Does that instrument give you a current and voltage reading at the same time. If so then for 80 watts with a 4s or 14.8volts you should be seeing a current draw or amps of 5.405 amps.

Another way to check it is:

If you have an ampmeter that can handle up to 80 amps, then you can put it in series and measure your current. Then put a voltmeter in parallel under load, and measure your voltage. Then multiply the current with your voltage to get the watts. I think that measurement of 80watts total is not correct.