Mcu 0093-NiMH-battery-charger

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).

Design criteria:

• 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