Extra Power

I bought a mobile GPS for the motorcycle a year or 2 back, and really haven't used it since I got my new(er) phone which has a better embedded gps. This portable unit is waterproof, and transmits driver instructions on the FM band. There was a small receiver which you'd mount to your helmet etc. Overall it was a great unit, except the battery was complete rubbish, with virtually zero lifespan. It just wasn't functional without supplied power from the mount-bracket which was wired to the bike battery.

So I decided to add my own power source so the kids could use it when we go geocaching.


So many screws between me and getting this thing apart. It was built like a brick with nice solid rubber bushings for every component, and metal brackets compressing everything together.


Finally cracked it open. (this is an out of sequence photo, but you get the idea)


COMPLETE RUBBISH BATTERY!! 1000 milli Amp Hours. That's functional for MINUTES, maybe an hour when running a backlit LCD and Windows CE with the GPS application and receiver running. The spec is fine if the unit is idle...but worthless when in use while portable.


So I made my own battery pack. I couldn't find a triple-AA pack at Jaycar, so grabbed 3x1's and stuck them together with hot-glue on a small aluminium plate I cut out of an old computer CD enclosure. ;-)


Hot glued the battery pack assembly to the back 1/2 of the GPS unit.


...and fed the wires through a small hole I drilled through earlier. I then re-soldered and heat-shrunk the original battery plug


At this point the very straight forward job was done. Put it all back together and VIOLA, 7500mAh battery pack (standard rechargeable batteries are 2500mAh/ea), and go have some fun with the kids.

However...during the process I either nicked, pinched, shorted-out, or otherwise destroyed the LCD screen. I was certain the unit was "booting" because I saw it flicker once, and small debugging LCD's on the PCB indicated it was working in its on/off/sleep states. I was VERY VERY angry at myself. This was a really straight forward job. Simple in every possible way. I was having a rare moment of actual...happiness...listening to music as I did this. Then **BLAM** you broke your $200 toy. Idiot.

So I'm pretty angry now. I walk up and down the hallway eating cookies by the hand full, then order a pizza to drown my sorrows in its pure awesomeness. /dramatic-effect.

I figure there's no way I can reasonably expect to replace the LCD. During a post-op inspection, I actually make things WORSE by shattering the glass screen that the touch-digitiser is adhered to (this is a second component, not the LCD itself)

Wow...I'm on fire.

In a fit of desperation I get the magnifier on the part/s, and write down their bazzilion-digit part numbers and try to find them online. I was really surprised to find them indexed on Google at all. Even better, a few places were selling them wholesale to importers from China, but only in orders of 5 or more. As I dig some more, it turns out the parts used in this GPS are actually really common Gizmologist project components, but I still can't find a source for single units.

Ebay? Wow some dude is selling them!!...from China. I ask him if he's selling the touch-screen as well. But replies he doesn't. Oddly, I find another seller with the touch-screen...but he doesn't have the LCD. So I order both (cost me ~$40 total) and put the whole project on hold for 10 days while I wait for shipping from both guys.

And they arrive on the same day!! In the same boxes...with the same labels. And the same return address? I guess they were both drop-shipping. Oh well, can't really complain, I got the parts!!!


I plug in the new parts, and I see light :-D Very very happy now. So glad I didn't destroy the little computer unit. Running on USB power at this point.


MY first test with the new battery pack as source power. Works fine, as it should ;-)


The unit doesn't have a speaker, but as mentioned earlier it does transmit audio via FM. There is actually a little speaker-out port on the PCB, so I decided to test it out. Unfortunately I didn't really have any lower-power piezo speakers to test it with, nor an oscilloscope to properly test the port. So I gave up on that (for now).

In this picture you can clearly see the speaker port just down-right from the battery-port. Same style plug. The FM antennae can be seen top left near the black alligator clip, connected by a short piece of grey wire. The SD card is standard SD, not micro/mini.

I'm just simply amased that in this day and age it's cheaper to produce this kind of product with an off-the-shelf mobile computer PCB, with shelf display parts, to run an essentially dedicated GPS unit as an application within Windows CE, rather than as a static firmware circuit. All for $200 bucks at a grocery chain!! (Aldi) I've played around with WinCE on this unit when I originally got it. I'm boggled by how powerful this 7yr old operating system is, and I still wonder how Apple is in 2011 able to get any market share with their i-products. I'm running a GPS "app" on this unit, I can web browse (albeit really hard with this actual unit due to limited input plugs...not part of its sale-design), watch videos, slide-show photos, listen to music etc from this 2004 operating system. The original iPhone was a 2007 release and "swept the world" with what was really just "off the shelf technology". Try and keep up guys ;-)

So anyway. Basic job complete. This puppy has "UNLIMITED POWA' " for the kids now :-D