This post describes my build of a new power supply and DC load tester for testing batteries and power supplies. Kudos go to Lawrence Glaister, VE7IT who is also building one and was instrumental in the co-design of this project.
Features:
- Dual adjustable supplies 0-24VDC at 5amps.
- 12VDC Fixed at 5 amps.
- 5VDC Fixed at 5 amps.
- Dual USB power ports.
- DC Load tester up to 20 amps (see note).
- All supplies are isolated and change be chained together.
- Load testor showsdisplays Time, Volts, Current and mAh.
- Load can run for user supplied time or voltage set point.
Missing Features to be added:
- Filter board for DC conditioning.
- Logging of Load test for input into spreadsheet etc.
Description:
I built this supply in and old rack mount case but it could be built into anything. Power supplies are off the shelf from our friends in China.
The DC Load was a custom build and all schematics and code for microcontroller is available from my github page. I will include links here as well. Schematics are drawn in Kicad. If you haven’t tried Kicad you should, it’s amazing and 100% freely available open source code. I use it under Linux.
Power supplies:
The four power supplies are split into two fixed and two variable supplies, each capable of sourcing 5 amps. The two fixed supplies are set at 12 and 5 VDC. The variable ones can realistically run from 1 volt up to 24.
Typical wiring for one panel is shown here: