Battery Wear Level Problems

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WafflePi

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So i got this ASUS X205TA for christmas recently, as it was a "pass down" but the person who gave it to me barley used it, maybe turned it on twice within the 5 month period they had it, and when i got it i charged it up and restored it. I recently installed HWMonitor and it says something about "Battery Wear Level" and currently it is at 17%, it seems to be going up quite quickly, as yesterday it was at 14%, i dont know what this means and im affraid that im gonig to have to replace this battery quicker than i thought, this laptop is quite cheap as it is retailed at about 200$, im not sure what to do so if someone can explain what battery wear level means, and if you could tell me if the spike from 14%, to 17% is abnormal. Thanks for any help. PS: Ever since they gave it to me on christmas, ive charged it about 2 times and have been using it since, and plus this is my first laptop ever so im a noob on this battery stuff :) thanks again.
 
As a battery gets older, it loses capacity. If the battery's capacity when new was 4000 mAh, and its current capacity is only 3600 mAh (90% of new), then it has a battery wear level of 10%.

That said, battery wear is mostly caused by deep charge cycles. That is, charging to 100% and discharging to 0%. Shallow cycles (say, charging to 70% and discharging to 30% put almost no wear on the battery.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Newer laptops (and phones, and electric vehicles) are programmed not to fully charge nor discharge the battery in order to prevent wear and maintain battery longevity. One of the ways I've seen some devices do this is by "faking out" Windows into thinking the battery has more wear than it really does. So the battery may be 4000 mAh when new, but the battery tells Windows it has 10% wear. This prevents Windows from charging it past 90%, thus preventing a deep cycle.

This is just one of the wear-prevention strategies out there, and I don't know if the ASUS X205TA is using it. So it could just be reporting a fake wear level to Windows. OTOH if the original owner let the battery discharge completely and left it that way, it may have self-discharged past 0% enough to damage the battery and the reported wear level may be accurate.

The only true test will be to monitor the wear level over several months of use. If it holds steady between 15%-20%, then it's probably nothing to worry about. If it continues wearing quickly, then the battery may have been damaged by the previous owner. (Measuring battery capacity and wear level is a bit of a black art, as it requires extremely accurate measurements of voltage. Things like discharge rate and temperature can drastically change the results, so a +/- 3% change in wear level day-to-day is not unusual.)
 
As a battery gets older, it loses capacity. If the battery's capacity when new was 4000 mAh, and its current capacity is only 3600 mAh (90% of new), then it has a battery wear level of 10%.

That said, battery wear is mostly caused by deep charge cycles. That is, charging to 100% and discharging to 0%. Shallow cycles (say, charging to 70% and discharging to 30% put almost no wear on the battery.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Newer laptops (and phones, and electric vehicles) are programmed not to fully charge nor discharge the battery in order to prevent wear and maintain battery longevity. One of the ways I've seen some devices do this is by "faking out" Windows into thinking the battery has more wear than it really does. So the battery may be 4000 mAh when new, but the battery tells Windows it has 10% wear. This prevents Windows from charging it past 90%, thus preventing a deep cycle.

This is just one of the wear-prevention strategies out there, and I don't know if the ASUS X205TA is using it. So it could just be reporting a fake wear level to Windows. OTOH if the original owner let the battery discharge completely and left it that way, it may have self-discharged past 0% enough to damage the battery and the reported wear level may be accurate.

The only true test will be to monitor the wear level over several months of use. If it holds steady between 15%-20%, then it's probably nothing to worry about. If it continues wearing quickly, then the battery may have been damaged by the previous owner. (Measuring battery capacity and wear level is a bit of a black art, as it requires extremely accurate measurements of voltage. Things like discharge rate and temperature can drastically change the results, so a +/- 3% change in wear level day-to-day is not unusual.)
 

WafflePi

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Aug 13, 2014
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thanks alot, really informative i feel alot better and releaved :), but a couple more questions since this is my first laptop, if my battery gets low and i charge it while using it, is that bad for the battery? If iput the laptop on a bed and it heats up is that bad for it? If i use the battery down to 10% and charge it back all the way up to 100% is that bad (as you said in the paragraph i can asume this is bad, just double checking) thanks again!
 
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