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Dustbuster voltage change

Discussion in 'Electronic Repair' started by [email protected], May 1, 2005.

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  1. Guest

    Hi,

    I am meant to be revising so have decided to repair a dustbuster
    instead.
    It is a 7.2v model and the transformer to charge it is knacked. Thus, I
    was thinking of running it of a 9.6v AA nicad pack for which I have a
    charger with a nice plug that would make life easy.

    I have fitted the pack and the suction is great, motor doesnt seem to
    get too hot and all would be well... but the batteries get absolutely
    scortching!

    How can I stop this happening? Do I need to put a resistor in to limit
    current flow (but that would reduce suction I assume?) or can I run two
    packs in parellel (current drawn will be the same - get 2x battery
    life and the heat divided between the two packs).

    Other option would be to use another battery type - an ideas? NiMH?
    Lead-acid?

    I know buying another one would be easier, but I'd rather experiment ;)

    Cheers
    squelch41
     
  2. James Sweet

    James Sweet Guest


    The batteries get hot because you're drawing a lot of power from them, what
    you need is higher capacity (A-Hr) cells or put multiple battery packs in
    parallel.
     
  3. Not a good idea to parallel Ni-Cads - etc. They tend to self discharge
    even quicker. Use larger capacity cells in series.
     
  4. Guest

    I put 2 sets in parellel but it ended up drawing 10A as opposed to the
    5A it was drawing from the single pack. The original batts are sub-c
    cells - presumably their additional amp-hour rating would enable them
    to run cool enough? Also, I suppose as it was a 7.2V, less current was
    drawn?
     
  5. James Sweet

    James Sweet Guest

    Yes as you increase the voltage the motor will draw more current as well,
    and in return you get a dramatic increase in horsepower.
     
  6. Guest

    So what sort of battery would be most suitable to cope with this?
    I would imagine lead acid?
     
  7. Guest

    Actually, having just looked, lead acid batteries seem to be in
    multiples of 6v which isnt really suitable.

    Would NiMH batteries be more suitable as they can provide more mAhs but
    I'd imagine they'd get just as hot especially as they have a higher
    internal resistance dont they?

    Thanks
     
  8. James Sweet

    James Sweet Guest


    Yes, usually these things use NiCd's, I would think NiMH would be fine with
    intermittant use though.
     
  9. Guest

    Are they likely to suffer from the same level of heat generation?
     
  10. Mike

    Mike Guest

    .... and a dramatic increase in smoke output (but only temporarily).
     
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