Macbook shuts down

For way too long I did not replace my battery on my mid 2012 Macbook pro. 30 mins from fully charged to 0 was the max. Today I got a new battery, replaced it with the old one, turned on the mac, only to see the battery was already at 65 percent of charge. For some reason I unplugged the cable and immediately it shut down. I turned it on again, noticing that the mac would only work when the charging cable was plugged in. I Worked for some 10 mins and it was still on 65 percent battery. Hovering the mouse over the battery symbol showed that it wasn´t charging. Still 65 percent. I turned it off, removed the 10 screws, and the lower case, took out the battery, inserted it again, put on the case and screws. Plugged it in, now it started to charge. And until 20 mins ago the battery was at 99 percent, when I removed the charger. Still, the mac shuts down.

Here are some battery details. Any tips would be appreciated