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4.5V battery

Discussion in 'Hobby Electronics' started by Michael C, Oct 8, 2005.

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  1. Michael C

    Michael C Guest

    As I don't have the time or money (or knowledge) to design my own
    electronics I'm taking an existing product and modifying it :) It runs off
    three 1.5V watch batteries in series. I'd like to replace this with a single
    4.5V rechargable battery and charge it from a USB port. Does a 4.5 volt
    battery exist that would take up a similar amount of space? What sort of
    cicuit would I need to charge the battery (if any).

    Many thanks,
  2. Phil Allison

    Phil Allison Guest

    "Michael C"

    * Yeah right - like all " watch batteries" are exactly the same size.

    ** Errr - how much space was that again ???

    ............ Phil
  3. John_H

    John_H Guest

    If you have power available all the time it's no more difficult to
    design and build a voltage regulator to eliminate batteries than a
    battery charger.

    AFAIK you won't get any rechargeable batteries that are compatable in
    size to watch batteries.

    Nor are watch batteries all the same technology. The best and most
    expensive are silver oxide, for which cheaper options exist if the
    voltage stability isn't critical.
  4. Michael C

    Michael C Guest

    Hi John,

    The device is USB but it is wireless so won't always have power. I do have a
    fair bit more space than the 3 watch batteries, probably enough for a single
    AA battery. I was thinking that I could have a usb plug on the device that
    was used for charging only, instead of supplying the customer yet another

  5. Phil Allison

    Phil Allison Guest

    "Michael C"

    ** Had to DRAG simple fact that out of the PITA prick.

    Go check the WES catalogue for Akai Video Backup Batteries.

    Cat # BVS8 = 4.8 volt, 80 mAH.

    Costs = $10 .

    ......... Phil
  6. John_H

    John_H Guest

    WES Components at Ashfield (NSW) list a 1.2V 80mAh NiMH that measures
    16mm x 6mm (tagged for PCB mounting). It's code no. is RB80. They're
    somewhat more expensive than watch batteries (probably close to

    Four in series would give you 4.8 volt.
  7. Michael C

    Michael C Guest

    When I originally posted I didn't have that much space but came up with a
    better way to do it.
    Thanks phil, I'll give them a call next week.
  8. Franc Zabkar

    Franc Zabkar Guest

    How would you go about charging them from a 5V source?

    -- Franc Zabkar

    Please remove one 'i' from my address when replying by email.
  9. Phil Allison

    Phil Allison Guest

    "Franc Zabkar"

    ** Boost regulator.

    ........... Phil
  10. Michael C

    Michael C Guest

    What's one of them then?

  11. Phil Allison

    Phil Allison Guest

    "Michael C"

    ** Try Google.

    .......... Phil
  12. John_H

    John_H Guest

    LM2750 -- $5.81 from Farnell (awaiting stock).
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