Telescope mounted battery power unit (Skywatcher 150/750 PDS)

I use 6V (you can go with 12V) 2200 mAh NiMH battery for RC cars (up to 75x55x17mm) to power my tracking system and primary mirror fan. Right now, it allows 4-hour-long imaging sessions (it doesn't drain the battery empty, I just never tried longer). I plan to also power dew heaters with it as well, hence the 3rd power socket. It mounts directly on the telescope body using 2 cm-wide Velcro strips. 

Each socket has a dedicated power switch, so all the equipment can be switched on/off from a single panel directly on the body.

I attached a STEP file, feel free to adjust it for you equipment (e.g. different telescope size).

You need:

1. A battery (i use this one)

2. 3-pin JST-XH connectors x3 - female for the box, male for your cables (i use this set). 3-pins are used because it's way more comfortable for the fingers to operate than 2-pins, also more durable.

3. 3 small toggle switches (like these), watch for your voltage (I used 12V with 6V battery)

4. Optional: 1 pair of 2-pin JST-XH connectors. I don't like the idea of permanently soldering the battery inside, so I connected it to the system via an extra connector.

5. Standard 5 mm LEDs x3 - aim for a lower brightness red color, so it doesn't annoy you during imaging sessions.

6. 1 Resistor (150 - 360 Ohm in case of 6V battery) for LEDs

7. Soldering iron and a bit of wire

8. 2cm (or less) wide Velcro strips 2x

How to:

1. Take the printed "Lid", insert switches, LEDs, JST sockets, solder all in place, leaving 2 wires with a connector for a battery.
   I soldered all the sockets+LEDs in parallel, LEDs share the "+" leg that is connected to the battery via a resistor, "-" is interrupted on each line's toggle switch, very simple.
   Check it for shorts!!!

2. Take the "Body" and insert the battery from the back side (the one that has no stopper lip inside), connect it to the Lid connector.

3. Test the switches - LEDs should light up. You might also want to measure the voltage on the sockets.

4. Push the Lid into the body from the top side until it's stopped by the ring-lip inside, it should sit against it and slide with quite a resistance. This will prevent it from falling out in future. If you feel unsure (e.g. your print tolerances are not super tight) - use some hot glue from the inside.

5. Put the battery inside. Mine is a little smaller than the box, so i added a few drops of the hot glue on the sides to prevent it from banging the walls during transportation

6. Put in the "Back cap" - look for the holes on the long side to match the holes in the body. Once in, put 2 pieces of filament all the way in to secure it in place. In my case, it was a friction fit; you can add some glue if you need it.

7. Put Velcro strips in the slots of the body, wrap it around the telescope body, and tighten firmly.