battery and screen (crack) question

Okay I just realize after charging my battery and unplugging it for a couple of minute my battery has life has drop down to 92%, when I check, I can see that I only have 4.2 hour remaining.I see that I only have 75 cycle count. Does this mean I need a new battery soon? If I bring it to apple, would they change it for me free of charge and without question since I'm still under warranty. Also what do I need to do for apple to replace my screen. I have three macbook in the house (1 is my sister, another is my father). They are both under warranty. My father macbook screen suddently crack. When I brought it to apple they just assume that it our taut. How my sister screen too has suddenly crack (now it has spread to a really big crack). How can I should that it not our fault for the crack screen and that it a manufacure problem.

P.S. the condition of the battery is normal

chloe_tran said:

Okay I just realize after charging my battery and unplugging it for a couple of minute my battery has life has drop down to 92%, when I check, I can see that I only have 4.2 hour remaining.I see that I only have 75 cycle count. Does this mean I need a new battery soon?

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Hard to say…what model laptop is it (be specific). Does it have the non-user replaceable battery or the user replaceable battery (in other words can you remove the battery on the bottom of the laptop)?

chloe_tran said:

If I bring it to apple, would they change it for me free of charge and without question since I'm still under warranty.

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Very unlikely. Applecare only covers repairs that are manufacturing defect related. Broken screens that are manufacturing defect related are pretty rare. Here at Mac-Forums we rarely hear of folks having cracked screens/displays…and when we do…it's almost always related to some sort of accident or rough handling (laptop was dropped, display was hit with a foreign object, someone sat on the laptop when it was closed, etc.).

chloe_tran said:

I have three macbook in the house (1 is my sister, another is my father). They are both under warranty. My father macbook screen suddently crack. When I brought it to apple they just assume that it our taut. How my sister screen too has suddenly crack (now it has spread to a really big crack).

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Three Apple laptops in the same house…all with cracked displays…is almost a statistical impossibility. You would almost be more likely to win the lottery…than have 3 Apple laptops with cracked displays due to manufacturing defects (especially if they are completely different models).

If this were true…we would be hearing of many many many more folks with cracking displays…and we simply do not hear of folks with this problem. As you experienced already…Apple does not believe that the display/displays cracked due to a manufacturing defect.

- Nick

For the battery. The model I have or it is early 2011

As for the screen, it only two crack screen and not three. We are very careful with the laptop since you have to pay alot for it. It good to take care of something that you pay for especially computer. The model of the two laptop are also early 2011

chloe_tran said:

For the battery. The model I have or it is early 2011

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This laptop has the non-user replaceable battery. This battery is supposed to have a 1000 cycle count lifespan..roughly speaking this means:

0 cycles = 100% battery life
100 cycles = 90% battery life
200 cycles = 80% battery life
.
.
.
900 cycles = 10% battery life

Thus if you currently have 75 battery cycles & 92% battery life…that's exactly what it should be (75 cycles = 92.5% battery life remaining).

- Nick

I check online and found that the early 2011 model can have 7 hour life span (for real life use). If I"m able to retain 92% of the battery, I would get around 6.4 hour of life but I'm only getting around 5 hours are so. Is this not how you calculate it. The 92% I mention on my first post was just for example. I can see my battery life dropping really quick. As meant ion, when I charge my laptop and after 15 minute or so it can droop down to 90 something percent to upper 80

chloe_tran said:

I check online and found that the early 2011 model can have 7 hour life span (for real life use). If I"m able to retain 92% of the battery, I would get around 6.4 hour of life but I'm only getting around 5 hours are so.

Is this not how you calculate it.

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Not exactly.

chloe_tran said:

The 92% I mention on my first post was just for example. I can see my battery life dropping really quick. As meant ion, when I charge my laptop and after 15 minute or so it can droop down to 90 something percent to upper 80

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There are two different percentages related to the battery being discussed here:

1. One is the percent of battery cycles remaining (battery has 1000 charge/discharge cycles when brand new). Earlier you mentioned 75 battery cycles on the computer…which equates to 92% of the battery cycles remaining.

2. Two is the percent of battery RUNTIME (hours & minutes) remaining on the current battery charge.

#2 seems to be what you're talking about (not #1)…which is the battery % that you see in the upper right of the menu bar. This percentage (hours/minutes remaining)…is a "dynamic" number…and it will change as the demand on the computer changes.

If you have the brightness on high, bluetooth on, WIFI on, and doing something demanding like watching internet videos…then battery runtime (on the current battery charge) will be shorter. If you turn brightness down, turn bluetooth off, don't watch videos, etc…battery runtime on the current charge will be longer.

- Nick