New Feature: Peltier Aging Diagnosis
Peltier elements are considered wear-free, but they can still age under certain operating conditions. High temperatures, rapid temperature cycles and excessive operating currents accelerate the aging process. Typical signs of aging are a decreasing COP (coefficient of performance) and increasing internal resistance.
With the new and free feature of the Meerstetter TEC Controllers, you can monitor the internal resistance of your Peltier element in real time. An increase in the internal resistance in relation to a reference temperature indicates progressive aging. If the measured internal resistance exceeds a user-defined threshold value, the TEC Controller optionally issues an error message. The measured internal resistance and the defined threshold value are visible in the TEC Configuration Software. The threshold value can also be individually configured there. Both values can be read out via digital interfaces and a GPIO pin can also be used for signaling if required.
The internal resistance is measured by briefly modulating a sine wave on the existing output signal. The effective internal resistance is calculated from the resulting alternating voltage and the alternating current - without noticeably disturbing ongoing operation.
Demonstration: Accelerated aging due to overloading
In an internal test, a Peltier element was operated for 2.5 days at 125 % of the maximum permissible current and subjected to rapid temperature cycles. The temperature transients were in the range of 10°C/s. The internal resistance was continuously monitored during the test.
The following diagram shows the course of the internal resistance over time:
Note: The internal resistance is temperature-dependent. Therefore, all measurements were carried out at two selected temperatures to ensure comparable results.
Recommendation: Replace at 15 % increase in internal resistance
Based on our tests, we recommend replacing the Peltier element if the internal resistance has increased by 15 % compared to the initial value at the same temperature. This proactive measure helps to avoid system failures and maintain the efficiency of your application.
Measurement modes & behavior of the aging diagnosis of Peltier elements
Three operating modes are available for maximum flexibility:
- Single: A single resistance measurement is carried out. The function is then automatically deactivated.
- Continuous: The internal resistance is measured continuously every 100 ms.
- Periodic: The measurement is carried out at a user-defined interval.
A single measurement takes around 100 ms. During this time, the voltage and current are “frozen” - however, the temperature is hardly affected in stable systems. Important: The function should not be activated during critical operating states or during autotuning of the controller.
Configuration of the Peltier Aging Diagnosis
The maximum amplitude for the modulation of current and voltage during the measurement is set in the TEC Configuration Software. The globally set current and voltage limits of the output stage are observed. The amplitude of the modulation adapts to the configured output limits.
The Peltier Aging Diagnosis is activated and configured using the TEC Configuration Software from Meerstetter. The limit value for the internal resistance is set there and the behavior is configured if it is exceeded. In the following tutorial video, we guide you step by step through the setup in the software and explain all the relevant functions.
Further detailed information on the setup can also be found in the TEC Family User Manual.
Downloads
- Configuration file for Peltier aging diagnosis demonstration
- Lookup table for Peltier aging diagnosis: Temperature cycling data
- TEC Family User Manual (PDF)
- TEC Configuration Software
Note: Please adapt the Imax in the configuration file to your specific requirements and your setup.
For further information or assistance, please contact our support team at support@meerstetter.ch.
Available soon – but you can try it today
We're offering early access to selected customers. If you'd like to test the feature ahead of release, just reach out – we’ll be happy to support you.
Meerstetter TEC Controller - precision, reliability, control
The TEC Controllers von Meerstetter Engineering stand for precision and offer state-of-the-art functions for temperature control with Peltier elements - now including Peltier diagnosis for aging monitoring. Developed for demanding applications in industry, research, medical technology and beyond. Discover our products and find the right TEC controller for your application.