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12v Batteries and Dew Heaters

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  • Bill Davis Jr
    Was out observing last night. Observed Mars, M45, M31, M13. Dew was not bad but my eyepiece was fogging up. I have been thinking of getting a dew heater and
    Message 1 of 5 , Oct 30, 2005
      Was out observing last night. Observed Mars, M45, M31, M13. Dew was
      not bad but my eyepiece was fogging up.

      I have been thinking of getting a dew heater and controller anyway.
      Can anyone tell me what I need to look for in:

      1. A 12v battery and a charger?

      2. Dew Controller and Heater?

      Battery will also on occasion power my scope. I own a
      Schmidt-Newtonian so would I need a heater more for the Collector or
      the Primary?

      Thanks,

      Bill
    • rodney owens
      Bill, You will need a dew heater for the corrector, yes. Hands down this is the best dew system on the market, low power consumption, and dirt cheap:
      Message 2 of 5 , Oct 30, 2005
        Bill,
        You will need a dew heater for the corrector, yes.
        Hands down this is the best dew system on the market, low power consumption, and dirt cheap:
         
        You will need a controller for it, they sell a cigarette lighter adapter for it, however the Kendricks controller is much nicer is regulating the power:
         
        Hands on Optics (www.handsonoptics.com) has all the Kendrick stuff in stock on the shelf.
         
        As far a battery goes, I use a 7amp/hr sealed gel battery for my scope, and a 8amp/hr for everything else.
         
        These are what most of our club members use, light weight and easy to transport. You can find there at most battery warehouse locations. I am not sure if there is one in Delaware though??
         
        I hope this helps some,
        Clear skies, Rodney (HAL) 
        ----- Original Message -----
        Sent: Sunday, October 30, 2005 9:01 AM
        Subject: [delmarvastargazers] 12v Batteries and Dew Heaters

        Was out observing last night. Observed Mars, M45, M31, M13. Dew was
        not bad but my eyepiece was fogging up.

        I have been thinking of getting a dew heater and controller anyway.
        Can anyone tell me what I need to look for in:

        1. A 12v battery and a charger?

        2. Dew Controller and Heater?

        Battery will also on occasion power my scope. I own a
        Schmidt-Newtonian so would I need a heater more for the Collector or
        the Primary?

        Thanks,

        Bill




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      • Jean-Paul Richard
        A remark: Dew heaters require a lot of power and, often, are of the on and off type. The on and off operation and related changes in voltage (depending on the
        Message 3 of 5 , Oct 30, 2005
          A remark:
          Dew heaters require a lot of power and, often, are of the
          on and off type. The on and off operation and related changes
          in voltage (depending on the impedance of the lines and internal
          resistance of the battery ) can interfere with proper operation
          of the telescope if the telescope is powered by the same battery.
          In that sense, two separate batteries are, in principle, a better
          solution.
          Heaters will draw of the order of 1Amp each (some less, some
          more). A 20 amp-hour battery would be the minimum I would
          consider. In cold weather, the voltage drop before the battery is
          near empty.
          Some controller permit variable power. Look for a controller
          that has a wide range of control. 40% to 100% is not enough
          (my original Kendrick did not do better than that).
          15% to 100% is a range I would favor. There is no sense in
          putting more heat than needed around your optics.
          Jean-Paul Richard.


          Bill Davis Jr wrote:

          >Was out observing last night. Observed Mars, M45, M31, M13. Dew was
          >not bad but my eyepiece was fogging up.
          >
          >I have been thinking of getting a dew heater and controller anyway.
          >Can anyone tell me what I need to look for in:
          >
          >1. A 12v battery and a charger?
          >
          >2. Dew Controller and Heater?
          >
          >Battery will also on occasion power my scope. I own a
          >Schmidt-Newtonian so would I need a heater more for the Collector or
          >the Primary?
          >
          >Thanks,
          >
          >Bill
          >
          >
          >
          >
          >
          >
          >Yahoo! Groups Links
          >
          >
          >
          >
          >
          >
          >
          >
          >
        • Norton Douglas (DTI)
          No matter what type of dew heater you put on the corrector plate, you WILL have heat waves in your light path that WILL degrade the image. A point proved last
          Message 4 of 5 , Oct 30, 2005
            Re: [delmarvastargazers] 12v Batteries and Dew Heaters

            No matter what type of dew heater you put on the corrector plate, you WILL have heat waves in your light path that WILL degrade the image. A point proved last night on Steve Long's C8. He was unsure of why M13 was showing muddy images after collimating it. I suggested turning off the dew heater and after 5 minutes the image was as sharp as either of us had seen through that scope before. Unfortunatley, dew is a problem for scopes with corrector plates. More so than most other designs. My suggestion is to plug away at observing until the front surface dews up, put the cap on the front, turn on the dew zapper and get a cup of coffee and take a break for 5 or 10 minutes. Wait until the dew burns off and then go back to observing with the dew zapper turned off. Assuming you want the best images possible out of your scope. Get a dew cap and that should delay the onset of dew except for those extraordinarily wet nights.








            Douglas A. Norton
            Department of Technology & Information
            William Penn Data Center
            Phone: 302-739-9604
            Fax: 302-739-3925
            Email: Douglas.Norton@...

            Sent from my BlackBerry Wireless Handheld


            -----Original Message-----
            From: delmarvastargazers@yahoogroups.com
            To: delmarvastargazers@yahoogroups.com
            Sent: Sun Oct 30 11:59:17 2005
            Subject: Re: [delmarvastargazers] 12v Batteries and Dew Heaters

            A remark:
                Dew heaters require a lot of power and, often, are of the
            on and off type. The on and off operation and related changes
            in voltage (depending on the impedance of the lines and internal
            resistance of the battery ) can interfere with proper operation
            of the telescope if the telescope is powered by the same battery.
                In that sense, two separate batteries are, in principle, a better
            solution.
                Heaters will draw of the order of 1Amp each (some less, some
            more). A 20 amp-hour battery would be the minimum I would
            consider. In cold weather, the voltage drop before the battery is
            near empty.
                Some controller permit variable power. Look for a controller
            that has a wide range of control. 40% to 100% is not enough
            (my original Kendrick did not do better than that).
            15% to 100% is a range I would favor. There is no sense in
            putting more heat than needed around your optics.
            Jean-Paul Richard.


            Bill Davis Jr wrote:

            >Was out observing last night. Observed Mars, M45, M31, M13. Dew was
            >not bad but my eyepiece was fogging up.
            >
            >I have been thinking of getting a dew heater and controller anyway.
            >Can anyone tell me what I need to look for in:
            >
            >1. A 12v battery and a charger?
            >
            >2. Dew Controller and Heater?
            >
            >Battery will also on occasion power my scope. I own a
            >Schmidt-Newtonian so would I need a heater more for the Collector or
            >the Primary?
            >
            >Thanks,
            >
            >Bill
            >
            >
            >
            >
            >
            >
            >Yahoo! Groups Links
            >
            >
            >
            >
            >
            >
            >

            >




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          • John Flynn
            ... I have a Celestron 11 on which I use a product called Dewbuster. Info is at www.dewbuster.com. This device has 2 differential heating outputs and 6
            Message 5 of 5 , Oct 30, 2005
              Bill Davis Jr wrote:
              > Was out observing last night. Observed Mars, M45, M31, M13. Dew was
              > not bad but my eyepiece was fogging up.
              >
              > I have been thinking of getting a dew heater and controller anyway.
              > Can anyone tell me what I need to look for in:
              >
              > 1. A 12v battery and a charger?
              >
              > 2. Dew Controller and Heater?
              >
              > Battery will also on occasion power my scope. I own a
              > Schmidt-Newtonian so would I need a heater more for the Collector or
              > the Primary?
              >
              > Thanks,
              >
              > Bill
              >
              >
              >
              > ------------------------------------------------------------------------
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              > <http://groups.yahoo.com/group/delmarvastargazers>" on the web.
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              > <mailto:delmarvastargazers-unsubscribe@yahoogroups.com?subject=Unsubscribe>
              >
              > * Your use of Yahoo! Groups is subject to the Yahoo! Terms of
              > Service <http://docs.yahoo.com/info/terms/>.
              >
              >
              > ------------------------------------------------------------------------
              >
              I have a Celestron 11" on which I use a product called Dewbuster. Info
              is at www.dewbuster.com. This device has 2 differential heating outputs
              and 6 unregulated outputs. On the regulated output you have 2
              thermocouples. One measures the air temp, the other the temperature of
              the heated surface. You can adjust the differential temp(surface
              temp-air temp) in small increments. I find that a 1 degree differential
              works well in keeping dew off the corrector and avoids the problem of
              heating too much or too little. I think this approach minimizes the
              current draw as well.
              In the summer in the SkyTent which is situated on bare soil, the
              humidity gets so high that water drips from the inside tent surfaces. I
              typically leave the dewbuster on 24/7 and have not had any problems with
              moisture in the scope which I keep covered when not using it. This is
              the best product I have found for dew prevention.
              Check out the website. It has a lot of good information.
              Anyway, that's my 2 cents worth.
              John
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