timer switch circuit?

Discussion in 'General Electronics Chat' started by casimirrx, Sep 14, 2011.

  1. casimirrx

    Thread Starter New Member

    Sep 14, 2011
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    I have a rechargeable flashlight plugged to an always hot 12v in my car. If the flashlight is not always charging and if left on the charging cradle it seems to discharge the flashlight battery rapidly so I choose to have it hot as to always have the flashlight charged. The obvious problem is that if I dont drive the car for four or five days, it drains the cars battery.
    There must be some sort of 'timed transistor' (for lack of knowledge of what such a thing may be called) available that would allow power to the unit for a certain amount of time, (say 72 hours) then cut power until its interrupted by either starting the car or pulling the light of the charging cradle. I got the idea from my wireless sony headphones that automatically stop charging after 16 hours I guess to preserve the battery life.
    Can someone help me with any ideas and what type of circuit or switch etc. I would need?

    Many thanks in advance!
     
  2. R!f@@

    AAC Fanatic!

    Apr 2, 2009
    8,754
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    Welcome to the forum.
    I did not get you.
    Mind telling me in details
     
  3. casimirrx

    Thread Starter New Member

    Sep 14, 2011
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    Thanks! I am trying to stop my rechargeable flashlight from draining my car battery with some sort of timer or switch.
     
  4. #12

    Expert

    Nov 30, 2010
    16,355
    6,852
    I suggest that it is easier to replace the defective battery in the flashlight. Then it will not have to be on the charger all the time and will keep its charge for weeks or months when not in use.
     
  5. casimirrx

    Thread Starter New Member

    Sep 14, 2011
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    Thanks for the reply. I should have been clearer. When I take the fully charged flashlight off the charger and set it on the shelf the charge lasts for quite awhile sometimes weeks before i can notice a appreciable difference. However if I leave the flashlight on the charging cradle not plugged to power, the light drains quickly in as much as a day or so. This would led me to believe the battery is fine with the light but perhaps being left on on the charger without power leaves the circuit open and drains the battery.
    As an update I have become aware of a product called ChargeGuard that claims to protect vehicles from accidental battery discharge,while still providing instant access to critical electronics. Anyone have any experience with these?
     
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