MacOS – Broken battery – downgraded performance

The fact that your computer shuts down at 50% remaining charge and also that your MagSafe LED remains orange makes me think that either the replacement battery isn't an official Apple part, that it is defective/DOA, or that your logic boards SMC is corrupted and needs to be reset.

If the battery is indeed new and Apple original than proceed with an SMC reset:

http://support.apple.com/kb/ht3964

This will tell the SMC chip to reset all power states and reboot so that it forgets the battery and MagSafe adapter momentarily and then rediscovers them.

Hope that helps

I can not repair your battery, but try to provide you with information to decide if the battery is EOL.

There are 3 conditions reported.

Replace Soon: The battery is functioning normally but holds less charge than it did when it was new.

Replace Now: The battery is functioning normally but holds significantly less charge than it did when it was new. You can continue to use the battery until you replace it without harming your computer.

Service Battery: The battery isn’t functioning normally, and you may or may not notice a change in its behavior or the amount of charge it holds. Take your computer in for service. You can continue to use your battery before it’s checked without harming your computer.

In About This Mac-- more info look for battery information such as:

Charge Information:

• Charge Remaining (mAh): 2147 (it shows this at 40% remaining based on current consumption)

• Fully Charged: No

• Charging: No

• Full Charge Capacity (mAh): 4829 (this indicates the age, or the capacity of the Battery)---> on a new and healthy battery for my MBA that should be in the range of 7500 mAh, so I lost some over 2 Years of use.

Health Information:

• Cycle Count: 480 (this is my battery on MBA 2012)

• Condition: Service Battery :(

• Battery Installed: Yes

• Amperage (mA): -1458 (this is your current consumption)
• Voltage (mV): 7612 (this is also a indicator of your battery health in how well can it keep the Voltage at load)

There is a circuit mounted on/in the battery, not part of your computer but part of battery, that reports battery information to your computer. That information is then used to present you with the battery conditions. If that circuit is faulty, you have to replace the battery, even if the battery it self is still in a good condition. There is no way to reset or repair that circuit.