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Increasing Battery life Question

Discussion in 'Power Electronics' started by spagettilegs, Dec 4, 2018.

  1. spagettilegs


    Dec 4, 2018
    I have a little machine that fires tennis balls for my dog and while I can plug it into the mains electricity, it's also portable. I can insert 6x D type standard batteries which last for a half hour or so..firing every few seconds.

    However I want to bring it onto a tennis court to fire balls for me and what I would like to do is rig up something externally I can wire up to it where it could last for hours.

    I have a 12v portable power source with a cigarette lighter type output. I was hoping I could use this in some way?
    Last edited: Dec 4, 2018
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Maybe 4 2V lead acid cells. Do you know anyone who's decommissioning a submarine? (You probably don't want cells that large)
  3. BobK


    Jan 5, 2010
    Alkaline D cells have a capacity of about 12Ah, so, if is lasting only 1/2 an hour, it pulls an outrageous amount of current. So, maybe the submarine batteries Steve suggests are just about right.

    You say you have a 12V portable source. How much current can it provide? And what capacity?

    A small portable generator might be your only hope.

  4. CircuitMaster


    Dec 17, 2016
    "24A" for half an hour, which is very unlikely. It might be time to replace the batteries with rechargable ones and buy a car cigarette lighter charger for "9VDC" batteries. I will post the links for them later.

    Isn't 12A/h too much? I see them with 600mA/h ?
  5. BobK


    Jan 5, 2010
    This datasheet shows 12000 mAh at 250 mA. It is down to about 10000 at 500mA, which is the highest current the characterize it at. If the drain in 1/2 hour it is probably drawing several amps, but not close to 24, which I doubt that it could ever supply. Using it an application this far away from what the datashhet shows is battery abuse.

    (*steve*) likes this.
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