On 18/02/2012 22:36, Arnt Karlsen wrote:
On Fri, 17 Feb 2012 13:51:27 +0100, Lorenzo wrote in message <[🔎] 4F3E4D4F.6090404@gmail.com>:Hi Darac, Thanks for the very insightful information... On 17/02/12 13:38, Darac Marjal wrote:On Fri, Feb 17, 2012 at 01:10:31PM +0100, Lorenzo Sutton wrote:I am running XFCE 4.8 on debian wheezy on my laptop and since about two weeks the xfce Power Manager gets the battery charge percentage wrong, the most critical problem being that the machine shuts off without any previous warning. I wonder where the problem might be. Indeed this battery is getting old (3 years now) and less efficient, but I can't explain why suddenly Xfce Power Manager is getting it so wrong given that it was working like a charm (even giving a pretty accurate esteem of remaining time). I imagine Power Manager is relying on some lower level (software, kernel?)features, maybe in the kernel?I believe this is a common failing with batteries. I might be wrong here, but as they age, the discharge profile of a battery changes such that the monitoring hardware tends to over-estimate the remaining capacity. This typically manifests as normal discharging down to, say, 10 or 15%, followed by a sudden step to 0%. Now, most power profiles are set up to warn of low battery at, say 10% and treat 5% as critical. If the battery capacity suddenly drops past the warning level into the critical level, the system has no choice but to take emergency measures. As for where this information comes from: XFCE Power Manager will query the ACPI daemon which is running in the background. That will talk to the kernel's ACPI subsystem will, in turn, will talk to the ACPI implementation in the BIOS. That, ultimately, is what decides what the battery level is. Only the BIOS really knows what the battery charge currently is, what a 'full charge' is and what 'zero charge' is. It MAY be possible to re-teach the BIOS about the current charge profile of the battery, but it's generally just easier to increase the warning level in Power Manager.HP advices a procedure (Windows only) to 'recalibrate' the battery..what kinda battery, LiPo, NiCd, NiMH?
Li-ion They have slightly different
discharge profiles, but "dive steeper" as they age. If you can get a new replacement or used spare battery from the vendor or Ebay, you can then gut the worst battery and fit new cells into the gutted battery housing. ..another way to extend laptop battery time, is stuff a laptop size box full of lipo cells to match the charge plug voltage, and drain the lipo box first, then have the laptop start draining its battery.
I've read about the freezer thing wonder if it works. ...
[2] I guess this could be reporduced in similar fashion. In particular Option two could probably simply be boot into grub..there's a game to play from grub, space invaders? Can it be hacked to draw a discharge diagram in the background, or write raw voltage, amperage etc numbers and timestamps to a file, e.g. /boot/grub/batterydischargeprofile , ideally per cell?
:)
..batteries usually fails because _one_ cell fails, this can be spotted early with load tests, the bad cell's voltage will drop lower than the good ones. Common lipo chargers can also be used to diagnose and prevent this this failure mode.and let it stay there until it completely discharges..this is a somewhat destructive test method, but it works on NiCd and was recommended to "wipe the memory effect", 50% discharges has a way of shaping the discharge curve so it drops sharply beyond the 50% or whatever you discharged it to, which has caused quite a few RC model aircraft crashes.
Only using it for boring spreadsheets ;) Lorenzo.