HvA investigated differences between laptop power supplies

The Amsterdam University of Applied Sciences (HvA) tested the power supplies of laptops on behalf of FHI and the Dutch EMC-ESD association based on EMC directive. The aim of these tests was to investigate whether there were differences between regular European A-brands and cheaper Asian B-brands. Was there interference or noise with certain models and could potentially dangerous situations arise? Although all tested chargers met the CE mark and NEN-EN-55022, there were certainly differences to be noted.

By Frank van de Ven

The tested power supplies from Europe were ordered from major online retailers such as Bol.com and Coolblue. Chargers from Asia came from AliExpress. According to the packaging, all products met the requirements of the CE mark. FHI and the EMC-ESD association wondered whether that was the case given the pricing. In collaboration with the Amsterdam University of Applied Sciences, research was conducted to see what the largest (quality) differences were.

Students Boris van Wessel and Youness Azoubairi started working on this research under the supervision of lecturer Dr. Cees Keyer. The aim of this study was to make people aware of EMC problems that can arise with a product that does not comply with the guidelines, to generate attention for the EMC field and to level the playing field. Products from Asia are often cheaper than European goods, but what is the quality actually like? The research did not reveal any major differences in quality, although it appeared that Asian power supplies cause more noise and interference. An order also arrived damaged and there is no warranty. Returning a package to China costs more than buying a new European product.

Noticeable difference
Four universal chargers were used for the test with a power between 60 and 65 Watts at a current of 3 to 3.25 A. The selected chargers were chosen based on their popularity. The Safe Mains Voltage Monitor was used for the test. This system was developed to safely measure the current drawn by the charger using a current clamp. To ensure that all chargers were exposed to the same power requirements, an electronic load was used during the measurements. A probe measured the minimum and maximum output voltage of the chargers.

When preparing the chargers for the measurements, the team discovered a noticeable difference in weight between the Asian and European chargers. The Asian loaders weighed significantly less than the European systems. Both the imported and European chargers have a mains spectrum that never exceeded the quasi-peak limits of NEN EN-55022. All tested equipment met the EMC standards.

Noise on the power grid

There were minimal differences in power consumption between the two tested European chargers. This did not apply to the Asian models, because there were larger differences between the minimum and maximum output voltage. Major differences were not only noticeable among each other. Compared to the European chargers, the output voltage of the Asian systems was very high.

The large differences between minimum and maximum output voltages are a point of attention for Asian chargers. All measured chargers meet the NEN-EN-55022 requirements. However, there are differences between the amount of noise and the voltages generated. The quality of Asian chargers with regard to EMC emissions depends on the model. A large difference in noise was measured on the power grid between the models. This does not apply to European chargers and the quality of the tested systems is very close.

The results of the research have been bundled in a white paper. That document is intended to make people aware of the importance of the EMC field. The results of the research will be discussed in an exclusive lunch session for the Dutch EMC-ESD association. Videos discussing the study will also appear later. A follow-up study may be planned in which increasing awareness and a fair level playing field are central.