New power boost issue

[the watchmaker]

Can Someren help me with this:
When i plug in the battery (3,7v 2000 ma, measures 4,14v) into the power boost the blue led lits. Then I plug in the charger (5,1v 2,5a, original raspberry), the yellow led lits ( so charging I presume).
When after that I disconnect the battery, leave charger in. Reconnect the battery the yellow led is out and green led lits. Battery full.....
This looks like if the power boost does not stop charging when charging is started when battery is connected. And that will exactly be the situation when everything is assembled.
Does more people have this one r can someone explains what is happening?

Thanks