"Shunt The Fangpusun PA HS200 is a highly intelligent current sensor with extremely low own consumption. The Fangpusun PA HS200 comes into play when (e.g.) an inverter is directly connected to the battery and the Fangpusun Tarcom or Power Tarcom charge controller cannot measure the current consumption. A shunt is also required when an additional generator (e.g. PV, wind ordiesel) directly charges the battery without being connected to a Fangpusun Tarcom charge controller. The current is measured contact-free via a Hall-effect sensor. The data is transmitted to the charge controller over a cable connection. Up to two Fangpusun PA HS200 shunts can be connected and the measured current can be selectively added to the charging current, battery current or load current as desired. " http://www.fangpusun.com/