asp?pnum=07345.978
Perhaps Davis would offer you a trade in value for your defective PCBA that would reduce the total cost. That would have to be arranged before hand though.
A video on how to replace the PCBA is here: http://www.davisnet.com/support/weather/Video/index.asp
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Hi, thanks everyone for your help.
I will have a look at the board when it stops snowing. Not sure if i'm confident enough enough to fix it myself, i will see if anyone can do the repairs here in the UK.
Kind regards,
Hasbo
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The super capacitor in the SIM has failed. It probably looks like this.
Digi-Key has the exact replacement.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=589-1002-ND
Ah, thank goodness for this forum once again! I have this exact problem; I killed 2 batteries before I realized something was wrong. My supercap looks very similar to that (like the end leaked little white foam-ish stuff). However, two problems:
1) Digi-key is estimating a 3-week lead time to ship that part and I can't seem to find it anywhere else. Any suggestions?
2) I have no idea how to install the capacitor, is there a thread elsewhere I haven't been able to find?
Thanks.
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You can also find the capacitor here:
http://www.sparkfun.com/commerce/product_info.php?products_id=746
If you have basic electronic soldering skills (or a friend who does!) and take your time, replacing the cap is no big deal.
-Dave
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If you have basic electronic soldering skills (or a friend who does!) and take your time, replacing the cap is no big deal.
Do be aware though that the supercap is a component that must be handled very carefully, otherwise you will do the replacement and find exactly the same problem recurring some time later. It is vital that no stress is placed on the supercap leads where they enter the supercap body. AIUI on later VP2W boards Davis now use a specially developed jig to bend the supercap leads in the safest way and also now glue the supercap to the PCB, to prevent the sort of subtle damage to the internal supercap structure that can cause the supercap to start failing later in its life.
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You can also find the capacitor here:
http://www.sparkfun.com/commerce/product_info.php?products_id=746
If you have basic electronic soldering skills (or a friend who does!) and take your time, replacing the cap is no big deal.
-Dave
This capacitor seems to be the most common reason for failure of the VP2 mentioned on this forum. Is it something I should order now and keep on hand to use when (not IF) it fails?
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I'm not fortunate to own the VP2 but have been reading up on this problem just the same. Having the value that capacitor has leads me to believe it's possibly used to sustain solar recharge voltage during the night or cloudy conditions. I would be interested to see when it does fail if you just snipped it out (removing the short circuit this way) if the sensor would continue to operate. I don't think the "batteries draining quickly" problem would continue with the short removed and you may be able to use it 'till the replacement arrives.
Dan
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Hi,
I have a wireless vantage pro 2 which I bought 3 years ago. I now have a problem that I have replaced the battery in the station twice within a couple of days after being completely discharged within a matter of hours. The station is transmiting ok using the solar power cell although the wind speed is staying at 0 but the direction works ok. Is this 2 separate problems or are they linked together. It's a shame I can't use the station properley at the moment as we have all this severe weather over here in england but I can only record any of it when its sunny.!
Hope someone can help,
Thanks, hasbo
hasbo, I don't have a Davis station, but I know Maplins sell supercaps if you fancy trying the repair yourself.
Alan
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This capacitor seems to be the most common reason for failure of the VP2 mentioned on this forum. Is it something I should order now and keep on hand to use when (not IF) it fails?
It depends how old your VP2 might be. There was a problem on the original batch of VP2 stations (eg early 2005) when the supercap leads were bent too close to to the supercap body prior to stuffing. Quite a percentage of boards from this batch did eventually give problems though the symptoms developed only slowly and for some of the boards it's just in recent months that the problem has surfaced, which is why it's got a higher profile in forums etc at present.
Various changes to the production process were made AIUI with the result that supercap issues should be progressively less likely on more recent stations, with the latest production tweaks made in late 2007. So stations made from late 2007 on are expected to show a very low incidence of supercap faults.
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I'm not fortunate to own the VP2 but have been reading up on this problem just the same. Having the value that capacitor has leads me to believe it's possibly used to sustain solar recharge voltage during the night or cloudy conditions. I would be interested to see when it does fail if you just snipped it out (removing the short circuit this way) if the sensor would continue to operate. I don't think the "batteries draining quickly" problem would continue with the short removed and you may be able to use it 'till the replacement arrives.
Dan, my station (with failed supercap at the moment) works great as long as the sun is out... as soon as darkness sets in, my ISS just stops transmitting. I don't have a battery installed right now because they only last a couple of days without the solar energy helping out at night.
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You can also find the capacitor here:
http://www.sparkfun.com/commerce/product_info.php?products_id=746
If you have basic electronic soldering skills (or a friend who does!) and take your time, replacing the cap is no big deal.
Thanks Dave, I have recruited a skilled friend. However, the Digi-Key capacitor is listed at 2.7V, while the SparkFun one is listed at 2.5V -- does that matter?
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mikejeep,
I don't have a battery installed right now because they only last a couple of days
It would be interesting to see how long a battery would last if you clipped one of the leads to the capacitor as Dan suggested.
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I'm not fortunate to own the VP2 but have been reading up on this problem just the same. Having the value that capacitor has leads me to believe it's possibly used to sustain solar recharge voltage during the night or cloudy conditions. I would be interested to see when it does fail if you just snipped it out (removing the short circuit this way) if the sensor would continue to operate. I don't think the "batteries draining quickly" problem would continue with the short removed and you may be able to use it 'till the replacement arrives.
Dan, my station (with failed supercap at the moment) works great as long as the sun is out... as soon as darkness sets in, my ISS just stops transmitting. I don't have a battery installed right now because they only last a couple of days without the solar energy helping out at night.
Dan
You can also find the capacitor here:
http://www.sparkfun.com/commerce/product_info.php?products_id=746
If you have basic electronic soldering skills (or a friend who does!) and take your time, replacing the cap is no big deal.
Thanks Dave, I have recruited a skilled friend. However, the Digi-Key capacitor is listed at 2.7V, while the SparkFun one is listed at 2.5V -- does that matter?
MikeJeep the capacitor working voltage for either of those should be fine (2.5V or 2.7). Look at the bad one you have now and read the voltage number on it. As long as the new replacement isn't lower than that, you're okay.
Thanks for the information you provided about your failed capacitor. It fits right in with my suspictions of what it's used for, sustaining solar voltage when needed.
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MikeJeep the capacitor working voltage for either of those should be fine (2.5V or 2.7). Look at the bad one you have now and read the voltage number on it. As long as the new replacement isn't lower than that, you're okay.
I checked and the original capacitor says 2.7V. So I should not get the 2.5V one recommeded earlier, correct? I'd love to save the 3 week lead time but it's not worth it if it won't work.
FWIW, I called Davis earlier today; they said it's a known problem with the supercap, but since I was 2 years out of warranty, I was on my own. They will replace the board for $70-$80, but agreed that spending $5 on a capacitor and trying it myself is a better idea at this point.
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Good design and circuit construction practice involves using components that are slightly over the needed voltage rating and if Davis built these right then that 2.7V rating should be high and you may be able to use the 2.5V. To be safe though I'd at least meet the 2.7V rating and forget the 2.5V. Maybe that's why they're going bad in the first place because the voltage rating that they currently use is too low. The extra 3 week lead time may be worth it to save you having to go through it all again.
Dan
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I don't have a battery installed right now because they only last a couple of days
It would be interesting to see how long a battery would last if you clipped one of the leads to the capacitor as Dan suggested.
Well in the interest of experimentation, I just cut one of the leads and dropped in a new battery; I did read on another forum that this prevented the battery from draining as quickly, so my fingers are crossed. It would be nice if this worked, then my station (and others in the future) wouldn't be down while waiting for parts.
Good design and circuit construction practice involves using components that are slightly over the needed voltage rating and if Davis built these right then that 2.7V rating should be high and you may be able to use the 2.5V. To be safe though I'd at least meet the 2.7V rating and forget the 2.5V. Maybe that's why they're going bad in the first place because the voltage rating that they currently use is too low. The extra 3 week lead time may be worth it to save you having to go through it all again.
Thanks Dan, I'll go the safe route and wait for the exact 2.7V replacement. No need to waste time and get stuck doing it all over again.
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No problem. Hope it all works out for you. I've been searching around on the internet for details on the 10f 2.7v capacitor trying to find other options available, such as a higher voltage rating. Nothing so far. Ideally if you could find a 10f in the same size package with a higher volt rating like 4 or 5 volts that would be the way to go. The amount of these failing that i've been reading about is amazing. Possibly a bad batch slipped through the QC department? or just under rated/spec'd.? Who knows. :roll:
Cheers,
Dan
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The amount of these failing that i've been reading about is amazing. Possibly a bad batch slipped through the QC department? or just under rated/spec'd.? Who knows.
See my post above for pointers to the likely cause. In a nutshell, it seems to be because supercaps (or at least the particular type used here) are mechanically less robust than traditional electrolytics and normal PCB assembly techniques (ie component preparation and board stuffing) can lead to subtle damage which causes problems in later life.
FWIW - and ultimately of course only time will tell - I haven't seen a supercap fault in a single board made after the latest production methodology tweaks were introduced in 2007.
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Thanks. I understand what you're saying and being retired from the electronics field I'm not up to speed with these new(?) farad caps. I know with the older electrolytics, ceramic's, mylar's, etc. didn't mind too much how you handled them. Sounds like these "supercaps" are a little more fragile.
Thanks again,
Dan
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From the Davis specification sheet for the wireless VP2:
Battery Life (3-Volt Lithium cell). . . . . . . . . . . . . . . . . . . . 8 months without sunlight - greater than 2 years depending on solar
charging
Battery Life (NiCad C-cells) . . . . . . . . . . . . . . . . . . . . . . . 1 year
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The super capacitor in the SIM has failed. It probably looks like this.
Digi-Key has the exact replacement.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=589-1002-ND
Would this work?
http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMuDCPMZUZ%252bYl45oKYEsy2zX2YktaCRCs7M%3d (http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMuDCPMZUZ%252bYl45oKYEsy2zX2YktaCRCs7M%3d)
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Specs look good - this is not really a difficult application. Should work just fine.
-Dave
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I don't have a battery installed right now because they only last a couple of days
It would be interesting to see how long a battery would last if you clipped one of the leads to the capacitor as Dan suggested.
Well in the interest of experimentation, I just cut one of the leads and dropped in a new battery; I did read on another forum that this prevented the battery from draining as quickly, so my fingers are crossed. It would be nice if this worked, then my station (and others in the future) wouldn't be down while waiting for parts.
FYI, it has been over a week since I clipped one lead, and I haven't had a problem since. It appears that when the supercap fails but remains connected, it sucks the battery dry. Based on Davis' claim of 8 months with no sunlight, I would have to guess one could operate like this for at least a year if the solar panels get normal sun during the day.
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FYI, it has been over a week since I clipped one lead, and I haven't had a problem since. It appears that when the supercap fails but remains connected, it sucks the battery dry. Based on Davis' claim of 8 months with no sunlight, I would have to guess one could operate like this for at least a year if the solar panels get normal sun during the day.
Another member with a potential super cap problem has posted recently. Just curious... is yours still working on the battery only?
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FYI, it has been over a week since I clipped one lead, and I haven't had a problem since. It appears that when the supercap fails but remains connected, it sucks the battery dry. Based on Davis' claim of 8 months with no sunlight, I would have to guess one could operate like this for at least a year if the solar panels get normal sun during the day.
Another member with a potential super cap problem has posted recently. Just curious... is yours still working on the battery only?
Yes it is! Since I clipped one of the leads it has been working just as it did before I had any problems. No low battery problems, no outages at night. The mailman actually delivered my new capacitor today, but since it's working fine I'm not in a big rush to take it down for a few days to have a friend solder it up.