Author Topic: Repeated signal dropouts  (Read 9927 times)

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Offline openvista

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Repeated signal dropouts
« on: January 01, 2018, 12:41:29 PM »
Since our cold spell began on Christmas (temps mostly below 10F with periods below zero), I've noticed an increasing amount of signal drop outs on my VP2 console.

At first, it was just the anemometer transmitter (6332), but as time went on my 1 month old ISS joined the show. FYI, the anemometer transmitter is about 2 years old. Batteries in both were replaced this past Spring (I moved the battery from the old ISS to the new ISS).

I've had occasional dropouts in the past but nothing like this. However, this is the first time since putting the station in service 2.5yrs ago that we've had a stretch of such low temperatures for so long.

Initially, I thought maybe there was something about the cold that lessened the range of the transmitters. This has been discussed here before in other threads (for example: https://www.wxforum.net/index.php?topic=24871.msg239377#msg239377). Accordingly, I moved the console to be higher and closer by about 15ft to both transmitters (ISS is ~50ft away and Anemometer is ~60ft thru 2 walls - 1 drywall and another drywall/wood/siding). Console diagnostics shows that I now average mid 40s signal strength for the anemometer and upper 50s for the ISS (out of a max of 60). When I'm free of extended dropouts, I'm consistently around 98 or 99% for packet reception. So I don't think the issue in the new location is range.

I also changed channels on both transmitters thinking, perhaps, it wasn't weather related but something to do with a new source of interference. Nope.

In my mind that leaves either the console (which isn't even 2 yrs old) or the CR123a batteries.

I noticed that this issue never occurs during bright, sunny days even when temps are in the single digits or colder. It always occurs when light is low or non-existent. So that would suggest the batteries. But if the batteries (replacement OEM Duracells) are depleted after only 8 months in cold weather, I would think the two other VP2 station owners in town (not to mention other forum members in similar or colder climates) would also be experiencing this issue.

If it's the console, why does this issue always occur at night? And why doesn't it occur simultaneously? I've never had the ISS and anemometer drop out at the same time.

None of this makes sense to me, but it has gotten so bad I've had to pull my station off my own weather site and replace it with a neighboring station (via Wunderground) at night.

When I'm feeling up to it (currently down with the flu), I will buy a couple CR123 batteries and see if that does the trick.

Thoughts?
Davis Vantage Pro2 FARS | https://marquetteweather.com | EW7933

Offline miraculon

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Re: Repeated signal dropouts
« Reply #1 on: January 02, 2018, 09:30:34 AM »
I am reasonably sure that this is due to the lithium battery out in the ISS having reduced output at cold temperatures. A quick Google search will find links explaining that the batteries are at about 50% of their room temperature "performance". I am supposing this means AH capability and perhaps voltage as a consequence.

I have been seeing this behavior as well. It seems that as soon as the super-cap runs out, and the temperature is single digits F, it will happen. I have lost comms on my long-range repeater setup as well as my ISS (this 2nd issue seems to be isolated to one older console, though).

The Texas Instruments CC1021 used by Davis has programmable power output registers. I suspect that Davis might have some preservation strategy when the battery is low that reduces power. I keep check the Low Batt indication for my repeater and other SIM transmitters, but they have not toggled status. It might be due to the time (midnight?) of reading the battery status.

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline openvista

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Re: Repeated signal dropouts
« Reply #2 on: January 02, 2018, 10:20:13 AM »
Thank you for the reply, Greg.

The Wikipedia article (https://en.wikipedia.org/wiki/Lithium_battery) on the battery chemistry (actually called a "lithium metal" battery as distinguished from a "lithium ion" battery), shows that it's supposed to have an operational range down to -30C. But, as you say, output in all batteries reduces as temperatures plunge below freezing. So even if there is some kind of output at -30C (-22F), it's probably not enough to power the ISS transmitter. From experience, it would seem the threshold for the ISS is higher. -15C (+5F) or colder for several hours would seem to be a safe, if somewhat rough, set of conditions necessary to produce these drop outs. The colder it gets and the longer the conditions persist, the more frequent are the drop outs.

But that begs the question, if this is true, why isn't this discussed more frequently on this forum? Officially, the VP2 is advertised as operating in temperatures down to -40C (-40F). I recall thread(s) complaining about that particular specification being unrealistically warm for station owners in northern locations (northern Scandinavia, much of Canada, Alaska, ND, MN, ME, etc) and many believed that Davis should produce a product specifically for these climates. Others countered that no company could be reasonably expected to do so as the cost would be too high. I do not recall anyone in those discussions saying, essentially: "-40C? Ha! Try operating these stations consistently below -15C and see what happens!"

I guess I'm at a loss to explain something that would seem to expose Davis to class-action litigation. I'm sure I don't have to explain how much of the globe gets and stays below -15C for stretches every winter. And yet, I can find no other reasonable hypothesis at the moment.
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Offline miraculon

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Re: Repeated signal dropouts
« Reply #3 on: January 02, 2018, 11:23:55 AM »
I can't fault Davis for the known behavior of batteries. They specified the best available type.

If there is a better low temperature battery that fits the CR123 form factor, I would be interested in learning about it.

I am considering installing a 5V regulator for the repeater, since I already have 15VDC out there for my preamplifier. I am not going up there is this weather, though!  :shock:

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline openvista

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Re: Repeated signal dropouts
« Reply #4 on: January 02, 2018, 02:11:38 PM »
If, indeed, the wireless SIM cannot reliably transmit below about 10F, I would certainly fault Davis.

Real-world performance data of a proprietary device cannot be replaced by a handful of anonymous screen names on an internet forum making opposite, anecdotal claims or the results of a Google search for "lithium battery output in cold weather conditions". Davis alone has the information we seek, either way.

That is unless we believe that in the decade or so Davis has been selling wireless VP2s worldwide, they wouldn't have collected enough support inquiries to know if there's a transmission problem with those units.  Extremely improbable. And yet that apparently hasn't stopped them from continuing to market it down to -40C has it?

Bottom line: if I had access to reliable information in 2015 that the station would start dropping offline below 10F, I would have purchased a wired version when I moved to this location at that time. Instead, since that time, I've purchased an additional wireless console and two wireless transmitters. And now I should just pony up for a wired console and 2 wired SIMs?
« Last Edit: January 02, 2018, 03:48:17 PM by openvista »
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Offline SnowHiker

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Re: Repeated signal dropouts
« Reply #5 on: January 02, 2018, 02:45:05 PM »

When I'm feeling up to it (currently down with the flu), I will buy a couple CR123 batteries and see if that does the trick.

Thoughts?
My thought is to get plenty of rest and drink lots of fluids.  :-)

For your station, if you have a long enough extension cord, you can try powering the ISS with the power adapter you have for your console for a cold night or so, then if the problem persists it's likely more than just a battery problem.

For what it's worth, I have an original VP and live in a cold climate (-41.5 F was the low last year, and the VP did record it, despite -40 being the advertised lower limit), and don't seem to have cold related dropouts.  However my ISS is less than 100 feet from the house, no metal or other major obstructions between the console and ISS, and a fairly rural area; so my signal could probably be somewhat weakened and I might not notice, even given the lesser range of the original VP.
« Last Edit: January 02, 2018, 02:46:40 PM by SnowHiker »

Offline LABob

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Re: Repeated signal dropouts
« Reply #6 on: January 02, 2018, 03:38:17 PM »
I can't fault Davis for the known behavior of batteries. They specified the best available type.

If there is a better low temperature battery that fits the CR123 form factor, I would be interested in learning about it.

If I understand how the ISS operates correctly, it only transmits a few times per minute. Couldn't it trickle charge the supercap from the battery and the use the supercap to power the transmission? I'm sure there is a tradeoff involved as there always is in life and physics, but might it be worth it?

Offline miraculon

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Re: Repeated signal dropouts
« Reply #7 on: January 02, 2018, 04:36:18 PM »
I can't fault Davis for the known behavior of batteries. They specified the best available type.

If there is a better low temperature battery that fits the CR123 form factor, I would be interested in learning about it.

If I understand how the ISS operates correctly, it only transmits a few times per minute. Couldn't it trickle charge the supercap from the battery and the use the supercap to power the transmission? I'm sure there is a tradeoff involved as there always is in life and physics, but might it be worth it?

I am almost certain that the super-cap runs the system until it is discharged. Then the battery takes over. I am not sure what you would gain by recharging the super-cap from the battery. I haven't reverse engineered the SIM transmitters, but I would guess that there is some diode steering that feeds the higher of the supplies (battery, super-cap & solar) to the circuitry.

The ISS (and Anemometer Transmitter) transmit wind data every 2.5 seconds. The other data is on a more leisurely schedule.

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline LABob

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Re: Repeated signal dropouts
« Reply #8 on: January 02, 2018, 04:46:31 PM »
I am not sure what you would gain by recharging the super-cap from the battery.

You would gain having a lower current demand on the battery, which may increase the ability of the station to transmit in cold weather (depending on other system characteristics). Instantaneously drawing the energy necessary for a transmission directly from the battery requires far more power than drawing that same energy over a period of time and banking it in the supercap.

Offline openvista

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Re: Repeated signal dropouts
« Reply #9 on: January 02, 2018, 06:02:07 PM »
OK, I have just replaced the battery in the ISS. The old one tested at 2.98V after about 20 minutes inside. New CR123a battery tested at 3.22V. That's not much drain. Replacement would seem like a long shot.

I'll wait to replace the wind transmitter battery until I'm feeling better and the weather cooperates.
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Offline floodcaster

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Re: Repeated signal dropouts
« Reply #10 on: January 02, 2018, 06:04:48 PM »
A timely thread indeed. Had a few dropouts with the recent subzero weather. I have 2 VP2 consoles and 1 Vue console. Both VP2 consoles had dropouts but not the Vue which was located further away and upstairs from the ISS. My (totally unscientific, unproven...etc) theory is that is that the (extreme) cold must affect the ISS transmission output signal strength, and the Vue console is a more sensitive receiver. Again, just my own theory. Counting the days 'til Spring. ;)
Bill


Offline Mattk

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Re: Repeated signal dropouts
« Reply #11 on: January 02, 2018, 08:04:36 PM »
.... The old one tested at 2.98V after about 20 minutes inside. New CR123a battery tested at 3.22V. That's not much drain. Replacement would seem like a long shot.

Tested at 2.98V, then with a load would be close to be considered flat.

Offline openvista

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Re: Repeated signal dropouts
« Reply #12 on: January 02, 2018, 10:11:45 PM »
Tested at 2.98V, then with a load would be close to be considered flat.

Well, if the battery is flat at 2.98V at room temperature, then how does the SIM function when it's well below freezing and the battery can only produce some fraction of its rated power due to physical limitations? Seems a fresh battery would be insufficient.
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Offline openvista

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Re: Repeated signal dropouts
« Reply #13 on: January 02, 2018, 10:45:10 PM »
Anyone know the exact voltage when Davis sends a "LOW" signal over the loop?

« Last Edit: January 03, 2018, 12:00:03 AM by openvista »
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Offline Mattk

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Re: Repeated signal dropouts
« Reply #14 on: January 02, 2018, 11:06:47 PM »
Tested at 2.98V, then with a load would be close to be considered flat.

Well, if the battery is flat at 2.98V at room temperature, then how does the SIM function when it's well below freezing and the battery can only produce some fraction of its rated power due to physical limitations? Seems a fresh battery would be insufficient.

It probably doesn't function real well at all. 2.85v is considered flat for a CR123a, 2.75v is considered totally dead

Offline openvista

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Re: Repeated signal dropouts
« Reply #15 on: January 02, 2018, 11:40:59 PM »
OK the battery I pulled out has an imprint on it that says "2010/04". Can I reasonably assume that's the manufacture date? I know the "guaranteed fresh" date is March 2019 which is not very far out. So, apparently, this battery, although purchased new and installed in April 2017, was sitting on a shelf somewhere for quite awhile.

The new Energizer I put in has a "07/17a" imprint and an expiration of 12/27. Get 'em while they're fresh, right?

I'll know whether the battery change corrects the dropouts as we have another blast of cold air coming with at least one night expected to get below 0F.
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Offline miraculon

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Re: Repeated signal dropouts
« Reply #16 on: January 03, 2018, 08:35:24 AM »
Anyone know the exact voltage when Davis sends a "LOW" signal over the loop?

A few years back I ran this test. This is when my Temp/Hum station was battery only before I added the solar panel. (they ship with solar these days)

"Flash" refers to the diagnostic LED. (which was normally kept off of course)

3.28   New
3.02   Run
2.87   OK
2.85   LOW
2.70   Flash-No Data
2.48   No Flashing

Has anyone had better results with more Farads in the super-cap for this? I wonder if more "F" would keep it going all night...

Greg H.



Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline LABob

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Re: Repeated signal dropouts
« Reply #17 on: January 03, 2018, 10:42:46 AM »
Anyone have an old ISS and really cold weather who's willing to test an RCR123A instead of a CR123A? The RCR123A is the same size but 3.7V instead of 3.0V. Even though rechargeables tend to perform more poorly in the cold capacity-wise, perhaps the higher nominal voltage would be enough to keep the ISS working at lower temps. Data for battery performance at temperature below -40 is hard to come by, but if the ISS can handle 3.7V (3.7V nominal, up to 4.2V fully charged no load) during warm weather I suspect the RCR123A would only sag to around 3.0V in extreme cold.

Offline openvista

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Re: Repeated signal dropouts
« Reply #18 on: January 03, 2018, 11:08:21 AM »
I've got an old SIM and an old 24hr FARS but not a spare console. Afraid I can't run that experiment.

Incidentally, I ordered a battery tester that will place the CR123a under load. The Davis voltage figures that Greg posted earlier, of course, are all determined under load. Simply putting a battery on a multimeter may return a deceiving value. So I should have a better idea of the health of the battery I removed yesterday by early next week (8th or 9th).
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Offline LABob

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Re: Repeated signal dropouts
« Reply #19 on: January 03, 2018, 11:15:06 AM »
Even my $4 Harbor Freight multimeter puts a small load on batteries to test their "real" voltage.

Offline openvista

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Re: Repeated signal dropouts
« Reply #20 on: January 03, 2018, 11:29:02 AM »
Sure so does mine (so does holding a battery between your fingers), but does that load approach the nominal load the battery would be under in the SIM?

Here's a DIY version of what I'm talking: http://www.instructables.com/id/Add-Battery-Test-to-a-Multimeter/
« Last Edit: January 03, 2018, 11:31:38 AM by openvista »
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Offline ValentineWeather

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Re: Repeated signal dropouts
« Reply #21 on: January 03, 2018, 11:33:52 AM »
I'm using the Surefire 123A with success down to -36 last winter. This year between 12AM New Years and  9 am it was in the -25F range. Surefire claims batteries working range -76 to 176 F.

I did put new batteries in the night I knew it was going to get real cold.
Randy

Offline miraculon

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Re: Repeated signal dropouts
« Reply #22 on: January 03, 2018, 11:44:44 AM »
The Sure Fire has 1550 mAH and is for "high drain devices". This should give it a better starting point vs. the temperature de-rating. I am going to order some.

Greg H.


Blitzortung Stations #706 and #1682
CoCoRaHS: MI-PI-1
CWOP: CW4114 and KE8DAF-13
WU: KMIROGER7
Amateur Radio Callsign: KE8DAF

Offline ValentineWeather

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Re: Repeated signal dropouts
« Reply #23 on: January 03, 2018, 11:45:51 AM »
At -37F is where it dropped out last winter so insulated the ISS this year just in case it went that low again.
Randy

Offline openvista

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Re: Repeated signal dropouts
« Reply #24 on: January 03, 2018, 11:51:47 AM »
If there's a Lowe's nearby, Greg, they have them. $5 for 2 pack (which is half the price of Duracell). I believe I may give them a try too.

Thanks, Randy, for the suggestion.
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