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My Bike Computer (Battery) Died

Discussion in 'Power Electronics' started by CDRIVE, Nov 29, 2013.

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  1. CDRIVE

    CDRIVE Hauling 10' pipe on a Trek Shift3

    4,960
    648
    May 8, 2012
    My bike computer is a Cateye Urban Wireless. After replacing the battery I lost the odometer reading that was at ~ 4,280 miles. This model doesn't appear to have any option to manually enter a preloaded ODO reading.

    Since I'm quite proud of this number I'm not agreeable to simply committing the original ODO to memory. So I'm looking for the most practical solution. Here's a list of solutions that I've pondered beginning with the most preferable. This because the battery life of the transmitter is based on miles peddled. This is because the transmitter is pulsed on by magnet sweeping past a hall effect sensor integral to the transmitter, which is affixed to the front fork.

    (1A) Attempt to simulate the transmitter with a keyed RF signal source.
    (1B) Increase the key rate to a value just below the computer's limit to read it.

    (2) Pulse an electromagnet taped to the transmitter's Hall Effect sensor. Adjust the key rate as in (1B).

    (3) Mount a magnet on a small disk that's connected to a motor shaft. Sweep it past the hall effect sensor and increase RPM to just below the rate that the computer or transmitter can handle.

    The problem with 2 & 3 is I have no idea how the transmitter will handle a rep rate many times faster than it was designed. After all, this is designed for an extremely brief duty cycle. I could very well burn it out while trying to stuff a year of cycling into minutes. For certain the CR2032 button battery, that powers the transmitter, will be sucked dry.

    Gee, after actually putting this down in print I think I am more agreeable to committing my current ODO to memory! :D

    Chris
     
  2. KJ6EAD

    KJ6EAD

    1,114
    158
    Aug 13, 2011
    Don't give up so easily. Connect a big 3V supply in lieu of the 2032 and use an electromagnet. Don't try to do it in minutes; take a few hours or days and give yourself an extra mile as compensation for the trouble.

    Those bike computers don't seem to have any data validation applied. I once changed the distance per revolution calibration on one to a figure that represented the travel of a 3" wheel!
     
    Last edited: Nov 29, 2013
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