Yep so the dna 30 loses 6% of the energy/watts/amps the battery puts out and converts it to heat in the circuitry.
So if the dna 200 is the same efficiency it eats up 12 watts at full output power so the battery is actually providing 212 watts not 200.
yet another reason to provide a bit of headroom on your battery ampacity limit for safety.
This was one thing I Really Liked about this Online Calculator...
Battery drain | Steam Engine | free vaping calculators
They made the Allowance for the Lose due to Non-Perfect Efficiency.