Project 12: Applications and Implications

The Project - Bike battery & tracker

What will it do?
I want to create a combined bike battery and tracker. My motivation for this is that on bike trips a battery to charge smartphone and other devices is very valuable and a hub dynamo in a bike is a very good way to create power. On the other hand the battery can be used to power the lights on the bike. Another thing that is very valuable today, as lots of bicycles are stolen and the majority is never found again, is a bike tracker. With this you can locate your bike in the case it gets stolen and get it back. The integration of both devices seems quite reasonable, as the tracker needs a battery to work and with a battery already in the bike it is not too much to put a tracker on top of it.

Tracker in the frame

in the handlebar

or in the lamp

Who has done what beforehand?
In the Fab Academy it looks like nobody has either done a tracker or a circuit for charging from a dynamo by its own. But there are quite some trackers commercially available. The problem is that there are downsides to all of them: They are available either integrated into accessories as lights/bottle holders or installed in the frame. As there are just a handful accessories available these are very easy to spot and to remove for a thieve. And the ones inside the frame have an extra battery, extra weight and need to be removed from the frame for charging. I found some DIY projects from other hobbyists, but they were only about the tracker itself. On example is this project.

Battery on the handlebar

and under it

What will I design?
- charging circuit to charge the battery
- tracking circuit
(- even more stuff if enough time is available: lights, lock)

What materials and components will be used?
(- bike with hub dynamo)
- battery (li-ion, good capacity)
- charging circuit: (rectifier, buffer capacitor, voltage converter, Li-Ion Charge Controller, )
- tracking circuit: (GPS module, GSM module, ATMega)
- PLA filament
- Plexiglas

Where will they come from and how much will they cost?
I am searching the parts on Mouser at the moment. I am not quite settled on the exact parts to use, but I think 60€ should be a realistic budget. For a complete bill of materials see the Final project page

Project Plan

What parts and systems will be made?
- pcb board with all the electronics on it (battery connection, connection to the dynamo/power source, charging circuit, tracking circuit)
- housing that fits into the bike frame with possibilities to connect a phone

What processes will be used?
3D Printing the case, milling the pcb, lasercutting caps, soldering, programming

Task list:
- make some more research on what to use
- order parts
- design schematics and board
- design housing
- solder and test electronics (test where antennas need to be)
- 3D print housing and optimize for fit in the bike frame
- write software to connect the device to the phone via BLE and GSM - test it

What questions need to be answered?
- Where in the bike frame does the antenna need to be to work properly?
- Does li-ion batteries get destroyed faster when charged with changing current? Can I do something against it?

How will it be evaluated?
- Does the connection from phone to tracker work via internet/call (to get current the position of the bike)
- Can I charge the battery? (with USB and dynamo)