Dual battery question

[thz71]

I just installed an 80 amp relay inbetween the dual batteries in my truck. Without the coil energized I'm only getting 12k ohms of resistance between the 2 batteries. Is that enough to keep them from draining eachother? Should I return that relay?

 

[thz71]

By that description, I suspect its a process of measuring problem.

Do you mean on that de-energised relay without anything connected to either terminal, 12k is observed across them ?
If batteries are connected, you cant measure resistance.

The batteries are connected to the terminals. Shouldn't it measure an open circuit with the relay not energized?

 

[thz71]

What you are seeing in this case is voltage difference between the batteries.
If using an ohm meter, & that voltage difference is very small, it "tricks" the ohm meter to where it thinks its seeing a resistive circuit.
If you energise that relay, it will measure zero ohms (or very close to zero) as would be expected.

To prove the relay contact is 100% open circuit without any resistive 'leakage',
You will need to remove at least one of battery lead from it and measure resistance across its terminals as usual.

In all, it sounds like its working normally, just confused on measuring to verify.

Ok the voltage difference thing makes sense thanks man I appreciate it!!