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This is a new battery and this gives the problem of Plugged In, Not Charging for the past two days. I have no clue as to why this is happening. Sometimes it does, sometimes it does not. Battery Wear is 8%.
Some times its status is Plugged In, Charging
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If someone could please help me diagnose this.

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2 Answers 2

up vote 15 down vote accepted

This is not a defect or a problem. Your battery firmware or software driver is probably configured to forego charging when the battery is very near to 100%, to save on charge cycles. Rechargeable batteries have a limited lifespan, and repeated charging can shorten it. Charging the battery also heats it up, which can shorten its lifespan. The firmware is just trying to protect you from these and increase the lifespan of the battery.

If this situation is unfamiliar to you, then it is likely that you have used devices in the past which report false charge levels to the user. For example, some devices will say that they are "100%" charged, even though the battery's theoretical maximum capacity has not been completely filled up. This user interface trick is sometimes used to prevent consumers from being concerned by exactly the symptoms of a non-problem which you are seeing.

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And if you want to prove this to yourself, let it discharge below 95% or so (the line usually seems to be there and your screenshots support this) and it should start charging when you plug it back in. –  Shinrai Jan 7 '13 at 16:37
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This is the case with my Lenovo and easy to test as noted bt @Shinrai –  Dave M Jan 7 '13 at 16:43
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Correct diagnosis, incorrect reason. Battery "memory" is specific to NiCd batteries only. Lithium batteries do not exhibit memory effect, in fact they often perform better when recharged at 25-50%. However, all rechargeable batteries do have a limited lifespan, and it is related to the number of charge cycles. The battery/charger are attempting to protect the battery by reducing the charge cycles when not specifically necessary. It may also be to reduce heat in the battery, which also shortens lifespan. –  techturtle Jan 7 '13 at 17:24
    
I agree with @techturtle upon doing further research. Can someone please suggest or make an edit to my answer that incorporates this knowledge? Thanks. –  ÃŁŁǫǛȉЖΦΤїҪ Jan 7 '13 at 17:39

There is another possibility aside from an intentional limit to protect the battery. Laptops often (I can confirm for some Dell and HP models) have a specific signal from the charger, which informs the laptop of the charger's maximum capacity.

Sometimes, the wire that carries the signal or the corresponding part of the socket is damaged, and the laptop can no longer receive this signal. When this happens, a laptop might assume the charger is rated lower and refuse to charge the battery, ostensibly to protect the charger from overloading (which can cause a fire). Some will even throttle the CPU. Normally, the laptop will alert you both within Windows and at boot time with rather obvious messages - so, as long as you are not getting those messages, you should be fine.

If you are getting warning messages concerning the inability to detect the charger rating, the charger may have to be replaced, and/or the laptop may have to be repaired.

Some possible BIOS messages:

Power Adapter not recognized.

The AC power adapter type cannot be determined. Your system will operate slower and the battery will not charge. Please connect a Dell 90W AC adapter or higher for best system operation.

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Click for full size

More information is available here.

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Should I try the good ol' Voltmeter to see if the charge is fine? –  Little Child Jan 7 '13 at 18:26
    
So, what if you see something like "8% available (plugged in, not charging)"? (I've actually seen this). –  psr Jan 7 '13 at 21:21
    
@LittleChild It's not that the charger can't provide the specified current; it's that the laptop is missing the signal so it cannot confirm how much the charger can provide and therefore reduces current draw as much as possible. There's an excellent breakdown of a Dell adaptor, with the signal wire damaged, here. –  Bob Jan 8 '13 at 1:55
    
@psr Then this just one possible cause, and you'll normally get a warning message. There have also been reports that some HP laptops have issues detecting the battery, and a solution is available here. –  Bob Jan 8 '13 at 2:01

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