Assembly spotlight: Timer Boxes

Sometimes good engineering can look like really boring projects. To design a system right, end to end, there are elements which are relatively simple, specific, and not all that exciting. Today we're looking at one of those projects: a timer circuit for our sister organization Electric Fleet.

Background:
Electric Fleet's customer is using a 48 volt Columbia Summit Utilitruck with a 12 volt light bar for security patrols around their campus. The vehicle has an onboard 12v DC-DC converter for powering headlights and accessories, however, it is tied to the cart's keyswitch and does not provide power when the cart is off. 

Problem:
Electric Fleet found in a user study that the customer's security team would need to operate the light bars while the cart was not running. We wanted to give them that functionality, but we didn't want them to inadvertently leave the light bar on and drain the batteries. 

Solution:
Electric Movement's solution was to design a timer circuit with its own DC-DC that would pull power for the light bar for 4 hours following the cart's shutoff. The timer circuit also has a low voltage shutoff to prevent the light bar from damaging the batteries. 

Eric, one of our electrical engineers, took the lead on this project in design as well as managing the assembly documentation and build. Caleb & Jay worked with Eric to assembly the PCBs, the enclosures and prepare the harness for installation. The team worked with panalized boards so they could build 5 at a time. They also used a reflow soldering technique which shaved hours off the process compared to hand soldering. Check out their assembly process start to finish: