Keep in mind that an 80W LED bulb draws about 8W to deliver the same amount of lumens, compared to an incandescent bulb. Also keep in mind that the transformer magnetic field saturates when driven with a square wave, so there are significant energy spikes during transitions (overshoot/undershoot/ringing), so simple measuring equipment such as analog meters will read higher than actual values. Basically, you've made a cheap power inverter.
