Gumstick Battery Charger Project Case

Last crawled date: 4 years, 2 months ago

This is a project box for a DIY gumstick battery charger. The box has the following features:
Slots to accommodate a circuit board
Ventilation for cooling the electronics
Hole to accommodate a 5mm LED
Holes to accommodate a power socket or directly wired power lead
A battery retainer, in case the battery wants to pop out
The negative terminal is made from single core mains conductor, with a diameter of 1.3mm -there is a hole in the side of the box to aid insertion. The wire is kinked such that it can make contact with the battery.
The positive terminal is cut from 0.3mm copper sheet -this is flexible enough to insert from within the box. The gap betweeen the copper terminal and the case is filled with some flexible material, like hot-melt glue. The ends of both terminals are folded around on the inside and soldered together.
The charging circuit is out of the scope of this project, but it can be quite simple like a suitably rated resistor, so long as a timer is used. I used a 2 transistor constant-current charger circuit (see diagram), which is designed to work on an input voltage of 5V and provides an average of around 210mA -this circuit also requires a timer. Transistor Q1 must be able to dissipate 820mW.