RE: Half stick no more power
Here is what Motocalc says for an E-flite Power 46: if you are trying to draw 100A and push 1800W into an 800W max motor... you are in deep trouble!
Motor: E-Flite 46BL Outrunner; 670rpm/V; 3.88A no-load; 0.04 Ohms.
Battery: FlightPower 3700 (20C); 5 series x 5 parallel cells; 3700mAh @ 3.7V; 0.0037 Ohms/cell.
Speed Control: Castle Creations Phoenix 80; 0.001 Ohms; High rate.
Drive System: Direct Drive; 14x10 (Pconst=1.17; Tconst=1) direct drive.
Airframe: Anything you want.
Motor Amps = 101.8
Motor Volts = 18.0
Input (W) = 1835.0
Prop RPM = 9345
Thrust (oz) = 182.8
PSpd (mph) = 88.5
Of course, your 5s 5000 pack has no hope of maintaining 18v under load, so your amp draw/watts-in will be a lot lower than this.