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Topic: Can I use two 9V batteries in series to power an Arduino Uno? (Read 19225 times) previous topic - next topic

jardane



I have 9V to jack (photo above) and I want to splice in a second 9V battery so I the Arduino will be running on 18V. Is there any potential issues with this?

I also want to splice in a switch too, so I can turn the whole device off to save on battery life but that's an afterthought.

JimboZA

It would be over the recommended 12V and just under the max of 20V, and anyway it works on 7V.....

Quote
The board can operate on an external supply of 6 to 20 volts.....  If using more than 12V, the voltage regulator may overheat and damage the board. The recommended range is 7 to 12 volts.
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polymorph

Why would you want to do that? The regulator on the Arduino Uno is a linear regulator. All the power, and I mean every bit of it, from the extra 9V regulator will be wasted as heat.
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jardane

I am going to be running a lot on the  Arduino UNO including a Digital-to-analog converter, an LM3914N-1 bar/dot controler, a micro SD card reader, a transistor that is pulling 5V to power a speaker and several LEDs.

I want to make sure i have enough power for everything.

Grumpy_Mike

But putting two batteries in seriese will not give you any more power than from one battery. It all gets wasted in the regulator.

jardane

It was recommended by a friend of mine and I thought it sounded odd, so I thought I would ask. So wound one 9V handle all my equipment?

JimboZA

#6
Oct 08, 2014, 05:22 pm Last Edit: Oct 08, 2014, 05:26 pm by JimboZA Reason: 1
Well those 9V things are notorious for not holding much energy. It may have enough power, but it probably won't last long, since energy is power x time.
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Your answer may already be here: https://forum.arduino.cc/index.php?topic=384198.0

jardane

It's for a prop so it's not going to be running 100% of the time and I can make the battery easy access so I can carry spares.

jremington

You can put identical batteries in parallel, then the combination will last about twice as long.

JimboZA

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Grumpy_Mike


You can put identical batteries in parallel, then the combination will last about twice as long.

No you can't.
They will cross charge and heat up.

JimboZA



You can put identical batteries in parallel, then the combination will last about twice as long.

No you can't.
They will cross charge and heat up.


Surely not if they were truly identical? (Not that they will be......)
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Grumpy_Mike

When someone asks for help I assume it is practical help they want, not theoretical help that postulates impossible conditions.

jardane

No batteries are ever truly identical even when brand new from the same pack.

JimboZA

Exactly, so stick to just one, assuming it can provide enough power in the first place.
Johannesburg hams call me: ZS6JMB on Highveld rep 145.7875 (-600 & 88.5 tone)
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Your answer may already be here: https://forum.arduino.cc/index.php?topic=384198.0

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