reading about the lifespan of Lithium Ion batteries has brought me to the conclusion that a new battery pack for the 6k should be designed.

Here are my ideas, though obviously I'm interested in more ideas, and getting this actually done.
Specs:
It must clip into the existing battery compartment

It should protrude as little as possible, and be to some extent rounded and "snag free"

It must use readily available off the shelf batteries of non-proprietary design. (like AAA)

It should be readily fabricatable... that is to say that someone of little artistic skill (say...me, for example) could take the design into some easy-to-find shop--like an autoglass/plexi place, or tank/welding/sheetmetal or electronics shop and get the basic components fabricated and possibly assembled with a minimum of trauma and expense.

My beginnings of an idea is to make an open faced metal box that has studs to match the bottom of the bl09, and either holes for the battery locks or tabs that run to the sled mount screw holes.
The box would take 4? 5? 6? aaa and the requisite terminals and voltage regulation. The open side would be mounted inward inside the battery well.

I think it would stick out the back about as about much as the thickness of another battery...if the angles of the box were oblique this would be useable.

My reason for using meatal is simply that sheetmetal is easy to cut and bend..and can readily be given a black matte finish to match the z.

even without the issue of li-Ion life expectancy, being able to snap in off-the-shelf batteries, without resorting to cabling, is appealing.

ideas? suggestions?

Sounds overly complicated. My vote is pick up a AAA usb charger and USB charge cable for the Z or a Pelican PSP Power Brick(which is thinner than a AAA, IIRC, if you sand off the letters) and use double sided sticky foam to adhere it to the back of the battery cover.

Now, if you're going for compilicated, for the sake of hacking, I'd recommend cramming a Pulse Wave Modulator(with supporting circuitry) and 4 AAA Lithium batteries in an Altoids tin for maximum battery life and geekiness.

I already have a pelican brick.

I'm trying to avoid wires running around, and as much external mess as possible.
I know someone who build a 9 volt battery based altoids charger. It is what I'll do if this idea doesn't pan out.

There is room (if the box can be made) for 6 AAA batts and accomanying mounts and circuitry (gotta double check th circuitry, though) in the well with less (but not a whole lot less) protrusion than the pelican struck on the back would create.

I'm going complicated one one end for simplicity on the other--a nice simple snap-in battery box that connects to the Z internally. BTW.... what is needed to make the Z think there is Batttery there? Just current? contacts?
There are three contacts..a clearly labeled + and - on the outsides of the trio and ..what? in the middle? ground?

To cut down on the big long cable and use the Pelican battery, I just made my own 5 inch cable. See here: home made 5 inch cable

But I am interested in this project, because I have a feeling that when the Sharp li-ion battery has been completely depleted maybe the Zaurus cannot be used even with an A/C adapter or external battery pack. Does anyone know if this is so?

I do know that without any battery in the bay, the A/C adapter will not power the Z. I just am not sure about a completely dead battery being in the bay.

I have taken some power readings from the li-ion battery. As you look at the battery that has been removed from the Z, the contact on the left is a positive, and the one on the right is negative. The reading (from my cheapo meter) is 4.2 volts across those 2 contacts. The middle contact is also a negative, and the reading from it to the positive contact on the left is 2.8 volts.

If you remove the battery, and plug in the Sharp A/C adapter, the readings from inside the Z, are 4.8 and 2.8 volts respectively.

If you put the right sized nail into the end of the A/C adapter's connector, and measure the voltage there, you get 5.4 volts. (The Pelican PSP battery is also 5.4 volts.)

I am wondering if the center contact is for charging the internal battery, and maybe for causing the battery charge indicator light to light? I need to purchase some brass or copper foil that I can cut into strips to see what kind of readings we get across those same contacts when the Z is plugged into the A/C adapter with the battery installed.

Also, AA NiMH batteries can be bought which are 2500 mAh, whereas AAA batteries I have seen so far are only 850 mAh. So even though AAA batteries would make a slimmer battery pack, the AA batteries would last almost 3 times longer. (Electronics experts feel free to correct me if I am wrong about this.)

Using a 4 battery pack with AA NiMH batteries in it gives a reading of 4 volts. (Probably need to charge those up a bit, as this should be 4.8 volts.) Putting the meter on only 3 batteries gives me the 2.8 volts that the center contacts seem to require. I need to work on this some more, but I believe we could make a NiMH battery pack to fit in the Z. Whether or not it could be charged within the Z using the A/C adapter, I'm not so sure about. Maybe? Need to investigate further.

Excellent! much useful info. do we want to look at a 3 AA pack then, or something more with a voltage regulator ( by nore; think 4 or possibly 5 will be the max).
I'll start looking for a shop to do the sheetmetal after thanks giving....and one we decide on a "standard"

I was thinking to use 6 AAA rechargeables..... but it sounds like 3 AA might be the simplest.. especially if they might get a charge off the Z.

pwm, can you say NOISE, and lots of it.

Not always. Most PDAs use a PWM to control the backlight brightness, and not many people complian about that noise. I'm not sure the factors that cause noise in the range most people find noticable, but I'm guessing a little research should turn that up.

Why not buy a new 3.7V Li-poly cell in about the same dimensions and replace the dead cell? If someone has opened the pack, you could search for the cell's part number and, if it's still manufactured, buy an exact replacement. If not, there are other cells we could use instead, but they might be less than 1500mAh.

This is very irresponsible and dangerous advice. Lithium batteries are toxic and explosive.

Nobody should try this without a thorough understanding of what you are doing, and the risks involved. Start here:

http://www.electronics-lab.com/articles/Li...ruct/index.html

and... I was thinking in terms of airports and train stations and gas stations as sources of readily available batteries (though using the z's charging circuit would improve things in that regard) not surgery beyond building the initial gadget

Been there; done that for many of my devices. Currently fixing my laptop 2nd dead battery with cells twice as big purchased on ebay. The 1st battery works 3 times longer thanks to these cells. Moreover once you've opened the box replacing afterwards them is a 5 minutes soldering operation.

Ofcourse, you could blow your head off doing that. Technical expertise is needed :-)