Can anyone telling me why this showing that my battery capacity is 69.7% where Battery percentage is 78.0%
Percentage is how much charge the battery holds. Capacity is an indicator of the life expectancy of the battery - found this out by searching and came across this interesting article. Please note that Lithium ion batteries are rotting from the time of manufacture so be sure to get any replacement battery with a 'current' manufacture date!:
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Correct, rechargeable batteries, weather ancient Nicads, Hydrates, or the newer Lithium Ion or Lithium Phosphates, have a battery capacity. And overtime, over the course of several charge cycles, or by keeping the battery at 100% all the time, you will lose your battery capacity.
Eventually, your battery will no longer hold a charge anymore. Its common for most notebook batteries to completely die after 10-years for quality ones, or 3 years for low quality ones. Which is why, once your capacity shows 25% or less, you should get a new battery for your notebook.
I personally use my notebook computer as a desktop. So, this means that I don't use the battery to keep my computer powered while on the go. I use my battery as more of a UPS, so when power goes out, I still have time to save my work, and shut the computer off.
But here's a cool thing, the way I got my settings setup, when the power goes out, my system will automatically suspend, which is for all intensive purposes like being off, and thus saves on the battery, and I don't have to be there to personally shut it off.
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In my opinion, I think that picture is showing erroneous readings.
For batteries, generally:
- Capacity for batteries is typically watt-hours (power x time) = Energy. For all other electrical sources that doesn’t apply but for batteries the norm is to use capacity to imply energy.
- Percentage should be State of Charge (SOC) a measure typically used in conjunction with full energy ability of a battery. Thus, SOC X Capacity = Remaining available watt-hours.
For your pic:
It seems Percent (a dimensionless measure) and capacity should be the same. I believe your pic is representing Percent as SOC and Capacity as Available energy/Total Energy (also = SOC). Finally, both SOC and Capacity incorporate a battery’s life, i.e., they both decline for same input energy as the battery ages.
In conclusion, for batteries and your pic, they both should be the same, as you already seem to have suspected. Something is off.
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And in regards to remaining battery capacity, SOH also demonstrates meaning. In my automotive & mower battery testing thread, I spoke of this, as I have a couple of bad batteries. One in particular is in seriously rough shape. Here is my picture that I took of the SOH of one of my bad batteries.
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Addendum to my earlier post:
My best guess as to what may be going on, based off two assumptions -
- The "Capacity" is derived from measuring the loaded battery voltage.
- The "Percentage" is derived from historical performance.
IF those two assumptions are true, then the deterioration of the battery shows voltage sag, which is common as batteries age. That explains why the "Capacity" is lower. The "Percentage" is calculated off historical life expectancy. If the voltage sag only started more recently, the earlier and more numerous values would take precedence in the distribution. For example, here is a distribution for a good battery.
Regardless of whether my assumptions are valid, you want to rely on the lower metric, the "Capacity" to be safe.
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Marked solution. 107
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