One of my other projects is a handheld data logger. All along I wanted it to run off batteries but only realised later in the design phase that I wanted it to be powered by rechargeable batteries and use the power from a USB connection to recharge the batteries.
I now realise that having a small, customisable charge controller is just the thing I need. That's where this project comes in. It can be used as a stand-alone application to recharge NiMH batteries (initially this design only caters for 2 NiMH AA batteries in series).
- use 2x NiMH batteries in series for 3V
- use the USB port to obtain the maximum charge current
- use battery temperature measurement for deltaT detection
- use battery voltage measurement for -deltaV detection