I Broke The Charging System On My C3000

[Blake]

Hi all

Well, my Z doesn't charge it's battery anymore.   It's my fault; I was experimenting with an alternative power source for the Z (a USB hub powered by a nice bicycle generator) and failed to exercise the sort of caution that something as beautiful (and pricey) as a c3000 deserves.

I compared my experimental power source with the power adapter that came with my USB hub using a volt meter. I am certain that I got the polarity and voltage correct. The rest is speculation on my part, I am not an EE and I was experimenting way outside my expertise as a programmer and a cyclist.

I hooked up the alternator's output (the frequency of this AC varies with the speed of the bicycle wheel and goes very low, maybe 10hz) to a bridge rectifier. This rectified DCish voltage I fed into a switching DC-DC converter (DE-SW050) which outputs 5v and can take up to 30v input. That 5v is powering a USB hub. The DE-SW050 has two capacitors built in, but I guess they are too small to smooth out the ripples when the frequency is low (the datasheet claimed 2% ripple which shouldn't hurt anything). The blue LED in the USB hub flickers visibly, which should have given me pause for thought. I guess I didn't think carefully about what rippling voltage might do to something expecting smooth DC.

I observed that this setup charged my least expensive USB device (an iPod nano) successfully. Here's where I acted hastily out of excitement: I plugged in the Z and went for a ride. After that, the Z does not seem to charge batteries. The charge light comes on, but I left a dead one in there over night and the Z didn't turn on in the morning. That was stupid. Oh well, live and learn. At least the Z still works.  

Anyway, two questions:

First, I've read somewhere on this forum that there is such a thing as an external BL-08 charger but haven't been able to find one. Anyone know where I can get one in the USA?

Second, does anyone have any idea which part I might have damaged (possibly a regulator that I cooked with too much current) or where it is on the board? Or any thoughts at all from an EE? I'm pretty much stumped and I'll probably just have to settle for charging batteries externally.

I opened the Z up and looked around, particularly near the power-related stuff. I couldn't see any evidence of damage.

This forum has been very helpful. Thanks, everyone!

[Blake]

Um, I found the external battery charger. It wasn't hiding, I just had a typo in my search.

[Blake]

IT'S ALIVE!  

I was wrong! It does still charge batteries. This is really hard for me to explain because there were too many variables.

I definitely did something to my Z that it didn't really like. At one point I was watching the GPE battery monitor while connecting and disconnecting the power. When I connected it, the charge indicator would rise a bit, but it never said the AC was connected.

At one point the charge light would not come on at all. Since it did this right after my experimental ride, I took it as a grave sign that I had borked it good. However, in RETROVISION (which is a bit like retrospect but with a 1950s feel) it was probably just lack of contact with my cheap imitation battery, because after I opened the Z up and closed it again, the charge light came on (coincidence). However, the Z still wouldn't turn on, even after leaving it charging for more than an hour. I can't explain that. Even a totally dead battery gets enough charge to boot the Z after 15 seconds, no? I don't mean one straight from the factory, I mean one that you just drained with the Z.

Thoroughly downhearted, I started searching for an external battery charger. Then I went to heat up some soup. When I came back, the Z was ON and displaying the login screen. Battery charge indicator said it was charging and at 50%. I hadn't even pressed the ON switch (for at least 10 minutes). I cannot explain that, but that is what happened.

What I learned from this ordeal:

1) Undervoltage and rippling voltage do not seem to damage the Zaurus in any serious way, though it did produce some results which confuse me
2) When pretending to be an EE, it's probably a good idea to consult a real one and to be more patient than I was
3) When in doubt, go heat up some soup and come back in a bit and everything will be fine (YMMV on that)

I'm so happy! Not only is my Z undamaged, but my bike-powered USB hub works, and just needs some smoothing capacitors or something to work with the Z. Tuesday I'm leaving for a long bike tour in Europe. With some luck I will have this working properly before then. The idea is to power my Zaurus, my iPod, a bluetooth GPS, and AAA rechargeable batteries with the bike. Huzzah!

[jpmatrix]

i had some battery trouble during my last holidays too :
-one time the zaurus didn't want to turn off ! one second after an "apm -s" it was back on again !
after a reboot it was ok...
-one time it didn't want to light up, even after charging the battery for several hours... corrected after a full battery off and reset...
-i had too some quick discharge over a night....

so strange troubles indeed... i wonder if it comes from kernel, or apm bug or from something else........ i've to try if this still happens with the latest 2.6.24-yonggun kernel...

[pelrun]

There's a big difference between the cx00's and the cxx00's - the newer clamshells don't have the low value fuses in them which are the reason the older models get blown charging circuits, such as my old 860...   Not that it is impossible to kill the newer ones, but I don't remember seeing any reports of the newer ones dying that way.

Really flat batteries can be a hassle to restart - it can take a while before it even looks like the battery is charging (led on etc), and maybe even a couple of plug-unplug cycles too. And the Z won't start until you already have a certain amount of battery charge - even with AC - which will take longer than just 15 minutes.

So count yourself lucky! And get some bigger smoothing caps... or just charge the batteries and use them to power the Z instead

[utx]

New Zaurus models have high value fuses.

There is a low risk of any damage from the external power source input - nothing except and charging/power circuit are connected directly to 5V.

Datasheet of the chip: http://www.penguin.cz/~utx/zaurus/datashee...rging/sc801.pdf

I see the annoying charging bug in 2.6.24, too. It nearly never charges (or at least indicate charging) when I plug power supply. I have to unplug and plug again. Then it works.