Author Topic: Davis Vantage Pro2 - Super Capacitor Replacement - DIY  (Read 2727 times)

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Online johnd

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #25 on: May 12, 2018, 04:25:50 AM »
Here's a thought:  rechargeable batteries.  Who needs an SC?

See Davis EM nodes.
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Offline dalecoy

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #26 on: May 12, 2018, 11:53:24 AM »
Here's a thought:  rechargeable batteries.  Who needs an SC?

See Davis EM nodes.

I couldn't find a schematic (to check for supercap), but I do see that it has a rechargeable lithium battery (plus D-cells for backup). 

I also see:
Quote
Why is my Vantage Connect or EnviroMonitor battery low?
There could be a number of reasons, including:

    * Obscured or lack of direct sunlight on the solar panel
    * Prolonged temperatures of -4 degrees F (-20 degrees C) and below
    * Possible physical malfunction

Nice system - $395 (plus sensors) per node, plus $795 for the gateway.  That's not a criticism, by the way - undoubtedly worth the price. 

Online johnd

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #27 on: May 12, 2018, 12:39:53 PM »
Nice system - $395 (plus sensors) per node, plus $795 for the gateway.  That's not a criticism, by the way - undoubtedly worth the price.

Plus the annual data plan too of course, but probably fair value for the features. Very OT for this thread but, since we're here, here's one of the sensor features called a TriScan (manufactured by Sentek). This is a single sensor able to measure moisture, temperature and salinity at 6 different depths simultaneously at 10cm intervals down to 60cm. The image - which is a standard wl.com 2.0 graphic from our site earlier today -  just shows moisture, but there are equivalent pictures for temperature (and I think salinity though we don't use that).

EM has many other features too like being able to handle multiple anemometers.
« Last Edit: May 12, 2018, 12:47:47 PM by johnd »
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Online Bushman

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #28 on: May 12, 2018, 03:15:01 PM »
Yeah, some nice LA cells would be fine with me!

Offline gvmelbrty

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #29 on: May 21, 2018, 05:02:32 PM »
FYI: Ryan at scaledinstruments.com has put together a nicely done pic-heavy super cap replacement tutorial.

Online Bushman

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #30 on: May 21, 2018, 06:56:39 PM »
That is a great tutorial (Thanks Ryan!) but there should be some mechanical attachment of the SC.  Hot glue etc.

Offline WheatonRon

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #31 on: May 21, 2018, 08:31:24 PM »
That is a great tutorial (Thanks Ryan!) but there should be some mechanical attachment of the SC.  Hot glue etc.

Ideally, a user replaceable super capacitor that easily plugs in and out of the PC board like a fuse in some boards. This feature, a color console, blue tooth or wifi connectivity between the console and a computer would be three great enhancements to the VP2 product line. Fortunately, one of my 3 wishes is in the process of being fixed—a WiFi data-logger discussed in a separate thread in this Forum, due by June 15, 2018, and to be sold (at least in the US and Canada) by Ryan at SI no less! The other two wishes really requires Davis to step up and address. One would think a refresh to the VP2 product line would fix this but since the VP2 has been around for over 10 years (my two consoles are 12 years old), with few rumors to support a VP3 release date, this date is likely not imminent.
« Last Edit: May 21, 2018, 08:34:00 PM by WheatonRon »
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Offline WiFiLogger

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #32 on: May 22, 2018, 05:52:18 PM »
If you buy something, you have 24 months of warranty.
If you have issue with capacitor after 5 years, that is ok.
I think your problem is that you don't have electronic service in the mall which will change this capacitor for $15 plus $5 for capacitor. With cleaning, painting etc.
If Davis would did use Ni-CD accu, or lead–acid battery you could have same problem, after 5 years you would have to replace this set. With same money or more.
Super capacitors are not perfect(there is no perfect technology). Davis make perfectly good decision to use it.
Maybe You just want to much from this equipment.

Online Bushman

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #33 on: May 22, 2018, 10:01:44 PM »
Not if the battery was plug and play!

Offline Old Tele man

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #34 on: May 23, 2018, 04:55:27 PM »
Electronically, a capacitor is a fast charge/discharge device, while battery is slow charge/discharge device.

Also, don't expect ANY battery to last for long; ie: car batteries seldom make it more than five years, so why expect weather batteries (or capacitor) to last longer?
« Last Edit: May 23, 2018, 05:00:05 PM by Old Tele man »
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Offline gvmelbrty

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #35 on: May 23, 2018, 06:59:14 PM »
That is a great tutorial (Thanks Ryan!) but there should be some mechanical attachment of the SC.  Hot glue etc.

Yeah, that bit of info should be in there. Mine is held down with a zip tie:


Online Bushman

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #36 on: May 23, 2018, 09:41:05 PM »
Electronically, a capacitor is a fast charge/discharge device, while battery is slow charge/discharge device.

Also, don't expect ANY battery to last for long; ie: car batteries seldom make it more than five years, so why expect weather batteries (or capacitor) to last longer?

And why don't car batteries last longer??

Offline SnowHiker

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #37 on: May 23, 2018, 09:53:45 PM »

And why don't car batteries last longer??
Why not just tell us, rather than asking useless questions that you really don't want an answer to, and then running around in circles?

Offline dalecoy

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #38 on: May 23, 2018, 10:20:37 PM »
And why don't car batteries last longer??

I Know!  I Know!  I Know!   Because they are Rechargeable!

Online Bushman

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #39 on: May 23, 2018, 10:36:33 PM »
And yet, my Toshiba laptop is on  the original rechargable battery - 9 years and  about (literally) a million km of air travel.  HOW could THAT be??

Offline Old Tele man

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #40 on: May 23, 2018, 11:30:22 PM »
And yet, my Toshiba laptop is on  the original rechargable battery - 9 years and  about (literally) a million km of air travel.  HOW could THAT be??
Q: "HOW could THAT be??

A: (1) different chemistry, (2) 100% sealed container, and (3) semi-controlled thermal environment.
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Offline miraculon

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #41 on: May 24, 2018, 08:05:32 AM »
Quote
So i ordered 2x 2.7 50F capacitors and began to upgrade.

With 100F, is the battery even necessary? Can it run all night on the super caps?
Perhaps pulling the battery out overnight might help show whether it can or not. It should be in the "worst case" which would be winter, which we are now past. (at least on this side of the Equator  :grin:)

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Offline SLOweather

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #42 on: May 24, 2018, 08:20:47 AM »
Many many moons ago, I collected data from an inadvertent experiment when the battery in an ISS went dead and wasn't noticed for a couple of weeks. In looking back at the database, in late November at about 35° N 120°W, on close to the least daylight time of the year, the stock ISS started up promptly a little after local sunrise, and ran for about 11 hours after sunset. This behavior was consistent over several days.

It remains unknown if the limiting factor was solar output or capacitor capacity.

Offline dalecoy

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #43 on: May 24, 2018, 11:53:51 AM »
Quote
So i ordered 2x 2.7 50F capacitors and began to upgrade.

With 100F, is the battery even necessary? Can it run all night on the super caps?
Perhaps pulling the battery out overnight might help show whether it can or not. It should be in the "worst case" which would be winter, which we are now past. (at least on this side of the Equator  :grin:)

Greg H.

As an engineer, I view Davis' design as rather elegant.

Solar panel to provide environmentally-friendly free power most of the time.
Supercap, charged by the solar panel during the day, to provide power at night.
A dry battery to provide a bit of power if there was not sufficient stored energy in the supercap (cloudy, etc.)

AND that battery provides days of full-time power in the event the solar panel or supercap completely fails, thus providing time to diagnose and correct the failure without major loss of data.  And of course the system monitors the battery voltage to provide several days of notification that there is a problem.

If the battery suddenly fails for some reason, the system will still continue to operate with perhaps some loss of before-daylight data.  And, of course, will provide warning of the situation.

[Oh, and the option of providing external power through the included jack.]

Going to a system of just solar-panel-plus-rechargeable-battery would:
1.  Require a substantially larger solar panel.
2.  Complicate the ability to diagnose impending battery (or solar panel) failure. (Less reliable warning)
3.  Cause total loss of data if, for some reason, either the solar panel or the battery suddenly fails.
« Last Edit: May 24, 2018, 11:56:57 AM by dalecoy »

Offline Aardvark

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #44 on: May 24, 2018, 12:17:23 PM »
I wish I had read this thread earlier.  On the  circuit board for the ISS,  yes there are two locations for a supercap, but according to Davis, when I replaced mine, the board was to use only one supercap.  The other location was a boo-boo.   They were not recommending to put in a supercap in both locations.    I am not sure if it just would split the storage or be a fail-safe in case the replacement failed.        What was recommended was to put in a cushion between the replacement supercap and the board of something.  I used a bit of foam tape.  The thought at the time was to minimize any vibration that might loosen the base of the cap.

I didn't do it the way Ryan suggested.  I put it directly on the board, but then again Ihave a low watt iron and experience.  Do use a heat sink between the supercap and the solder joint.
« Last Edit: May 24, 2018, 12:25:58 PM by Aardvark »
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Offline dalecoy

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #45 on: May 24, 2018, 12:37:37 PM »
I wish I had read this thread earlier.  On the  circuit board for the ISS,  yes there are two locations for a supercap, but according to Davis, when I replaced mine, the board was to use only one supercap.  The other location was a boo-boo.   They were not recommending to put in a supercap in both locations.    I am not sure if it just would split the storage or be a fail-safe in case the replacement failed.   

It's a mixed bag.  Of course, if neither supercap ever fails, then having two is rather good.  More storage when sunlight is good, etc.

If there's a failure, both supercaps will not fail at the same time.  If the supercap fails "open circuit", then everything is still OK.  The other supercap continues to work.  If the supercap fails "shorted" (or leaks conductive slime onto the circuit board), then it's bad news.  And unfortunately, the "shorted or slimed" failure mode happens more often than "open circuit".  And you have two chances of that.

Summary: Two is good if neither fails, or if one fails "open circuit".

Another factor: Recent manufacture supercaps are much more reliable than early ones were.  Seldom fail.

Personal opinion:  Given the odds, I would probably use two.

Offline Old Tele man

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #46 on: May 24, 2018, 12:48:22 PM »
I wish I had read this thread earlier.  On the  circuit board for the ISS,  yes there are two locations for a supercap, but according to Davis, when I replaced mine, the board was to use only one supercap.  The other location was a boo-boo.   They were not recommending to put in a supercap in both locations.    I am not sure if it just would split the storage or be a fail-safe in case the replacement failed.        What was recommended was to put in a cushion between the replacement supercap and the board of something.  I used a bit of foam tape.  The thought at the time was to minimize any vibration that might loosen the base of the cap.

I didn't do it the way Ryan suggested.  I put it directly on the board, but then again Ihave a low watt iron and experience.  Do use a heat sink between the supercap and the solder joint.
About the only *true* problem with using two supercaps is the *possibility* of overloading/working whatever 'regulating/limiting' circuitry DAVIS has designed-in (to ensure too much voltage doesn't zap ICs) between the solar cell and the supercap. Something designed to handle ONE supercap may not be strong enough to handle charging TWO supercaps...just depends upon how much "design margin" DAVIS incorporated.
« Last Edit: May 24, 2018, 12:52:48 PM by Old Tele man »
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Offline dalecoy

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #47 on: May 24, 2018, 01:41:15 PM »
About the only *true* problem with using two supercaps is the *possibility* of overloading/working whatever 'regulating/limiting' circuitry DAVIS has designed-in (to ensure too much voltage doesn't zap ICs) between the solar cell and the supercap. Something designed to handle ONE supercap may not be strong enough to handle charging TWO supercaps...just depends upon how much "design margin" DAVIS incorporated.

Technically correct, of course - and would also depend on the characteristics of the actual replacement supercaps chosen.

In this actual case, there is no such regulating/limiting circuitry.  The voltage is limited by the maximum possible sunlight intensity (i.e., physics of the solar cell).  And the supercap is capable of accepting much more current than the solar cell can possibly produce. 

Or, as explained by Martin H Magnusson, Lund University · Department of Physics"
"A perhaps simpler way to see it: A solar cell is a diode, and the IV-curve shifts downward linearly with the illumination. Isc is thus proportional to the illumination, while Voc changes logarithmically."

Offline Old Tele man

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #48 on: May 24, 2018, 04:51:11 PM »
About the only *true* problem with using two supercaps is the *possibility* of overloading/working whatever 'regulating/limiting' circuitry DAVIS has designed-in (to ensure too much voltage doesn't zap ICs) between the solar cell and the supercap. Something designed to handle ONE supercap may not be strong enough to handle charging TWO supercaps...just depends upon how much "design margin" DAVIS incorporated.

Technically correct, of course - and would also depend on the characteristics of the actual replacement supercaps chosen.

In this actual case, there is no such regulating/limiting circuitry.  The voltage is limited by the maximum possible sunlight intensity (i.e., physics of the solar cell).  And the supercap is capable of accepting much more current than the solar cell can possibly produce. 

Or, as explained by Martin H Magnusson, Lund University · Department of Physics"
"A perhaps simpler way to see it: A solar cell is a diode, and the IV-curve shifts downward linearly with the illumination. Isc is thus proportional to the illumination, while Voc changes logarithmically."
Ah-h-h-h, but too high VOLTAGE is definitely NOT healthy for all the IC devices that are ALSO being fed from that supercap.
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Offline dalecoy

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Re: Davis Vantage Pro2 - Super Capacitor Replacement - DIY
« Reply #49 on: May 24, 2018, 05:24:27 PM »
The voltage is limited by the maximum possible sunlight intensity (i.e., physics of the solar cell).
Ah-h-h-h, but too high VOLTAGE is definitely NOT healthy for all the IC devices that are ALSO being fed from that supercap.

Too high voltage is also not healthy for the supercap. 

What's the output voltage (at maximum solar intensity) of the Davis solar panel supplied with the VP2?  OK, subtract one diode-drop (0.7 volts) (because of the reverse-current protection required). 

What voltage do you come up with?