Sources of Power for the Mini-Scanner

The Mini-Scanner normally draws power from the car via the Diagnostic Link Connector (DLC).  Power is always present here, even when the car is turned off.  This is why the Mini-Scanner cannot simply turn itself on automatically when you turn on the car.  This page discusses other ways of providing power to the Mini-Scanner.  You might want to operate the Mini-Scanner outside the car to use the Flash Loader to update firmware.  Or, you might just want to explore the Mini-Scanner settings and options in the comfort of your living room.

Power for the Firmware Updates

You can use the car to provide power when you use the Flash Loader to update firmware.  You do not need to turn the car on.  In this situation, you have to be prepared to take a computer to the Mini-Scanner (which is in the car) and a portable computer is obviously best.

You can also take the Mini-Scanner to the computer to perform a firmware update by removing it from the car.  Perhaps you don't have a portable computer and therefore can't get the computer and the car close enough together to connect up the serial cable.  Or, you might just want to be more comfortably settled than sitting in the car with a computer on your lap.  In this case, you will need a source of power for the Mini-Scanner.

9V Smoke Alarm Battery

The picture at right shows the Mini-Scanner powered from a 9V smoke-alarm battery.  Click the picture or here for a closer view.    A fresh alkaline battery should run the Mini-Scanner for five hours or more, as long as the display backlight is turned off.  With the backlight on, the battery will be exhausted in an hour or even less.  It is not advisable to upload new firmware when the battery is anywhere near exhaustion, but if it fails you can just start again with a new battery.  Nickel-Cadmium or Nickel-Metal-Hydride rechargable batteries will work as well as alkalines and you can make sure they are fully charged before you start.

The battery is connected to the leftmost two pins of JP3.  This is the ten-pin header to which the DLC adapter cable is normally attached.  It will be empty because you have taken the Mini-Scanner out of the car.  In the larger picture, you can see "JP3" marked in white on the green printed circuit board (PCB).  Pin 1 is also marked with a tiny "1" just to the left of the yellow LED.  Pin 2 is in the bottom row below pin 1, then pin 3 is back in the top row to the left of pin 1, then pin 4 below that, etc.  Zig-zagging along to the left and counting pins, you will see that the battery is connected to pins 9 and 10.  The red wire, positive, connects to pin 9 in the top row.  The black wire, negative, connects to pin 10 in the bottom row.  Make sure you connect the battery to the correct pair of pins and that you get the polarity the right way round (leftmost pair of pins, red at the top, black at the bottom).  See below for a complete description of JP3.

The clip that snaps onto the battery is available from stores such as Radio Shack.  A complete hookup, which includes this clip assembled to a socket that fits over the pins, is available as an optional, extra cost item on the Mini-Scanner order form.

Other Power Sources

The Mini-Scanner will run from any source of DC (direct current) power from 8 to 16 volts.  Without the display backlight, its current consumption is about 50 mA.  With the backlight, it is about 170 mA.

Examples of suitable power sources that you may have around are a cordless power tool battery of up to 14.4 volts, a 12 volt lead-acid battery or a "wall-wart" power adapter.  Some inexpensive wall-warts deliver their DC with a large residual AC "ripple".  I recommend against using a wall-wart unless you know it has a properly smoothed DC output.

As described above, power can be connected to the Mini-Scanner using JP3, the ten-pin header normally connected to the DLC adapter cable.  The positive connection must be to pin 9.  The negative connection can be to any even numbered pin as they are all connected to circuit ground.  Pin 10 is convenient, being just below pin 9.  The table below represents JP3 as viewed with the Mini-Scanner held upright (with the buttons at the top).


9 (VBAT)

7 (LOUT)

5 (KIN)

3 (KOUT)

1 (NC)

10 (GND)

8 (GND)

6 (GND)

4 (GND)

2 (GND)

Last edited July 6, 2003.  All material Copyright 2003 Graham Davies.  No liability accepted.