Quote Originally Posted by n00b 0f l337 View Post
No peltier element will always use more then they move. If you drop a 137W usage peltier from 15.2V to 5; You reduce from 9amps to 3amps rougly. That now means 15W consumption. Now your going to be closer to around 14-15W movement, however I've never seen a peltier that will begin moving more then they consume.

A couple of years ago, my boss had me measure efficiency curves for a wide range of TECs. The results were dismal. I ran them over their functional range in terms of voltage and hot side temp. We had excellent lab facilities so the heat flow measurements were solid. All of the advertised efficiencies were totally bogus. Some measured as low as 10%, the good ones around 50% at their best - so basically agreeing with your numbers above. At high load, 40% is good.