I have a same problem. New battery from iFixit that reports as 100% healthy and able to take a full 6725mAh charge. However it drains much faster than the estimated times and only achieves around an 1hr of use under normal usage.
What's noticeable is that swell as just draining much more quickly than battery menu reports it also charges much more quickly than expected. It says around 1h 30m Unti Full plugged in with a charge of 50%. It actually did this in 30 minutes.
So lets say it's charging and discharging 3x faster than it should be doing given it's reported health and stats. Any thoughts on how this could be fixed. If not does iFixit provide something like a 12 month warranty under which I could get this battery if it's bad replaced?