Powering your Spot 2 GPS from USB

The SPOT GPS is widely used during endurance racing for tracking purposes—and in some instances for emergency rescue. They run off Energizer Lithium AAA batteries which are often difficult to source. My generation 2 lasts about 5 days under ideal conditions before requiring batteries, and the generation 3 are said to last about three times as long.  I’ve tried running my Spot 2 with rechargeable batteries, but I’ve not had much more than a day between charges. So I’ve come up with a simple ‘hack’ of the Spot 2 which will allow you to run it from either AAA batteries or USB.  Not needed for the Spot 3 which has USB power (although not waterproof if using it unlike with this hack!).

Requirements:

  • 15 minutes of time
  • USB cable
  • Spot 2 GPS with 3 x batteries installed
  • USB power source
  • multi-meter
  • 2 x blade terminal sets
  • hot glue
  • drill bit same diameter as blade terminal
  • Optional: tenacious tape

1  Prepare the USB cable

Cut the end off a USB cable and locate the power lines. These are usually red (+)and black (-). They are connected to pins 1 and 4:

image

Check the cable with a multi-meter by plugging it into a USB power bank. It should have +5 volts.

2.  Locate the positions of the positive and negative terminals in the spot

Open the back cover of the Spot to show the three batteries in place. The top left terminal is negative; the bottom right is positive. Check this with the multi meter.

Mark a line on the outside area with a pencil in line with each of these terminals.

Measure the distance from the outside of the cover area to where these terminals are on the inside.

3.   Bend blade terminals

Get two blade terminals and bend them to 90 degrees.

4.  Drill hole in back cover above location of the terminals

With a drill bit of the appropriate size (3.5 mm for my blade terminals) drill holes directly above the battery terminals. 

Insert the two blade terminal ends into the holes. They will extend into the battery compartment and be directly above the battery terminals.

image

5.  Replace cover and hot glue

Replace the cover and press the blade terminals hard down. It is important that they be in contact with the battery terminals, while having about 1-2 mm clearance above the back cover to insert the terminal blades.

Check with a multi meter that there is + 5 volts coming through.

Use hot glue to hold terminals in place and to completely seal them from water getting into the battery area.

image

Note: Before the hot glue sets check that there is still +5 volts of power!

6.  Connect cables and cover with tape

Once the hot glue has set, carefully insert the cable with blade terminals on the ends. Check that there are +5 volts of power.

image

At this stage for extra protection I covered the back with tenacious tape (or something similar). This will prevent the wires from being pulled out.

Remove the batteries from inside the unit and connect the USB plug to an external power source. You should now be able to power the Spot from the power source. Since this runs in parallel with your batteries, you can also use it with the batteries as well.

image

A Note On Power Packs

With this approach if you are using a dynamo and connect the Spot, with batteries in the Spot, to a USB charging point it should last a very very long time before you need to change the batteries.

I tested the Spot 2 with the above Goal Zero USB power pack and got about 60 hours of continuous running before the Goal Zero power pack was depleted.

When I ran the Spot with several other smaller power packs that I purchased online, it shut down within a very short time frame. I suspect that between signals the Spot is going into some form of power save mode and the battery packs turn off to save power.

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One response to “Powering your Spot 2 GPS from USB

  1. Pingback: Powering Your Gadgets For Endurance Races | Chris Bennett's Triathlon and Cycling Blog

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