Author Topic: Replacing 24-hr FARS and Batteries  (Read 1927 times)

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Offline jchen

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Replacing 24-hr FARS and Batteries
« on: May 12, 2011, 01:41:05 PM »
My Vantage Pro 2 Plus (6163) has been in service for about five years. I replaced the fan and batteries two years ago. I was doing spring maintenance last week and noticed that during the day, the fan was not running. I have ordered the combo fan/battery replacement kit (7758B) and plan to to the repairs this weekend. It occurred to me that perhaps the solar panel powering the FARS may have also gone south.

Does anyone know what the nominal output voltage of the FARS solar panel is?

Davis Vantage Pro2 Plus - 24hr-FARS
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Offline Ladd

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Re: Replacing 24-hr FARS and Batteries
« Reply #1 on: July 28, 2018, 11:51:09 AM »
Bump:

I would like to know this also. My NiCd batteries are either no longer being recharged or are not being recharged fully, as the 24-hour fan is no longer running in the early morning.

Offline jerryg

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Re: Replacing 24-hr FARS and Batteries
« Reply #2 on: July 28, 2018, 12:03:12 PM »
The last time i measured the voltage it ran around 2.4 volts in full sun not plugged in to the fars.

Offline Ladd

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Re: Replacing 24-hr FARS and Batteries
« Reply #3 on: July 28, 2018, 01:01:15 PM »
Thanks for the response.

I just checked my 24-hour FARS solar panel and it is putting out 2.8 to 3.0 in full sun. So the lack of battery recharging isn't due to the solar panel.

I checked the connection from the solar panel wires to the small PCB board and it is quite loose, so perhaps that is the problem. I have tightened up the metal contacts inside the plastic connector housing so that the connector sits more firmly on the pins on the PCB board.

The fan, which would not turn previously when the solar panel was in full sun, now starts up every time it is in sun and keeps going when in the shade (albeit more slowly). If voltage is now going to the fan, perhaps voltage will also now go to recharging the two batteries.
« Last Edit: July 28, 2018, 01:03:08 PM by Ladd »

Offline Bobvelle

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Re: Replacing 24-hr FARS and Batteries
« Reply #4 on: July 28, 2018, 01:14:28 PM »
My Vantage Pro 2 Plus (6163) has been in service for about five years. I replaced the fan and batteries two years ago. I was doing spring maintenance last week and noticed that during the day, the fan was not running. I have ordered the combo fan/battery replacement kit (7758B) and plan to to the repairs this weekend. It occurred to me that perhaps the solar panel powering the FARS may have also gone south.

Does anyone know what the nominal output voltage of the FARS solar panel is?

While I might have a lot to learn in the area of meteorology, I do have a vast amount of knowledge & experience in the area of solar power and batteries.
The Davis Photovoltaic (PV) modules are made of monocrystalline silicon wafers encapsulated with an acrylic resin. The life of mono silicon PV modules is about 50+ years. Though the industry standard for output above 80% is 20-25 years. There are no moving parts to wear out. The tiny foil buss lines can sometimes crack or split but this would take a lot of flexing and you would only lose a percentage of power. You can get 'snail trails' which are areas between buss lines that short and leave crooked, blurry brown lines. But again, only a small amount of loss. So unless there is a clear break in the conductors connected from the + & - terminals to your equipment, (in which case you could repair or replace the wire), corroded contacts or the loss of transparency in the resin, I'd rule out an issue with the panels 'Going Bad'.

In the Davis 24hr FARS system, as with most solar / battery storage systems, the weakest link is the batteries. Especially in a daily charge/discharge cycle.
Rechargeable batteries have a finite number of charge cycles. some as low as 300 to as high as 1000. Once this number is reached, the batteries are no more good.
Next wound be the fan motor, then the conductors and connections in between, and last, the PV panel.

Offline Old Tele man

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Re: Replacing 24-hr FARS and Batteries
« Reply #5 on: July 28, 2018, 01:31:56 PM »
These are cheap commutating DC-motors which can "stick" when the commutators wearout, causing the motor initially to be hard/slow to start but eventually sticking and NOT starting at all, both drawing lots of current from battery and eventually killing the battery. The motor will typically RUN -- if you give it a whirl with your finger -- but it won't start by itself.
« Last Edit: July 28, 2018, 01:33:58 PM by Old Tele man »
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Offline BigOkie

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Re: Replacing 24-hr FARS and Batteries
« Reply #6 on: July 28, 2018, 01:53:44 PM »
My last maintenance cycle I decided to replace the crappy NiCD rechargeables that come with the Davis and use AA NiMH batteries with C adapters.  They've worked great and don't wear out nearly as fast as NiCD batteries do.
Current setup: Davis Vantage Pro 2 Plus Wireless
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Offline Old Tele man

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Re: Replacing 24-hr FARS and Batteries
« Reply #7 on: July 28, 2018, 02:12:22 PM »
I have 5000mAh NiMh cells in my VP2 (from Rainman Weather) now.
« Last Edit: July 28, 2018, 02:21:51 PM by Old Tele man »
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Offline Aardvark

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Re: Replacing 24-hr FARS and Batteries
« Reply #8 on: July 29, 2018, 12:12:43 AM »
I suggest if you haven't done it already,  replace the two rechargeable batteries with fresh fully charged batteries.   I got a charger from Amazon that will discharge the battery then charge it up. wasn't expensive.

I found that the solar panel can maintain and top off the charge but can't fully charge the batteries.ies.   

What I have done is chucked the batteries it came with and had 2 top of the line.

Good luck.

Offline dport

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Re: Replacing 24-hr FARS and Batteries
« Reply #9 on: July 29, 2018, 07:34:19 AM »
Appreciate the info here.  I’m starting to wonder if I should replace my batteries in the fall prior to the low sun angle in the winter.  I live just outside of Philadelphia.  While we do not get extremely cloudy weather in the winter like Chicago or Pittsburgh, we can still go several days without sun.  I just bought my VP2 in late May.  Wondering if the batteries will perform appropriately through the winter. 

Offline Bobvelle

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Re: Replacing 24-hr FARS and Batteries
« Reply #10 on: July 29, 2018, 09:48:49 AM »
Appreciate the info here.  I’m starting to wonder if I should replace my batteries in the fall prior to the low sun angle in the winter.  I live just outside of Philadelphia.  While we do not get extremely cloudy weather in the winter like Chicago or Pittsburgh, we can still go several days without sun.  I just bought my VP2 in late May.  Wondering if the batteries will perform appropriately through the winter.

New rechargeables will work perfectly if they get proper charge current. But how much they get daily?.. this is likely impossible to predict.
If you have concerns, I would get a extra set of batteries and take Aardvark's excellent advice and get an independent charger. Keeping rechargeables charged and rotating them out will GREATLY extend the life of the batteries.
« Last Edit: July 29, 2018, 09:56:39 AM by Bobvelle »