I have always left my Macbook open (I hardly turn it off) with the charger on. Is it alright or is leaving the Mac connected to the charger unnecessarily can damage the computer?
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Charging a Macbook
- Thread starter rustyclx
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Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug any time you need to, regardless of the charged percentage, and you never need to completely drain your battery. Just make sure you don't run on AC power exclusively, as your battery needs to be used regularly to stay healthy.
The link below should answer most, if not all, of your battery/charging questions. If you haven't already done so, I highly recommend you take the time to read it. 
What about calibration? Though, to be honest, I've never calibrated my current MBP.
Even if left plugged in all the time the battery will still partially cycle, the charger doesn't charge to 100% and then just hold it there. The battery will be allowed to discharge down to about 95% while plugged in before the charger brings it back up. Use your laptop however you see fit, the charger is smart.
My MBP has been plugged in the vast majority of its life and is over a year old, the battery is still quite healthy. The battery is actually at 97% charged right now, going through one of the partial discharge/charge cycles.
Charge Information:
Charge Remaining (mAh): 6483
Fully Charged: Yes
Charging: No
Full Charge Capacity (mAh): 6666
Health Information:
Cycle Count: 20
Condition: Normal
My MBP has been plugged in the vast majority of its life and is over a year old, the battery is still quite healthy. The battery is actually at 97% charged right now, going through one of the partial discharge/charge cycles.
Charge Information:
Charge Remaining (mAh): 6483
Fully Charged: Yes
Charging: No
Full Charge Capacity (mAh): 6666
Health Information:
Cycle Count: 20
Condition: Normal
The built-in batteries in the newer Mac unibody notebooks come pre-calibrated and do not require regular calibration like the removable batteries in older Apple notebooks. Read the Battery FAQ for details on this and other battery questions.
That's not true. In fact, it's designed to prevent such short discharges and recharges. Read the CHARGING section of the Battery FAQ for details.
I don't need to read it, I've watched this happen with MY OWN EYES and is part of typical laptop charger design. Once the battery is charged the battery charge circuit turns off and the laptop runs off the brick. The battery will naturally, slowly discharge over time. The charger will not re-enable the charge circuit until the battery drops down to about 95% at which point it kicks back on and charges the battery back up to 100%. The charger doesn't apply a constant float charge to the battery to maintain 100%.
It won't charge until it drops to around 93%, but it doesn't constantly drain and recharge. Once fully charged, it runs on AC power, so it won't drain the battery. Unless you're talking about a very long time, the battery remains fully charged while running on AC power.
I think the confusion here is that you assumed I meant the laptop would actively discharge the battery on purpose while plugged in.
It seems to take 1-2 weeks for the battery to discharge enough to kick the trickle charge back on and bring it back up to 100%.