On 3/16/2024 6:24 AM, Philip Herlihy wrote:
In article <MPG.405e9e5633ff3813989ab5@news.eternal-september.org>, Philip Herlihy wrote...
In article <ustvec$1e302$1@dont-email.me>, ...w¡ñ§±¤ñ wrote...
Philip Herlihy wrote on 3/13/24 4:12 PM:
The machine is a Dell XPS 13. Partitions (in Disk Management) are (rounded):
500MB EFI System partition
225GB OS
852MB now Unallocated after my meddling
10GB Recovery Partition
1GB Recovery Partition
...
There's another glitch with this machine. The user (not content with transporting the machine with the power plug inserted and banging hell out of the power socket - repaird) has evidently left it plugged in 24/7 (when not bouncing it off door-frames). So the battery has about 90s life in it from an
indicated 100% charge.
I've realised that unless it's left "on charge" for many minutes then when it's
logged-in the "Critical Power" event kicks in (at 2%) and hibernates the thing.
I turned that off, but then decided it was safer to leave that mechanism in place to avoid possible corruption. But I'd like to increase the 'Critical' level from 2% to (maybe?) 7%. I find the Control Panel applet simply ignores attempted changes, and I have to use powercfg with some GUID weirdness to achieve this. As I said, I'm getting too old for this s***...
There is mention here, that the schema can be reset, and maybe
after that you could try again to set it.
https://superuser.com/questions/1341383/how-to-stop-computer-from-entering-sleep-under-critical-battery-trigger-met-mi
There is also a picture of the settings section, in the article.
Since the field can be set to weird values, it almost implies
somehow that this is adaptive ? And adjusts itself ? Otherwise,
how would one individual report his was set to 86%.
https://i.stack.imgur.com/I93RH.png
There is a chip inside the battery pack, which at a minimum
contains a tiny flash memory. And the charge history of the
pack is recorded in there. The OS reads the chip when the
OS boots, and it keeps the table in RAM, and writes it back
out at some point. And since the chip has a "serial number",
this allows the battery pack itself, to carry a summary
of its life history. One of the parameters, is how many
charge cycles it has gone through.
Some laptops, have a charge controller (chip on laptop mobo)
that can be set to "only charge to 80%" and this significantly
reduces the impact on the battery from the "user plugs in
24/7" case. That hasn't always been there, so not all laptops
have that. The setting may be in a separate application,
added to the C: drive.
What it's doing, is removing Phase 2 from the
battery charge process. The charger only does CC to get
to 80%, instead of the CC-CV to get to 100%. The CV or
Constant Voltage phase is known as "topping up" and squeezes
the last bit of charge into the battery, from 80% to 100%.
The time spent at 100% charge (or 4.2V per cell), is what
damages the pack. Once at 100% and the charger has switched
off, the battery starts to relax at that point, and drops
back to 3.7V on its own. Car batteries behave a bit like
that too. In terms of relaxing. One difference is, you
can "float" a car battery at 13.5V instead of allowing it
to relax to 12.6V or so, whereas you cannot float a Lithium
cell. When a lithium cell is full, it's full.
The lithium cell would have to drop significantly, before
another charge cycle starts. The charger cannot start at
3.7V, because the pack is still full at that point. It
would need a bit of hysteresis and maybe start charging
again at 3.5V or so. Even if sleeping, it should not
be "on-charge" constantly, and it should be taking
a break once in a while. But the number of charge cycles,
if left plugged in, it still probably quite high.
Paul
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