High Charging Rate. Found Voltage Drop Need Guidance Please

This is an example of a Bosch spst high current NOTICE the difference: There is no normally closed contact. Both the 87 terminals are normally open

You can tell with an ohmeter by probing 30, and both 87 terminals. If there is NO continuity between 30 and either 87 terminal then it is an NO (normally open spst relay

relaydiag-spst.jpg