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nspace01
member
Reged: 02/25/08
Posts: 23
Loc: Fort Smith, AR
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For several months I have had a problem in that my Celestron PowerTank would show Low Power at star parties from time to time, after I had had it on charge till it said "Ready For Use (Fully Charged)".
Friday night AOAS hosted a star party for the area girl scouts.........and, sure enough, the PowerTank was dead...............
Time for a replacement.
Instead of buying a new powertank or the equivalent (12 volt, 17 ah), or replacing the internal battery, I decided to "Build" a new one.
So I did a little research on the internet and got a pretty good idea of what I needed.
I went to Wal-Mart and got a "Marine Deep Cycle Battery" and a marine case to fit it, and four female lighter plugs.
I placed the battery in the box, perfect fit. In the lid of the battery box, on the side opposite the side of where the battery posts are, I measured and drilled 1 1/8" holes for the female lighter plugs and 1/8" holes for the mounting screws.
I mounted the lighter plugs in the the battery case lid. I wired the four plugs "In parallel", i.e., each plug is wired directly to each battery post (Luckily, marine batteries have "Thumb Screw Battery Posts" and this makes it easy to hookup.
That is it..................................
After I use the battery at a star party or if it sets unused for a length of time, I will put it on the battery charger till it shows a "Full Charge"
Advantages: I no longer have to worry about my power sorce going dead, The marine battery has better than 10X the number of Amp hours. The cost for the components cost just a little more than a replacement Celestron PowerTank......
Disadvantages: Mucho Heavy.........about 50 lbs......
www.aoas.org
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nSpace01
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Current Equipment:
Meade 10" SCT OTA
Meade SN-10 OTA
Celestron Wide Field C102 F5 OTA
Celestron CG-5-GT Advanced Computerized Mount
Celestron PowerTank 17
20 x 40 x 100mm APM Binocular Telescope
DIY Parallel Binocular Mount
Night Vision Binoculars
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gregj888
sage
Reged: 03/26/06
Posts: 301
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nSpace01
Did you put a fuse in the line to each "plug"...?
If not, you should!!! Inline fuse holders and butt splices are available at the auto parts store if Wally World doesn't have them.
Good idea BTW, much more power for the price.
Greg
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blb
sage
Reged: 11/25/05
Posts: 214
Loc: Piedmont NC
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Hey I have built two from the plans here on CN and they work great. I agree that the only draw back is there weight but the usually do not run down if properly cared for. they are a wonderful dependable power sorce. I just wish I could find the same thing that was lighter.
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C-11, C-6, XT10i Dob, ETX125PE, TV102, & AT66
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walt r
Post Laureate
Reged: 02/13/07
Posts: 3459
Loc: Doylestown, PA
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The best thing to do to keep batteries fully charged is buy a good 3-stage charger. Then the charger can be left on forever and the battery is always at peak charge, ready to use and the battery will last for many years.
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Walt
Obsession 18" f/4.45 #1370 AN/SC
MK67 Deluxe 6" f/12 Mak-Cass, Super Polaris GEM, JMI MicroMax DSC
DIY 60mm f/6 Achromat
Cookbook 245 CCD
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Mr Magoo
scholastic sledgehammer
Reged: 11/05/05
Posts: 999
Loc: Franklin, Indiana
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Quote:
Hey I have built two from the plans here on CN and they work great.
Do you have a link to those plans?
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Ken
Franklin, IN
Member, Indiana Astronomical Society
B.S.A. Astronomy Merit Badge Counselor
6" f/10 Dob
Vintage Sears Discoverer 4-6305A 60mm
Vintage Manon 60mm (The Marsha Scope)
Criterion RV-6
My CN Photo Gallery
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blb
sage
Reged: 11/25/05
Posts: 214
Loc: Piedmont NC
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Hi Ken,
You can find it under the "Articles" at the top of the page. Then click "How to" at the top of the list. The write up is approx. one third the way down and is titled "How to Construct a Portable Power Supply" by Bob Kerner. The directions are great but not having an electrical background I would read a little and draw a sketch (plan),then read some more and sketch some more. It was necessary for me to have a plan to do this. Good luck, It's a great accessory.
Buddy
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C-11, C-6, XT10i Dob, ETX125PE, TV102, & AT66
Edited by blb (10/25/09 08:26 PM)
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Gunner
professor emeritus
Reged: 06/20/06
Posts: 516
Loc: Bellville,Texas
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Here's a couple of shots of mine I built this year, most parts came from Radio Shack.
It has 4 female plugs, 2 fuse holders and a on/off switch.
Allen
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Orion 190mm Mak-Newt w/Orion 80ED Guidescope
Orion XT12i w/ Moonlite Cr-2 and Flocked
Orion 8" Reflector Flocked
Orion Atlas EQ-G mount
Orion Autoguider
Orion X-Y Guide Star Finder
Canon EOS Rebel XTi ( un-modified )
Edited by Gunner (10/26/09 04:26 PM)
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Gunner
professor emeritus
Reged: 06/20/06
Posts: 516
Loc: Bellville,Texas
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One more.
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Orion 190mm Mak-Newt w/Orion 80ED Guidescope
Orion XT12i w/ Moonlite Cr-2 and Flocked
Orion 8" Reflector Flocked
Orion Atlas EQ-G mount
Orion Autoguider
Orion X-Y Guide Star Finder
Canon EOS Rebel XTi ( un-modified )
Edited by Gunner (10/26/09 04:28 PM)
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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My DIY power supply consists of two alligator clips connected to a cigarette lighter plug, which has a one-to-three plug multiplier plugged into that. All I do is clip it onto my deep cycle battery and I'm GTG. To avoid the clips from coming off, I tie any cords that are plugged into the thing around a table leg, and set the battery underneath my observing table. This system has served me faithfully with no problems for 8 years now.
Any benefits to having a box? My batteries (I have two ~80AH deep cycle batteries) all have handles on them, so it wouldn't make the battery any more portable, only less. Fuses- well, in eight years, I've maybe shorted out my battery once I think, and it caused no harm I could ever tell.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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Chris Rowland
sage
Reged: 02/28/05
Posts: 268
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I urge people not to use crocodile clips to connect to batteries. The chance of connecting them round the wrong way, especially in the dark, seems too high to me. Fuses won't protect the electronics. Diodes might - if it's all got them.
Chris
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gregj888
sage
Reged: 03/26/06
Posts: 301
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Diodes in the line are also a good idea but please use fuses as well. You will not like the result of shorting out one of these batteries... and it will likely mess up your dark adaption :-(
Greg
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Quote:
I urge people not to use crocodile clips to connect to batteries. The chance of connecting them round the wrong way, especially in the dark, seems too high to me. Fuses won't protect the electronics. Diodes might - if it's all got them.
Chris
In eight years of using aligator clips, I have never once connected the battery the wrong way. Batteries are clearly labelled with + and -, and red and black is very easy to tell the difference between, even under a red light.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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tatarjj
Pooh-Bah
Reged: 04/20/04
Posts: 1134
Loc: Austin, TX
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Quote:
Diodes in the line are also a good idea but please use fuses as well. You will not like the result of shorting out one of these batteries... and it will likely mess up your dark adaption :-(
Greg
The one time I shorted out my battery, it was not due to any fault of mine. There was a fault in my cable that caused the short. Basically, there was a little flash of white light, and the cord got hot. I just removed it immediately and spent the next 10 minutes finding the problem. No big deal, really! Furthermore, due to the resistivity of the cord and the internal resistance of the battery, not much amperage was thrown during the short. Note that true deep cycle marine batteries will have higher internal resistances than a regular car battery.
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John T.
Austin, TX
25" f/4.2 Dob
18" Obsession #701
4" Stellar Vue Achromat
8X56 Binos
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