Re: Power

There isn't enough room in the chumby for one of those.

Re: Power

Ok - I admit to being a bit of a nag about safety.
But elegant fail safe design is sadly still a mindset more than any ruleset.
I DO respect that some of us here are quite qualified to evaluate risks.
Then again- the lord protects fools and children using more capable fools as his instrumentality. So ask yourself several times - is a proposed hack SAFE?
That includes thinking thru stupid human tricks. EG " 9vdc wall wart having SAME plug as a 12vdc wall wart. So your "9v rechargable" which is actually a SEVEN volt
battery finds itself soaking up an actual seven volt overvoltage as that 12v wall wart lightly loaded is around that zone . And it's inside a fabric covered device on your bedside table. Which at 0darkthirty reaches ignition and Darwin may wake up to smile at your NOT waking up. Sorta  "you bet your life" but it's not only yours.

As I said above.

"Power storages are only as safe as their energy density to stability ratios allow"

That said from grim history lessons describing havoc unleashed by ignoring that rule. Google for " LIPO cell fire" *READ* the stories! Then notice the breakpoints in usage.

MY reading breaks it down as "Hobby/Hacker" " Appliance Operator" and "Industrial/other"groupings.  The "Appliance Operator" group includes laptop, phone and similar mass produced applications. Now the laptop group alone has become a sleep losing nightmare.
Why did I phrase that last one that way? Ok folks- let;s review a basic detail here.

Chumby is primarily directed as a BEDSIDE device.

Therefore any safety risks such as dodgy hacked power sources are doubleplus unsane and likely to be a Very Bad Idea. So just plain don't do anything you'd not feel safe sleeping next yourself, Because someone else may be sleeping next to YOUR proposed design. There's a good reason why UL and CSA have the rules they do. Past literally fatal errors. We need to be our own watchdogs. Absent sending our hacks for testing, we need to be very aware of what we are playing with. OR-True story time, my timer actuated coffeepot that the cat knocked over into a pile of laundry- Seems the devil did not want my company yet as all that was lost were some towels scorched  before the thermal fuse in the pot opened.
The "timer" was a lamp timer into which an old percolator was plugged in along with my stereo- and this was back in 1976!

Which adds something to my self quoted line re: Safe power.

"Design everything as if screwing up could kill - or you will risk doing both at once"

53 (edited by chumbawomba 2007-03-02 16:21:44)

Re: Power

orenbeck wrote:

Ok - I admit to being a bit of a nag about safety.

But elegant fail safe design is sadly still a mindset more than any ruleset.

"the lord protects fools and children using more capable fools as his instrumentality. "

"Design everything as if screwing up could kill - or you will risk doing both at once"

Oren... I love u, man.

I been there in the post-lipo-pop-burn-smoke-and-panicked-scamper.

not a bit of fun, really.

Re: Power

Aww, thanks.

I read  your other post in the Cuumbyware thread.
Yep, the LiPo cells are not quite tamed yet.
The LiS chemistry is very viable for many portable uses,
but makes me nervous for bedrooms.

Re: Power

A safer alternative (I think, I don't know too much about this) would be to just rig up either 8 AAA-D batteries (speaking generally about alkaline batteries, that's about 13600 mAh if each battery puts out 1700 mAh, which translates into about 68 hours[ish] time, not counting lost energy, etc) in series, and use those. It would be heavy and inconvenient, but by god, the thing would be able to be pulled out of the wall for a good period of time. Alkaline is a lot safer than Li-on and LiPo, and AA batteries are cheap to replace. However, you would need to make sure that the output to the chumby would remain constant.

Re: Power

speaking generally about alkaline batteries, that's about 13600 mAh if each battery puts out 1700 mAh, which translates into about 68 hours[ish] time, not counting lost energy, etc

You're making the same mistake I made when I first thought about the problem, the voltage/current relationship of batteries. 8 Alkalines in series will give you 1.5V x 8 = 12V, but at the same current each battery is rated (which for alkaline translates to 2Ah+/-). The other option is to pull 6V from the batteries at .5C which gives you 4A (or 3V for 8Ah, and so forth in either direction, minus voltage regulation, etc).

The benefit of Lithium Ion in this case is two fold: one, you're getting 3.7V native, which means two of them in series gets you to 7.4V, which is enough to drive Chumby (I've actually managed to go as low as about 6V and the Chumby will still turn on and boot up). Two, it's a lot more dense energy-wise than the alkalines: two AA-sized lithium ion batteries will hold nearly as much energy as 6 of the alkalines.

The biggest problem with Lithium Ion is safety: the batteries need overvolt protection, undervolt protection, they need to be limited to certain current drain rates, their temperature needs to be monitored, they need to be babied or they'll balloon up to twice their size or turn into firecrackers. (The former I have experienced, the latter I hope to never).

Re: Power

I think people at Chumby Inc. are going to be shocked when they discover that the average Joe will NOT be paying $180 for an electronic clock, just sitting by their bedside. I certainly won't. Adding a battery is worth the extra $20 to the price of the Chumby. It's sad because I saw lots of people sitting at cafes, watching their Chumbys, only to be crushed by the fact the stupid thing has to remain plugged into the wall outlet. You NEED this thing to be portable, otherwise it's just a slower and stupider computer: I sit at my computer for HOURS, gathering information. I need something like Chumby to go with me and GIVE me information on the run. There are lots of electronic gadgets that do stuff like this, but none that packs it all in one box like Chumby. Please please please someone invent a battery and sell it on Ebay to the rest of us Joes......Damon

Re: Power

But you'd still need wifi. So where are you going to take it where have Wifi but you can't plug it in?
I can really only see this as a home/work device. (I like the idea of leaving the chumby on your desk. For news, of course ;-) )

Re: Power

Well, I mostly have the battery thing worked out, at least for the daughtercard I use from time to time, but you end up giving up a lot just to use it (like there's practically no way for me to solder the shipping accelerometer onto my board due to the BGA packaging, and it doesn't have connections for anything but power, the second USB port and the headphone port). There's also the problem of monitoring battery life; I've got a crude kernel driver for the monitor module I'm using, but I don't have access to Flash enough to create a widget, and even if I did, I have no idea how to communicate over SPI using Flash or if it's even possible/will be possible.

It's not actually that hard when it comes down to it, but making one that feels finished enough to sell to people and convince them to tear apart their chumby to replace the daughtercard is going to be a hard sell. You can make your own battery packs from kits like those found on SparkFun, or you can forge your own way like I did and throw something together yourself. I ended up using chips sampled from TI, the UCC3911 due to the much smaller number of external components needed and the BQ5017T as the charger because it charges two cells and has a small pin-out comparatively (and the fact that both chips are still incredibly cheap at about a dollar a piece). The circuit is made pretty straight forwardly based on the datasheets for the recommended implementation. An ideal solution would be to add a small microcontroller to the circuit for monitoring the power level instead of using the bend sensor's input as the charger also has a pin that indicates when a charger is plugged in, and the protection IC has a low power warning indicator (as well as an overvolt and undervolt indicator). Right now I have both wired to LEDs, but it'd be just as easy to read the pins with a controller. There are some other unwanted things too like picking the sense resistor and charge MOSFET is a pain, ideally they'd be built in or something, and the charge time is very long due to wanting to try my best to stick with the shipped power supply brick and not picking one with a higher current capacity. The biggest upside is the battery life is amazing, something like 7 hours with two 2.4Ahr cells. I should probably clock it at some point. And it actually works unlike the former circuit I came up with; it has a very nasty oversight in its design that only lets it work with one battery at a time and not two.

The beauty of the device is that it is very hackable, but the nightmare of it is that almost the instant you start hacking, you go outside of the realm of what the current software is capable of, and you have to start building new solutions. I've contemplated getting OpenMoko or Poky up and running on the Chumby, but the fear with both of those is bricking the platform (and the fact that almost nobody still uses Linux 2.4.x for much anymore). I'm still catting around with the idea of trying to get some subset of them working, but it's on the back burner as we're basically all sitting around in wait. What I've ended up doing is basically hacking the RSS widget to display information from the local webserver, and modifying the page it displays with another program which is reading from my driver, but right now it's pretty ugly and unusable for much more than reading the state of the battery charge and displaying it with all of the other widgets in the loop.

I think for now it's best to wait on some more finalized data of what the Chumby will ship like and what it's final hardware and software situation is going to be before we continue moving forward. I know that's hard to hear for a lot of us alpha owners, but if they've got the beta shipping now, it won't be long before we can buy one and get to hacking for real and making something others can really use.

Re: Power

Interesting post! I have to admit that I have felt like i am very much in a holding pattern myself. The craft hacks are also quite destructive to the chumby case and surround, and there is no guarantee that what I've done so far will fit the production models. I need measurements to be fairly precise and there is very little point spending time documenting the things I have done that will be of no use beyond alpha users, among which there seem to be very few crafty types. I want to make hacks that will be used - not a source of confusion or frustration. Also, even if I convince new owners to tear off their lovely leather cases, getting a fresh, professional looking case on a dismantled chumby is a bit trickier than it appears.

So bring on that "hacking for real"! I'm still keen to keep going...  wink

Re: Power

So far I have been able to go semi portable. I hang in internet cafe's, shoot even McDonalds has wifi. But they also have plugs. If you set your clock to get it's time from the internet then you solve that. It is a conversation piece that is for sure. I thought wearing a dress to a gas station was an attention getter. It does not compare.
I really thought it would be easier to disabled.  The only opening in the leather is to the battery compartment. I have not read all the post but that's what I am doing now. catching up on the history that I missed.

Grow Real Nerve Fully Rely On God Today!

Re: Power

I'm wondering about disassembly of the first 50 myself...are the plastic/rubber pieces all glued together?

They were held together by tension or screws in the alpha so pulling it apart and putting it back together was a breeze. However, the bezel/screen kept popping out of the rubber surround. Particularly as it lost tension over 12 months.

That and I snapped a bend sensor. Is there glue on the contacts now?

Re: Power

I still dont see why Chumby Industries doesnt build an approved battery pack. Either a 12V rechargable 'RC car' type or a case that could house a number of AA or C type batteries.

The cost to develop and sell it is tiny, the return is large enough when you can claim the chumby to be truly portable.

Re: Power

JamesA wrote:

I still dont see why Chumby Industries doesnt build an approved battery pack. Either a 12V rechargable 'RC car' type or a case that could house a number of AA or C type batteries.

The cost to develop and sell it is tiny, the return is large enough when you can claim the chumby to be truly portable.

I have a  Sony PSP with a LI-ION battery pack.  The wireless KILLS that power.  You probably wouldn't get much more than an hour with AA or C packs, if even that, with a Chumby.
Without the wireless, unless we could download the widgets to memory and run them offline, the Chumby is basically just a clock, which means you always have to be within range of a wireless net.

Now, Bluetooth uses less power than RF wireless, I think.  Correct me if I'm wrong.
If you have Bluetooth in the chumby, maybe the power of AA or Cs could last longer, but then you'd need a Bluetooth USB transmitter/receiver on your PC, which kills the portability anyway!
Portability within a house isn't that important to me.  I have plenty of outlets.
What I want is to be able to transfer the chumby from one outlet to the other without having to power off the unit, I think a 9V would suffice for that.

"We will find a way, or we will make one."

Re: Power

I'm pretty sure this wasn't addressed.
The reason you can't make a second, more expensive, better battery'd version is...?

Re: Power

Zootch wrote:

I'm pretty sure this wasn't addressed.
The reason you can't make a second, more expensive, better battery'd version is...?

Well, we're pretty busy getting the first version out onto the market at the moment.

Re: Power

then my fear is they produce more and more, newer, better, more expensive versions linearly forever much like Apple's iPod

Re: Power

Zootch wrote:

then my fear is they produce more and more, newer, better, more expensive versions linearly forever much like Apple's iPod

We'll certainly need the freedom to evolve the product as the market changes, however, for a small company, we'd lose the economies of scale if we had too many versions out there to support.

I'm not sure what you mean about Apple - the iPod line has always been within certain price ranges for each model type.  They tend to introduce newer models at the high end of the price range, and push the pricing of older models down, but the price range itself is remarkably consistent.

For instance, the first iPod that shipped in 2001 was 5GB and priced at $399.

The current 6th-gen Classic, the direct descendent of that model, has 160GB and video, and is priced at $349.

69 (edited by martinbogo 2007-10-06 00:34:59)

Re: Power

Okay, I just recieved and unboxed my Chumby today ... and I already have taken it apart to get a good look at the hardware.    Other than the screen, is there -anything- on the board that needs to be at more than logic-level 5V, really?    With all the room on the bottom of the chumby, I could easily assemble a 7.4V/2200mAh lithium-polymer cell w/ an AVR controlled charging circuit.   If a 9V ~500mAh battery can last 30 minutes consuming 4.5 watts of power .. that means that modest and light cell would run the Chumby for at least an hour and a half.   

I'm not saying the chumby is a PDA or anything, but even on day one .. it's nice to be able to take it with me on the couch and play with the features.  The Chumby's design begs to be played with, shaken, and touched.  It's certainly nicely padded on the inside with the beanbag beans. 

What are the actual voltage and power requirements, and what on the board that requires that 12V input?

Re: Power

Sorry to dig up an old topic, but I have to add my $0.02 on this topic...

I'm going to battery power my Chumby(s) using A123 batteries (Lithium Iron nanophosphate), which have virtually zero chance of exploding and don't share any of the bad points that most Lithium Ion and Lithium Polymer batteries share.  These batteries are being used in the next generation hybrid and electric vehicles, even in public busses and aircraft.  The batteries have been out in stores since 2006, although only in one product that I know of (DeWalt's contractor-grade 36V cordless power packs [DC9360]).  Charge time is 15 minutes, and discharge is at least 25C continuous.  Cycle life is VERY high.  IMO these batteries have a pretty good track record of being safe.  They were developed at MIT which should attest for something wink  China has started manufacturing these batteries now so prices are on the way down.  They should eventually be cheap enough even for a Chumby.  In the mean-time I think a charge circuit and a few cells could be turned into a 'standard hack' for most casual Chumby users.

Official site: http://www.a123systems.com/
Wikipedia link: http://en.wikipedia.org/wiki/A123
dissecting DeWalt packs: http://www.slkelectronics.com/DeWalt/packs.htm

Re: Power

Nothing on the board requires 12V. 12V simply allows us to use diodes to switch between the 9V supply and the 12V supply.
12 is just higher than 9, and it's a standard, cheaply available power adapter.

9V is the cheapest, most commonly available single-battery solution that's higher than 5V.

The logic is all around cost. Yes, you can do fancier things with more batteries, but it drives up cost. We spend hours optimizing out pennies so we can have a sustainable business selling consumer electronics hardware for $179 as a small company with shallow pockets, and we are working every day on working to reduce the cost of the core device even more so that you can buy more chumbys for less.

That being said, for those who believe portability is a must-have, we're waiting for someone to make the battery pack that just latches onto the rear of the chumby. It's a business opportunity for someone else bold enough to venture into that space.

Once concept for this is to build a piggy-back battery pack that uses the USB ports on the back as a mechanical mount--you can pass through the connectors to the other side if you want to still use them--and also has a plug that goes into the 2.5mm barrel plug on the back; facing outwards is again another 2.5mm barrel jack, so you can use your existing wall transformer with this pack when plugged in. Within the pack is the charging and monitoring circuits; you can check the voltage either by LEDs on the pack or if you got fancy, feed it through via the USB over a USB-serial converter and a built-in hub.

With this solution, you have a little pack that just snaps onto the back of the chumby, passes through the power and USB signals, and contains your battery power and status monitoring. Lots of people on the forum are saying you can do it for $20--and I think they are probably right, given some...assumptions...so go and do it!

7BAA 2E53 01C1 DCFF 497B  E7F0 9699 A303 78F0 D9B9

Re: Power

bunnie wrote:

With this solution, you have a little pack that just snaps onto the back of the chumby, passes through the power and USB signals, and contains your battery power and status monitoring. Lots of people on the forum are saying you can do it for $20--and I think they are probably right, given some...assumptions...so go and do it!

Now that would be cool!

Looking forward to the arrival of the Chumby I ordered for my brother's birthday (and the second one I ordered for myself!)  wink

Re: Power

bunnie wrote:

With this solution, you have a little pack that just snaps onto the back of the chumby, passes through the power and USB signals, and contains your battery power and status monitoring. Lots of people on the forum are saying you can do it for $20--and I think they are probably right, given some...assumptions...so go and do it!

So who made this power pack?? Its been a few months now.

Re: Power

Yes, I too am interested!

Re: Power

Is the Chumby Energy Star compliant?

BZ