# Using 4 AA Batteries To Power An Arduino Uno

I have a project that i want to have run on AC or DC power. I found a battery holder for 4 AA batteries. Can i hook the pack up to the Voltage in pin on the arduino to power the arduino uno?

Yes.

No, if the batteries are rechargeable cells, such as NiMH, since you’d only have about
4 * 1.2V = 4.8V nominal. A “qualified” yes, if the batteries are alkaline, as then you’d
have 4 * 1.5V = 6V, which will work if the board has an LDO [low dropout] voltage
regulator. Better to get a battery holder for 6 cells instead.

Also, what do you mean run on AC power? That doesn’t sound good.

dhenry: Yes.

No.

If you hook four new alkalines up to the vin pin you'll have over six volts going in there. Not good.

What's the best way to power the arduino with batteries using the voltage in pin?

Unfortunately there's a bit of a gap between the 5V needed by the USB/Vin pin and the 6-7V the voltage regulator is happy with. This leaves you with two options:

a) Six 1.5V batteries connected to the Arduino power plug.

b) Three 1.5V batteries and a DC booster circuit ( eg. http://www.ebay.com/sch/i.html?_nkw=5v+dc+boost ) connected to the Vin pin.

fungus:

dhenry:
Yes.

No.

If you hook four new alkalines up to the vin pin you’ll have over six volts going in there. Not good.

OP asked about using four NiMH cells. You said No to using four new alkaline cells. So how about answering the OP’s specific question.

NiMH batteries have replaced NiCd for many roles, notably small rechargeable batteries. NiMH batteries are very common for AA (penlight-size) batteries, which have nominal charge capacities (C) ranging from 1100 mA·h to 2800 mA·h at 1.2 V, measured at the rate that discharges the cell in five hours. Useful discharge capacity is a decreasing function of the discharge rate, but up to a rate of around 1×C (full discharge in one hour), it does not differ significantly from the nominal capacity.[4] NiMH batteries normally operate at 1.2 V per cell, somewhat lower than conventional 1.5 V cells, but will operate most devices designed for that voltage.

I would have no issue with powering an arduino board with four NiMH series connected cells attaching to the board via the USB connector by hacking an old spare USB cable.

Lefty

He didn't actually, Lefty: he asked about 4xAA and didn't say what type.

Could I connect the battery pack to the voltage in pin, or would I need to hack a USB cable and plug it into the USB in in the arduino? Thanks for the help :-)

I would have no issue with powering an arduino board with four NiMH series connected cells attaching to the board via the USB connector by hacking an old spare USB cable.

Forget the USB cable, connect the batteries to the power jack. That's what it's for. Use 6 cells, however, not 4.

Also, I don't understand lefty's comment, as he's got you connecting 4.8V to power a 5V regulator that requires at least 6V to operate properly. Not good.

oric_dan(333):

I would have no issue with powering an arduino board with four NiMH series connected cells attaching to the board via the USB connector by hacking an old spare USB cable.

Forget the USB cable, connect the batteries to the power jack. That's what it's for. Use 6 cells, however, not 4.

Also, I don't understand lefty's comment, as he's got you connecting 4.8V to power a 5V regulator that requires at least 6V to operate properly. Not good.

No, I suggested wiring the 4.8vdc from the battery pack to the USB connector, but you somehow changed that to connecting it to the external power connector and then stated confusion of my idea.

JimboZA:

He didn't actually, Lefty: he asked about 4xAA and didn't say what type.

Your right, it was replay #2 that suggested rechargeable NiMH cells which is a good choice.

Lefty

Also, I don't understand lefty's comment, as he's got you connecting 4.8V to power a 5V regulator that requires at least 6V to operate properly. Not good.

No, I suggested wiring the 4.8vdc from the battery pack to the USB connector, but you somehow changed that to connecting it to the external power connector and then stated confusion of my idea

Du-uh, still makes no sense. ??? How are you getting 5V onto the Arduino chip?

Ok, it's a trick question. He has a new 3.3V Arduino UNO board, right?

oric_dan(333):

Also, I don't understand lefty's comment, as he's got you connecting 4.8V to power a 5V regulator that requires at least 6V to operate properly. Not good.

No, I suggested wiring the 4.8vdc from the battery pack to the USB connector, but you somehow changed that to connecting it to the external power connector and then stated confusion of my idea

Du-uh, still makes no sense. ??? How are you getting 5V onto the Arduino chip?

Ok, it's a trick question. He has a new 3.3V Arduino UNO board, right?

Simple really. Take a spare USB cable, hack off the PC end, extract the USB +5vdc and ground wires, wire that to the 4.8vdc battery back, plug the usb cable into the arduino's USB connector. That way the battery pack will power the arduino board (any arduino board that has a USB connector) just like the PC does when you plug the board into your PC. Advantages, external power applied to the arduino board will still auto switch to the external power if desired at any time saving battery drain. battery pack will be protected by the arduino's on board 500ma thermofuse.

Is that clear enough?

Lefty

No, it's not at all clear. Are you saying the USB chip on the UNO board takes in 4.8V and outputs 5V? If so, you could explain that part. Or are you saying you're gonna run the Arduino chip off of the unregulated 4.8V coming in?

For my part, I don't want my Arduino chips running at any funny Vcc levels, so I prefer using the 6 AA-cells as noted earlier, and applying to the power jack, so the Arduino is running at 5V off the v.reg. Then, I know what the heck's going on.

oric_dan(333): No, it's not at all clear. Are you saying the USB chip on the UNO board takes in 4.8V and outputs 5V? If so, you could explain that part. Or are you saying you're gonna run the Arduino chip off of the unregulated 4.8V coming in?

I guess you have never read or studied an arduino schematic drawing? The USB +5vdc does not 'go through' the USB chip, it powers the USB chip and every thing else on the board wired to the arduino 5 volt bus. Put +5vdc on to the USB connector and everything on the arduino board that uses +5vdc will be powered up, no PC required, the on board USB chip has nothing to do with board power, just serial data to and from the PC to avr chip.

For my part, I don't want my Arduino chips running at any funny Vcc levels, so I prefer using the 6 AA-cells as noted earlier, and applying to the power jack, so the Arduino is running at 5V off the v.reg. Then, I know what the heck's going on.

The problem of going through the on board 5 volt regulator is that you are wasting battery duration (mAH capacity) by having to supply the minimum drop output input voltage to the regulator just to have the regulator waste it as heat dissipation. 4.8 vdc is well within the USB voltage specification for the USB standard 4.75 to 5.25 I believe. Because you don't understand something doesn't mean it's not a better/safer/more efficient method. ;) Lefty

retrolefty: OP asked about using four NiMH cells. You said No to using four new alkaline cells. So how about answering the OP's specific question.

No he didn't.

Besides, four newly-charged NiMH cells will also produce over 5V so they don't work either.

The "1.5V battery" is a myth. Batteries, ALL batteries start out at a much higher voltage when new (or newly charged) then drop down rapidly to their working voltage. This is usually 1.2-1.3V. Alkalines and NiMH aren't much different in these respects.

retrolefty:
Simple really. Take a spare USB cable, hack off the PC end, extract the USB +5vdc and ground wires, wire that to the 4.8vdc battery back, plug the usb cable into the arduino’s USB connector. That way the battery pack will power the arduino board (any arduino board that has a USB connector) just like the PC does when you plug the board into your PC. Advantages, external power applied to the arduino board will still auto switch to the external power if desired at any time saving battery drain. battery pack will be protected by the arduino’s on board 500ma thermofuse.

Is that clear enough?

Perfectly clear.

All except the “4.8V battery pack”. Where do you buy those…?

fungus:

retrolefty:
OP asked about using four NiMH cells. You said No to using four new alkaline cells. So how about answering the OP’s specific question.

No he didn’t.

Four newly-charged NiMH cells will also produce about 6V so they don’t work either.

The “1.5V battery” is a myth. Batteries, ALL batteries start out at a much higher voltage when new (or newly charged) then drop down rapidly to their working voltage. This is usually 1.2-1.3V. Alkalines and NiMH aren’t much different in these respects.

We can agree to disagree I guess. Nicad and NiMH have different terminal voltage and discharge curves then non-rechargable Alkaline cells. They aren’t much different in only their physical dimensions.

Lefty

fungus:

retrolefty: Simple really. Take a spare USB cable, hack off the PC end, extract the USB +5vdc and ground wires, wire that to the 4.8vdc battery back, plug the usb cable into the arduino's USB connector. That way the battery pack will power the arduino board (any arduino board that has a USB connector) just like the PC does when you plug the board into your PC. Advantages, external power applied to the arduino board will still auto switch to the external power if desired at any time saving battery drain. battery pack will be protected by the arduino's on board 500ma thermofuse.

Is that clear enough?

Perfectly clear.

All except the "4.8V battery pack". Where do you buy those...?

I like these http://www.taydaelectronics.com/aa-battery-holder-4.html or http://www.taydaelectronics.com/aa-battery-holder-3.html Load them up with 4 AA Nimh rechargeable cells and your off to the races. I think Radio Shack also carries them.