The circuit in Figure 1 solves the problem with two PUTs (programmable unijunction transistors), one connected to each SCR. Performance is good because the circuit does not 'fold back' as inexpensive ...

An optical isolation feature ensures complete protection of the relays' circuit control elements from transients in the load.

Standard features include overtemperature protection; phase loss inhibit; on-board led indicators; 5V and 15V outputs for customer control circuits; and fault signals.

This 12V SCR battery charger circuit differs from the norm in a number of ways, all of which make it difficult to understand.