ups_project

UPS_Project

Solid Emergency Power System For Computer (120V AC), Ham Gear (12V DC) and Workbench (12V DC)

This is an accidental project. It all started when the battery in my 10 year old UPS (Un-interruptible Power System) failed. This left me with a charger and inverter that would power the computer, but it needed a new battery. After looking at the potential cost of a replacement unit, I decided to purchase a new automotive battery (for much less money) and install this outside the hamshack in a plastic box. By running heavy wires (with an in-line fuse) into the hamshack and connecting these to the former UPS unit I had my computer's emergency power restored. With the larger battery (475 AH) it now runs the computer for several hours in event of a mains power failure.

Then I installed a set of Solar Cells (three 6 volt cells in series) and built a simple regulator (LM-317 driving a source-follower MOSFET) to hold the battery just above where the UPS charger would kick into charge mode. This lets me use solar power to keep the battery charged, but still allows the UPS to charge it when there is no sunlight. An isolation diode keeps reverse potentials out of the solar cell charger and cells.

Once the computer power needs were satisfied, it was obvious that I could also use this 12 volt DC source to power my ham gear and for the workbench where I do circuit development work. For this I added a 10A fused lead from the battery to the workbench and installed a set of five 2-conductor Molex sockets for DC access on the bench. A similar fused lead and Molex sockets was added for powering various radio equipment at the operating position. The popular "Power Pole" connectors may have been a better choice but I find them too expensive, and I already had the Molex plugs and sockets (salvaged connectors from computer power supplies and floppy drives).

Direct-Conversion receivers are very quiet when running from a solid battery power source (no mains hum, reduced background noise, etc.).

Components Required:

• A working UPS unit (battery does not have to work)
• A 12 Volt Automotive Battery (Bigger is Better)
• A Solar Panel Capable of 18 Volts at 1 to 6 Amperes In Full Sun (optional)
• A Plastic Box For The Battery
• Miscellaneous Fuses, Wire, Connectors, etc.