Re: [iPAQ] H38xx power drain problems

On Tue, 2004-01-20 at 12:52, Nils Faerber wrote:
> Strange.
> Sure you have not had a user RTC alarm set?

That was my first thought too, though I'm fairly sure I didn't.
Certainly there wasn't any evidence of gpe-announce or anything like
that being run.

> I also think that the charging threshold, this 10mA thing, is utterly
> wrong. First this does no good to LiIon batteries. They do not like it
> very much to be fed up to the limit all the time. The last 5-10% (i.e.
> 90-95%) are very critical. Most charging circuits reduce the charging
> current to very low when entering the last 10% (to be charged). Likewise
> it is also recommended that LiIon batteries must not be fully charger
> again unless they have lost a certain amount of capacity; mostly the 10%
> threshold is used again. This means that charging should only be done if
> the capacity drops below 90%.

The iPAQ charger certainly supplies only a very low current for the last
phase of charging. This is where the 10mA trigger point for the LED
comes from: if the battery is 95% charged by that time and you're in a
hurry to use the ipaq, you don't necessarily want to wait around for an
hour to get the final 5% charge.

> The effect you get when you always charge the battery is the "lazy
> battery" effect, i.e. you get a reading != empty (even more than 50%)
> but any higher than usual battery load, e.g. WLAN, would cause a battery
> fault - this what happened to an older H36xx iPAQ now :(

Ah. I wasn't aware that li-polymer batteries suffered from that
effect. They certainly do wear out, and it doesn't surprise me too much
to hear that the battery on your h3600 is shot, but I hadn't heard that
top-up charging would accelerate the process.

> Oh well... I see what I can do ;)

Okay, cool. Let me know what you come up with.

p.
Received on Wed Jan 21 2004 - 13:38:03 EST