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Weather Station

Discussion in 'Power Electronics' started by 01sporty, Dec 10, 2018.

  1. 01sporty

    01sporty

    12
    1
    May 1, 2012
    I bought a weather station with the intent of putting the 5 in 1 sensor array on the roof. The sensor array requires 4 AA cells which I really don't want to be climbing up on the roof to change. I figured I'd just find out what voltage it uses and run a wire down and plug in a 7.4v lipo pack with the appropriate voltage regulator.
    Well, I got the weather station and the batteries are wired like this:
    [​IMG]

    Why did they do it like that? Why have two positive leads and one negative lead coming from the battery pack to the pcb? Why not a single positive and single negative?

    More to the point, can I run a wire from my 7.4 lipo pack up to the weather station, reduce the voltage to 3.3v with a LD1117v33 voltage regulator and drive both positive leads on the pcb. Or, should I use 2 regulators just to be safe?
     
  2. Bluejets

    Bluejets

    3,520
    714
    Oct 5, 2014
    It's a split rail power supply as shown and without any other details (schematics etc) it would be impossible to know.
    Perhaps just put your 4 cell pack at the bottom and run 3 wires as shown.
     
  3. BobK

    BobK

    7,643
    1,662
    Jan 5, 2010
    Are you sure you have that diagram right? It is odd. It give 2 separate 3V supplies with a common ground, not a split supply like @Bluejets said. Can't think of any reason they would do that.

    Bob
     
  4. 01sporty

    01sporty

    12
    1
    May 1, 2012
    Yes, I'm quite sure it's correct. It looked odd the way the batteries were arraigned so I checked the path with a VOM. I still didn't quite get it so I took it apart. They run two red positive wires up from the battery compartment but connect the negative together and run a single black wire up. At the board, the wires terminate like shown in the diagram. It's like the board is performing two separate functions with two separate positive feeds and a common ground. But even if that were so, I don't understand why it all would need separate positive feeds.
     
  5. VenomBallistics

    VenomBallistics

    72
    26
    Aug 30, 2018
    I can think of reasons ... run time requirements meet volumetric constraints.
    if I had to guess inside the black box beyond the batteries, we'll find a pair of diodes so the batteries don't drain each other.
    LiPoly would be inappropriate in this application since the cell never sees the kind of discharge rate its designed for.
    this might be a job for NiCad or NiMH
     
  6. Bluejets

    Bluejets

    3,520
    714
    Oct 5, 2014
    True Bob....early morning reply sorry.

    Perhaps if the Op supplies a make/model could be helpful.
    Some of these rooftop units have an add-on remote battery pack unit with 30 ft lead and a clip-in adaptor to the original battery compartment.
     
    Last edited: Dec 10, 2018
  7. 01sporty

    01sporty

    12
    1
    May 1, 2012
    This is the unit: https://www.acurite.com/pro-5-in-1-weather-station-with-hd-display.html

    Let me re-frame the question. If I run my 7.4v battery pack through the before mentioned voltage regulator, am I likely to do damage?
     
  8. Bluejets

    Bluejets

    3,520
    714
    Oct 5, 2014
    I wouldn't at least not at this stage.
    Most are still trying to determine the actual connections.
    It seems unlikely they would do the connections as you have shown (possible but unlikely)

    How did you determine those connections?
    Can you show a photo?
     
  9. CircuitMaster

    CircuitMaster

    48
    1
    Dec 17, 2016
    EMC compatibility is 1 option. The other is that they are powering 2 different modules inside, but that means 2 batteries will get drained faster.
     
  10. Harald Kapp

    Harald Kapp Moderator Moderator

    9,383
    1,914
    Nov 17, 2011
  11. 01sporty

    01sporty

    12
    1
    May 1, 2012
    Well I got some time to get back to this project.
    Here's the picture someone wanted:
    [​IMG]

    I believe the two SS12's are diodes that were mentioned.
    Turns out the solution is incredibly simple. Run 3v to either hot lead and it's happy. You can take two of the batteries out of either side and it functions exactly the same as with all 4 batteries.
     
    (*steve*) likes this.
  12. albert001

    albert001

    10
    0
    Dec 21, 2018
    Seems you have figured it out?

    There's several reviews from the remote battery pack offered by Acurite.

    https://www.acurite.com/remote-battery-pack-for-5-in-1-weather-sensors.html

    [​IMG]

    One review from a person that swapped the remote batteries with a 7.4v lithium rechargeable and then connected the 7.4v to a solar panel.
    It may be possible to install ICR14500 3.7V X2= 7.4 Volt 650mAh Li-ion Cylindrical Rechargeable

    You can find them individually or in packs and are the same size as AAs. Sometimes used with drones, remote vehicles, etc.

    You would then require a lithium charger which can be either ac/dc or solar. For AC/DC a balance charger would work, for solar you need a solar panel and a solar charge controller such as e.g. https://www.ebay.com/itm/Solar-Pane...epid=1751391177&hash=item4b0c09baf3:rk:1:pf:0

    However it would be better to find a 7.4V lithium battery pack such as e.g.

    https://www.ebay.com/itm/Canon-Batt...6G3p:sc:USPSFirstClass!98547!US!-1:rk:19:pf:0

    or better yet a 7.4 5600 mah

    https://www.ebay.com/itm/Motorola-7...=item5b4d3e85d2:g:LTkAAOSwQJhUcnc1:rk:21:pf:0

    All you need then is a lithium charger which I think since it's outdoors a solar panel and with charge controller would be a better solution.
     
    Last edited: Dec 24, 2018
  13. 01sporty

    01sporty

    12
    1
    May 1, 2012
    I do have it figured out. Sort of.

    As I mentioned earlier, the unit is not running on 6v. It runs on 3v. The goofy wiring is what started this thread. Still not sure why they did it that way.

    The voltage regulator didn't work out like I hoped but I had a step down converter on hand and it works swimmingly.
    https://www.ebay.com/itm/1PCS-DC-DC...=item1a3e93a104:g:broAAOSwSn1b~zgV:rk:13:pf:0

    I'm done with throw-away batteries anywhere I can make the switch.
     
  14. albert001

    albert001

    10
    0
    Dec 21, 2018
    Ok, you must have a different weather station then if the remote sensor run on 3 volts.

    One person's review for the 5-in-1 weather sensors battery pack
    _______________
    I installed this so as not to have to climb radio tower, However this thing eats batteries like no tomorrow. However there is a bright side. I used a different battery on the lower half. I used a 7.4v lithium ion that is rechargeable and done so with a small solar panel. I was replacing batteries about every two weeks. My suggestion would be to replace the battery holder that has 4x1.5v=6v with a 7.4v as mentioned above.
    ________________

    So according to one review the remote battery pack for a 5-in-1 weather station is 6 volts? There's no voltage specifications from the website.

    I've used those step down / up converters before. With that converter you can have quite a leeway for output voltage which is I assume configurable. So you could probably use most any lithium rechargeable batteries.

    Input voltage: 4V-35V
    Output voltage: 1.23V-30V

    However it should be possible to create a ~3 volt battery pack using rechargeable batteries wired in parallel so the voltage output would be either 3 or 3.7 volts. output

    3 volt rechargeable = 3 volt battery pack (or possibly you can use 3.7 Volt lithium instead to create a 3.7 V battery pack.) You can go with nimh rechargeable 1.2/1.5 volts they would need to be wired for 3 volt output.

    There are 1.2 volt AA lithium rechargeable but their usually more expensive.

    Personally if your remote sensors require 3 volts I would try to create and use a 3.7 lithium battery pack. There's usually enough tolerance to allow up to 3.7 volts for a 3 volt device.

    There are 3.7V Li-ion 18650 and 14250 3.6V/1200mAh lithium rechargeable s.

    I8650's are often used for laptop batteries but are usually wired for higher voltage output. You can probably just rewire the laptop battery so to be able to accept a 4.2 volt lithium charger with 3.7V output.
     
    Last edited: Dec 24, 2018
  15. albert001

    albert001

    10
    0
    Dec 21, 2018
    I contacted Acurite about the battery packs voltage output and they responded.

    “The voltage output information follows:
    3.0VDC in Parallel”

    So you can either use your regulator or create a 3 volt battery pack which I think can be up to 3.7 volts? Depends on the sensors input voltage range specification.
     
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