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I bought a new laptop battery on Amazon for my Thinkpad. When I plug it into my computer, the computer tells me the battery has 91% capacity. Am I being ripped off or is it normal for the battery to initially report a capacity of less than 100%?

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migrated from stackoverflow.com Nov 13 '09 at 19:45

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Though a different question, read the quote from the first answer... It seems pretty relevant. Is it better to use laptop on battery or on ac power? –  Sivvy Nov 13 '09 at 19:56

3 Answers 3

My experience with thinkpads (2) is that this will change over the next few days. They seem to start low and then build charge.

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The Thinkpads have very conservative charging circuits/controls which helps extend the useful life of the battery. However, it also means that many times the charge percentage hovers in the 90's rather than always going up to 100%. –  Brian Knoblauch Jan 28 '10 at 13:39
    
@BrianKnoblauch What do you mean by "charge"? Do you mean that the battery charges only up to 90% of its design capacity? (See my related question: superuser.com/questions/726274/… .) –  landroni Mar 8 at 7:50
    
Yes, in order to extend the useful lifetime of the battery, it may only charge into the 90% charged range. –  Brian Knoblauch Mar 8 at 12:04

If you have not charged the battery yet, I'd say that any reading at all is perfectly fine. You should charge it completely, then see where things stand.

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It seems possible that you wouldn't be shipped a 100% charged battery.

It seems possible that the computer needs to cycle the battery fully the first time to know what 100% would be.

It seems possible you were ripped off, depending on the quality of the 3rd party seller, but unlikely, unless it was a very, very good deal.

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