Chosen Solution
I purchased a new battery for my MacBook Pro (Late 2008/Early 2009) from iFixit and it won’t hold a charge. It takes ten or more hours to charge and when charged the meter only shows about 2.5 hours. Within a few minutes of operation the meter goes to red and shows less than ten minutes remaining. I then reinstalled the old battery, which was working ok but the charge only lasted 1.5 to 2 hours, and it started doing what the new battery is doing. Are there any settings that need to be set when installing a new battery in this model?
Try an SMC and PRAM/NVRAM reset, sometimes these are needed when installing new batteries. This should resolve the issue with it taking a long time to charge (usually it gets stuck at 20hrs to charge up), but it sounds like it could be a faulty battery if not
