Typical ‘LUCAS’ ALTERNATOR - Capricorn Controls

1 Capricorn Controls Application Note Page 1 of 3 E. & O. E. The Proven Solution to Power Controls AN02CA01-1 Typical LUCAS ALTERNATOR This is the most common arrangement where the Charging ALTERNATOR has three connections : B+, B- and WL . With the engine stationary and the Fuel Solenoid energised, excitation current will pass through the internal power resistor (lighting the Charge Failure LED) to the WL terminal which will be close to Battery Ve. As the engine is cranked, the voltage at WL will rise and when the engine is running normally this voltage will be at or above that of the Battery, reducing the excitation current to zero and extinguishing the Charge Failure LED.

2 The ALTERNATOR is now excited and charging the Battery. If at any time, the Charging ALTERNATOR fails (to charge the Battery), the potential at the WL terminal will fall to zero and the Charge Failure LED will be Lit. Note: the internal 82 Ohm power resistor is a compromise value to suit both 12V and 24V systems. Very occasionally, a 12V ALTERNATOR will not excite with this value and an external diode and power resistor must be added as shown below .. Rate Diode for 1A 100V and mount resistor for adequate ventilation For test purposes, temporarily connect an Analogue or Digital Voltmeter between the WL terminal (+Ve) and Battery Ve, see overleaf.

3 4 5 8 WL RSM, EPM or KSM Engine Controllers + Battery -- Charging ALTERNATOR FUEL SOLENOID RELAY 82 Ohm 6W Resistor Charge Fail LED D 100 Ohm 6W Resistor Capricorn Controls Application Note Page 2 of 3 E. & O. E. The Proven Solution to Power Controls AN02CA01-1 Typical YANMAR ALTERNATOR Certain Charging alternators (typically found on YANMAR engines) have a L Lamp Terminal and a separate IG Ignition Terminal as shown above. Capricorn Controls manufacture some Engine Controllers with connected as shown dotted for direct connection to IG terminal without the need for the external diode (D1).

4 Please refer to our latest Data & Application Notes or contact Technical Support for guidance. Engine Cranking Fuel On ------------- Engine Not Running ------------- Charge Fail LED Lit Engine Running -------------------- Charging ALTERNATOR Excited Charging the Battery ------------------------ Charge Fail LED not Lit Voltmeter reading (WL to Battery -Ve) Time Battery +Ve 4 5 7 8 L RSM, EPM or KSM Engine Controllers + Battery -- * Charging ALTERNATOR FUEL SOLENOID RELAY 82 Ohm 6W Resistor Charge Fail LED IG D1 Note: Diode D1 should be rated at 3A 200V PIV or as specified by the ALTERNATOR manufacturer *.

5 See note Capricorn Controls Application Note Page 3 of 3 E. & O. E. The Proven Solution to Power Controls AN02CA01-1 Typical BOSCH ALTERNATOR NOTES: Note: the internal 82 Ohm power resistor is a compromise value to suit both 12V and 24V systems. Very occasionally, a 12V ALTERNATOR will not excite with this value and an external diode and power resistor must be added as shown below .. Rate Diode for 1A 100V and mount resistor for adequate ventilation 4 5 7 8 D+ RSM, EPM or KSM Engine Controllers + Battery -- * Charging ALTERNATOR FUEL SOLENOID RELAY 82 Ohm 6W Resistor Charge Fail LED W Note: the W terminal is a Pulse output to drive a Tachometer or other speed sensing circuit.

6 B+ B- 100 Ohm 6W Resistor