powering arduino nano w/ battery pack

Using Arduino IDE 1.x
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I am using four rechargeable AA batteries in series to power an arduino nano. Should I be using the 5V pin or the VIN pin? Also would this be a regulated or unregulated power source?

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lyrical10:
I am using four rechargeable AA batteries in series to power an arduino nano. Should I be using the 5V pin or the VIN pin? Also would this be a regulated or unregulated power source?

If the type of rechargeable AA batteries (4 in series) is less then 5.5 vdc when fully charged then wiring them to the 5V pin is the best method. Applying +5 vdc to the Vin pin won't work as that is below the on-board +5vdc regulator's input voltage requirement. Technically a battery is not a regulated voltage source as the battery voltage will decrease as it discharges. However the arduino board will function fine with the battey, with the only disadvantage that analogRead values will lose some accuracy as the battery voltage decreases.

Lefty

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Thanks retrolefty. That was very helpful. Could I use a 9v battery in the VIN pin or could that damage the arduino? I've read many varying opinion's online. I'm wondering what the best battery option would be to power the arduino and 5 servos. Wouldn't 4 AAs drain very quickly?

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lyrical10:
Thanks retrolefty. That was very helpful. Could I use a 9v battery in the VIN pin or could that damage the arduino? I've read many varying opinion's online. I'm wondering what the best battery option would be to power the arduino and 5 servos. Wouldn't 4 AAs drain very quickly?

A nine volt battery will work via the Vin pin, however it's a very poor choice as they have very small current capacity and are among the most expensive batteries sold Vs the actual energy density supplied. They work best for smoke detectors, for Arduino projects they are an expensive joke and waste of your hobby dollars.

Servos consume current, the amount varies with specific servo model, mechanical load attached to the servos, how far they are commanded to move, how many will be moving at the same time, etc etc. I usually budget 1 amp capacity per servo. Four AA alkaline cells will power an arduino and 5 servos, just not for very long, depending on prior sentence. If they are rechargeable then that may not be a big deal, if not plan on spending lots of money feeding your servos batteries. Lots of rechargeable battery types and sizes are avalible. It's really hard to estimate battery size at project inception. Often one can use a properly sized DC power supply to support the project through prototyping and once completed one can measure the actual current consumption value and then based on desired battery duration, calculate the proper battery capacity required to meet the objectives. It's all about the math (and the budget :wink: )

Lefty