OIP
Posts: 7
Joined: Tue Aug 23, 2011 11:43 pm
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 1:42 am

I read that the total power consumption of the R-Pi would be 1watt at full load. I am assuming that this is not including external devices. At 1 Watt I think that 3 x 1.5v AA batteries would last for about 15 - 18 hours? However this would supply 4.5 volts... Could R-Pi work with this PD or would it have to be... say 5v?

Something that I am looking at is a portable unit with a rugged case, solar panel for charging and a LCD screen possibly with "touch-screen". This will ramp up the power requirements somewhat and even more so if there could be a GPRS/3G modem also added to this. Another idea would be to add AX.25 data link layer protocol support.

Perhaps a 12v battery might be best and this could be put through a regulator to supply the 5v to the board and still have 12v in case it is required.

A few uses that we would like to support/develop are:

Speech to sign language translator.
Remote location emergency broadcast receiver.
Educational resources/network for remote areas.
Medical/emergency first aid communication.
Inter-village communication network.

I do think that power consumption and cost of screens are the most important points to consider for what we would like to achieve with R-Pi at the moment so it would be very interesting to get our hands on them when they become available to begin prototyping etc...

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 2:16 am

Actually, you won't need to do any sort of power regulating. At the present, they are planning to use a power supply that can naturally accept any 6-20V power supply. We've discussed using a battery in a couple other threads, and it should be theoretically possible. The only hold up will be charging the battery. It would certainly be possible to unplug it and charge it every time the battery was low. But I don't think that is really want any of us are looking for with a battery. This kind of set up would have a battery that would be attached as a backup when it wasn't receiving power. This kind of circuitry can be kind of pricey (though if you know how to build/buy it cheaply that would be pretty awesome)
Dear forum: Play nice ;-)

obarthelemy
Posts: 1407
Joined: Tue Aug 09, 2011 10:53 pm

Re: Power consumption?

Wed Aug 24, 2011 2:48 am

My engineer cousin tells me I can have batteries act as UPSes, only taking over when mains power goes out, with a couple of diodes. They'd not be recharged from the mains though, so you'll need to check and swap them every once in a while, both due to aging and getting used up every time mains power goes out.

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 2:59 am

Ah, well that's a good, affordable, practical solution. Not quite as much as I'd like, but it's a good first step (especially since the things I've seen that do the full deal are in the 50 dollar range
Dear forum: Play nice ;-)

miauto
Posts: 11
Joined: Mon Aug 22, 2011 1:01 pm

Re: Power consumption?

Wed Aug 24, 2011 6:43 am

Quote from obarthelemy on August 24, 2011, 03:48
My engineer cousin tells me I can have batteries act as UPSes, only taking over when mains power goes out, with a couple of diodes. They'd not be recharged from the mains though, so you'll need to check and swap them every once in a while, both due to aging and getting used up every time mains power goes out.

so you are suggesting we could attach 3xAA batteries for autonomy power consumption, and if you connect a power supply via usb, this batteries could be charged again, right?

using a connector like the attached one?

ShiftPlusOne
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 6228
Joined: Fri Jul 29, 2011 5:36 pm
Location: The unfashionable end of the western spiral arm of the Galaxy

Re: Power consumption?

Wed Aug 24, 2011 7:46 am

It's likely that you won't be able to connect a power supply via USB and if you could that wouldn't charge the batteries. Charging circuits aren't that easy. I've never done them, but I am sure that once I get an R-Pi I'll give it a go.

obarthelemy
Posts: 1407
Joined: Tue Aug 09, 2011 10:53 pm

Re: Power consumption?

Wed Aug 24, 2011 8:42 am

I've asked him for schematics. But in any case, NO, the batteries will never recharge again, they'll take over when mains gets cut, but need *changing* once they get low. It's really only for backup if you need 24x7 operation but do have access to mains.

User avatar
Lob0426
Posts: 2198
Joined: Fri Aug 05, 2011 4:30 pm
Location: Susanville CA.
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 12:21 pm

The voltage range so far is 6 to 20 volts. You would need at least four alkaline batteries. That 9volt harness would work just fine. Makes sure you use a diode to prevent recharging of alkaline type batteries. Rechargeable batteries lose a certain percentage of charge per day, depending on type. Make sure you set a schedule to recharge them regulary so they are not dead when they are needed most.
512MB version 2.0 as WordPress Server
Motorola Lapdock with Pi2B
Modded Rev 1.0 with pin headers at USB

http://rich1.dyndns.tv/
(RS)Allied ships old stock to reward its Customers for long wait!

OIP
Posts: 7
Joined: Tue Aug 23, 2011 11:43 pm
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 12:29 pm

Yeah, I remember once upon a time when it was common practice just to pass voltage through the rechargeable battery and hope the user remembers to disconnect it to prevent over-charging LOL.

These days you really need more complex circuitry. A simpler solution would be to have a separate battery charger (even solar powered) and use that instead. The fact that these are produced in such vast quantities should make it a cheap solution which could be shared in a community. It also makes the R-Pi devices simpler.

Although we will not be making the units themselves, we are very keen to draw up designs and encourage other organizations to produce kits or complete units. We are looking mostly at isolated communities around the globe and getting someone to supply everything needed in kit form then supplying these to a local group that can put them together and distribute them to villages and such-like would be beneficial for a number of reasons.

What we will provide is a central repository for translations, verbal and non-verbal method of communication and emergency information. This is just scraping the tip of the iceberg of what we will be providing but from the moment I heard about Raspberry Pi, I thought that this would be perfect. I had been researching into other single-board PCs and on the whole, they seemed to be too costly for the communities that would benefit most from them. There are still concerns regarding the price of screens though as not every local village has access to power or a TV.

There are already many large organizations working in these areas so for the most part it will require showing them that it would be a good idea to get involved with supply/distribution/etc. I don't know if the Raspberry Pi has had any contact or thoughts to initiate such contacts with other organizations with this in mind?

jacklang
Posts: 166
Joined: Thu Aug 04, 2011 10:59 am

Re: Power consumption?

Wed Aug 24, 2011 12:52 pm

Quote from OIP on August 24, 2011, 13:29
There are still concerns regarding the price of screens though as not every local village has access to power or a TV.

There are already many large organizations working in these areas so for the most part it will require showing them that it would be a good idea to get involved with supply/distribution/etc. I don't know if the Raspberry Pi has had any contact or thoughts to initiate such contacts with other organizations with this in mind?

We've been talking a bit to http://www.humanitariancentre.org/ who have an ICT4D program, but would welcome approaches from other organisations. However I'm wary of falling into some of the problems that the OLPC program found, especially that of believing we know what is good for other people. For example it won't help people to have a mainly text based system if they can't read or write, where a cheap smartphone might be a better solution. There may also be other cultural issues.

The initial use I envisaged was more in urban periphery slums and shanty towns, where power and screens are more likely available, rather than rural isolated villages.

OIP
Posts: 7
Joined: Tue Aug 23, 2011 11:43 pm
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 1:31 pm

Quote from jacklang on August 24, 2011, 13:52
We've been talking a bit to http://www.humanitariancentre.org/ who have an ICT4D program, but would welcome approaches from other organisations. However I'm wary of falling into some of the problems that the OLPC program found, especially that of believing we know what is good for other people. For example it won't help people to have a mainly text based system if they can't read or write, where a cheap smartphone might be a better solution. There may also be other cultural issues.

The initial use I envisaged was more in urban periphery slums and shanty towns, where power and screens are more likely available, rather than rural isolated villages.


Yeah, the problem you mention can be a big problem when things are pushed onto people in the manner that has happened far too many times before.

What we are going to provide will be accessible via PC, smartphone and other methods. We would like to see an alternative device produced that can be used for a wide range of purposes which also just so happens to be able to utilise our servers and services. If it is cheap enough and low maintenance then it would be a good candidate for distribution to areas which may not otherwise be able to have access to such things.

On other note:
We are also planning to publish some videos and other learning materials for electronics, computing, etc, etc... Having a modular system which allows people to slot a into b and get their own computer running might encourage them to look more into this technology. This is more-so if they a successful in their first endeavors which can't always be said for desktop boxes.

Our purpose as a whole is not specifically engineered towards "third-world" countries and such-like but because of many reasons, we need to take into consideration the local situation/issues before expending a great deal of time and effort in developing something. It's simple market research at its fundamental level and important to carry out whether it's a product/service you plan to bring to London, New York, Tagum City, the Federal Democratic Republic of Ethiopia or anywhere else.

My own personal thoughts on this is:
There are many people who, given a task to research a potential market, would organise surveys, do other clever market research methods like blind testing and consumer focus groups etc etc etc... But the same company/individual who is tasked to do the same thing: just the area of interest is at a different location in the world... They don't do the market research, instead they decide what's in "these people's best interest".

They go to more lengths to find out what the people in their own neighborhood think and want than what they do for cultures they've never had first hand knowledge of.

But this is going way off-topic now...

What we want to do is provide services and other things that the widest range of people can make use of and contribute to if they wish. But I do agree completely with your post.

jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 26459
Joined: Sat Jul 30, 2011 7:41 pm

Re: Power consumption?

Wed Aug 24, 2011 8:00 pm

With regard to batteries, we use battery packs from R/C cars (I think) to power development kits using very similar processors to the Raspi (basically bare GPU's). They are also capable of running LCD panels and cameras that are on the boards. However, I am not sure how long the charge lasts! They are 2300mAH NiCd's I think, and are bigger than the board! I'll try on on the Raspi tomorrow if I remember and take a photo.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed.
I've been saying "Mucho" to my Spanish friend a lot more lately. It means a lot to him.

miauto
Posts: 11
Joined: Mon Aug 22, 2011 1:01 pm

Re: Power consumption?

Wed Aug 24, 2011 8:59 pm

Quote from jamesh on August 24, 2011, 21:00
With regard to batteries, we use battery packs from R/C cars (I think) to power development kits using very similar processors to the Raspi (basically bare GPU's). They are also capable of running LCD panels and cameras that are on the boards. However, I am not sure how long the charge lasts! They are 2300mAH NiCd's I think, and are bigger than the board! I'll try on on the Raspi tomorrow if I remember and take a photo.

would be awesome to have some news from real experiences! there will be lots of people that will try to create prototypes for applications that need self autonomous battery systems. I thought it was going to be easier. How then are engineers designing for telephones and smartphones? what kind of circuits are they using to recharge the battery through the usb connector? would be costly if you implement this circuits into your board?

Svartalf
Posts: 596
Joined: Fri Jul 29, 2011 6:50 pm

Re: Power consumption?

Wed Aug 24, 2011 9:10 pm

Quote from miauto on August 24, 2011, 21:59
would be awesome to have some news from real experiences! there will be lots of people that will try to create prototypes for applications that need self autonomous battery systems. I thought it was going to be easier. How then are engineers designing for telephones and smartphones? what kind of circuits are they using to recharge the battery through the usb connector? would be costly if you implement this circuits into your board?

They're adding power management chips like you'd find on the laptops that're designed for the purpose on mobile phones and tablets. It'd raise the price a bit to add one- not a good idea for the first generation of devices unless you're coming up with a daughterboard so that someone can just cobble up the mobile device accordingly. Not half bad an idea as a collaboration project once the first type A and type B boards show up.

Svartalf
Posts: 596
Joined: Fri Jul 29, 2011 6:50 pm

Re: Power consumption?

Wed Aug 24, 2011 9:15 pm

Quote from jamesh on August 24, 2011, 21:00
With regard to batteries, we use battery packs from R/C cars (I think) to power development kits using very similar processors to the Raspi (basically bare GPU's).

The OMAP3 based devices will run a little over 10 hours with the CPU running full tilt, driving a WVGA LCD, etc. with a 13.5 watt-hour battery. I know this because that was what the engineering prototypes for the Open Pandora handheld were doing. Firing up the GPU cost you about 3-4 hours from that figure. I'm suspecting that you're running slightly longer runtimes since the SoC consumes about 1/2 to 1/3rd the watt hours.

Of course a Li-Po battery's going to be roughly the same size as the R-Pi. :D

OIP
Posts: 7
Joined: Tue Aug 23, 2011 11:43 pm
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 9:43 pm

I just had a thought... What about power over ethernet?

Not totally related to the topic but it might be an interesting addition.

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: Power consumption?

Wed Aug 24, 2011 10:00 pm

P.O.E. has been discussed a couple times (I for one like the idea myself ;) ), but there are a couple issues. For one (and really the big issue here) I'm not certain that the LAN9512 chip that is giving us the ethernet (and USB) ports on the model B is capable of supporting POE. Yes, it would be possible to use a different chip, but that would drive the cost up, increase the size of the PCB, etc, etc. Assuming that the LAN9512 can support POE, there comes the question, "would it be worth designing the circuitry to allow POE?" Keeping in mind that this is the r-pi team is a charity, their target audience isn't likely to have POE support.

Still... now that I think about it, you can provide POE support for the r-pi yourself. I'll make a new thread in which we can discuss it. It's a great idea ;)
Dear forum: Play nice ;-)

Svartalf
Posts: 596
Joined: Fri Jul 29, 2011 6:50 pm

Re: Power consumption?

Wed Aug 24, 2011 10:58 pm

Quote from OIP on August 24, 2011, 22:43
I just had a thought... What about power over ethernet?

Not totally related to the topic but it might be an interesting addition.

It is an interesting addition. Off the shelf, you can add POE to your R-Pi with an injector/splitter pair bought for about $30 retail per R-Pi depending on how hard you look for the kits.

Now, having said this...it's not going to be TOO hard to hack up something a bunch cheaper as an educational project. :D

http://www.google.com/url?sa=t.....38;cad=rja
http://www.eidusa.com/Electron.....jector.htm
http://www.design-reuse.com/ar.....2-3af.html

Heh... You can be simplistic and simply opt for Mode B support without POE detection and simply cobble cables or adapter jacks up to power things. Doing things truly automagically along with the phantom power Mode A support (More juice on the far end if the device actually supports the mode...) runs the price up and requires a special PHY that supports the jiggery-pokery for it.

User avatar
Lob0426
Posts: 2198
Joined: Fri Aug 05, 2011 4:30 pm
Location: Susanville CA.
Contact: Website

Re: Power consumption?

Thu Aug 25, 2011 12:36 am

From what I can find the LAN9512/LAN9512i chipset may support PoE.
http://www.smsc.com/media/Down...../an813.pdf
The data sheet does not cover PoE.
Anyone have other information.
512MB version 2.0 as WordPress Server
Motorola Lapdock with Pi2B
Modded Rev 1.0 with pin headers at USB

http://rich1.dyndns.tv/
(RS)Allied ships old stock to reward its Customers for long wait!

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: Power consumption?

Thu Aug 25, 2011 2:40 am

I've read over the datasheets and I'm fairly confident that the LAN9512 does *not* support PoE. If it did support it, you can bet they'd make some fairly clear mention about it. Also, remember that the ethernet port is actually connected via the USB port. I've never really seen a USB ethernet adapter that can support PoE.

But I started this thread in which we can discuss making PoE a reality... er, kinda.
Dear forum: Play nice ;-)

whoover
Posts: 4
Joined: Thu Aug 25, 2011 10:36 am

Re: Power consumption?

Thu Aug 25, 2011 5:22 pm

If you want a battery+solar solution @ a cheap price-piont try the Arctic C1 http://www.arctic.ac/en/p/powe.....obile.html. You can get one of these on ebay for ~$18 (incl shipping). It has an internal 4440 mWh Li-ion battery that outputs 5v-500mA via usb (includes other adaptors as well). If you chain a few of these together it should be able to power the R-Pi ;)

Svartalf
Posts: 596
Joined: Fri Jul 29, 2011 6:50 pm

Re: Power consumption?

Thu Aug 25, 2011 10:02 pm

Heh... The solar chargers for mobile phones will probably be able to power an R-Pi.

miauto
Posts: 11
Joined: Mon Aug 22, 2011 1:01 pm

Re: Power consumption?

Fri Aug 26, 2011 8:24 am

Quote from Svartalf on August 24, 2011, 22:10
Quote from miauto on August 24, 2011, 21:59
would be awesome to have some news from real experiences! there will be lots of people that will try to create prototypes for applications that need self autonomous battery systems. I thought it was going to be easier. How then are engineers designing for telephones and smartphones? what kind of circuits are they using to recharge the battery through the usb connector? would be costly if you implement this circuits into your board?

They're adding power management chips like you'd find on the laptops that're designed for the purpose on mobile phones and tablets. It'd raise the price a bit to add one- not a good idea for the first generation of devices unless you're coming up with a daughterboard so that someone can just cobble up the mobile device accordingly. Not half bad an idea as a collaboration project once the first type A and type B boards show up.

Are you sure it could increase the price that much? i am seeing even smaller comercial products, like bluetooth earphones and hundred of different portable devices, that you can charge the battery through the usb connector, and the device is tiny like a coin.

Could you give me another idea if i want rasperri pi as a portable device?

User avatar
abishur
Posts: 4477
Joined: Thu Jul 28, 2011 4:10 am
Location: USA
Contact: Website

Re: Power consumption?

Fri Aug 26, 2011 2:31 pm

You could just power it off a battery yourself. Any time the battery went dead you'd have to put it in a separate battery charger. The idea here is that it is only attached to one power option at a time, it's either battery powered or it's plugged into the wall and the battery is off to the side. It's not a great solution, but it's one that would only cost you the price of the battery instead of the kind of cash required for the circuit described above... though thinking about it "out loud" there might be a way to use a couple of relays to make a cheap (though perhaps clunky) solution for this....
Dear forum: Play nice ;-)

Svartalf
Posts: 596
Joined: Fri Jul 29, 2011 6:50 pm

Re: Power consumption?

Fri Aug 26, 2011 5:12 pm

Quote from miauto on August 26, 2011, 09:24
Are you sure it could increase the price that much? i am seeing even smaller comercial products, like bluetooth earphones and hundred of different portable devices, that you can charge the battery through the usb connector, and the device is tiny like a coin.

Could you give me another idea if i want rasperri pi as a portable device?

Differing design there and they're using a charge controller chip designed to handle that class of device- just because you see something "cheap" that does what you think it does, doesn't mean it maps to other things.

Now, if you're going to do it on the cheap and are careful, using Ni-MH batteries, all you need do is place a battery on the plus and minus leads and just hope your supply will not overcharge the battery. However, that being said, a charge failure with a Ni-Mh battery's not too spectacular, but a charge failure with a Li-Ion/Li-Poly battery tends to be rather spectacular.

Return to “General discussion”