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DC Speed Motor with Batteries

  1. May 10, 2008 #1
    Hey Everybody!!....i have an Inquiry!!......

    Can you run a motor of maximun 12000 RPM with batteries??.....

    I mean....can you drive a DC motor of those speeds with batteries??...or perhaps can you do an adaptation so you can plug it to the AC line of the Alternator in the car so you can use the motor on outsides???....
  2. jcsd
  3. May 10, 2008 #2


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    Last edited: May 10, 2008
  4. May 10, 2008 #3
    Just remember; with a DC motor Voltage=speed and Current=torque
    If you have a motor rated at X volts at Y rpm then it will run Y rpm at X volts, however, you may need current enough to turn it (torque).
  5. May 11, 2008 #4
    ok heres the thing.....i work at a Hospital in the medical equipment section...we need to go to a Rural (country) deep in the "jungle" zone to obtain Blood samples of the people...

    what i want to do is to modify the circuit of a Blood Centrifuge so we can take it to the jungle and perhaps run it with batteries to take the blood samples....

    so do you think its possible???...to run a Blood Centrifuge with batteries???......im thinking yes....cause the new Hand Drills run with batteries!!
  6. May 11, 2008 #5
    Then there is your answer. Convert a drill battery to use with the centrifuge. If it will supply enough amps and last long enough to process then you are in business. Test it out. The centrifuge should give an amp or watt rating on it. The drill battery will also. From this you can estimate power requirement and how long it should run. Baterries have to be recharged.
  7. May 11, 2008 #6
    Instead use a gear box with high transmission ratio and supply less energy or better drive manually. At least it is fail proof.
  8. May 12, 2008 #7


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    What do you plug your centrifuge into now?
    If you are using a vehicle of some sort to go back country, then you already have a battery.
    Depending on the centrifuge requirements an inverter (for AC mains) or DC/DC converter (for some sort of DC power source)
  9. May 14, 2008 #8
    Im thinking to buy a Good Batterie Powered Drill.....open it and modified it to conver it into a Blood Centrifuge!!....and design the digital circuit to control its RPMs and the time.....

    so do you think its a good idea??......will the batteries withstand the Power needed??....

    or maybe could a plug to the Car`s Batterie??.....im thinking...with the Car turned on...the alternator will work...the motor wont stall....so i would connect it to the batterie and then i would have the power needed......
  10. May 14, 2008 #9


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    If you will have access to a car in the field, then NoTime's suggestion of an inverter would be the easiest way to do this. Hopefully the centrifuge (or the manual) has it's current or power requirement written on it, you would then buy one that can supply that much power.

    As for using the battery and rewiring the centrifuge, you'd need to find out the voltage and current requirements of the motor before choosing a suitable battery. Cordless drill batteries come in a range between 7V and 28V (and maybe more), so you wouldn't just go out and buy any old drill battery without first finding out what is really needed.
  11. May 14, 2008 #10


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    A few simple numbers might help in understanding what you need.

    First, any setup that gives longer duration of operation will be heavier in weight. If transportation is on the ground, this won't be much of a problem, if any air transportation is involved, a major problem might be encountered.

    Batteries are rated in Amp Hours, the larger this number the heavier the battery.
    If you use a 12 volt battery, and a 120 volt inverter, this will be a 10 to 1 step up and will give a 120 volt modified sine wave (make sure the centrifuge will operate on a chopped voltage). Pure sine wave inverters are on the market, but at a much higher price (going into the deep jungle on a very tight budget, might not be a good idea) do your research and buy the best of everything you can afford.

    For every amp the centrifuge draws, the current from the battery will be around 10 times that much (example of 120V and 5A centrifuge will draw 12V at 50A from the battery).

    I don't think i would consider a trip into the deep jungle, without a hand driven (small) 12 volt generator, and a small (as large as possible) solar panel. Test have shown that an average sustained output of human power to be in the 100 to 200 watt range, (12v 10a is 120 watts) an hour or two of hand cranking might be required to recharge a depleted battery to the level of starting an engine.

    There are a few people getting into remote power systems, getting one already engineered would be an easy approach.

    Things to consider, and learn in detail should be,
    1. Physical size and weight of the power conversion system.
    2. Power demand of all equipment to be used, (in watts), and how long they will operate at any given process.
    3. Recharging of batteries using the (vehicle) engine would be best done only when driving from place to place.
    4. How much energy will be used over how much time, what amount of hand power, and solar power could produce the overall needs. Could the man power of the local population be hired to turn a proper sized generator ( how much power in wattage over 24 hours to supply the needed use of equipment during the work day).

    Hope this might be a little help in giving you things to look at and consider as you make your plans.:smile:

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