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Thread: Can I power a Teensy 3.2 With 4 AAs?

  1. #1

    Can I power a Teensy 3.2 With 4 AAs?

    I know the official max Vin is 6V and that although the regulator chip can handle up to 10V, it isnt recommended due to thermal dissipation. But in practice, would I risk killing my T3.2 with 4 alkaline AAs? Fresh they would put out about 6.6V total but probably only for about 15-20 minutes before they drop down below 6.

    I have a circuit that needs 4AAs to run a motor and would like to not have to add an external regulator for the Teensy...

    Thanks!

  2. #2
    Senior Member+ Theremingenieur's Avatar
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    Everything depends on how much current you draw from the voltage regulator. The total power dissipation in the voltage regulator is roughly (Vin - Vout) / Iout. Vout is 3.3V, Iout is the current needed by the Teensy, depending on F_CPU and the activity of internal peripherals, plus the current you draw from the 3.3V pin for external peripherals. Measure the currents and do the calculus to see if you can remain within the specs with a 10% higher Vin.

  3. #3
    or just put a 10R in series to drop a volt or so....

  4. #4
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    or even a diode so that the voltage is <6 new cells and drop is semi constant with current
    either junction for 0.5-0.6 or barrier for 0.3-0.5 volt drop

  5. #5
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    I'm using regularly 4 D cells for a Teensy 3.6. Should be similar for T3.2.

  6. #6
    Senior Member+ MichaelMeissner's Avatar
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    Or alternatively, use NiMH AA rechargeable batteries. These batteries have a nominal voltage of 1.2 volts (4.8 volts for 4). I believe freshly charged they might be 1.38 volts (5.52 volts for 4). IIRC, rechargeable batteries tend to have less of a voltage slope than non-rechargeable lithium/alkaline batteries. Plus over time, it would be cheaper since since you don't have to keep buying new batteries and then throwing them away to fill the landfills.

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