Timer relay with main power supply isolated
Printed From: the12volt.comForum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=142707
Printed Date: May 13, 2025 at 3:51 AM
Topic: Timer relay with main power supply isolated
Posted By: chris-stoffa
Subject: Timer relay with main power supply isolated
Date Posted: March 02, 2017 at 5:52 PM
Hi, I have a problem on a construction machine (12V DC) when the battery isolator (negative switched) is switched off without enough time for the engine controller to store its data. This only happens when the ignition is switched off and directly after that the battery isolator is switched off (without a 30 second delay). The engine controller will then store an error which is not self healing and requires the engine manufacturer to plug in and remove. Any ideas on the best way to overcome this problem? Without getting new operators... I am thinking a timer relay with a capacitor to store enough energy to keep the contact closed for at least 30 seconds if the main battery isolator was switched off? I have attached the standard wiring diagram of the relay for the engine controller and the main battery isolator switch. 
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Chris
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Chris