# Overpowering a peltier element

I have a peltier element rated at 15.4V, 6A, and 60 watts that I got from China and has no datasheet to be found. When I drive it with a 12 volt power supply, I can get up to about 5.5 amps giving a power output of over 60 watts. Is this an issue? Maybe the specs I have are misleading, but they don't make very much sense to me. is going over the rated power okay if I keep it cool? I have a heatsink on the hot side and it is not even noticeably warm. Is driving it over the rated power going to hurt it? It doesn't make sense to me that the given current and voltage levels would yield so much more power than it is rated for. It makes me think the 60 watts is just a suggestion. It says TEC1-12706 on it, but as far as I can tell, that is not unique to the particular product.

15.4V x 6A is over 90W, not 60. So 60W is not the "rated power" but the heat pumping capacity.

This is in line with other Peltier coolers I've seen - they take about 1.5W of electrical power to pump 1W of heat, whereas a compressor-based refrigerator would pump 3-4W of heat for the same 1.5W input power.

So you can use it at 12V, 5.5A (66W in) and it'll probably pump about 40W.

Add these together (106W) and add a safety margin : plan your heatsink/cooling to remove something like 120W from the hot side.

The current and voltage rating of a Peltier are ususally the maximum cooling point. You should also consider them the maximum value to not exceed to avoid damage.

While there is probably some margin past the maximum cooling point before damage occurs, it is stupid to go there anyway. The cooling power of a peltier is proportional to the current thru it, but the internal heat caused is proportional to the square of the current. Eventually the square wins over linear, and at some point adding more current actually decreases the overall cooling capability. Put another way, the incremental current causes more internal heating than additional cooling power to get rid of that heat. This is what the maximum cooling point is, and which is why you don't want to exceed it even if no damage is done.

You might try looking at a few TEC data sheets, such as this one. http://www.hebeiltd.com.cn/peltier.datasheet/TEC1-12706.pdf You'll note that, for a given current, the voltage required increases as the hot side temperature rises. Since you don't have a data sheet, I suggest that the ratings you've got are probably based on a somewhat elevated temperature.

As for damaging the TEC by driving too much current through it, apparently the answer is yes. See, for instance, http://assets.newport.com/webDocuments-EN/images/AN14_TEC_Drive_Current_IX.pdf where the subject of thermal runaway is mentioned.

In general, it's true that the more voltage you apply, the more power the TEC will produce. However, that's not what you are interested in: you want to go for cooling effect, and that depends on several factors. Efficiency depends on things like your heat sink capability.