Determine the voltage used by the relay
Select the use voltage of the relay according to the voltage platform of the vehicle. For example, there are 12V and 24V platforms on commercial vehicles, so the coil voltage of the selected relay must match the voltage platform of the vehicle. The contact gap of the relay used to switch 24V loads is much larger than that of the vehicle. To switch the contact gap of the 12V load, if the relay marked with 12V is used to switch the 24V load, it may not be able to break the arc and cause the relay to burn out. Because the pure electric light truck low-voltage system is a 12V platform, Hongfa HFV15/12 type is used relay.

Choose the packaging method according to the environment in which the relay is used
The plug-in electromagnetic relays commonly used in automobiles are generally placed in the relay box, and the dust-proof cover type is usually used, while the plastic-sealed type is used for those with waterproof requirements. In the shell and bottom plate, the cooling fan relay of this model is arranged in the chassis fuse box, so the dust cover type can be selected.