Table 1.

Prioritized list of techniques used for optimizing sleep current on Cave Pearl data loggers and associated sleep current reduction.

Techniques for Optimizing Sleep Current	Approximate Reduction
Put the microcontroller into the deepest power down modes between readings	5 mA
Disconnect ‘always-on’ indicator LED’s on the Arduino and on sensor boards	~5 mA each
Choose 3.3 V sensor IC’s with low-power sleep modes	0.05–0.1 mA each
Power the RTC from an Arduino output pin, rather than the 3.3 V rail	0.09 mA
Remove power from sensors/devices via a transistor controlled by a digital pin	sensor dependent
Test and select SD cards with the low sleep current	0.05–0.1 mA
Select an Arduino that uses a more efficient MCP1700 series regulator	20–25% savings
When combined, these techniques can reduce a data logger’s sleep current to ~0.1 mA.