3 AAA batteries with a "dummy" usb cable

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AlainD

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Hi

Is it possible to power the Teensy (3.2) with 3x AAA batteries connected to a cable that does plugin to the Teensy usb port?

USB is rated 5V, which is more than the max 4.5V with 3xAAA.


I like to use the usb plug instead of the seperate power supply pins if possible.
Seems to me a nice fool proof solution if it works.

Alain
 
Teensy 3.2 can run on Vin 3.7 to 5.5V which is is regulated down on board to 3.3V. Note that odd things will happen as the battereis flatten past ~3.7 where the 3.3V reg out will start to fall, in addition and anything connected to Vin will see the battery voltage rather than 5V, since there is nothing magically stepping it up.

Also check your actual battery voltages. Fresh Alkalines will be somewhat higher than 1.5V per battery and may approach 6V total. Second is if you are using rechargables you may have a fully charged voltage of something like 1.2V that will barely reach the regulator input voltage.

So yes it is possible put you will have to think about what happens at the various edge cases.
 
MichaelMeissner said:
I would probably think about using a step-up/step-down converter that changes the battery power to 5 volts (or 5.2 volts if you use an adjustable adapter, to allow for power loss in the wires).

I tend to like the step-up/step-down converters pololu.com sells (note, they can get hot):

The Adafruit verter is another one that I've used occasionally:
Click to expand...

If I only would use two AAA's would it be doable with the :
https://www.adafruit.com/product/1903 ?

Am I correct that a Teensy 3.2 with no power "hungry" extra electronics would use about 40mA at 5V or less?
And that two 800mAh AAA's at 3V would deliver about 400mAh or 10 hours of actual use?
 
GremlinWrangler said:
Teensy 3.2 can run on Vin 3.7 to 5.5V which is is regulated down on board to 3.3V. Note that odd things will happen as the battereis flatten past ~3.7 where the 3.3V reg out will start to fall, in addition and anything connected to Vin will see the battery voltage rather than 5V, since there is nothing magically stepping it up.

Also check your actual battery voltages. Fresh Alkalines will be somewhat higher than 1.5V per battery and may approach 6V total. Second is if you are using rechargables you may have a fully charged voltage of something like 1.2V that will barely reach the regulator input voltage.

So yes it is possible put you will have to think about what happens at the various edge cases.
Click to expand...

Would fresh 3 AAA's (or AA's) be able to deliver more than 6V, that would be 2V per piece?
 
AlainD said:
Would fresh 3 AAA's (or AA's) be able to deliver more than 6V, that would be 2V per piece?
Click to expand...
Don't remember the exact numbers for the highest values I've seen, but fresh batteries (alkaline or carbon-zinc) can measure up to 1.65V in a no load condition. Still under 5V for three, and any load will drop the output voltage somewhat.

Even NiZn (1.6V nominal, up to 1.9V on freshly charged cells) would be under 6V.

On the other hand Lithium batteries can deliver 3V or more per cell, so you need to watch out for those. However, they are not commonly encountered.
 
floating. said:
Don't remember the exact numbers for the highest values I've seen, but fresh batteries (alkaline or carbon-zinc) can measure up to 1.65V in a no load condition. Still under 5V for three, and any load will drop the output voltage somewhat.

Even NiZn (1.6V nominal, up to 1.9V on freshly charged cells) would be under 6V.

On the other hand Lithium batteries can deliver 3V or more per cell, so you need to watch out for those. However, they are not commonly encountered.
Click to expand...

Thanks, the most that I found was about 1.6V (alkaline) under a very light load. This seems in line with you're 1.65V with no load.
 
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