Small DC motor power

Discussion in 'Power Electronics' started by awwwt, Jun 30, 2016.

  1. awwwt

    Thread Starter New Member

    Aug 24, 2015

    I have a small DC motor, rated at 0.9 - 1.6 volts. I’d like to power it with a small 1.5v coin cell, or two - such as the CR44. At the moment these batteries aren’t really powering it to a very good speed / strength and I was wondering if this could be resolved with some simple circuitry.

    I was wondering if I could get some suggestions on where to start researching by way of stepping up / amplifying the current, or any suggestions on to make the motor more powerful in general. I might be wrong, but I was thinking of looking into using an op amp or a transistor? I am very new to this so sorry if it seems extremely simple.

    Thanks in advance!
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
    Does the motor run at an acceptable speed from an AA battery or , to put it another way, what is the actual voltage across the motor when running from the CR44?

    If the motor has 1.5V across it and it isn't fast/powerful enough then you need a different motor, though you could try running it at 3V. This will reduce its life but may still be acceptable.
  3. BobTPH

    Active Member

    Jun 5, 2013
    Most likely the coin cell cannot produce enough current to run the motor. The only thing you can do is use a bigger battery. These coin cells are not designed to run things like motors. Even using them to light an LED is beyond their intended use.

  4. dendad

    New Member

    Feb 20, 2016
    What is you application and what is the load on the motor?
    Unfortunately, you cannot get something for nothing. A small cell will not do a lot of work so it may be the coin cell is not the way to go. Adding extra circuitry will not help as it sounds like you are exceeding the coin cell's capacity already so no more power is available. You could boost the voltage but the current available would go down as the cell cannot supply more power.
    Also, the coin cell will run flat fairly rapidly driving a motor.
    Look at it as a tiny water tank with a very thin pipe.
    The pressure is determined by the height. A 1 gallon tank at 100 above will have the same pressure at the end of the thin pipe at ground level as a large dam with a wide pipe at the same height. But the dam can do a lot more work.
    But if the dam feeds via a thin pipe, it too cannot do much instantaneous work, but can do the work for a longer time.
    The pressure is the voltage (Volts) and the water flow down the pipe is the current (Amps). The size of the pipe can equate to the internal resistance (Ohms). The work is pressure x current (Watts). The size of the dam is the capacity (Amp/hours).
    I hope this simplification helps a bit.
    Last edited: Jun 30, 2016
  5. shteii01

    AAC Fanatic!

    Feb 19, 2010
    Like Bob said, not enough current. You have two choices:
    1. Use several small batteries connected in parallel, this way voltage stays the same, but current is increased.
    2. Use bigger battery.

    Getting those coin/pill shaped batteries in parallel is a pain. I think I would look for AAA/AA battery holder that is wired for parallel.