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I just bought a lithium-ion battery for a Lenovo ThinkPad T61, and frustratingly it displays being able to charge only at 91% of its design capacity (65.16 Wh out of the designed 71.28 Wh).

liv@malou-laptop:~$ upower -i /org/freedesktop/UPower/devices/battery_BAT0  native-path:          /sys/devices/LNXSYSTM:00/LNXSYBUS:00/PNP0A08:00/device:00/PNP0C09:00/PNP0C0A:00/power_supply/BAT0
  vendor:               SANYO
  model:                92P1137
  serial:               13312
  power supply:         yes
  updated:              Sat 08 Mar 2014 08:30:17 AM CET (7 seconds ago)
  has history:          yes
  has statistics:       yes
  battery
    present:             yes
    rechargeable:        yes
    state:               discharging
    energy:              61.86 Wh
    energy-empty:        0 Wh
    energy-full:         65.16 Wh
    energy-full-design:  71.28 Wh
    energy-rate:         27.174 W
    voltage:             11.929 V
    time to empty:       2.3 hours
    percentage:          94.9355%
    capacity:            91.4141%
    technology:          lithium-ion
[..]

The vendor recommends 3 full charge/discharge cycles to initialize the battery. But upon reading SuperUser (Control charging and discharging of laptop battery and this article Lithium-ion battery preservation), I hear that I should avoid:

  • 0% discharges
  • 100% charges
  • allowing the battery to overheat (i.e. should keep it under ventilated conditions)

So how do you correctly initialize such a battery? Charging to 99% and discharging to 1% in cool conditions?

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1 Answer 1

A really good li-ion battery that is fresh, does not change or advantage from 3 full charge/discharge cycles. Most of the battery experts would say that is true.
There are exceptions to this rule :-) Many of the china batteries , really do actually change in the capacity held, for the in Spec voltage range they operate in, when cycled 2-3 times.
My testing discludes any calibrations , that make it look like things have changed, because my tests are based on the raw cell items.

When they discuss 0% discharges and 100% charges, they are specifically referring to setting up a charge alogrythm which keeps the battery in a smaller range. Within the smaller range the negative things that happens MORE at the highs, and the negative things that happen MORE at the lows, will allow the battery to last longer. (99% and 1% is little different)

It should be understood that in most cases (any properly built products) There is already a low stopping point, and a high stopping point, that is Fully within the specs for the operation of the cells within the data sheet of the manufacture of it. The 100% and even 0% is fully within specs in any properly done products.

Staying away from the "normal" highs and lows That the curcuit designs usually have covered, is over and above expectations, and can extend the life of the cells. The quantity is not 99% it is to keep off the highs, more like 90% or 80% , the ammount has varying longevity As the max high is reduced. The lows are similar more like 10-20% if you expect to see a change in longevity.
There is less of an effect from being low, as long as the cell is subsuquently charged soon, it is bad "Staying low". There is more of an effect from being high (at all) and staying high, meaning you would want the charge curcuit to stop charging to that level, to begin with to get that advantage.

In many of my experiments with this , there are some very low quality of Li-ion cells that it does not make much differecne at all what you do, they die over time anyway. In the same sence there are very high quality of li-ion cells which I have both pampered and just used normal , and they have lasted up-to 8-10 Years (well beyond what they should).
It would help if more of the people explaining the way to preserve the batteries , would also indicate that the Quality of the original cells can make MORE differance then the pampering of them, although Both is good too.

There are generally 2 different ways being used to show the human the charge states , one is to use only voltage, the other is to actually measure the quantity of energy that enters and leaves the cell.
For voltage only methods, there is no such claim of calibration, the curcuit only knows what it sees, the % is guessing the charge state using a formula that mostly works.
For the Miliamp aware info/smart curcuit stuf, full cycling the cell every once in a while will better display the charge state. "Calibrating" would include bringing it down to its spec Low (0% to the human) and charging it to its spec high (100% to the human).
Each method has defecincies in representing the charge level properly and fully, but both methods are ok, and within what the human would want to know.

Which brings up the text stats shown on the battery you got here. It does not look like it was fully charged. And there are so many other things one could say. But it is possible to get a "full charged" flag on a computer prior to the battery being 100% charged, using either method. The (proper) li-ion charge method goes slower and slower as the battey reaches a full state, so it does not gas.
(generally) The last 20% (80-100) of a li-ion charge can take As long as the first 80% because of this slowdown. Different computerised items will flag for a full charge when it reaches this 80+% level. (when it sees the peak voltage). An Ok time to take it off charge for pampering it. Computerised devices can also flag for 100% charge only when the charge has fully stopped , which is an actual 100%.

All of this is general, there is many variations in both the real and the unreal way things act, are calibrated, and display on the computers, it is easy to tweak a few things in firmwere to be different, or make people feel better, or new alogrythms that think more or use methods that can have ramifications.

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So, bottom line (this is a cheapish battery): not to worry about 91% capacity, but simply do 90% charge and 10% discharge cycles? –  landroni Mar 8 '14 at 8:12
    
I would do the cycling that the distributer/seller recommended, probably in real use situations, as opposed to wasting the power. I would full charge when needed, I would pamper when I could. 90% and 10% are good points without loosing to much capacity, and gaining possible longevity. –  Psycogeek Mar 8 '14 at 9:12

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