#### seaslug

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View attachment 528921

Sea, When iwas trying to calculate the efficiency of the driver i simply added the vf of the pair of 72v cobs and approximated that i was around 90% efficient. Im wondering if my math makes no sense at all. I was using the attached graph.

I think you're only doing the first step. Say there is 144Vf total on our string of LEDs. How do you read the Mean Well efficiency chart? We need to know what the fraction of total power is, expressed as a percentage of total allowable load. The maximum (constant current region) voltage for the HLG-120H-C700 is 215V. In this example, the load would be 144V / 215V = 67% Looking at the chart you provided, this puts the driver efficiency at just over 92%.