The Telescope Battery Box

Living in the city lights I need to travel a bit to find dark skys.  While some on my local haunts, such as Hickory Hill and Chiefland, have AC power available others, like Crowley, don't (at least without a 1,000 ft extension).  Portable 12v power seemed like a reasonable solution.  I considered the commercial astronomy power packs on the market bit felt that their cost was too high for the small amount of power that they offered.  Dew is a big problem around here and Kendrick's get a workout.  Twelve volt deep cycle batteries were easy to get locally and all I needed was a box to out it in.  Poking around the web I saw some great ideas for building wooden battery boxes.  My concern was making them rain proof enough to handle the Florida monsoons.   I decided to start with a $7 marine battery box from Wal-Mart and it worked so well  I ended up building three of them.

All modifications were to the removable lids of each box.  The basic version has two 12v lighter sockets each with its own fuse protection (a must!!).  For the lighter sockets I chose a marine version because it is rust resistance and has a built-in flip-open cap.  Beside each socket is the fuse holder for that socket. 

Inside of the lid

Inside the lid is a marine power block (you could use a crimp to save some cost) that ties everything together.  I use Outdoor Goop to seal everything and prevent the wires from moving around.  I was amazed at how well it sticks to the black plastic of the box.

Below is the first lid that I made and it has some bells and whistles.  I added a volt meter, On/Off switch and a red LED and three 12V sockets.  Later models used the battery clips as the On/Off and I picked up a battery tester that plugs into the lighter socket to test voltage.  The LED works great, but was never used.  It has been in use now for over two years without a problem.

My batteries range from 31 amp hour (ah) to 125ah.  The 125ah  fits in the box but it is a little (1/2") too tall to close the lid completely.  The 31ah has enough room left in the box to hold spare fuses, a 3ah charger, battery tester and a 120v inverter.  After a few years of use I like the 65ah battery for one night outings.  it keeps the dew heaters and the scope's drives going all night (the 34ah has ran dry about 1am then the dew is bad).  

During the recent hurricane trio this year ('94) we lost power for over four days after hurricane Frances.  The scope batteries, with a small 75 watt inverter, kept the air pump going on the fish tank.  I did recharge the batteries at a nearby house that still had power.  Who would have thunk that astronomy would keep fish alive, maybe Pisces?.  Actually, the third hurricane, Ivan, is still in the Caribbean as I write this so the batteries are charged and ready.

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