AVS UK has designed, built, and tested a torsional thrust balance system with wireless radio frequency (RF) power transfer at the electric propulsion lab at the Surrey Space Centre (SSC). Following integration, and characterisation tests such as wireless power transfer efficiency, and thermal drift, it was used for the main test campaign of AQUAJET, an ECR thruster development model built by AVS UK. The thrust balance is tested through a measurement range from a few µN to several mN. This paper covers the detailed description of the balance design, calibration process, achieved calibration and measurement accuracy, and results of first AQUAJET thrust measurements.