Calex Charger Teardown
This showcases a teardown and de-potting of a Calex 1200 charger from a 2016 DSR model, following a total failure of the charger.
- Odometer estimate when the charger failed: 31000 miles.
- Symptoms observed prior to the fault:
- Excessive sparking at the inlet despite cleaning and using a hospital-grade cord.
- Prior failure at 30,000 miles of the Sevcon DC-DC converter.
- General Observations
- A component on the board overheated and caught fire.
- The fire burned through the board.
- The rubbery potting extinguished and contained the fire.
- Design Observations
- The board is mounted on the upper side of the charger casing, with the largest/heaviest components suspended below it within a great mass of potting.
- The board itself is mounted very close to the surface that is flush with the underside of the main powerpack casing on the S platform.
- The rubbery potting fills the case volumetrically, and is likely poured in as a substance which then sets chemically or thermally.
- The board surface is nearly as large as the enclosure, and seems too thin for its span to support the mounted components on its own.
- The components seem mainly supported by the potting.
- The board's unusual size could be an attempt to increase the distance between components.
- This might be intended to reduce the intensity of heat buildup inside the charger, after the 2014-2015 design proved to be prone to failure.
- The board's capacitor banks do not seem adequately shielded from current inrush.
- This lack of shielding probably plays interacts with a dirty charging inlet and possibly also interacts with a glitchy DC-DC converter on the main/output bus.
- Stock Charger Teardown blog post shows a 2015 S' charger with a somewhat different board layout.
The photos presented are all oriented with the rear/connection side of the charger pointing to the right.