"mike" wrote in message
news
On 5/19/2017 9:33 AM, Jim Wilkins wrote:
...
The symptom is that the battery gauge decays slowly for a while
then drops instantly to a much lower number. The laptop senses
impending doom, but you've blocked that.
I've had laptops run two hours past the point when the battery
gauge hit zero. Problem is that when it dies, you lose whatever
you were working on.
...

The "fuel gauge" IC counts Coulombs in and out to determine actual
Lithium battery capacity, on the assumption that they recharge at 100%
efficiency. It resets its capacity estimate if the battery is nearly
fully discharged and recharged, but if only partly discharged it can't
detect the slow loss of capacity with age and retains the old, overly
optimistic number from the last full cycle. That's why the sudden jump
when it realizes it's wrong.

When you give the battery another full cycle it can measure and update
the battery capacity to its new, lower value.

As an experiment I reduced the low voltage trip as far as possible and
got almost as much run time from an old Dell battery below the 5%
level as from 100% to 5%. It appears that Li-Ion cells can be
discharged down to or even below 2.7V briefly without much damage. The
normal settings are above 3.0V.
http://batteryuniversity.com/learn/a...oltage_cut_off

This gives you the battery voltage:
https://www.hwinfo.com/

-jsw