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Thread: issues powering Teensy 3.2 via battery

  1. #1
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    issues powering Teensy 3.2 via battery

    As the title suggests, I'd like to power my Teensy using a battery, but i'm having issues. The battery in question is 9v and i've built a basic voltage divider to step that down to 5.1v for the Teensy. as soon as i attach Vin on the Teensy to the 5.1v node, voltage at the node drops to 1.6v and the 3.3v out also sits at 1.6v. This occurs when using a power supply as well. If i attach the power supply directly to Vin and set it to 5v, current is drawn and voltage at Vin and 3.3v out drops to 1.6v. The only way i can successfully power the Teensy is via USB, yielding 4.9v at vin and 3.3v at the 3.3v out. is there a trick to powering it through Vin, or is my Teensy just not functioning correctly? sorry if this has been asked before..i tried in vain to find anything related to it.

  2. #2
    Senior Member+ Frank B's Avatar
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    A voltage divider is not a good solution (as you can see).
    You need a voltage regulator or step-down converter.

    Or, most easy, a USB-Powerbank instead of the battery.

  3. #3
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    I'm working with some very limiting space constraints, so i'm not sure the power bank would be an option. something like this should work though? https://www.amazon.com/Zixtec-LM2596..._t4_B014Y3OT6Y

  4. #4
    Senior Member+ MichaelMeissner's Avatar
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    Quote Originally Posted by mecha_idiot View Post
    I'm working with some very limiting space constraints, so i'm not sure the power bank would be an option. something like this should work though? https://www.amazon.com/Zixtec-LM2596..._t4_B014Y3OT6Y
    They probably will work. But I would think typically you would want a unit with a fixed voltage output rather one that can vary depending on the potentiometer setting. The variable ones are great for testing, but I can certainly imagine it getting changed in the field by accident.

    While I don't buy that many, I tend to go to pololu.com to by regulators (assuming you live in the USA). I believe pololu makes their own regulators rather than importing them. You would need to size the regulator based on the expected power available and power needed. They just announced their black friday sales through monday.



    I typically use li-po batteries, but I tend to prefer the step up/step down regulators to provide flexibility in the power (at the expense of a little loss in efficiency in the conversion). I like this regulator which can deliver either 3.3v or 5v (depending on a solder jumper) with a cut-off if the input is less than 3v:


    Do note the caution that regulators can get hot to touch.

  5. #5
    Senior Member+ Frank B's Avatar
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    Michael is (as always) right.

    Yes, these potentiometers can be dangerous.
    Please measure the voltage before you connect the Teensy.

    I fear a 9V-Block will not last very long.

  6. #6
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    Michael, Frank, thank you both for the assistance. I ordered the https://www.pololu.com/product/2873 and i'll let you know if it works. I'm still a bit confused as to why supplying 5v directly to Vin via the power supply didn't work as expected though.

  7. #7
    Senior Member+ defragster's Avatar
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    I saw this item on the new Teensy Distributor page: Proto Supplies : MP2315 Mini Adjustable DC-DC Step-Down Module
    It is adjustable and step down only - but has onboard resistors to solder to get a chosen fixed voltage by soldering selected pad. Just ordered a couple with free shipping at $75, else $10 shipping - and in my state so will be quick.

    That site protosupplies.com has a number of useful items and a very informative easy to read/navigate website. Ken is also responsive in stocking desired items it seems { will be adding digikey 64MB Flash and low profile headers }

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