battery life & flying?

[saakmotu]

I just took my Z6k on its first cross country trip.

When Ileft the house it was fully charged.
Iused it for about 5 minutes with the wifi hotspot at the JetBlue JFK terminal then performed a complete "shutdown -h now" before boarding.
At that point the battery indicator was still showing a full charge.

I din't use the Z during the flight at all (I watched TV instead).

Upon arriving at my hotel and powering up, the battery indicated that it was "Low"

I've flown with my 5000d with no battery problems, even when I've used it in-flight.
Is there something different about these Lithium Polymer batteries in the 6k that makes them susceptible to altitude?

So far it seems to be recharging and I have managed to peck out this entire message over hotel wifi, so I'm not too concerned, but what if I had wanted to listen to some mp3s on the plane?

[BarryW]

Flying won't hurt the battery.  The airplane is pressurized to something like 1000 feet.  If you checked your z with your luggage, which you didn't, but if you did the baggage compartment is not heated, which could do something to the batteries.  Probably just a glitch with the power meter.

[fierywater]

Once I took my SL-6000 out of my pocket to find that it said low battery, despite the fact that I hadn't used it much at all. After restarting it, it said the battery was full again. It's a bit buggy.

[dougeeebear]

It probably had jet lag.
It thought it was hours later than it actually was, therefore consumed more battery.  
Sorry, that was really stupid, but a little humor never hurts.

[saakmotu]

gee,.. I didn't think about the timezone issue...
good one.. (except I was flying west)

ok, on the return flight I tried the same thing... fully charged and "shutdown -h now"

since it was a red-eye flight, I slept instead of playing mp3s or even taking the Z out of it's case (I made my own, if you must know  )

when I got home I couldn't turn it on, even with a reset and battery removal, etc...

I put it on the charger for about 10 minutes and then it did startup.

Again it showed the battery as "low" but this time it also gave me a message that the internal battery was exhausted and not to use the unit until it was fully recharged.

Now, I'm pretty sure I've left it off for 5+ hours before while remaining more or less at sea level, and still had a charge, etc. I am going to retest this tonight.

Perhaps it sat on the shelf at Amazon for too long before I bought it... either way, I think a call to Sharp is in order.

oh, and no, of course I did _not_ check it.. it was in my carry-on down at my feet the whole time

[BarryW]

Why are you shutting down from command line??  Just put it to sleep with the power button, it should stay like that for a couple days, if not the battery is screwed up.

[saakmotu]

1) to power off all approved electronic devices during takeoff/landing
    (I know, it's probably fine in suspend mode, as would be a Palm Pilot, but like I want it to be _MY_ fault that the plane crashes)

2) shouldn't it use less power if shutdown than suspended?


Yes, I am thinking that there is something wrong with the battery...
but I will test it tonight while sleeping (hopefully I'll be able to get more than 5 hours of sleep)

[Zar2Cool]

You would think it would use less power. I don't charge my 5600 for a week plus if I only use it now and then. When I did a shutdown, the batt was about dead when I started it back up.

With all the other stuff, like cell phones, pagers, etc.. that are left on. I don't think a PDA is going to bring down a 747.

[kopsis]

I wouldn't bet any money on "shutdown -h" actually powering off the hardware. In fact, I'm not even certain that the Z hardware includes a mechanism for powering off. What's more likely is that "shutdown -h" runs all the Linux shutdown scripts, terminates all processes, turns off what hardware it can (backlight and maybe display) and then throws the kernel into some kind of busy wait loop. However, since the kernel is now "stuck", none of the CPU power management code is running so CPU utilization essentially spikes up to 100% and the Z happily drains its battery.

If you want to completely power down a Zaurus, your shutdown command should be followed by removing the battery. But take it from someone who's currently working for an aerospace electronics company ... simply suspending your Z is a perfectly adequate "shutdown" as far as the plane's electronics are concerned. The RF emissions from keeping the RAM powered and the CPU sleeping are insignificant (and a lot less than having the CPU running a full speed busy wait loop) and certainly not enough to interfere with anything.

[Bundabrg]

Actually I might add (with my C860 though, so it may not apply here) that when I issue a 'shutdown -h now' or 'halt', the machine appears to shutdown but I feel its still chewing up the power and not actually turned off (IE hung at the end of the script with screen off etc). This is probably one of the reasons (with the C860 anyway) that I have to pull the battery to restart it.

 - Bundabrg

Edit: Bah! Beat me by 3 minutes!

[iamasmith]

ay) and then throws the kernel into some kind of busy wait loop. However, since the kernel is now "stuck", none of the CPU power management code is running so CPU utilization essentially spikes up to 100.....

again really interesting stuff, I had assumed up to now that the ARM instruction set probably carried something like the HLT instruction that you get on x86 processors or that the processor could trigger via IO a halt of it's own clock.

In any case even if the processor does stop it may not be wise to assume that the kernel shutdown has triggered a power off for all peripheral hardware... i.e. WLAN may have a power down or suspend mode. When the Z is suspended the WLAN hardware actually may go to suspend or powered down. If there is nothing that actually triggers the WLAN hardware to properly power down when you shutdown -h now then it will suck the battery dry pretty quickly I guess. And a WLAN card in a device that looks dead and is blasting away (I think a lot of these have a bit of intelligence on board) could be just what the airline doesn't want.

I think Dave's suggestion is spot on again, if you think you have to shut down then take the battery out too to be sure. I would suggest suspending is safer because power management can run.

- Andy

[kopsis]

I had assumed up to now that the ARM instruction set probably carried something like the HLT instruction that you get on x86 processors or that the processor could trigger via IO a halt of it's own clock.

HLT instructions don't necessarily do anything to drop the CPU's power usage. They often just block the execution of the next instruction until the next interrupt. The processor typically stays fully powered up and clocked.

That's not to say that there aren't ways to get the Xscale into a low power state (obviously suspend does it), just that they weren't wired in to the "shutdown" code. Since Sharp didn't provide any built-in means for the user to execute a shutdown, I doubt that proper support for full shutdown was ever a design requirement. I don't think Sharp ever fully accounted for Linux savvy Zaurus users. Remember that the Z was really designed for the PocketPC crowd ... not the "hacker" community that it's found a home with in the US.

[BarryW]

Also I beleve with handhelds a total power down will basically hard reset it.  I could be wrong with the Z's but that is what happens with pocket pc's.  Also your handheld won't put out enough rf to do anything to an aircraft's avionics.  The wireless card maby, but not the processor or memory.

[bluedevils]

The older 5 series zaurii were structured like the pocket pc, but the newer zaurii generally would only reset the clock.  If I had a 6000, I would be paranoid and pull the battery.  I wouldn't be worried about suspend mode, but the fact that the 6000 could be turned on.  I'm not sure how the wireless section of the 6000 works, but I wouldn't want to take the chance.  I know this is an opinion from a non 6000 user, but it might explain saakmotu's concerns

[soundwave106]

Yep. When you take the battery out of the SL-6000, the only thing that resets is the clock.