New battery won't fully charge

I bought a new battery from iFixit and replaced my old battery, and now, despite calibrating the battery 3 times, resetting the SMC and PRAM, it won't charge past 90%. If I unplug my computer soon after the level says 100% and my charger is green, it drops down to 89%. If I leave it charged for a couple hours afterwards, it will eventually charge, and will discharge normally, but I have no idea of knowing when it's fully charged (both System Report & coconut battery say it's fully charged at that point).

While my old battery wouldn't last as long as it had before (the Genius Bar said it was functioning at 60%), I never had this issue with it, which is why I assume it must be something with the new battery and not another part.

Any ideas would be much appreciated, I've done everything I can think of.

Thanks!