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Raspberry Pi Zero – Conserve power and reduce draw to 30mA

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Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#41

Post by alkonaut »

What is the practical difference between 500mA and 30mA? Both are way too high for battery power, and both are low power in terms of cooling and electricity cost?

A sensor node with a 5Ah battery would have a budget of .5mAh to have the battery last s year. That is still two orders of magnitude under the Pi. Power is interesting for cooling and economics until you get below a few watts, at which point the power costs nearly nothing and the cooling is done without heat sink in air without fans.

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#42

Post by kwhitefoot »

janjongboom wrote: post #25

Why are we even using a Raspberry Pi for battery powered projects... 30 mA draw is so high you'll be changing batteries every 2 days, and that is without doing anything. Compare that to f.e. a normal phone chipset with deep sleep, which draws about 9 mA with a cellular connection, or .1-.2 mA in flight mode. Or, if you just use the Pi for sensor readings, get a proper microcontroller, where current is measured in mic…

That's what people who don't own smartphones say about smartphones.

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#44

Post by cstross »

Please can somebody build a case for the Pi Zero in the form factor of the Psion 5?

https://en.wikipedia.org/wiki/Psion_Series_5

(The patents on the folding keyboard will probably have expired by now -- the design dates to 1994-95 -- and with a 30mA draw the Pi 0 is within spitting distance of the sort of power the Psion 5's twin AA cells delivered. Add an e-ink display and a wee USB bluetooth peripheral for i/o (wifi too, if it can be done within battery limits) and it could be the second coming of the form factor of the Sharp Zaurus Z-1 Netwalker (only with a better keyboard and more usefully open software stack):

http://www.engadget.com/2009/08/27/sharps-5-inch-pc-z1-netwa...

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#45

Post by radiorental »

janjongboom wrote: post #25

Why are we even using a Raspberry Pi for battery powered projects... 30 mA draw is so high you'll be changing batteries every 2 days, and that is without doing anything. Compare that to f.e. a normal phone chipset with deep sleep, which draws about 9 mA with a cellular connection, or .1-.2 mA in flight mode. Or, if you just use the Pi for sensor readings, get a proper microcontroller, where current is measured in mic…

First and foremost, the Raspi boards are for teaching. That's the goal of the foundation. I would guess the vast majority of people who buy a raspi are dipping their toes in to the world of hardware - not building semi/permanent applications.

Yes there are absolutely better suited platforms.

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#46

Post by jacquesm »

cstross wrote: post #44

Please can somebody build a case for the Pi Zero in the form factor of the Psion 5? https://en.wikipedia.org/wiki/Psion_Series_5 (The patents on the folding keyboard will probably have expired by now -- the design dates to 1994-95 -- and with a 30mA draw the Pi 0 is within spitting distance of the sort of power the Psion 5's twin AA cells delivered. Add an e-ink display and a wee USB bluetooth peripheral for i/o (wif…

Now there is one design that should make it to thingyverse.

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#47

Post by smcl »

Andrenid wrote: post #28
janjongboom wrote: post #25

Why are we even using a Raspberry Pi for battery powered projects... 30 mA draw is so high you'll be changing batteries every 2 days, and that is without doing anything. Compare that to f.e. a normal phone chipset with deep sleep, which draws about 9 mA with a cellular connection, or .1-.2 mA in flight mode. Or, if you just use the Pi for sensor readings, get a proper microcontroller, where current is measured in mic…

For someone like me who has only just started playing with microcontrollers thanks to the Arduino and RasPi and has never touched/played with anything else.. could you give any suggestions/links on what I should consider using for sensors? I have a bunch of "nodes" I need to make, each one has a single sensor (temperature, moisture, light, or distance using a sonic sensor) that will send back to a Raspberry Pi base s…

If you need something that has clock speed in the hundreds of MHz and RAM in the hundreds of MBs then the Arietta G25 is maybe a good option - http://www.acmesystems.it/arietta.

Until this current wave of boards (CHIP, RPi zero) it was pretty much on its own in the land of dev boards - substantially beefier than Arduino, ESP8266 and Teensy 3.2 but way leaner than the RPi and BBB et al.

I still think it's a nice piece of kit even in the context of these new ARM boards.

Update: found some numbers on current draw - looks like out of the box it sits around 40mA idle, so slightly more than they tweaked the RPi Zero down to. http://www.robertoasquini.com/?p=148

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#48

Post by jacquesm »

alkonaut wrote: post #41

What is the practical difference between 500mA and 30mA? Both are way too high for battery power, and both are low power in terms of cooling and electricity cost? A sensor node with a 5Ah battery would have a budget of .5mAh to have the battery last s year. That is still two orders of magnitude under the Pi. Power is interesting for cooling and economics until you get below a few watts, at which point the power costs…

30 mA periodically gets within the range that you could do some interesting things with systems that only power up periodically and are recharged by solar.

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#49

Post by yasth »

cstross wrote: post #44

Please can somebody build a case for the Pi Zero in the form factor of the Psion 5? https://en.wikipedia.org/wiki/Psion_Series_5 (The patents on the folding keyboard will probably have expired by now -- the design dates to 1994-95 -- and with a 30mA draw the Pi 0 is within spitting distance of the sort of power the Psion 5's twin AA cells delivered. Add an e-ink display and a wee USB bluetooth peripheral for i/o (wif…

Were you to want to, you'd have much much more space and could just convert a lot of the body to li-ion which is probably a better use than really trying to get it last that long on AAs. (Also there are probably better processors, unless you really need the graphics performance (though not all the time of course), it really is true that the RPi is a GPU with a CPU accessory, shame it is so hard to do compute with the GPU)

Anyways for your needs I'd look at the CHIP, which is much like the rPi 0 except it has WIFI and BT connectivity, plus built in power control and charging circuitry (and costs $9 (or $8 if you are fast)) [1]

A hackish job is probably possible, the hard part would be sourcing the display.

[1] http://makezine.com/2015/11/28/chip-vs-pi-zero/

Re: Raspberry Pi Zero – Conserve power and reduce draw to 30mA

#50

Post by StavrosK »

lemevi wrote: post #9
perlin wrote: post #8

We've actually found that the RPi doesn't draw enough power, specifically to the USB ports. Our peripherals are within the USB spec of a 500ma max pull, but even so we are experiencing sporadic CPU brownouts. The first thought was to double the max_usb_current in /boot/config.txt, but that only lengthened the time between brownouts. We looked into hacks that could increase the current even more, such as this bypass m…

Have you tried a BeagleBone Black or any kind of BeagleBoard? What are you scaling RPi's for? Arduino and Raspberry pis strike me as toys compared to BBB's. BBBs are a lot less forgiving and require way more understanding of basic electronics to do anything with, even as simple as lighting an external LED will break your BBB if you didn't do it right, but they seem more powerful in terms of what you can do (although…

Wait, how can you break the BBB with a LED? I'm going to use one for a LEGO robot, and I'd like to not fry it :P
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