Dataloggers @ SmartSpark Energy Systems
After graduating with my degree in Electrical Engineering, I sort of fell into
working at SmartSpark, the company I was moonlighting for while a student.
They were designing a family of charge balancing
devices for long strings of batteries. My first task,
among others, was to design, assemble and test a family of embeddable dataloggers.
The purpose of these loggers was to gather all the data we could about batteries
including temperature, current,
and individual cell voltages. These values were sampled at programmable time intervals,
and the data stored as a CSV table on a FAT-16 file system on an SD card. All used
some variant of the MSP430, since it is low power, has relatively cheap development tools,
and a very nice set of a/d peripherals are available on board.
The family grew to five versions for different projects we were working with, four of which
are shown at right. The far left in the photo was the first prototype, the next one
for an "intelligent" battery pack, and the next two were versions of a standalone
version to be installed in the customers' equipment. The most tricky thing about
doing this, which kept getting in the way, was doing cheap, relatively high
accuracy current measurement.
The final version I worked on was for a really, really slick product that SSES
has. This product is called ForeverPower, a battery-free
box that provides small amounts of power for long-term unattended loads. The datalogger
in this photo was used in some of our early testing for ForeverPower. Two of these units
were mounted on the roof of our building. I learned
a great deal about weatherproofing electronics and low-power design. I'm a big believer
in MSP430's now. The dev kits are cheap, the facilities are wonderful, and there is a
fair amount of available libraries out there to make certain tasks easier. I used enclosures
that I had in my personal parts archive, and I modified the boxes, mounted
the batteries, and wired up the connectors in my apartment. This was easier than
crudding up the Lab at work with extra tools and plastic shavings.
This particular unit has channels for time, temperature, current, and voltages.
This is a twelve channel board installed atop one of our charge balancing boards.
This unit does 12 voltage channels, a current, a temperature, and time. The logger
PCB, sitting up on standoffs, is only something like 1.5" x 3" . To my knowledge
SmartSpark Energy Systems is still developing these units for internal development,
specifically the one for ForeverPower, which was not exactly bug free when my
career plans changed.
