Voltage sensing relay always letting through a small current

[dantastic]

I have a Durite 140A voltage sensing relay wired up to a fuse box where things like CB radio and extra USB sockets are connected. As I was troubleshooting a strange issue I realised that the relay is actually always letting through a very small current. When the engine is running I'm getting the full 14.something volts through but with the engine off and the battery a small bit discharged to the point where the relay should disconnect I'm getting a reading of 0.5v. It's a simple enough circuit and nothing can get power from anywhere else so there is no "feedback".

I'm just wondering if this is normal, if anyone else has experienced this. The relay is probably 8 years old or so and I don't know if it always did this.

[Peaklander]

Where are you measuring the 0.5v do you mean output side and ground/chassis? Sounds like a bit of back feed through all that gear from the engine side of the system. 

[Cynic-al]

Would disconnecting the output and measure at the relay to see if the relay is letting through or it's some sort of grounding thing help prove or disprove? 

[dantastic]

Measuring between the output side of the relay and the negative pole on the battery.

I suppose I really should remove all the fuses and measure again with absolutely nothing connected. Only reason I didn't was because I couldn't see where a back feed could possibly be introduced. I suppose a back feed is the most likely explanation though.

[Peaklander]

If the relay is electro-mechanical and theres nothing except your fused circuits connected to the output poles then the voltage has to come from somewhere else. That's assuming there is a current flowing when you are measuring your 0.5v. Otherwise it's probably nothing to worry about anyway.