HRB Changes for 36V Operation

The standard HRB-324 has relay coils for 24v operation. However, if the appropriate series resistors are fitted, these can be operated from 36v instead of 24v.

There are 4 possible resistor positions, R5, R6, R7 and R8 on the circuit. There are positions for the resistors just behind the 6 way input connector. Resistor positions are shown below. Beneath each resistor is a scratch-through link which must be broken to engage the resistor.

For 36v operation, 820 ohms 1/4 watt should be suitable (relay coil resistance is about 1600 ohms). When modified thus, the same wiring is used as for the 24v system with the 12v tap (if required) done the same way as for a 24v battery.