Resolved Seeking Advice on Building an Aluma 12V DC cable for Battery Operation

Discussion in 'Aluma Series' started by William Castleman, Aug 26, 2019.

  1. William Castleman

    William Castleman Standard User

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    Does anyone else have experience building a 12V DC cable for battery operation using their Aluma camera?

    Diffraction Limited does not yet appear to offer a 12V DC cable with battery connectors for Aluma cameras. My initial attempt to make a cable using generic 6-pin-mini-DIN connectors and 6 wire cable failed. Although I got the solders correct, and everything checked out using the wiring diagram in the user manual and tested correctly for voltage using my digital multimeter, the cable wouldn’t power up the camera. A close comparison of the normal 6-pin-mini-DIN power connector for the Aluma and my generic connector reveals slight differences, and I suspect that my male connector pins are not fully engaging the female plug connectors on the camera or on the extension cord.

    Has anyone out there built one or know who can supply one?
    Thanks in advance for any suggestions.
     
  2. Doug

    Doug Staff Member

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    I'm not sure why your connector wouldn't work... perhaps it didn't mate correctly? We do offer an extension cable, http://diffractionlimited.com/product/aluma-extension-cable/ that could be modified to do the job.

    For a less-expensive solution, IIRC we use a Kycon part, which a quick search says would be KMDLAX-6P-KPPSR. Should be able to get that from Digikey or Mouser. This is a better option because it's a locking connector so it won't fall out.

    If you have a long cable run make sure to use as large a gauge wire as possible, to avoid voltage drop.
     
  3. Colin Haig

    Colin Haig Staff Member

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    We'll discuss making a 12VDC cable as a standard product.
     
  4. William Castleman

    William Castleman Standard User

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    Thank you, Doug, for the two suggestions. The KMDLAX-6P-KPPSR looks like a much heavier duty connector than what I used. I'm using burglar alarm cable with 22 AWG wires which should hold 13.9V battery power in the 12V voltage range OK in a 10 ft cable. I thought about cutting and splicing my extension cable to use on the trip.....but was holding that for a last resort given the $99 purchase price ($50 shipping charge from Canada!). All of my SBIG cameras have had 12V DC cables for battery operation (STL-11000M; ST-10XME; ST-8300) which I used. I would think that a 12V DC cable for Aluma cameras would be popular with camera owners, Colin. Thanks again all for your help. I'll report back with my experience in 12 to 14 days.
     
  5. Doug

    Doug Staff Member

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    You'll get a 2V drop with that size of conductor. If the source voltage drops much below 13.9V then it could cause problems. Are you powering from a battery? If so it probably won't hold 13.9V under load.
     
  6. Colin Haig

    Colin Haig Staff Member

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  7. Colin Haig

    Colin Haig Staff Member

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  8. William Castleman

    William Castleman Standard User

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    Thank you Doug and Colin,
    Voltage drop off probably explains why my first cable didn't work. I had already ordered the KMDLAX-6P-KPPSR for Thursday delivery and will go ahead and construct a 12" cable to attach from my marine battery to my existing extension cord to the camera. If it works, it may be of use to others going down this path. Voltage drop off with the 12" cable adapter and 22Awg wire starting at 12.6 battery voltage only drops to 12.4V per your recommended calculator. By the way, recommended wire sizes for KMDLAX-6P-KPPSR connectors are 26-30 Awg. I doubt if there is enough room in the connector to attach 6 18 Awg wires. You would need to be a ninja solderer even if there were room ;^)
    Thank you for making the 12V Dc power cable available for Aluma cameras. I expect to order one on Friday.
     
  9. Doug

    Doug Staff Member

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    Use short wires at the connector and solder them to thicker wires for the long run.

    Be sure to connect all the pins to distribute the current among all of them. Otherwise you will exceed the pin current rating.
     
  10. Colin Haig

    Colin Haig Staff Member

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    I think you've missed something critical there. You need to calculated TOTAL length from the battery to camera, at full load of the Aluma (which can be 6Amps).
    I can't imagine a telescope so small that 12" is enough cable hee hee.
     
  11. William Castleman

    William Castleman Standard User

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    Advice and humor are appreciated. The 12 inches is to get from the battery to my existing extension cord that attaches to the camera. I'm not sure how much power drop off you get with a stock Aluma power extension cable. What gauge is the wire in it?

    Also, I have gone ahead and ordered the 12V DC Aluma cable on line that you so graciously listed. Time is running out to set up and test my system on battery power. I'm not sure of the level of performance I will get running the Aluma on one battery and my mount (AP 1100GTO), focuser and laptop on another battery. I'm taking multiple marine lead-acid deep cycle batteries. Recharging options are being tested with my available Solar panels/generator. Remote dark sky imaging time is priceless.
     
  12. Colin Haig

    Colin Haig Staff Member

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    When do you leave?
     
  13. William Castleman

    William Castleman Standard User

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    I leave Sept. 19. I'll finalize tests the week of Sept 9-15. If I can't confidently work out 12V DC power requirements of the Aluma camera and other issues with the camera by that week, I'll go with my STL-11000M and a wide field system that has lower overall power requirements. I'd like to take the Aluma, but it isn't a big deal if it's not ready for reliable remote use.
     
  14. William Castleman

    William Castleman Standard User

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    Post Updated September 4, 2019:

    Thank you to Doug and Colin for advice on how to make a 12V DC cable for my Aluma 694. Based on their advice, I made a 12 inch adapter cable to connect from a cigarette-lighter-style connector on a 12v marine battery to the 12 foot power extension that came with my camera and connects to the camera. I also constructed an 8 foot 12V DC cable that connects to the camera without the use of the extension cord which offers better performance (less voltage loss). I am now running the battery tests with the camera needed before going on my trip. I have been informed by Diffraction Limited sales that I can expect receiving the 12V DC cable that I ordered before I leave on my trip.

    Information on construction of the 12 inch 12V DC Cable (See attached photo)
    1. Kmdlax-6p-kppsr connector (locking style 6-pin mini din connector) (source Mouser.com)
    This is a high-quality, precision-engineered connector that locks into the female socket. It has solder cups that accept up to 26 gauge tinned wires and is composed of 8 separate parts. Kycon has an assembly instruction sheet and an assembly instruction video that are both very helpful and accessible from the mouser web site.
    The wiring pattern listed in Appendix 2 of the Aluma manual shows the pin number identification when looking into the camera connector. The male plug wiring pattern is the mirror image of the female camera connector.

    2. 26 Awg wire (source Amazon.com)
    This is the largest recommended gauge multi-strand wire that will fit into the solder cups after it has been tinned.

    3. Recycled cigarette-lighter-style connector with 18 gauge wire.
    I upgraded the internal fuse from AGC-5 amps to AGC-7 amps since the camera can draw 6+ amps under heavy loads. 26 gauge connector wires (3 inch length) were soldered onto the 18 gauge wires and covered with heat shrink tubing.

    Performance of 12 inch 12V DC Cable with Kmdlax-6p-kppsr and cigarette-lighter-style adapter -

    Voltage Drop Using AC Power Source with 13.8V DC Output
    · 12 inch 12V DC Cable with Kmdlax-6p-kppsr and cigarette-lighter-style adapter: 0.3V
    · Diffraction Limited 12 foot power extension cable (stock with Aluma cameras): 0.2V
    · Battery power take off cable (terminal clips to cigarette-lighter-style adapter): 0V

    Background information on tests: Tests were run with the Aluma camera running at 67% cooler power and 2 second 1x1 image download. Camera voltage measurement was taken from the FITS header. Power source voltage was measured with a volt meter.
    Volt readings from power sources: 1) Diffraction Limited (DL) AC power source: output 12.1V DC; Pyramid AC power source: output 13.8V DC; Partially-discharged marine lead-acid 80 Amp-hour battery: output 12.4V DC.
    Difference in voltage reading between DL AC power source plugged into camera and camera running at 67% cooling power: 0.4V (i.e., drop from 12.1V to 11.7V). Voltage differences vary with cooler power levels.



    Performance of 8 Foot 16 Gauge 12V DC Cable with Kmdlax-6p-kppsr and Battery Clamp Connectors -
    Construction of 8 foot power cable: (See attached photo 2)
    · 8 foot long 16 AWG multi-strand lamp wire with soldered battery terminal clips
    · Kmdlax-6p-kppsr connector with 26 AWG connecting wires similar to that used in the 12 inch cable


    Voltage Drop Using Marine Battery with 12.4V DC Output
    · 12 inch 12V DC Cable with Kmdlax-6p-kppsr and cigarette-lighter-style adapter connected to Diffraction Limited 12 foot power extension cable (stock with Aluma cameras): 0.3V
    · 8 Foot 16 Gauge 12V DC Cable with Kmdlax-6p-kppsr and Battery Clamp Connectors: 0.1V

    Cost of construction project: I would have saved money by buying the commercially built cable had it been available. If you have the tools, supplies, and many parts on hand, the cost of the Kmdlax-6p-kppsr is $3.21 USD plus shipping.



    12vDCcable_P9041498.jpg 8ft_12vDC_P9071502.jpg
     
    Last edited: Sep 4, 2019
  15. William Castleman

    William Castleman Standard User

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    I received and tested the 12V DC cable that Diffraction Limited constructed and shipped to me. It is a 14 foot cable with cigarette-lighter-style connector on one end and Kmdlax-6p-kppsr-style connector on the other end to lock into the female plug on the camera. It also comes with a battery power take-off cable (terminal clips to cigarette-lighter-style adapter). See attached photo.
    I tested the 14 foot Diffraction Limited 12V DC cable and battery take-off cable for voltage drop using methods identical to those listed in the previous post. I also retested my homemade 8 foot cable.

    Voltage Drop Using Marine Battery with 12.4V DC Output
    · Homemade 8-Foot, 16-Gauge 12V DC cable: 0.1V
    · Diffraction Limited 14-foot 12V DC cable and battery power take off: 0.3V

    I am unable to run my homemade 8-foot cable through the mount to the camera. However, it is very efficient. The 14 foot Diffraction Limited cable is a better choice for through-mount cabling on my AP 1100GTO.
    Post hurricane (Dorian) weather in Florida improved markedly, and I was able to complete all of my 12V DC camera tests and am ready to go on my trip.

    Thank you to Doug and Colin and to others at Diffraction Limited for all of your help with the 12V DC cable for my Aluma 694.

    DL_12vDCcable_label_P9111518.jpg
     
  16. Colin Haig

    Colin Haig Staff Member

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