11.1 is very low. First check the battery with a voltmeter. If its the same as your bird is saying then your wiring isnt an issue.

Are you running with the big motor or idling? Some motors wont charge the battery unless its over 2000 rpm which should be past idle speed.

Watch your voltage when running the big motor, should be climbing pretty fast. If not you may have a weak output voltage or a bad connection on the power cable from your motor.

Toss that battery on a charger. Should go to 12.8+.