The idea of battery box arised when I realized that my small 7Ah battery can be used for powering my DSLR kit (P2Z, 40D, dew heaters etc) for only 2-3 hours in cold weather. I decided to purchase a gel battery but such battery alone is a bit cumbersome to carry.

After some tinkering I discovered that two 15 to 20Ah gel batteries can nicely fit into a toolbox designed to carry power tools (drill etc). The batteries are stored inside the box, protected from bumps or rough handling by a couple of layers of bubble foam.

These batteries have their ground (-) terminals connected internally to prevent possible ground loops in the equipment. Both are fused @ 7,5A and there are switches to connect/disconnect them (handy, as it is best to make all connections first and than switch on power). I have purchased two voltage indicators with 6 LED each, which allow me to quickly judge visually the status of batteries (red - charging, any of green - above 10.5V, two yellow - above 10V, one yellow - above 9,5V). This allows me to stop the imaging session when I know the batteries are going to be dead soon.

Power terminals are my standard - "military-like" connectors which can handle up to 10A, prevent proper polarity of the connection and do have a large knob to positively lock the connector in place. Actually after some deliberating I have modified all my astro gear to use the same standard - so any device can be connected to any socket and it will always work. Some people use cigarette lighter plugs and sockets - which work but are large and do not ensure contact at all times - plug can be easily accidentally pulled out from the socket. I believe my "military" system is more reliable, easier to use and more compact - at a cost of the need to modify every single plug on every power cord. You will see these plugs and sockets all around my astro gear pages. For powering from car cigarette lighter socket I have soldered a converter to my "military" system, another one was made with alligator clamps to use with larger marine battery, is such need arises.

A 1,5A gel battery charger was modified by adding the "military" plug - all I need to do after the session is to plug the charger into one of the output sockets and turn on the power - the same socket is used for charging and for lading current from the battery. I also have a couple of 2A and 4A power supplies which were modified to use the same socket standard.

In the typical conditions, one battery is used to power the mount drive and dew heater (when some electronic noise can be generated), another to power my CCD, USB hub and USB to RS232 converter. As my equipment has rather low power drain, this power box lasts entire night of imaging with Mach-1 and Starlight Express SXV-M25 CCD camera. Also, I can power the 12V to canon converter from the same source if I elect to go after DSLR imaging.