[Vibrant General] BruceElliott:
Neither. "Conditioning" skews the discharge curve from which the battery indicator indexes it percentages. As a result, the battery appears to discharge at slower rate ("better battery life") over the first two-thirds or so of the discharge cycle and then craters like a lead balloon at the end of the discharge cycle. (You really need to have a battery indicator that shows discharge in 1% increments, such as "blue segmented battery mod" to see this.)

To understand this requires a light understanding of the so-called "battery stat tables." There is an entry in the battery stat tables for each percentage of remaining battery charge, in increments of 1%. So, the table contains entries 100%, 99%,... down to 1%. Associated with each percent of remaining charge entry in the table is a battery terminal voltage and a timestamp. Unfortunately, the smart phone cannot measure actual remaining battery charge. All the system knows is a series of battery terminal voltage measurement taken at even periodic intervals. The algorithm builds the battery stat table to relate each measured voltage to a corresponding “percentage of remaining charge” entry in the table. In normal operation, the system accumulates these measurements over several charge/discharge cycles and analyzes the rates of changes of voltages to refine the discharge curve. After several charge/discharge cycles the percentages, which are displayed on the screen as a battery indicator, become more refined and accurate.

At some point someone apparently thought that it would be a good idea to attempt to manipulate the process of building the battery stat tables. This resulted in the so-called "conditioning procedure." The conditioning procedure consists of fully charging the battery, then deleting the battery stats, and then draining the battery quickly and completely using heavy loads, perhaps in 1 to 2 hours.

What this accomplishes is that the battery stat mechanism builds a new, steep discharge curve based upon the rapid discharge operation. This crude, initial discharge curve has "learned" that the battery should discharge quickly, because it did so during its "training” discharge. More specifically, each "percentage discharge" entry for the first 1/2 to 2/3 of the discharge curve (corresponding to the first 50-75 table entries) will be associated with an abnormally lower voltage (due to the faster rate of decrease in voltage during the "training" discharge cycle) than would be the case if the table had been built normally, over time.

Now, let us think about what happens during the subsequent discharge cycle. We charge the battery to full. Now we begin to use the phone normally, discharging the unit over a period of 12-18 hours, for example. Now the phone experiences a slower rate of change of battery voltage over time, because the load is much lower than that of the forced "training" discharge. Now the algorithm measures a voltage and then attempts to map that voltage to a corresponding percentage discharge table entry. The result is that the battery indicator on the phone shows a very low rate of discharge over many hours. This leads people to erroneously conclude that the "battery conditioning" procedure results in improved battery life. However, this is merely an illusion. The battery indicator is, at this point, simply displaying an incorrect number for the remaining battery life. As a consequence, the battery indicator must "catch up with reality" later in the discharge cycle. This is manifested toward the end of the discharge cycle as the battery indicator drops precipitously from perhaps 35% to zero in a very small amount of time. In any case, fortunately, the weirdness done by "battery conditioning" goes away within a few days as the battery stat algorithm tunes the discharge curve each discharge cycle to bring it ever further in line with the actual average usage of the phone owner. It is a myth that the battery stats become inaccurate over time. To the contrary, the algorithm continuously tunes the tables based upon usage patterns so that the battery indicator becomes more and more accurate.

I do not know where this practice originated, but I do have a cynical hypothesis. The ROM cookers typically mix-and-match code elements from different software releases and otherwise change up the timing, sequencing, etc. of various processes. Doing so may have battery life consequences, because the resulting mish-mash of components may hinder or prevent sleep mode operation, cause processes to run for more time than they should, etc. You can see how "battery conditioning" could mask an acute battery performance problem during the first few hours after a person has flashed a ROM and is watching performance characteristics especially closely. ‘Nuf said on this subject.

Sample battery discharge chart and accompanying notes attached below.