WXforum.net
Weather Station Hardware => Davis Instruments Weather Stations => Topic started by: WXman on May 30, 2018, 11:52:21 AM
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I noticed that the fan on my VP2 wasn't running.
I dropped the shields down to access the fan, gave it a little push with my finger, and it started running very very slowly. Hmm.. odd.
I pulled the solar cover off the ISS control box and laid it down on top of the box horizontally, still hooked up, so that the sun hit it more directly and the fan started running faster.
When the cover is attached to the ISS normally, it won't run the fan hard at all. The station is facing south as directed by the instructions.
Do you guys think that my fan is getting tired and needs replacement? or is the solar panel to blame?
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I had this same thing happen. With a "push" the fan would run, but stop again the next day.
I did replace the fan and it resolved the issue. (I also rebuilt the fan assembly using a new motor from Jameco, but that became a spare)
I did an "autopsy" on the motor afterwards and the brushes had worn out. See https://www.wxforum.net/index.php?topic=27073.0 (https://www.wxforum.net/index.php?topic=27073.0)
Greg H.
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Do you have the DFARS unit, Daytime only? .. Reason I'm asking the solar cell cover you mentioned on ISS cover doesn't work with the fan unless you have the Daytime (DFARS) kit...
The 24 hour FARS uses the much larger solar cell mounted below for charging batteries and provides extra solar power day time sun.
Regardless if you needed to manually spin fan to start it, that could be a sign fan is failing unless somehow batteries were drained 24 hour fars and/or solar shield covered from sun.
Here are the 2 different solar panels. The kit is for daytime only charges supercap and also powers fan.
The full 24 hr shield uses two different solar cells.
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I noticed that the fan on my VP2 wasn't running.
I dropped the shields down to access the fan, gave it a little push with my finger, and it started running very very slowly. Hmm.. odd.
Not at all, I've seen this too many times with stock motors, exactly why I went a/c. Junk that thing and try this if you want to stay with the stock set-up.
https://www.jameco.com/z/RF-500TB-18280-R-Nichibo-Taiwan-3-Volt-DC-Motor-2104-Rpm-1-3-Volt-Range_2158442.html
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Thanks guys. Yes, it's a daytime FARS unit. It was recently refurbished by Davis at a cost of $200. So I'm not exactly happy but I'm sure it's been enough months now that they won't cover it. Does swapping out these fan motors require any soldering or electrical knowledge? It is completely plug and play, other than centering the motor?
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Thanks guys. Yes, it's a daytime FARS unit. It was recently refurbished by Davis at a cost of $200. So I'm not exactly happy but I'm sure it's been enough months now that they won't cover it. Does swapping out these fan motors require any soldering or electrical knowledge? It is completely plug and play, other than centering the motor?
For the Jameco motor replacement, it does require some soldering skill. Also, you will need to "dig out" the motor from a bunch of hot melt glue.
If you are just replacing the entire fan assembly, it is not that bad. Just keep track of the plates as you disassemble the shield. I used pencil and numbered them.
Greg H.
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Ok thanks. Yeah I've replaced the fans before. It's actually not bad. 3 screws and a simple snap connection between the fan and wiring. But, it's $40.
Guess I'll decide which way to go and maybe work on that this weekend. With summer coming, it's prime time for the FARS.
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That is one of the good points about DFARS vs 24 hr. The sensor is more open so the Dfars fan can die sometimes without notice depending on sun intensity, the 24 hr is different you would notice right away it does better job aspirating around the clock but requires operational fan to draw air into sensor chamber.
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Thanks guys. Yes, it's a daytime FARS unit. It was recently refurbished by Davis at a cost of $200. So I'm not exactly happy but I'm sure it's been enough months now that they won't cover it. Does swapping out these fan motors require any soldering or electrical knowledge? It is completely plug and play, other than centering the motor?
For the Jameco motor replacement, it does require some soldering skill. Also, you will need to "dig out" the motor from a bunch of hot melt glue.
If you are just replacing the entire fan assembly, it is not that bad. Just keep track of the plates as you disassemble the shield. I used pencil and numbered them.
Greg H.
Curious as to why you would need to number the plates? Obviously the bottom and top plates are physically different, but most plates in the middle are the same?
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Somewhat related, can anyone tell me the specific p/n or description for the connector on the solar panel lead? Buying components to go stand-alone and based on the tiny solar panels, I've thought it would be more reliable to power from an external solar panel/battery/charge controller setup. So I'd need to either procure the connector on the solar panel leads or procure the jack on the console A/C adapter. If you can tell me both of those p/ns that would be great. Might Ryan at Scaled Instruments have these pieces?
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Steven the Davis larger solar cell is more than enough to charge a set of 'C' batteries for nighttime and power the fan.
They are 3v fans and run about 2.4v if memory serves. If you run at higher voltage the fan won't last long so larger panels aren't necessary.
If you want a more reliable fan that really pulls some serious air (Don't go too high) some here are using AC fans.
I use this AC fan. Just make sure you are on a GFCI circuit outside. It will run for years 24/7 and never fail, rated at -40C for cold climates. Remember draw air across sensor so fan heat is exhausted out top of shield and not down on sensor.
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Thanks guys. Yes, it's a daytime FARS unit. It was recently refurbished by Davis at a cost of $200. So I'm not exactly happy but I'm sure it's been enough months now that they won't cover it. Does swapping out these fan motors require any soldering or electrical knowledge? It is completely plug and play, other than centering the motor?
For the Jameco motor replacement, it does require some soldering skill. Also, you will need to "dig out" the motor from a bunch of hot melt glue.
If you are just replacing the entire fan assembly, it is not that bad. Just keep track of the plates as you disassemble the shield. I used pencil and numbered them.
Greg H.
Curious as to why you would need to number the plates? Obviously the bottom and top plates are physically different, but most plates in the middle are the same?
I just wanted to get them in the same order. I thought that there were a couple of oddball ones in the stack if I remember correctly.
Greg H.
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But, it's $40.
And you'll have the same crappy motor and $37 bucks less in your pocket vs the Jameco motor.
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Thanks guys. Yes, it's a daytime FARS unit. It was recently refurbished by Davis at a cost of $200. So I'm not exactly happy but I'm sure it's been enough months now that they won't cover it. Does swapping out these fan motors require any soldering or electrical knowledge? It is completely plug and play, other than centering the motor?
For the Jameco motor replacement, it does require some soldering skill. Also, you will need to "dig out" the motor from a bunch of hot melt glue.
If you are just replacing the entire fan assembly, it is not that bad. Just keep track of the plates as you disassemble the shield. I used pencil and numbered them.
Greg H.
Curious as to why you would need to number the plates? Obviously the bottom and top plates are physically different, but most plates in the middle are the same?
I thought that there were a couple of oddball ones in the stack if I remember correctly.
Greg H.
No sir, they're all the same. However, they can be a little frustrating to line up properly.
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Steven the Davis larger solar cell is more than enough to charge a set of 'C' batteries for nighttime and power the fan.
They are 3v fans and run about 2.4v if memory serves. If you run at higher voltage the fan won't last long so larger panels aren't necessary.
If you want a more reliable fan that really pulls some serious air (Don't go too high) some here are using AC fans.
I use this AC fan. Just make sure you are on a GFCI circuit outside. It will run for years 24/7 and never fail, rated at -40C for cold climates. Remember draw air across sensor so fan heat is exhausted out top of shield and not down on sensor.
That's the fan I have, suggested by Randy. Installed on 7/10/17 and haven't looked back!
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Steven the Davis larger solar cell is more than enough to charge a set of 'C' batteries for nighttime and power the fan.
They are 3v fans and run about 2.4v if memory serves. If you run at higher voltage the fan won't last long so larger panels aren't necessary.
If you want a more reliable fan that really pulls some serious air (Don't go too high) some here are using AC fans.
I use this AC fan. Just make sure you are on a GFCI circuit outside. It will run for years 24/7 and never fail, rated at -40C for cold climates. Remember draw air across sensor so fan heat is exhausted out top of shield and not down on sensor.
No, wasn't looking to go A/C - just the opposite. Goal is self-contained setup and knew that external solar panel, 12V battery and charge controller with stepdown to fan voltage would ensure fan ran at optimum speed throughout the day rather than slowing so much with marginal sunlight hitting the 10 sq inch panel.
So no one can tell me the connectors on the solar panel lead and for the console A/C adapter? There are a couple dozen jack styles for A/C adapters.
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No, wasn't looking to go A/C - just the opposite. Goal is self-contained setup and knew that external solar panel, 12V battery and charge controller with stepdown to fan voltage would ensure fan ran at optimum speed throughout the day rather than slowing so much with marginal sunlight hitting the 10 sq inch panel.
So no one can tell me the connectors on the solar panel lead and for the console A/C adapter? There are a couple dozen jack styles for A/C adapters.
The drawing on the Davis #6625 AC adapter which plugs into the ISS J11 connector (above the CR123A battery) shows the OUTSIDE metal ring is NEGATIVE(-) and the INSIDE receptacle is POSITIVE(+).
The solar panel for my spare ISS (looking down at backside) has the left wire being NEGATIVE and the right wire (with white strobe lines on insulation) being POSITIVE, which translates to J31 Solar Panel on ISS being: top pin is NEG and bottom pin (closest to CR123A battery) is POS.
Pretty easy to figure out positive/negative, but need enough information to order the connectors from Digikey or elsewhere.
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Okay, so I disassembled the fan and took the old motor out and installed the new motor. Soldered the connections back just like they were before. Reinstalled everything and I've got the exact same symptoms. Fan won't run unless I give it a flip with my finger and only then will it run if the solar panel is directly facing the Sun at a 90 degree angle. I checked battery voltage and it is at 2.9 volts. What in the world is going on here? Solar panel going bad?
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I checked battery voltage and it is at 2.9 volts. What in the world is going on here? Solar panel going bad?
The battery voltage has nothing to do with the fan in full sun, because the solar panel itself powers the fan. When there's less than "full" sun, then the batteries start to contribute. You need to check what voltage the solar panel itself is putting out, should be around 2.4-2.5 vdc iirc, but with a full charge on the battery, makes me think it's ok. Strange....
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Okay, so I disassembled the fan and took the old motor out and installed the new motor. Soldered the connections back just like they were before. Reinstalled everything and I've got the exact same symptoms. Fan won't run unless I give it a flip with my finger and only then will it run if the solar panel is directly facing the Sun at a 90 degree angle. I checked battery voltage and it is at 2.9 volts. What in the world is going on here? Solar panel going bad?
What happens if you replace the batteries (temporarily of course) with good non-rechargeable ones?
What's the output voltage of the solar panel when directly facing the sun (preferably when disconnected from the fan)?
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BTW, I know this sounds like :roll:, but since you put in another motor only, are you positive the fan blades are not in any contact with the housing? These motors have nowhere near enough torque to make any kind of contact.
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Yep I centered the fan perfectly using wooden shims. It's good and solid. Tomorrow when the sun is back up I will take measurements of the output voltage at the solar panel. Don't know why it skipped my mind to do that tonight. Is it possible for the solar panels to go bad like that?
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Is it possible for the solar panels to go bad like that?
Haven't seen it, but I'm sure it can. As I said earlier though, if the panel was bad, your batteries would be dead.
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Yes, it's a daytime FARS unit.
Wow, I completely spaced this portion of the thread. #-o Since this is a DFARS, you have no batteries that get charged in the first place. Sorry, but others will have to help as I have no idea what the output voltage is for DFARS. :oops:
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I checked battery voltage and it is at 2.9 volts.
I assumed this was applicable. But now I assume you checked the ISS batteries? [Yes, I know what "ass u me" means]
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I checked battery voltage and it is at 2.9 volts.
But now I assume you checked the ISS batteries? [Yes, I know what "ass u me" means]
It's DFARS. The battery has nothing to do with the fan, just the transmitter. The solar panel only charges the super-cap and runs the fan when there's ample sunlight.
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I checked battery voltage and it is at 2.9 volts.
But now I assume you checked the ISS batteries? [Yes, I know what "ass u me" means]
It's DFARS. The battery has nothing to do with the fan, just the transmitter. The solar panel only charges the super-cap and runs the fan when there's ample sunlight.
I understand that. I was just trying to verify what battery voltage Wxman measured.
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I pulled the battery out of the ISS, took it to my workshop, threw the volt meter on it, and got 2.9 volts. So I assumed it was not the problem and popped it back in.
The fan motor has been changed, as mentioned, so it's not the problem either.
So I guess that leaves two possibilities: the solar panel or something on the ISS circuit board.
Does anyone know what the output voltage FROM the solar panel on the ISS cover TO the DFARS fan should be? I'll test mine this afternoon to see what it's putting out.
Also, I would love to buy a supplemental solar panel to wire in also and that way I can face it to the west and have the fan run until the sun actually sets during summer.
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I just checked my dfars solar panel. I'm getting 2.35 volts directly toward the sun. This isn't normal sun angle however. My larger dfars panel comes with 24hr. shield at normal sun angle for cell this time of year facing south is only putting out 1.9 volts.
So around 1.9v would be about what you see at normal sun angle dead of summer. As sun angle is lower more inline with solar cell angle this fall and spring voltage would go up I'm assuming.
Check voltage output on both cells dfars panel one goes to fan the other for charging super capacitor.
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In addition to measuring the voltage of the solar panel with the panel disconnected,
Check the voltage at the fan terminals with the solar panel connected and facing the sun.
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I did have one DFARS panel go bad, only happened the one time so its really rare considering.
Only half the panel went bad the Dfars are split panels. If they are showing voltage regardless of how much depending on sun angle time of day, fan load etc. the panel is good. When a panel goes bad it will show 0 volts.
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I did have one DFARS panel go bad, only happened the one time so its really rare considering.
Only half the panel went bad the Dfars are split panels. If they are showing voltage regardless of how much depending on sun angle time of day, fan load etc. the panel is good. When a panel goes bad it will show 0 volts.
There are solar panel failure modes that result in reduced (non-zero) voltage, and also in reduced current capability.
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okay so I got some readings and I learn something new. The upper portion of the solar panel does not have any control over the fan. It's the bottom portion that makes the fan run. I tested the upper portion and got 2.2V facing west toward the sun, and 2.1V facing south mounted to ISS. But...the bottom portion only outputs 1.83V when facing the sun and drops off to 0.25V when mounted on ISS facing south. At the fan, I get 1.72V with the panel facing the sun. At this point the fan will run. As soon as I turn the solar panel in any direction away from direct sun angle the voltage drops off so fast that the fan won't run.
So, it appears that my solar panel cover is to blame. Does anybody know of a supplemental solar panel that I could tie in along with this one to supply additional voltage? I would like to mount it and face it to the West so that the fan will run for more of the day.
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So, it appears that my solar panel cover is to blame. Does anybody know of a supplemental solar panel that I could tie in along with this one to supply additional voltage? I would like to mount it and face it to the West so that the fan will run for more of the day.
You shouldn't need to supplement anything. I would merely buy another panel cover.
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-116-pro2-solar-cover-for-daytime-fan-aspirated-radiation-shield-kit/
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If you want a more reliable fan that really pulls some serious air (Don't go too high) some here are using AC fans.
This deserves repeating. If you're able, this solves ALL the problems you're experiencing/addressing. Can't recommend this enough.
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okay so I got some readings and I learn something new. The upper portion of the solar panel does not have any control over the fan. It's the bottom portion that makes the fan run. I tested the upper portion and got 2.2V facing west toward the sun, and 2.1V facing south mounted to ISS. But...the bottom portion only outputs 1.83V when facing the sun and drops off to 0.25V when mounted on ISS facing south. At the fan, I get 1.72V with the panel facing the sun. At this point the fan will run. As soon as I turn the solar panel in any direction away from direct sun angle the voltage drops off so fast that the fan won't run.
So, it appears that my solar panel cover is to blame. Does anybody know of a supplemental solar panel that I could tie in along with this one to supply additional voltage? I would like to mount it and face it to the West so that the fan will run for more of the day.
First I would wire the top (good) panel into fan just to make sure... Worst thing to happen is you will drain some of the transmitter battery. These transmitters can go months without any solar. I have one in the garage running just on battery. Plus doesn't take a lot of sun for super cap to charge. If fan spins normally you will have no doubt. Maybe even try it like that sharing panel for awhile, I'm not convinced you need a full panel just for supercap and transmitter signal.
As far as replacement I would just order a new cover or add the larger solar panel used on 24 hr fars.
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-116-pro2-solar-cover-for-daytime-fan-aspirated-radiation-shield-kit/
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-119-pro2-24hr-spars-solar-panel/
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okay so I got some readings and I learn something new. The upper portion of the solar panel does not have any control over the fan. It's the bottom portion that makes the fan run. I tested the upper portion and got 2.2V facing west toward the sun, and 2.1V facing south mounted to ISS. But...the bottom portion only outputs 1.83V when facing the sun and drops off to 0.25V when mounted on ISS facing south. At the fan, I get 1.72V with the panel facing the sun. At this point the fan will run. As soon as I turn the solar panel in any direction away from direct sun angle the voltage drops off so fast that the fan won't run.
So, it appears that my solar panel cover is to blame. Does anybody know of a supplemental solar panel that I could tie in along with this one to supply additional voltage? I would like to mount it and face it to the West so that the fan will run for more of the day.
or add the larger solar panel used on 24 hr fars.
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-119-pro2-24hr-spars-solar-panel/
If you don't want/can't do a/c, I'll give you this, used of course, but still should work just fine. It's merely siting in my spare parts bin collecting dust, as I'll probably never use it again.
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Good deal.. [ You are not allowed to view attachments ]
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okay so I got some readings and I learn something new. The upper portion of the solar panel does not have any control over the fan. It's the bottom portion that makes the fan run. I tested the upper portion and got 2.2V facing west toward the sun, and 2.1V facing south mounted to ISS. But...the bottom portion only outputs 1.83V when facing the sun and drops off to 0.25V when mounted on ISS facing south. At the fan, I get 1.72V with the panel facing the sun. At this point the fan will run. As soon as I turn the solar panel in any direction away from direct sun angle the voltage drops off so fast that the fan won't run.
So, it appears that my solar panel cover is to blame. Does anybody know of a supplemental solar panel that I could tie in along with this one to supply additional voltage? I would like to mount it and face it to the West so that the fan will run for more of the day.
or add the larger solar panel used on 24 hr fars.
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-119-pro2-24hr-spars-solar-panel/
If you don't want/can't do a/c, I'll give you this, used of course, but still should work just fine. It's merely siting in my spare parts bin collecting dust, as I'll probably never use it again.
You have a spare solar cover you'll never use again? That would be great. But it looks like they are relatively inexpensive at scaled instruments so I don't mind buying one if you think you may ever have another use for yours.
I can't do AC because it's just not feasible in the location where my station is out in the field.
Reason I was considering a second panel to face west is that I figured it would help keep the fan going longer as the sun is setting and the air is still hot and humid for a while. But I guess I'll try a new cover first and see how it works.
Thanks for all the help.
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okay so I got some readings and I learn something new. The upper portion of the solar panel does not have any control over the fan. It's the bottom portion that makes the fan run. I tested the upper portion and got 2.2V facing west toward the sun, and 2.1V facing south mounted to ISS. But...the bottom portion only outputs 1.83V when facing the sun and drops off to 0.25V when mounted on ISS facing south. At the fan, I get 1.72V with the panel facing the sun. At this point the fan will run. As soon as I turn the solar panel in any direction away from direct sun angle the voltage drops off so fast that the fan won't run.
So, it appears that my solar panel cover is to blame. Does anybody know of a supplemental solar panel that I could tie in along with this one to supply additional voltage? I would like to mount it and face it to the West so that the fan will run for more of the day.
or add the larger solar panel used on 24 hr fars.
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-119-pro2-24hr-spars-solar-panel/
If you don't want/can't do a/c, I'll give you this, used of course, but still should work just fine. It's merely siting in my spare parts bin collecting dust, as I'll probably never use it again.
You have a spare solar cover you'll never use again?
No sir, not a cover, this is the panel that charges the fan's batteries and runs the fan itself on the 24hr FARS. I no longer use it.
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-119-pro2-24hr-spars-solar-panel/
If you're getting a new solar cover for the DFARS, I'd see if that solves your issues before messing with the 24hr panel. If you decide you still want it, it yours.
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Thanks everyone for the help. I'm going to order a new cover pretty soon and hopefully that'll fix the issues.
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So I'm still trying to diagnose this. :roll:
I finally got a new solar cover. I checked voltage at the terminals on the cover. Both the top panel and the bottom panel are putting out 2.5 volts. OK so I plug it up to the ISS and the fan still doesn't come on. Sigh..
So I checked voltage at the terminals on the solar cover WITH IT PLUGGED UP TO THE ISS and now I get 0.52 volts.
So, when it's not plugged up it puts out good voltage and when it is plugged up the voltage drops. I then checked my old panel and it turns out that it's the same way. So my solar cover wasn't the problem afterall.
So what's going on here? Fan is new, cover is fine, battery is fine. Why is my voltage dropping and not allowing my fan to run??
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okay so I got some readings and I learn something new. The upper portion of the solar panel does not have any control over the fan. It's the bottom portion that makes the fan run. I tested the upper portion and got 2.2V facing west toward the sun, and 2.1V facing south mounted to ISS. But...the bottom portion only outputs 1.83V when facing the sun and drops off to 0.25V when mounted on ISS facing south. At the fan, I get 1.72V with the panel facing the sun. At this point the fan will run. As soon as I turn the solar panel in any direction away from direct sun angle the voltage drops off so fast that the fan won't run.
So, it appears that my solar panel cover is to blame. Does anybody know of a supplemental solar panel that I could tie in along with this one to supply additional voltage? I would like to mount it and face it to the West so that the fan will run for more of the day.
First I would wire the top (good) panel into fan just to make sure... Worst thing to happen is you will drain some of the transmitter battery. These transmitters can go months without any solar. I have one in the garage running just on battery. Plus doesn't take a lot of sun for super cap to charge. If fan spins normally you will have no doubt. Maybe even try it like that sharing panel for awhile, I'm not convinced you need a full panel just for supercap and transmitter signal.
As far as replacement I would just order a new cover or add the larger solar panel used on 24 hr fars.
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-116-pro2-solar-cover-for-daytime-fan-aspirated-radiation-shield-kit/
https://www.scaledinstruments.com/shop/davis-instruments/davis-7345-119-pro2-24hr-spars-solar-panel/
Crap, I paid $62 at Ambient for the 7345.116 cover, wish I had seen this sooner.
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So I'm still trying to diagnose this. :roll:
I finally got a new solar cover. I checked voltage at the terminals on the cover. Both the top panel and the bottom panel are putting out 2.5 volts. OK so I plug it up to the ISS and the fan still doesn't come on. Sigh..
So I checked voltage at the terminals on the solar cover WITH IT PLUGGED UP TO THE ISS and now I get 0.52 volts.
So, when it's not plugged up it puts out good voltage and when it is plugged up the voltage drops. I then checked my old panel and it turns out that it's the same way. So my solar cover wasn't the problem afterall.
So what's going on here? Fan is new, cover is fine, battery is fine. Why is my voltage dropping and not allowing my fan to run??
Battery would have nothing to do with Dfar fan that's part of the ISS transmitter.
Double check everything make sure all plugs are wired correctly.
And you say fan is new? Freely spins by hand inside where it sits no obstruction binding fan like a cable etc.
The upper solar panel is plugged into the ISS for charging capacitor
The lower solar panel is plugged into the fan assembly wire
Fan Assembly wire is plugged into fan
Voltages are good until you plug fan in and it doesn't spin
If all correct i would say fan is bad drawing the extra current.
You may need to contact Davis but go over manual again and check fan for free movement and all plugs are correct.
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Yes, fan is new, but the old one it replaced works exactly the same. That is, if I give them a flip with my finger they'll take off and run slowly IF the panel is aimed directly at the sun. So, I don't think the fan is the issue.
And now I've got two solar covers that both are working exactly the same. 2.5 volts unplugged, 0.5 volts plugged into the fan.
So I just need to figure out where the voltage drop is happening. Could a faulty wire cause that? The DFARS is wired directly from the solar cover to the fan, right? The ISS circuit board doesn't act as a middle man?
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Yes, fan is new, but the old one it replaced works exactly the same. That is, if I give them a flip with my finger they'll take off and run slowly IF the panel is aimed directly at the sun. So, I don't think the fan is the issue.
And now I've got two solar covers that both are working exactly the same. 2.5 volts unplugged, 0.5 volts plugged into the fan.
So I just need to figure out where the voltage drop is happening. Could a faulty wire cause that? The DFARS is wired directly from the solar cover to the fan, right? The ISS circuit board doesn't act as a middle man?
There is a little board sitting as the middleman between the solar, the two batteries, and the fan. I would check that board out. Said board is 100% split away from the ISS box and its own solar panel. It's under a little white pop-off half dome cover, that looks just like this: https://www.scaledinstruments.com/shop/davis-instruments/davis-7342-514-vantage-pro2-spars-pcba-junction-board-shield/
https://www.scaledinstruments.com/shop/davis-instruments/davis-7315-053a-pro2-24hr-spars-pcba-circuit/
I honestly wish that little board had the monitor plugs on it, and plugged into the ISS. It would be able to see charge level and fan speed...
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But mine is a daytime FARS so I don't have that cover.
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Have you tried to contact Davis and give them everything you know including voltages. I keep going back fan but don't want you to do it without Davis input first.
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No, I haven't contacted Davis. I'm sure they'd say I need to buy one of THEIR replacement fans and they can't help me since I'm using a universal fan motor of a different brand.
And to tell you the truth, I think that may be my next move. I eliminated the wiring as a culprit because I connected the solar cover terminals directly to the fan terminals and got the same results. 2.5 volts disconnected, but down to below 0.2 volts when connected. So, it surely has to be an issue at the fan itself. The solar cover is fine and the wiring is fine.
I ordered the exact fan motor that others have said they used with success. So this is odd. But I think at this point the next logical step is to order a Davis fan. I guess I'll try that and see what happens. #-o
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I didn't realize it wasn't a Davis fan. I've never tried one of those aftermarket motors but very possible you just got a bad unit.
After everything you've tried yes I would try a stock Davis fan.
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I can't speak for anyone else's experiences with the Jameco fan motors. But I bought 2 a while back and both have been very picky on voltage. 4-5 volts (5 volt xfmr) it ran for over a year 24/7. When I upped the xfmr to a 7 volts, the fan really pulled some air but burnt-out in less than a month. That was my bad for running the fan over spec voltage. But I noticed that below 3v it was very very weak and based on that, <2.5v would barley run at all, at least with the two I had.
If I had to guess, it appears the model motor you have is drawing more current (amps) that that little 1.2w PV module can put out. Open voltage on a PV panel means nothing. You can have panel that reads 40v open but not create but 2mA of current under a load. Maybe Jameco changed there motor coil windings without a part # change ??