Help - Search - Members - Calendar
Full Version: Charging Level Monitor On C860/oz3.5.3
OESF Forums > Distros, Development, and Model Specific Forums > Model Specific Forums > Cxx0 Hardware
jan
I'm using the Sharp 1700mAh accu.

Fully charged without Wifi it seems to last forever while the level slowly decreases. However when it hits around 50% it will rapidly discharge to 6% causing a battery warning.

When plugging the charger (while OZ/OPIE is suspended) it takes two tries to make the orange LED go on. Usually (but not always) when charging in suspended mode, the orange LED will remain on forever (24hours, AC adapter can do 2.5A at 5V). When I unsuspend the Z (with AC plugged) I get first a "critical" battery warning, then the software realizes the battery is actually at 100%.

I don't really care about the state of the LED and I can do without a precise estimate of the charge level but I don't want to harm the accu. Is there something wrong? Am I suposed not to suspend the Z while charging? Am I a suposed to unplug AC after 4 hours?
gromituk
QUOTE(jan @ Mar 20 2006, 06:26 PM)
AC adapter can do 2.5A at 5V

Gulp - I've heard nasty things about using chargers with too high a capacity - I think the Z relies on current limiting within the charger. I'd recommend you use a charger that can't supply more than 1A, and I hope you haven't fried your charging circuit or reduced the life of the battery too much in the mean time.
lardman
What kernel version are you running?

There were some issues with the charging in the early 2.6.x kernels, which were fixed by RP. The fact the charging light never goes out may be to do with your battery dying and not being able to hold sufficient charge for the kernel to realise it's at its capacity (iirc - I must have another look at the source and see if this is correct.)


Si
jan
QUOTE(lardman @ Mar 21 2006, 12:09 PM)
What kernel version are you running?
*


2.6.11 from OZ3.5.3

BTW: LED works as expected when charging without suspending.

QUOTE(gromituk)
Gulp - I've heard nasty things about using chargers with too high a capacity - I think the Z relies on current limiting within the charger. I'd recommend you use a charger that can't supply more than 1A, and I hope you haven't fried your charging circuit or reduced the life of the battery too much in the mean time.


I don't think you are right here. First, power sources don't have "capacities". The most common are constant voltage sources, the provide a stable voltage (however only if the current drawn is with a valid range, mine is designed for 0...2.5A). Constant voltage sources don't regulate the current by any means. It's generally a bad idea to "charge" accus by plugging a constant voltage source. That's why devices have charging circuits to control charging currents.

Then, there are constant current sources. To provide a constant current the voltage will vary. You can charge NiMH or NiCd batteries with a constant current source given you know when to stop. However, if plug a constant current source to an (idle) device, you'll probably burn it because of the high voltage.

There are devices that can limit both current and voltage (used in labs). Basicly those switch between constant current and constant voltage mode by prefering whatever gives lower figures. If you set such a power supply to 5.0V and 1.0A, what you get is NOT 5.0V/1.0A but either 5.0V and current <1.0A or 1.0A and voltage < 5.0V. I agree, they make good safety nets. But we don't ever want the voltage to be below 5.0V.

I don't know anything about Sharps charging circuit. It may well be that it behaves different if the current is limited and it may even be that this intended by Sharp, but I doubt it. Good charging circuits should control currents more precisely. However for any precise control you need a well defined basis to start with. As dealing with constant voltages is much easier than with constant currents, device designer choose a constant voltage as their basis.

BTW: The official world voltage adapter by Sharp does 2A, only the tiny Japanese one is rated 1A. IIRC USB provides usually a not so stable 5V (500mA max) and you can charge some Zaurii via USB.

If do know more than I know, let me know. I agree that adapters which cannot do high currents are kind of a safety feature (such as disconnecting from the net gives you saftey from viruses) but what kills devices is usually too high voltages. (High charging current may decrease the batteries lifetime, but firstly this should be influenced by the choices of an adapter and secondly it's not as bad as frying the Z.) Low (unstable) voltages (as from current limits) usually don't do much harm but you can't expect the battery will get charged properly.
Hrw
I would consider updating to 3.5.4.1-alpha1 or atleast 3.5.4 and then test does those problems still exist.

OZ 3.5.3 + 2.6.11 is now nearly year old code..
jan
QUOTE(Hrw @ Mar 23 2006, 09:52 PM)
I would consider updating to 3.5.4.1-alpha1 or atleast 3.5.4 and then test does those problems still exist.

OZ 3.5.3 + 2.6.11 is now nearly year old code..
*


Hmm. I was going to wait for 3.5.4.1 final. I'll give 3.5.4 a try when I find the time.
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.
Invision Power Board © 2001-2014 Invision Power Services, Inc.