Battery wiring questions (yes, Ive read all the tutorials)

[7ender 10+ year member]

So iv'e got a few questions about battery wiring which I was hoping someone could answer. I've read quite a few threads on this, but still can't find some answers.

I'm planning on running an odyssey pc625 (18ah drycell, only cause I have one lying around) under hood along with my main battery.

So to wiring them:

1. Since that batteries are both underhood, the length of the wire between them is only about 4ft. I know i'm supposed to use 2 fuses, one near each battery, but do I still need to even though the fuses will be so close together? I hear alot of people say the fuse can be 18" from each battery, in which case I can almost run the distance between the batteries with one fuse and two 18" pieces of wire on each side. Hope that makes sense.

2. Does it make a difference where the smaller battery is and in which order it's wired? I thought it'd all be the same since they're in parallel, but I also see alot of people saying stuff about their trunk battery being close to their amps. What would that matter for? I'm planning on leaving my amp power wires all connected to my main battery, and just running some more wire to my smaller battery on the other side of my hood.

3. I don't have anymore 1/0 gauge lying around, would 4ga work? I see everyone using 1/0, but again this is such a short run is it still necessary?

Thanks =), hope my questions aren't too...stupid lol.

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[KyleBechtold 5,000+ posts]

you don't need a fuse for them unless it passes the engine or on any metal

 

[thegreatestpenn 5,000+ posts]

you'd be better suited putting the second battery in the trunk near your amp IMO.

 

[7ender 10+ year member]

Is there a reason for that? I'm just curious. It'd be muchhhh more convenient to be able to put it under hood. Not only do I have the extra space for one, but i'm also on a tight budget and can't afford two more 15ft runs of wire

 

[thegreatestpenn 5,000+ posts]

u don't need a new run of wire for the batt, just use the main run you already have and run it through the batt before it gets to the amp.

I say put the amp in the trunk because then your amp will pull from it before it pulls from the batt under the hood. Path of least resistance ya know

 

[bubbagumper6 5,000+ posts]

you shouldn't need more wire, you should already have a run of wire running to the trunk for the amp (just hook that to the battery, then run a short lead from the battery to the amp) and ground the battery to the chassis (I think it's overkill to run a wire connecting the negative terminals)

And the closer the battery to the amp the better, you'll get less of a voltage drop at the amp.

 

[7ender 10+ year member]

OHH I get it now //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif.

So will those two runs of 4ga be enough then? I do have one more run of 4ga I can run....loll but id' much prefer to leave it as it is if that's enough.

Okay, so i'm going to try to explain everything I'm planning on, and hope to try and make this clear. I might need a drawing //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif.

So, i'm going to have two runs of 4ga running from my front main battery to my rear smaller battery, fused on both ends (for a total of 4 fuses). Then, i'm going to have one run of 1/0 going to my larger amp, and one run of 4ga running to my smaller amp coming off my trunk battery. Do these need to be fused as well?

 

[bubbagumper6 5,000+ posts]

No you shouldn't need to fuse the wires going to your amps. You should really run 1/0 from the front to the back...better to do it the right way now, than have to go back and fix it later

 

[7ender 10+ year member]

Hmm. I JUST ran a second run of 4ga this afternoon...(I already had one, just added another).

How necessary will it be to have 1/0? Worth ripping everything out and buying new wire?

 

[SethPhillips 5,000+ posts]

i would run the biggest wire you can. also run a ground from batt to batt.

when you are wiring two batt's it basically turns them into one bigger batt. you are definitely better off putting the second batt closer to the amp, and grounding that to the chassis of the vehicle as well.

make sure you do the electrical upgrade known as the big 3.

 

[7ender 10+ year member]

Already done the big 3.

My biggest concern now is that my two runs of 4ga aren't going to be enough //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif.

Also, are you guys sure I don't need a fuse going from my rear batt to amps?

 

[7ender 10+ year member]

^^^

 

[G.W.Kush]

Already done the big 3.
My biggest concern now is that my two runs of 4ga aren't going to be enough //content.invisioncic.com/y282845/emoticons/frown.gif.a3531fa0534503350665a1e957861287.gif.

Also, are you guys sure I don't need a fuse going from my rear batt to amps?

your fine.

its enough.