Science Buddies: "Ask an Expert"

We have done the science buddies project "Icy Hot Electricity: The Thermoelectric Effect" by Dr. David B. Whyte (https://www.sciencebuddies.org/science- ... p055.shtml). In this project, we remove the semiconductor (bismuth telluride) thermoelectric device from a Roadpro 7 Liter 12V Cooler/Warmer (model RPAT-788), together with the heat sinks and the fan attached to the device. Then we create a temperature difference across the device, making its top part hot while keeping its bottom cold. In response, a voltage would be generated at the output of the device, which we then measure. Such a device typically has a number of p-type and n-type semiconductor elements, where one p-type and one n-type element form a couple. Each couple will generate a certain voltage. All the couples are connected in series, so the output voltage from the device is the sum of the voltages from all the couples.

We have measured the voltage for the device, but we like to know the voltage generated by each element or couple, given by (measured voltage/number of couples).

Does anybody know how many elements or couples are in the Roadpro cooler's semiconductor device, or the device's model number, or how we may be able to find the information?

Thank you in advance for all the help.

Albert

alberthome - I tried to read several Peltier effect spec sheets, but the individual Vf (forward voltage per cell) doesn't seem to be an item discussed. All of the commercial assemblies are fabricated of many P-N couples or cells wired in series. In your device you could try to count the rows and columns between the hot and cold collector plates (the P-N couple could look like two elements) and divide the voltage applied to the assembly by the number of P-N couples. That would tell you what the average Vf is per cell. The literature I did find most helpful suggests that this forward voltage is very low, in the order of 60 millivolts per cell (when generating a thermal difference). Check out part 2 of this link. It might be just the information you need. In that you are looking for the opposite effect, voltage generated by each cell when hot and cold sources are applied, it is basically the same approach. Divide the voltage generated across the assembly by the number of cells.

http://www.tellurex.com/technology/peltier-faq.php

Rick Marz