Dual battery setup questions

[454-k10]

My dual battery setup has parts inline on the positive side of my auxiliary battery. Does anyone know what they are?

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This is on the passenger side just off the isolator. There is also one about a foot away from the battery and accessories are attached to a post going that way. I'm thinking it's an older fuse.

 

[Snoots]

That appears to be a 30 Amp circuit breaker. If it is, it's made to auto-reset shortly after the fault has been removed.

 

[highdesertrange]

yes auto reset circuit breaker. both ends of the crossover circuit should be fused. btw that wire is way to small for a proper dual battery set up as is the breaker. highdesertranger