This shows that your accelerometer is broken. (or, more likely, that the vector is mislabeled) Try this thought experiment. Assume your phone is really accele

This shows that your accelerometer is broken. (or, more likely, that the vector is mislabeled) Try this thought experiment. Assume your phone is really accelerating downwards when at rest. Then let it enter a free fall i.e. drop it. Now it's accelerating down even more so the downwards acceleration should show an increase. Actually, it goes to zero. Relative to a free-fall, being stationary is an acceleration upwards.