MacBook battery charges with low wattage

I’ve been using my early 2011 MBP for a while since I got a new ssd and battery for it about 2 weeks ago, and its frigging fast. One problem that I noticed right away was that when it was discharging from full, the percentage would plummet and hang around the 2%-7% range for about an hour. But I attributed that to it being brand new and let it go through a few charge cycles.

The main problem is that it charges super slow. From 0%, charge current was about 3.2 Amps at about 40 watts, which was expected. But as it charged up to 20% it started to taper off to 2 amps at around 26 watts. And it kept going lower from there to 14 watts at 30%. I don’t know why, but when I unplugged the charger and plugged it back in, it jumped back up to 26 watts and holding steady around there. Still not 40 watts but it’ll charge faster. I don’t know if this is like a “break-in” process or something is wrong with my battery or logic board.

I’ve already tried cleaning out the MagSafe connector on both ends, resetting the smc, hitting the pram, reseated the battery twice, and using a UPS. I also tested the MagSafe charger on a 13” MacBook and it charged with 30 watts all the way up to 80%. And just for the record I am using the 85w brick, which is in pretty good shape. Sorry for the wall of text, but hopefully I can find some answers here.

Edit:

Dropped from 39% to 2% before I could get coconut battery open.

Screenshots of coconutbattery not connected:

Coconutbattery connected:

Edit 2:

To be honest I don’t think there’s really a fix for this problem. There was another thread on this here: Slow charging and sudden battery life loss

There were a few people in there that are experiencing the same problem I am, even across multiple batteries. I think if I were to ask for an exchange I would only run into the same problems. All across the same time frame. I’m just going to deal with it and hope that it sorts itself out.

Edit 3:

I believe that I’ve eliminated enough variables to conclude that the battery is indeed at fault. The charger works correctly, there’s no junk in the battery connector or MagSafe connector, the smc reset had no effect, and a software update had no effect. I saw that my 2009 13” MacBook had the same battery connector that this 2011 one did, so I switched them. Even though that 2009 battery was a 60 wh battery, it still took more power even at a higher charge level, and the fixit battery struggled to pull even 7 watts at 70%. I don’t know why this battery behaves this way, but I’m going to put as much use on it as I can, I hope it evens itself out.