direfulfoil23
Posts: 40
Joined: Fri May 06, 2016 6:30 pm

Raspberry Pi Power Usage

Sun Jun 19, 2016 6:00 pm

Hello all,

I've been doing some reading on the power consumption of the raspberry pi, and I'm trying to figure out if I were to hook it up to a battery what I would have to do, but it's all a bit confusing to figure out so I have a few questions. I want to hook it up to a battery and that battery to be able to power it all day on it's own power, but to be charged by a solar panel so that it never runs out of charge, but I can't figure out how much power the raspberry pi uses say in an hour to find the appropriate battery that has 24 amp hours of that draw. Also, I know a lot of batteries use DC and the raspberry pi uses AC right? So what problems would that create that I would have to deal with, and would that change the amount of power I would need in the battery? And my final question is, for the correct battery what kind of solar panel power outputs would I need to keep the battery constantly charged?

Thanks for your time and help.

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rpdom
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Location: Chelmsford, Essex, UK

Re: Raspberry Pi Power Usage

Sun Jun 19, 2016 6:20 pm

(Big block of text is hard to read. I've broken it down into easy to read/answer bits)
direfulfoil23 wrote:I've been doing some reading on the power consumption of the raspberry pi, and I'm trying to figure out if I were to hook it up to a battery what I would have to do, but it's all a bit confusing to figure out so I have a few questions.

I want to hook it up to a battery and that battery to be able to power it all day on it's own power, but to be charged by a solar panel so that it never runs out of charge, but I can't figure out how much power the raspberry pi uses say in an hour to find the appropriate battery that has 24 amp hours of that draw.
Which model Pi? They have very different current needs.
Also, I know a lot of batteries use DC and the raspberry pi uses AC right?
Wrong. The Pi uses 5 Volts DC (give or take a little).

The Pi is usually powered with a power supply that converts your home AC mains to 5V DC.
So what problems would that create that I would have to deal with, and would that change the amount of power I would need in the battery?
Not relevant.
And my final question is, for the correct battery what kind of solar panel power outputs would I need to keep the battery constantly charged?
You would need a big battery and a big solar panel.

What sort of battery are you thinking of using?

How much sunlight do you get where you are?

You will probably need a "Deep discharge" or "Leisure" 12 volt battery that can be charged from the solar panel, then a good 12V to 5V converter to power the Pi.

blaablaaguy
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Joined: Sun Sep 27, 2015 3:26 pm

Re: Raspberry Pi Power Usage

Sun Jun 19, 2016 6:21 pm

See this to learn how to measure current. https://learn.sparkfun.com/tutorials/ho ... ng-current
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JoshMilner
Posts: 3
Joined: Thu Jun 16, 2016 5:39 pm

Re: Raspberry Pi Power Usage

Sun Jun 19, 2016 6:26 pm

Hi Direfulfoil23,
I'm really interest in this thread and have a keen interest in both solar and RPi. My shed is currently in the process of solar power and it will be a complete off grid system, my question is what are you using the pi for as depending what you plug into the pi's USB ports it may use more power.

I'm also doing some raspberry pi cctv cameras with a cloud network and I'm planning on them all running on solar power then the wifi router on solar too so in a power cut we wouldn't loose the CCTV my plan with it was to build a camera and run it continually plugged in to a meter plug you can buy off the bay to work out the power consumption of one camera unit.

Josh

direfulfoil23
Posts: 40
Joined: Fri May 06, 2016 6:30 pm

Re: Raspberry Pi Power Usage

Sun Jun 19, 2016 6:38 pm

rpdom wrote:(Big block of text is hard to read. I've broken it down into easy to read/answer bits)
direfulfoil23 wrote:I've been doing some reading on the power consumption of the raspberry pi, and I'm trying to figure out if I were to hook it up to a battery what I would have to do, but it's all a bit confusing to figure out so I have a few questions.

I want to hook it up to a battery and that battery to be able to power it all day on it's own power, but to be charged by a solar panel so that it never runs out of charge, but I can't figure out how much power the raspberry pi uses say in an hour to find the appropriate battery that has 24 amp hours of that draw.
Which model Pi? They have very different current needs.
I'm using the Raspberry Pi B+. Thanks for the help, a lot of it answered what I needed to know.

direfulfoil23
Posts: 40
Joined: Fri May 06, 2016 6:30 pm

Re: Raspberry Pi Power Usage

Sun Jun 19, 2016 6:41 pm

JoshMilner wrote:Hi Direfulfoil23,
I'm really interest in this thread and have a keen interest in both solar and RPi. My shed is currently in the process of solar power and it will be a complete off grid system, my question is what are you using the pi for as depending what you plug into the pi's USB ports it may use more power.

I'm also doing some raspberry pi cctv cameras with a cloud network and I'm planning on them all running on solar power then the wifi router on solar too so in a power cut we wouldn't loose the CCTV my plan with it was to build a camera and run it continually plugged in to a meter plug you can buy off the bay to work out the power consumption of one camera unit.

Josh
For this project I'm just using a few of the GPIO Pins (I think the max power they used was 50 milliamps) but I don't think I'm going to use any of the USB ports. What I'm trying to do is have the raspberry pi open a door powered by actuators every sunrise and sunset automatically. Come to think of it I have to figure out what the actuators power requirements will be...

darkbibble
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Location: corby, england

Re: Raspberry Pi Power Usage

Sun Jun 19, 2016 6:48 pm

that could be accomplished easily with a pi zero which runs under 200mA without a display and usb plugged in. tho you will need a separate power supply for the actuator.
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direfulfoil23
Posts: 40
Joined: Fri May 06, 2016 6:30 pm

Re: Raspberry Pi Power Usage

Mon Jun 20, 2016 12:40 am

darkbibble wrote:that could be accomplished easily with a pi zero which runs under 200mA without a display and usb plugged in. tho you will need a separate power supply for the actuator.
Yeah but Raspberry Pi Zero's are kind of impossible to find, I could get one but it'd be part of a pack with a bunch of cables I already have for the same price as a Raspberry Pi 2 or 3.

geoffr
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Location: Melbourne, VIC

Re: Raspberry Pi Power Usage

Mon Jun 20, 2016 1:36 am

direfulfoil23 wrote:
darkbibble wrote:that could be accomplished easily with a pi zero which runs under 200mA without a display and usb plugged in. tho you will need a separate power supply for the actuator.
Yeah but Raspberry Pi Zero's are kind of impossible to find, I could get one but it'd be part of a pack with a bunch of cables I already have for the same price as a Raspberry Pi 2 or 3.
Depending on where you live, Pi Zeros are becoming easier to come by. The Pi Hut and Pimorini tend to have stock every Week now. You can subscribe to notifications on their website. It is also useful to stalk the Pi Hut on Twitter to get a better idea of when stock will be available. Usually, stock gets made available by the Pi Hut and 09:00 UK time on Wednesday.

I have seen a Pi Zero drawing under 200mA with a WiFi adapter connected to the USB port.

Depending how keen you are to reduce power consumption, you could also use a RTC alarm to bring the Pi up an hour or two before it needs to do its job, and the shut down again once your job is done. That will however require a bit of extra circuitry to hook up the alarm pin of a RTC....

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HawaiianPi
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Re: Raspberry Pi Power Usage

Mon Jun 20, 2016 2:12 am

geoffr wrote:...I have seen a Pi Zero drawing under 200mA with a WiFi adapter connected to the USB port...
Yup, my GF's Zero sits around 170-180mA with a USB WiFi adapter connected to my network. It'll go a little over 250mA with Sysbench pushing the CPU. It bumps up to the 300-350mA range (briefly) with a sudo apt-get upgrade if it's actually writing data to the SD card, and that's about where my Pi3 idles.
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