The phone is somewhat unaware of the capacity of the battery and fully unaware of the actual capacity. can be easily tricked by clearing battery stats via recovery at varying percentages and/or altering the batterystats.bin. This is because the battery % is an interpretation of various inputs. You may recall that older devices used to plummet the first 10% or so because it would read 100% when it was really varying between 90% or so and 100% over and over and just never changing the percentage displayed. This is what encouraged people to do "bump" charging and the exact inverse situation is probably happening here. One thing that could be occurring with LG is a systematic pattern of charging similar in effect to "bump" charging and it could be that it is charging to more than what the algorithms interpret as being 100%. If that were the case, there is a concern about the longevity of the batter (bump charging is horrible as a wear and tear factor).
Battery University once said, "Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory." As of about 2010 or 2011 it became unnecessary to pull a device off of the charger as soon as it neared 100%. One effect we may be observing is that OEM's are using different strategies to report battery stats based on newer, more intelligent behaviors that are better for the battery itself. If LG has discovered and implemented a way of gently bumping a charge without damaging the battery, that'd be a pretty cool thing.
TL
R version: There is no way of exactly measuring a battery charge levels via the smartphone at any particular point in time. Other things can be measured that give a somewhat accurate depiction of it. But it is a ballpark figure, not a concrete value.
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