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Topic: battery powering an arduino (Read 1 time) previous topic - next topic



I've built a nice little project (a MIDI controller for the Behringer DEQ2496 - I'll write it up somewhere when I have time).  The project is designed to be portable.  At the moment I have the arduino in a handheld case along with a 9v PP3 battery, connected with a wire similar to http://www.sparkfun.com/products/10512

To turn the arduino off, I unplug the wire.  To turn the arduino on, I plug in the wire.  This is not ideal.

Ideally (and I know this might be a bit ambitious), I'd like to be able to have a rechargeable battery, that the project runs off when it's not plugged into the mains.  When it is plugged into the mains, I'd like it to run off the mains, and recharge the battery.  Additionally I'd like an on/off button/switch, so that I can save the battery when I'm not using it.  Finally (I said it might be a bit ambitious), I'd like a battery indicator.  I'm thinking of attaching a graphic display to the project, so if this data could possibly be sent to the arduino, I could display the battery status on the screen.

Any idea which parts of this are feasible, and which parts aren't?

What I know about batteries could be fitted onto the back of a postage stamp, so if anybody has ever come across a nice tutorial on them, I'd appreciate it. 



Simple chemistries are easy... you can pretty much use a transistor switch such that when there's power via the mains input, it turns off the battery input.  Then, using a diode, you can have the mains PSU send power through the battery to charge it.  Loads of examples online, and it's pretty darn simple to set up.

Li-Ion or Li-Po are more complicated.  You can't treat them like a large capacitor -- you need a dedicated charging circuit to monitor and control both the charge and discharge cycles.  (If you want battery status, you kinda need this anyway.)  There are lots of one-chip solutions to this.  Search through this forum, and check the playground.  It's a common topic.


I remember that there is an Arduino that has an integrated Li-Po charger that does exactly what you're asking for. I don't remember the name, but I'm sure Google would find it for you.
I only provide help via the forum - please do not contact me for private consultancy.


I remember that there is an Arduino that has an integrated Li-Po charger



May 04, 2012, 11:53 am Last Edit: May 04, 2012, 12:05 pm by storm Reason: 1

now I like that.  it's even got a xbee connector built in.  thanks very much

out of interest do you know of one that has multiple hardware serial ports?


one that has multiple hardware serial ports

That would be the Arduino Mega, with ATmega2560 (4 UARTs). ATmega644P and 1284P have 2 UARTs.

James C4S


out of interest do you know of one that has multiple hardware serial ports?

You might be interested in this description:

The ATmega328 chip only has 1 serial port.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com

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