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### Topic: Power consumption and battery life question. (Read 637 times)previous topic - next topic

#### mikejonesab1

##### Jan 17, 2013, 06:04 am
I am working on an project that requires power for these parts: serial jpg camera, sound sensor, temp sensor, ambient light sensor, barometric sensor, sd card, and WiFi adapter.

All these components are not running at the same time or continuously. Rather like this: camera will take a picture and store it, temp reading and store it, sound reading and store it, light reading and store it, then connect to WiFi and upload to server. This will be done about once a minute.

I would very much like this to be battery operated for flexibility. So my question is how long will something like this last on standard disposable batteries? on rechargeable batteries? Or at the very least give me tips on how to calculate this.

Thank you in advance!

--Mike

#### JimboZA

#1
##### Jan 17, 2013, 06:08 amLast Edit: Jan 17, 2013, 06:24 am by JimboZA Reason: 1
Well I guess the first thing is to find out the current draw under various circumstances, such as "standby" or "taking reading". The maker's sheets might tell you something, or if not you might have to set up a test with an ammeter.

Edit... then something along these lines....

1) Calculate the maximum current required at any moment, to make sure you get a power source capable of that instantaneous supply
2.1) Estimate how long each event takes ... ie how long in seconds is a "take reading", then multiply each of those by each event's current to get a mAseconds estimate for each event. Include the standby as events too remember....
2.2) Add up all the events' mAseconds and get an estimate of the mAhour rating required for battery, bearing in mind what you calculated in (1). (Or divide it into the mAh rating of a known battery and find the hours)
Johannesburg hams call me: ZS6JMB on Highveld rep 145.7875 (-600 & 88.5 tone)

#2
##### Jan 17, 2013, 06:20 am
Sounds like a couple hundred mA worth of parts. SD card and wifi typically being the big hitters.
Need at least 3 AAs for ~2000-2500mAH.  Maybe get 10-12 hours from it.
Cs, Ds, will give you a lot more.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

#### mikejonesab1

#3
##### Jan 17, 2013, 06:51 am
Thank you all. That is more or less what I was looking for.

#### Boffin1

#4
##### Jan 17, 2013, 07:33 am
The 7 amphour ( or more ) alarm type batteries are quite cheap if you have the space.
45 years of editing projects with a knife and soldering iron, then I found Arduino !

#### dhenry

#5
##### Jan 17, 2013, 01:35 pm
Quote
how long will something like this last on standard disposable batteries?

Without actually measuring, it is hard to know.

You should look at those peripherals and think if you can turn them on / off on demand, as a way to reduce power consumption.

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