We have designed an "always ON" electronic home automation device which goes behind the switchboard (inside the wall.) This is the first commercial product that I am designing, so bear with me for obvious things.
The total maximum consumption of the device is 600-800 mA. It has an ESP32 module as a controller along with four ATmega328 microcontrollers and around six relays connected outside or away from this device.
This device is powered from 2 A, 5 V i.e 10 W AC to DC converter from one of the reputed brands from China - UA10-220S05P2 (10 W, 5 V) datasheet. In order to reduce the size of this converter, we have removed the outer plastic casing of the AC to DC converter (a picture of this is attached.)
After testing this device for around a year and a half continuously without turning AC to DC converter off, we are facing issues with AC to DC converters. When we opened and saw, it is found that either one and/or both, 400 V 10 uF electrolytic capacitors which are used near rectifier has an open vent and oil leakage from them.
We have tested this on 4 to 5 devices. After approximately 1 year to 1.5 years all the device's AC to DC converters stopped working and has the same issue. To confirm that it is problem only with the suspected capacitor, we removed and replaced this capacitor and the device is working again.
Our guess is that the long-term issue is caused by heat build-up inside the product enclosure, degrading AC/DC converter performance. We tried using an aluminium plate around the AC/DC converter as a heat sink, but I'm not sure it works better.
Any ideas/suggestions/feedback on:
- What could be the issues that could be cause it? Any known-standard solution/ideas you could share for it.
- How to conveniently to test such long term issues? How can these be emulated so that we know the proposed solution is working?
- Was removing the plastic casing a bad idea? When we tried aluminum shield (which should be better than plastic case - in terms of heat dissipation,) we found little difference (temperature on and around AC/DC converter inside our product) when compared with the one without case.