Because the  power input is designed to be connected to a local bus and to have inductive load kickbacks suppressed, it cannot withstand a charging system load dump, heavy inductive kickbacks, or heavy surge pulses. 

Therefore a suppression KIT is strongly recommended for 12V and 24V applications.

The P/Ns are 

1) 8923-1272.KIT. 

This kit is for a 24V system.  It will suppress alternator load dump from alternators within the 200A range, as well as indirect lightning pulses that may be coupled to the power bus. Parallel inductive loads still need to be suppressed because pulses from unsuppressed parallel loads may be clamped at voltages too high to protect the control. 

This kit is for a 12V system with an alternator within the 100A range, unsuppressed switched inductive loads in parallel with the control, and indirect lightning pulses that may be coupled to the power bus. 

Both kits contain 2 diodes and 1 varistor

Figure below shows how it is connected