Battery Analyzer for RC Power
Figure 6. Splash screen when the program is first loaded.
ing sure that no other program is using Comm1. Comm1
should be available on most computers and already
assigned to the serial port. The standard serial port has
somewhat been abandoned for the newer, high speed connections like USB and FIRE WIRE, making the easy-to-use
standard port an excellent control solution. If a different
Comm resource is needed, the program can be modified
to use a different Comm selection.
After the computer has been set up, the interface
board needs to have power applied. I use a simple nine-volt
battery to power the board, but any 9-12 volt DC source
will work. Once the board has power, the RC battery pack
can be connected to the test-load.
Figure 6 shows the splash screen that is displayed
when you first load the program. You must select either a
six-cell or single-cell test from the “plot type” menu. An
option to test a single cell is included, but isn’t explored in
this article (see special notes). After selecting the six-cell
test, Figure 7 shows the program ready for business. You
must then select the test time using the option buttons.
There are a total of 120 samples taken with a sample
rate of five seconds for 10 minutes, or a sample rate of
10 seconds for the 20-minute run.
Finally, the cut-off voltage must be entered before
testing can happen. The cut-off voltage is the minimum
voltage level that a battery can safely be discharged
without damage. A typical cut-off voltage for a single-cell is
0.9 volts, making the cut-off for a six-cell pack 5. 4 volts
(0.9 x 6). The load is disconnected from the battery when
the voltage meets the entered cut-off value. It is important
to know the proper cut-off value of the pack under test and
enter a safe value slightly above the manufacturer’s spec.
A value of 5. 6 is a good value to work with if you want to
Once the time and cut-off values are entered, the
“start plot” button can be clicked to begin the testing. The
Figure 7. The program is ready.
load will be connected and the interface board will start
sending data. During testing, a graph is drawn showing the
voltage trend while the voltage readout is updated with
every new sample value. Each sample is placed in a table
during testing, and can be viewed in real time. The test will