Handy Test Battery and Charger

This provides a handy portable logic-level power source for bench top use during testing.

It is based on a 2AH 16500 Li-Ion battery and has these modules:

1. A charger with USB input and  JST output connectors,

2. A DC-DC converter.

It has switches to provide these outputs:

1. 4.2V from the charger if the USB is connected.

2. Direct from the battery,

3. Fixed and variable voltage from the DC-DC converter,

The charger has a switch to select 3 charging currents in the constant-current region: 100, 200 and 500 MA. Its maximum output voltage is 4.2V.

The DC-DC converter has a recessed slide switch to select its output voltage: 3.3. 5. or variable 0.8 to 9V. The slide switch is so tiny and recessed it needs a tool such as a tweezer to operate.

A switch connects the battery. Another switch selects whether the output positive (red) terminal is connected to the battery or the DC-DC converter, It has a center-off position.