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Looking to power a peltier with <9V

Discussion in 'Power Electronics' started by DavidV, Nov 21, 2018.

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  1. DavidV


    Dec 5, 2017
    Hi All,

    I am working on a project for the into High school physics class I teach.

    I want to make a small battery driven Peltier cooler, but am limited to a max input of 9V. The Peltier plates I have appear to be most efficient at currents around 5A. I can use any combination of non-Lithium (school restrictions) batteries as long as the final output voltage does not exceed 9V. As a result I cannot just put some 9V batteries in series to up the voltage past 9V. The high current does not need to last vary long, a max of 10 seconds in fact. I also need to cool the Peltier quickly looking to drop the temp of the cold side about 30°F in less than 10 seconds (that is why I don't care if the battery are drained after 10 s).

    I can use transformers to boost the voltage but still need high enough current to drive the Peltier. I have an adjustable VDC to VDC step up that I can put my 9V max in and get 12V out but still need to get the 5A out.

    Is there any combination of batteries that can provide the 60W power to get 12V and 5A out. I can use any combinations of batteries as long as the output is <9V.

    I have tried 4 x 9V in parallel but can only get 2.4A out.

    Any suggestions?
    6 x D, C, AA, AAA?
    6V lantern batteries?

    Thanks in advance.
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    9 V blocks are nit suitable for high currents, not even for a short period. I recommend at least AA (not AAA) or C or D cells for that purpose.
    A step-up converter like e.g.this one can deliver up to 10 A at 12 V output.
    The input current of the converter will be proportionally higher as you'll have to input more power than the output delivers to account for internal losses.
  3. DavidV


    Dec 5, 2017
    Thank you very much. You confirmed what I thought. I tried the 9V because I had them and could connect them in series easily. I could get a different Pertlier but I have this particular type lying around. I also have some different converters in a parts box somewhere. If I remember correctly the converters will take 4-12V input. Would I be better off with smaller voltages in parallel as input to get enough power or higher voltage. For example, if I used 12 AA would I be better stacking 3 for 4.5 V and running 4 sets in parallel or stack 6 for 9V with 2 sets in parallel?

    Thanks again.
  4. duke37


    Jan 9, 2011
    I would try a 6V/12V battery charger of the old type.
    A 4A charger should be able to run more than 4A for 10sec.
    Why does the efficiency change with current level?
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    If you search the internet you may be able to find USB powered drink coolers.

    These run a Peltier from 5V and at a fairly low current. You would certainly be able to power them from 4 1.5V batteries, but I would choose C or D cells (unless you can use rechargeable AA NiMH).
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