Teardown MPOW Solar-Powered Security Light

2017-09-05 | By All About Circuits

License: See Original Project

Security is a very important aspect of life and one device that is commonly found in homes is motion activated lights. In this teardown, we will look at a motion activated security light that uses solar power, which makes it independent of the mains electricity.

The Security Light

The device has a triangular shape to it in order to maximize the charging ability of the solar cell. The lights point downward toward the ground as to light up the area (remember, this will be fixed high up on a wall), and the lighting area also contains the motion detector dome.

The motion activated security light

This dome will most likely contain a PIR sensor which detects changes in IR light as opposed to absolute values. The security light has multiple options that control the brightness of the light but all options will activate the system when it gets dark. This feature is easily implemented using the solar panel (it can act as both a sensor and a power source).

The solar panel on the topside of the security light

The IR dome and light array

The back of the unit contains the instructions for the device including the sliding button options and wall fitting instructions. No screws are visible on the backside which suggests that they may be underneath the instruction sticker. Once removed, several screws were revealed and thus access to the inside was made possible.

Backside of the unit and instructions

Sticker removed showing fittings

The Lithium-Ion Battery

The small compartment that can be seen on the back of the security light contains a single lithium-ion battery. These battery types are becoming ever more common in electronic products for their convenient size, large capacities, and for their longer life as compared to other battery technologies. The battery shown here is stated to have a capacity of 1200 mAh with a nominal voltage of 3.7 V. Therefore, this battery can supply 4.44 W of power for a single hour before running out of charge.

The battery compartment opened up revealing the battery

The battery specs as displayed on the battery itself

Internal Electronics

The security light is rather simple in construction with mostly surface mount parts being used. The PCB has several wires connecting to other components (such as the lights and battery), and is held in place with three screws (this is unusual because three screws allow for one corner to move up and down). The traces visible on the PCB are very wide which suggests that most of this PCB is power control for charging the battery and powering the lights.

The PCB housed in the product

Close up of the main PCB fixed in place

PCB removed from the security light

The first IC of interest is the DC1608, which returns no results when looking for datasheets online. However, by looking at the configuration of traces going to and from the IC, as well as nearby components, this 8 pin SOIC is most likely the IC responsible for controlling the lights. Underneath the PCB are various traces going from the pins of the IC to the switch selector and the topside of the PCB shows a large copper plane from one of the light wires connecting to the IC.

The unidentifiable DC1608 IC

The second IC of interest is the DW03D which is stated online as a lithium-ion battery charger/controller. This IC will be responsible for taking the power generated by the solar cell and ensuring that the li-ion battery is correctly charged. According to online resources, the IC is manufactured by Shenzhen Fuman Electronics Co.

The DW03D Li-Ion Controller

The underside of the PCB only contains the PIR sensor that has the designation PIR AL312, which is a common fully integrated PIR detector found in many products. This sensor sits inside the dome which detects changes in IR reflection and once detected, will trigger an output. The dome itself helps to gather IR emissions from the environment and direct them onto the sensor itself (which is a small silicon die that sits underneath a glass window).

The PIR Sensor on the underside of the PCB

The Lights PCB

The lights sits on a different PCB found inside the security light. Unlike the first PCB which uses FR4 as its base material (a high quality PCB substrate), the light PCB uses a cheaper FR2 material (one made with epoxy bonded paper as opposed to fiberglass). However, FR2 does have advantages including lower costs and increased tooling life. The LEDs are of the surface mount variety and all connections are made on one side only.

The underside of the light PCB

The topside of the PCB

Summary

This security light shows how it only takes few components to make a circuit that can charge a battery, detect motion, and emit light upon detection. Testing the device showed that this light can definitely light up a large area upon detecting motion and will do well as a security light. The use of common parts such as the PIR sensor help to keep the part count low as well as the cost.