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I want to add a second battery somewhere inside the car, most likely in the foot of the passenger seat but possibly behind the driver's seat. I already have a voltage relay and I'll go get the appropriate cables once I get everything measured out (first need to decide where to put this). It'll be an AGM and I'm going to use it for charging accessories.

Question is, I can't find a good way to run the cables from the main battery to inside the car. Mine's a 2000 and the battery sits right in front of the passenger's seat. I'm willing to drill holes for the cables but accessing a good spot seems a little tricky. Does anyone have suggestions or ideas?

Thanks

 
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What kinda accessories are you charging that you need a whole other battery?

Voltage relay? 12V automotive relay for switching between batteries or power on/off?

You running the batteries in parallel or is this a standalone battery?

 
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I wouldn't have it in the passenger compartment, put it in the trunk. Much safer

 
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I'm going to attach an inverter and charge my laptop and phone. That will probably be 95% of the use scenario. I live in my Civic and although it's a bit cramped, I do have space to spare for another battery in exchange for the extra power supply. The relay I have is for charging so that the second battery charges when the car's running but otherwise does not sap juice from the starter battery. So the second battery will be connected parallel to the starter battery with a charging relay in between their positive terminals.

 
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I though about that too, but I live in my Civic and all the seats are taken out so there will be no passenger. Having the battery in the passenger compartment minimizes the cable length I need and also utilizes a space I already have. The trunk to the driver's seat area is all open anyway with the seats removed. I'll be opening the trunk pretty frequently with items coming in and out, so I wanted to minimize the battery connections being exposed to anything outside the car as much as possible. But taking a better look at how I'll probably end up running the cables, I think the trunk might be a better spot. Thanks.