The housing was planned in OpenSCAD. It is 50 cm wide, 40 cm high and 35 cm deep.
It was made with plywood (10 mm) and has 6 outer boards and one internal board to seperate the batteries from the rest of the electronics. All inner edges are stabilized with 20x20 mm bars.
The result is somewhat heavy, but very robust! This fullfills some requirements: Made for rough enviroment and cheap.
I did not make this housing myself, but let my talented hobby-carpenter father do this (he also has better tools for woodworking than I).
The OpenSCAD files are also on GIT.
After deciding for the quick and cheap car radio solution, I scetched up some schematics with Visio:
This covers the important parts of the schematics:
- Battery packs with fuses
- Charge connectors with balance contacts
- Main switch with power LED
- Volt and Ampere meter
- Small uC (MSP430) for a very simplified battery voltage check (I know, you should monitor every cell in series, but meh, I switch off at a fairly high voltage)
- Status LED
- Car radio with speaker
- 5 V DC/DC for USB Connectors
The software for the MSP430F2274. I had a really small board laying around. The fairly short source code can be found in my bitbucket: https://bitbucket.org/DoubleyouL/s.a.r.a.h.
Now to the fun part, assembly! Just look at the pictures in the galery.
- Under Car Illumination
- Paint job
- Wheels (this thing is heavy!) --> Done
- DC/DC for USB chargers --> Done