Apple Laptop Battery

Keep the battery cool and don't leave it in the sun
Lithium batteries come with built-in circuitry that protects them from overheating, so leaving a laptop to charge overnight or over a couple of days won't damage it. However, if a Apple lithium laptop battery is over-charged for too long (eg a week) it will start to heat up. Overheating is a lithium battery's main enemy and could result in permanent damage to the battery. The Apple laptop battery can also get overheated if your machine is left in the sun or near a radiator, so avoid doing this as well.
Keep the AC power adapter plugged in only when you need to charge the battery
One of the most common issues with laptop batteries is overheating. Not that the batteries are designed poorly or improperly but due to, in most cases, user wear and tear. While the laptop is using the AC adapter for power the Apple battery acts as a back up in case of a loss of power or accidental unplugging. During this AC power use the battery becomes hotter than it would if being used independently. To lessen the chances of this overheating, which leads to a shorter life expectancy of the battery, keep the AC power adapter plugged in only if you need to charge the battery while using the device.
How to calculate your Apple laptop battery's life?
Generally, Apple laptop batteries offered by us have two ratings as parts the specifications:Voltage(Volt) and Amp Hour(mAh).One thousand Milliamperes equals 1 Ampere.Some batteries are also rated by Watt-Hours(Wh).This is found by multiplying the Volts and the Amperes together.
If the battery does not have the Wh rating printed on it, it will most likely have a couple of other numbers that you can use to calculate the Wh rating.
Look for the voltage (V) and Amp Hour (Ah or mAh) ratings so you can do the math yourself by multiplying V x Ah. If you see 6600mAh it's the same as 6.6Ah (divide by 1000) which is what you multiply by the voltage.
For example, if you have a battery with the specifications of 11.1V and 6600mAh, you would multiply 11.1 x 6.6 which equals a 73.26 Wh rating.
If you use 25 watts per hour as the average consumption for a laptop, you would expect to get almost 3 hours out of a 73.26 Wh rated battery. Note:The actual Apple laptop battery life that you will achieve will vary widely based on the exact equipment installed in your laptop and what you do with it.