Swollen Battery Apple A1382

The sign of a swollen battery was I couldn't press down the touchpad like I could before.  I have been using a separate keyboard and a touchpad for quite some time so I didn't notice that until I used the built-in touchpad.  I almost forgot if it's supposed to be that way.

An online search on the touchpad anomaly returns me the result that it may be caused by a swollen battery.  And as it turned out it was really the battery.

I removed the battery and the touchpad worked just like before.

I could work without the internal battery but anytime if the power cable knocked loose, the system will just shut down.

I went to the usual source like macsales but the third party battery is asking for almost $100.  I even went so far as to chat with them in order to get a discount coupon code.  Alas there was none for me.

After much deliberation, I ended up ordering from eBay.

The battery came as real as it can be except the serial number on the sticker doesn't match what's reported by the MacOS.  Battery health is Normal and has 2 cycle counts.  The manufacturer reported is SMP, same as the original battery that came with the MBP.

macsales still have video suggesting to calibrate the battery or the power management system of the MacBook ... On the other hand, there seems some consensus that the Li-ion battery doesn't need that or draining it to zero percent does harm to the battery actually.  I am a bit confused.  So I didn't do that calibration at least not intentionally.

The original battery is supposed to last for seven hours on a full charge.  It seems like the battery depletes on a linear fashion up to when it's 30% then before I knew it it dropped to 7% which stays there for more than 30 minutes and still going unchanged ...  I guess I am waiting for the system to shut down itself.  It's about 5 hours now.  I don't think it lasts 7 hours but definitely more than 5 hours and it's still going at 7%.  Maybe that's why it needs calibration, not so much on the battery but for the system PMS to know the battery better so it can accurately report the battery power as it depletes?  I really don't know.

100% Battery power began at 8:06 AM
7% at 1:34PM (It has been 7% for a long time)
7% at 1:51PM
2% at 2PM, also message to plug in
shutdown at 2:10PM
so it's 6 hours.

UPDATE: 4/6/2019
The replacement battery seems performing just fine.  So I am happy I didn't buy the more expensive one, most of the time the MBP is powered with an A/C adapter anyway.  Plus this is an old machine I don't want to invest more than I need or afford.  In a year or two I hope I can afford a better machine down the road.