Portable power and distribution on a budget.

Portable power and distribution on a budget.

Everyone with an imaging setup wants to be able to get to a dark sky location and capture a night or two of stunning images, whether galaxies, nebula, clusters, or our own Milky Way.  But no one wants to haul heavy power equipment or pay the outrageous prices for power banks and overpriced power distribution modules.  Since I must save money everywhere I can and still get my fix of taking pictures of the night wonders of our universe, to date I have been limited to as far as my extension cord can reach from the nearest power source.   Yea, plugging in to my, or my sister in laws, house.  This hasn’t been the best of options, as you are probably aware.  I live in a Bortle 4 location, she lives in a Bortle 5 location.

Fortunately, I do have some working knowledge, passed down from my electrical engineer father, of wiring and avoiding getting kicked across a room by a 12-volt deep cycle battery and the 450 cranking amps it can deliver.  (I just happened to have one laying around that I wasn’t using.)  I found an article on Cloudy Nights of a person that took a battery box, mounted some 12v sockets and a power monitor, and basically made his own portable power bank.  Well, I thought that was a pretty good idea.  My problem though, is that I need power distribution I can mount on the scope so I can limit the number of cords that run from the power supply to the equipment that needs the power.  One cord to the mount, one cord to a distribution unit.  That means, yep, I must have a distribution unit.  (I have one in my house, but I don’t think a 200 amp breaker box is quite the solution, nor do I think my wife will allow me to remove it for a hobby that she still gets upset over every time I by something else for it.  She likes her lights and heat.)

So, first, the power.

I bought a battery box and a couple of car cigarette lighter female sockets and waterproof toggle switches.  I put the large holes for the lighters in the sides of the top.  I positioned them in the sides so in heavy dew situations, water wouldn’t run down beside the male plugs and short it out, leading to damaged equipment and/or exploding battery, which, of course, would lead to more damaged equipment, including a dent in the frying pan that hit me in the head.  I then mounted the waterproof toggle switches in the top of the lid for ease of access, not to mention it would keep me from accidentally turning them on when carrying from the truck out to the middle of that field, full of ground hog holes, in the middle of the night.  Since all the imaging equipment is center positive, I ran the red wire from the center post of the socket to the “On” side of the toggle switch.  I then attached the battery side wire to the “Off” side of the toggle switch and to the positive (+) terminal of the battery.  I then connected the black wire directly from the side post of the socket to the negative (-) terminal of the battery.  I repeated this on the opposite socket and toggle switch on the other end of the lid.  This gave me one port on each end of the battery box, one for the mount, and one to run up to the scope for distribution.

(I know what you’re thinking.  He’s got this sitting on a pool table, and he’s worried about spending a little money on power?  The previous owners left it with the house, and it’s a cheap one anyway.)

Of course, I left enough cable to allow me to remove the lid and charge the battery.  One day I will add charging terminals to the outside of the box, but that’s another story.  This part of the system cost me a grand total of $34.93.  Add an additional for the previously purchased battery, $135.99, it’s $170.92.  That’s a savings of at least $250 for a power pack to last 2 nights, and not too bad for 30 minutes work.

Now for distribution. 

I bought a small plastic container with attached lid, five 5mm x 2.1 mm power ports, a small power distribution block, and some wire.  Add some male plugs for the sockets above and a few 2.1 mm powercords at 1 foot each, and I had everything I needed to make my PDU, except my soldering iron and solder.  (I haven’t used that since we moved here 4 and a half years ago.  Now where is that da** thing?) I dug through some boxes of tools I have in the closet and found the solder quick enough, but the iron wasn’t so easy.

I looked in the hall closet, I looked in my wife’s desk, I look in her office closet, I looked in the spare bedroom closet, I looked in my desk (that didn’t take long since I have no drawers or cabinets in my desk).  I searched the tv stand and the China cupboard.  I finally put on some shoes and took a stroll down to the shed. (It’s cold out there when all you have on is shoes.)  Sitting right on top of the toolbox.  Guess you just have to look in the right building.  While I was there, I went ahead and picked up an 11 mm drill bit for the power ports.  (Wouldn’t do to make another trip down there.  Heck, it must 50 or 60 steps to get there.)

I drilled 6 holes in the plastic container and ran my cable in one end, stripped the wire on one end back ¼ inch, and attached it to the end of the distribution block.  I put a wire bushing on the cable and pushed it in to the hole to hold the cable in place so it wouldn’t jiggle around and break inside the box or rub the insulation off the wire on the edge of the plastic hole.  I didn’t leave enough wire inside the box to mount the block correctly, so I pushed the bushing back out of the hole (not an easy task now) and fed a little more wire though.  This allow me to mount the block in the correct spot, but now the wire was in the way and there wasn’t enough to move it so I could get to the screw hole in the block.  So, back out, feed more cable in, put the block in place.  This time I was able to put the screw in and secure it to the bottom of the box.  Now I have a screw sticking out the bottom side of the box, so I have to buy some rubber feet for it.  (Should have thought of that.)  I then cut some wire and added my first port.   I have tremors, so soldering the wire on to the post of the port was interesting at best, but I managed to get it done.  I slipped the wires and port into the box, put the provided lock washer and nut on it, slipped the stripped wire into the block, and took it to my scope and power bank to test.  What do you know, it actually worked.   An hour later I had all 5 ports in and tested. 

I’ve got to say, that was a fun project.  Total cost:  $123.97 (without the actual battery of course, and $150 an hour , consulting fees, 2 hours of my time).  In just these small parts, I would say a $500 savings over buying a power bank and power distribution unit.  That’s pretty significant.

Now if I just had some clear skies and a dark place to take it.

If you want me to make one for you, let me know.  (Don’t worry, I’ll only charge you $50 an hour.)

Clear skies!!

Waxman