2nd Battery

[Noobie34]

Hey i am putting in a 2nd battery in my trunk and wanted to make sure i had it right. I have 2 amps the Rockford Fosgate Prime 1200x1 and the Punch p400X4. I have a 200-amp fuse under hood to a block that has a 120 for the 1200 and 60 fuse for the 400. Do i just add another 200 amp fuse before the second battery and run 2 4-gauge power wires off that 1 with 120 fuse and then another with a 60 to those amps? So ill have a 200 amp by my main battery and another 200 amp 12-18 inches before my second battery is that correct?

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[Noobie34]

Is there another thread I can view for more info on this subject?

 

[Popwarhomie 5,000+ posts]

Positive from front battery to rear battery. Fuse at front battery and another at rear battery. Fuse rating would depend on what your wire is rated at for the length you are using. All amp wiring would be connected to the rear battery.

 

[2023 LTZ]

You’ll have the positive from the front to the back battery. Then the positive off the battery is fused then to the distribution block then the amps. Ideally a mini anl fuse block so each can be its own prescribed fuse. Keep the same front fuse as the fuses are in case of failure. In that case the fuse blows rather than start a fire.

the pic doesn’t show the grounds or fuse block that rested on the battery.
You’ll fuse to the wires capacity.

 

[2023 LTZ]

Idk
It seems to be working fine.
Positive to positive negative to negative is parallel.

 

[2023 LTZ]

It’s 5v preout to amps. Then amped from there. Cross over volt area shouldn’t be affected.

 

[HardofWhoring]

WTF are you talking about? I really don't think you can be this dumb. I think you're just a pathetic troll.

 

[2023 LTZ]

This person is on a different thread asking how to correctly hook up a preamp under the seat. If not a troll there’s a serious language barrier.

 

[Doxquzme Premium Member]

Is there another thread I can view for more info on this subject?

Unless it is a simple, lets say 500 watt install where I’m only running 1 or 2 grounds, I run power and ground front to back. I don’t chassis ground anymore, well not on unibody cars anyway. I always double the size of the return (ground) run. Current build, 2012 Mazda 3 2.5T (unibody), I run 1/0 gauge OFC copper to 2nd battery in the back for power and 2/0 gauge OFC wire back to the front for ground and use breakers/fuses (breakers under the hood when I can) and fuses prior to the 2nd battery equal to the ones under the hood and fuse distro blocks or individual inline fuses, either or running to the amps after the battery. That affords me power and ground in one place back where all the amps, battery and caps are.. Mazda build has (4) 4AWG grounds and (2) 1/0 AWG grounds, (6 fairly big grounds) for (2) Focal FPS2300’s and a single DS18 EXL-P2500X1D, the extra three are for (2) T-spec 3 farad caps, 1 each of the Focal amps, a stinger 5 farad hybrid cap for the DS18). Granted, the T-spec caps are most likely not needed but they do look cool! I know everyone has an opinion on this type of grounding configuration but I’ve never had any ground (or ground loop or lack of ground/power) issue since I started doing it this way. I believe in the “overbuilt is better” philosophy! Also, twisted pair RCA’s and speaker wire work better and are much easier than using foil ever wrapping anything in foil.

 

[2023 LTZ]

What did you ground the front battery to?
You have positive and negative distribution from the rear battery to those caps and amps then grounded back to the front?

 

[Doxquzme Premium Member]

Power and ground are linear connections when done this way (well they’re linear in thie circuit in any case). Here we go...all wire is OFC copper, full big three under thehood added to exxisting wire, all real AWG wire. I have 1/0 awg power from front to back, 2/0 awg from back to the front. Instead of grounding everything off the chassis in the back (given that it is a unibody car) I just use multiple distro blocks as splitters to route power and as reverse splitters on the ground combining the grounds back into the 2/0 ground run (think of it like using power distro’s in reverse). Picture both wires going from the front to the back where the 2nd (1200 watt AGM) battery awaits. Fuses for the 2nd battery are in-line prior to (within 18” of) the 2nd, battery in the back. Then a small section of cable to the battery using 2/0 to 1/0 reducers where needed on the ground side and straight in on the power side. A single 1/0 to dual 1/0 Stinger battery terminal splitter connects each cable to its respective terminal. So, we now have cables running from front to back, back to front, 2nd battery fused (+) and (-). From each of the stinger terminals remaining single 1/0 open connection, I run a single section of 1/0 from the battery, about 14” long. Now, at the other end of those 14” runs, I connect a single 1/0 to double 1/0 splitter giving me two 1/0 outputs (or inputs for the grounds as you will see later). Let’s cover the power line first. From one of the two 1/0 block power leads, I connect a single 1/0 to double 4awg splitter which feeds 4awg to the two T-spec caps, then to inline fuses, then to the two Focal FPS 2300’s ,The other power single 1/0 power lead goes to my 5 farad stinger hybrid cap, then to a fuse then to my DS18 EXL 2500.1D. Now, for the grounds. I now have 6 grounds to contend with (3 for the amps and 3 for the caps). Four, 4awg’s from the two caps and two amps and two 1/0awg’s.one from the stinger cap and one from the Mono amp. I run both of the1/0 grounds back to a dual 1/0 to single 1/0 distro block, run that 1/0 to one of the two open ground connections i split earlier. I then run all four 4AWG grounds from the caps the amps, to a quad 4awg to single 1/0 distro block. Then, from that single 1/0 off that block to the other 1/0 input on the ground splitter from the ground battery lead. Done!

Easy-peasy right? Clear as mud huh? Don’t fret; I had to draw it out, almost to scale just to order all the stuff! I’m going to have to draw it out again and take picture so I don’t have to explain this anymore, hurts the brain!

 

[2023 LTZ]

So what’s it grounded to under the hood?
Just the negative battery terminal?

 

[Doxquzme Premium Member]

Nothing changes but... the big three upgrade adds 1/0 girth to the existing power wires and 2/0 girth to the grounds. Grounds are all part of the same path, increasing all the electrical (battery and ground) cable under the hood covers all you need. There’s really no difference grounding to the chassis locally back where the amps and caps are or back to the batteries to the chassis, it's all the same ground. Just because it passes the battery on the way doesn't change the properties of how it works. I know this throws people off sometimes but grounding to the chassis has always been done to reduce resistance as it is the shortest path to ground. Using 2/0 or 4/0 wire back to the front battery does the same thing. Unfortunately, today’s cars are not one big ground anymore; they are made of sections which are glued together which changes the characteristics of the grounding area/material. Sheet metal is a lot thinner too and outer body panels that all use to be metal share the skin with urethane panels too. Most of the time it’s not an issue, but I like it done this way, it’s clean, and it’s affective and I never have to troubleshoot ground loops.

 

[HardofWhoring]

Nothing changes but... the big three upgrade adds 1/0 girth to the existing power wires and 2/0 girth to the grounds. Grounds are all part of the same path, increasing all the electrical (battery and ground) cable under the hood covers all you need. There’s really no difference grounding to the chassis locally back where the amps and caps are or back to the batteries to the chassis, it's all the same ground. Just because it passes the battery on the way doesn't change the properties of how it works. I know this throws people off sometimes but grounding to the chassis has always been done to reduce resistance as it is the shortest path to ground. Using 2/0 or 4/0 wire back to the front battery does the same thing. Unfortunately, today’s cars are not one big ground anymore; they are made of sections which are glued together which changes the characteristics of the grounding area/material. Sheet metal is a lot thinner too and outer body panels that all use to be metal share the skin with urethane panels too. Most of the time it’s not an issue, but I like it done this way, it’s clean, and it’s affective and I never have to troubleshoot ground loops.

It's the same ground; its NOT the same PATH TO GROUND. Battery is not ground, and there is NO REASON to be grounding through your negative battery terminal. What you have done is now ground not only your vehicle but your entire stereo through your battery negative terminal. Your power wires are split from the positive terminal, and also has the added power from the alternator. You have then took all of that, and combined it to flow through the negative terminal.

You have also added resistance making them that long. It might work, but you put more work and money in to a worse option, when you could have just grounded to chassis, (which is where ground is).

Not sure where you came up with some panels are not ground because they are glued together with thin sheet metal, etc.... A unibody still has a structural frame with thicker metal. (You can usually see it where they tell you to jack up the vehicle there), it's not just in the engine bay.

You also said you fused your grounds. You need to get rid of that.