New Battery for my Vintage MacBook
Lithium cells degrade over time so getting a new cell is always better three years shelf life or worse. Worse, if the part falls into deep discharge, it will be ruined. I have no issue with old batteries but I charge them up to 50% every 6 months to avoid deep discharge.

When you can get a cell that you know was put into long term storage properly, then buy from the vendor that you trust most. In this case, you're rolling the dice that the Apple part was made towards the end of the production run and not the beginning. You always have to do extra work with aftermarket parts, since some manufacturers cut corners and are even unsafe.



Here's Apple's take on this: http://www.apple.com/batteries/maximizing-performance/

Store it half-charged when you store it long term.

If you want to store your device long term, two key factors will affect the overall health of your battery: the environmental temperature and the percentage of charge on the battery when it’s powered down for storage. Therefore, we recommend the following:

Do not fully charge or fully discharge your device’s battery — charge it to around 50%. If you store a device when its battery is fully discharged, the battery could fall into a deep discharge state, which renders it incapable of holding a charge. Conversely, if you store it fully charged for an extended period of time, the battery may lose some capacity, leading to shorter battery life.


Power down the device to avoid additional battery use.
Place your device in a cool, moisture-free environment that’s less than 90° F (32° C).
If you plan to store your device for longer than six months, charge it to 50% every six months.
Depending on how long you store your device, it may be in a low-battery state when you remove it from long-term storage. After it’s removed from storage, it may require 20 minutes of charging with the original adapter before you can use it.