■ FIGURE 3.
be heard. This completes the
calibration. The calibration data is
stored in non-volatile Flash memory.
You only need to calibrate once. The
Battery Marvel is now ready to use.
To erase the calibration
data/recalibrate, boot your kit with
pins 3 and 4 of J1 (the center pins)
temporarily connected. This erases
the calibration data. Remove the
jumper on pins 3 and 4 and calibrate
as before by attaching your 12.00V
have a 12.00V DC reference available (or a variable
voltage source which can be adjusted to precisely 12.00V
DC output), you may want to build one using the four
extra components included with your kit. Build the circuit
in Figure 3 using the components as shown. Perfboard,
breadboard, or wirewrap construction is fine.
Attach any 14-37V DC supply to the input and adjust
R101 until Vout is exactly 12.00V DC. Two 9V batteries
wired in series makes a good 18V input if you don’t have
a power supply.
Before calibrating, ensure the ambient temperature is
as close to 70°F as possible. The Battery Marvel assumes
during calibration that the ambient temperature is 70°F
and will calibrate its temperature sensor accordingly.
Connect your completed Battery Marvel to the
12.00V DC reference source of your choice. It should
make a “tick-tock” sound for 30 seconds, and the LED
should alternately blink red/green. A brief alert will then
Once everything checks out, trim
the stainless steel mesh and place it
in the small recessed area in the case.
Peel the backing from the self-adhesive Battery Marvel label and
attach it to the front, fitting it carefully
into the recessed area in the case.
Insert the wires through the holes
in the case and solder them into
place. Solder the red wire to the “+”
connection on the PCB. Make sure
the LED and the clear window in the
label line up, then press the back of the case into place.
We recommend that you wait before gluing the back —
just in case. Tape the back in place temporary. Attach the
Velcro to the back of the case.
A good mounting location is right on the battery itself,
though you can also mount the Battery Marvel in any
other convenient location, including inside your vehicle. If
you decide to mount it farther from the battery, use 14
gauge or larger wire so the voltage drop is minimized.
I hope you have as much fun building and using this
kit as I had creating it! Your Battery Marvel should provide
you with many years of trouble-free service. NV
ITEM QTY DESCRIPTION SUPPLIER P/N