dual battery questions

[crunky944]

I have a 97 C3500 with the aux battery setup.
Will a bad aux battery affect the starting battery in any way? I had to jump start my truck last night. This morning my volt meter read 12.4 on both the starting battery and the aux. Was reading about 12.9-13v running. The aux battery smells slightly sulfated so I pulled it out and now with just the starting battery I'm getting 14.2v running at idle.

Is a bad aux battery keeping my starting battery from getting a proper charge?

 

[df2x4]

Depends on how they're wired up. If there's an isolator, it shouldn't matter. If there isn't, the dead aux battery could definitely be draining the good one.

 

[RichLo]

Yea, depends on how its wired. I had to put a 3-way RV switch on my grounds to separate them when it wasn't running on my plow truck.

 

[Sparkysikes]

Definitely I killed a optima when a friend shorted out one and I didn't know it

 

[Sparkysikes]

So I had to buy 2 more

 

[DallasTahoe]

If you replace the battery, it’s best to replace both at the same time with the same size battery


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