Electronic – hot swapping battery


I have a telescope with a computerized mount and some additional controlling systems. The mount requires a 5-10 minute long calibration process (to track stars accurately) every time it is powered.

I use a 12V battery to power all the things (they all use 12v), and the average battery life is around 3-4 hours. Some deep sky objects require 6+ hours of observation. I can do that only when I connect the mount to AC power due to the limited power of the battery.

Usually dark sites (far away from city lights) do not provide electricity.

How can I make my system battery hot swap-able? Is keeping a low capacity battery (enough for 1-2 minutes) on the system all the time parallel to the main battery good idea (with a diode in between to prevent backup battery charging the primary battery)?

Best Answer

Your requirements are pretty simple. You'll need a pair of connectors for the batteries and a pair of diodes. Make a connection setup like this


simulate this circuit – Schematic created using CircuitLab

Now you can connect or disconnect either connector as you wish. As long as one battery is always connected, you should have no problems.

Your diodes should be rated for at least 12 volts (20 or more is better), and at least the current required by the controller, probably at least 1 amp. Also, since the diodes will drop some voltage, Schottky diodes are preferred. Something like a 1N5820 should do you just fine. You can try sources like Jameco, Digikey or Mouser, or any number of other suppliers.

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