New Relay Saves 100mW

A project log for Arduino MPPT Solar Charge Controller

The charge controller consists of a buck converter that is controlled by an Arduino via a half-bridge driver.

TobiasTobias 05/28/2016 at 00:130 Comments
Relay current: 24.3 mA
System power: 408.3 mW
Relay current: 8.14 mA
System power: 295.1 mW

With the new relay, the power consumption of the system on battery power is under 300mW. The purpose of the relay is to make sure that when the system has turned itself off, no leakage current discharges the battery over long periods of storage. So it only uses power when enough solar power or battery charge are available.

Since the new relay pulls so few mA, I tried to run it directly from the Arduino port, but strangely, the system uses less power with the transistor than without! So the transistor stays.