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Peltier Cooler connected to Power Supply, is this configuration safe?

  1. Apr 26, 2012 #1
    I am building a Peltier Cooler with the circuit diagram below. The power supply will be a battery, but for testing purposes I am connecting it to a stationary power supply.

    http://dl.dropbox.com/u/10419947/circuit.png

    I suspect that the peltier coolers which are rated at 30A will draw as much current and power as possible once I switch the power supply on, potentially destroying the supply itself even though I do not intend to deliver anything above 10 A. Are my fears warranted? I prefer not to try my luck as the power supply costs a fortune to replace.

    Thanks in advance.
     
  2. jcsd
  3. Apr 26, 2012 #2

    NascentOxygen

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    Staff: Mentor

    ➤ Some power supplies have a current limiter so you can set the max current.

    ➤ Do you have manufacturer's technical data that indicates how many volts the Peltier devices need for 10A?
     
  4. Apr 26, 2012 #3

    vk6kro

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    Science Advisor

    You have the coolers in series, so each will get 3.5 volts maximum.

    You can estimate the resistance of the cells by working out the resistance under full power.

    R = E / I so R = 14 volts/ 30 amps = 0.4 ohms. (This is just an estimate because these devices may not be linear. I tried a lower powered Peltier and it was linear, though.)

    So, if you just put 4 of these in series across 14 volts, you would get a current of 14 volts / (4 * 0.4 ohms) or 8.75 amps. So, the current switched by the MosFet should be less than this.
    Much less than their 30 amp rating.
    So, the Peltiers should be OK.
    You could put a 10 amp fuse in series with the Peltiers to make sure the power supply is not overloaded.

    Your symbol is for a NPN transistor.

    Peltier devices get hot on one side and cold on the other side, so you have to have a heatsink on the hot side to carry the heat away.
     
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