Hello folks,

I'm going to be relocating my battery into the trunk of my Integra. Just wanted to ask if there were any pros or cons to running the power cable in the following manners:

Over the carpet: people might trip over it, but at least I will be able to inspect the wire frequently, and it probably won't get abraided through. I can tie it down once every foot or so.
vs. Under carpet: Looks cleaner, but more likely to get pinched in case of a car accident? Might get abraided, and I wouldn't know it.

Running down the center of the car (near the center console): less likely to get damaged in an accident, but wire becomes longer.
vs. Running along the passenger side, by the door sill

An any case, I'm going to be using a fuse for the battery.

 

Pinching your power wire is the least of your worries in an accident.

It should be run under the carpet and secured to the vehicle. If it's run under panels/consoles seats/whatever, it won't be abraded.

 

Don't even think about running it out in the open.

Run it down the passenger door sill just like you'd run an amp wire.

USE A GROMMET WHERE IT PASSES THROUGH THE FIREWALL

DO NOT REST THE WIRE AGAINST ANY METAL EDGE

USE GOOD FLEXIBLE STRANDED WIRE OF AT LEAST 4 GAUGE

FUSE THE WIRE WITHIN A FEW INCHES OF IT'S CONNECTION TO THE BATTERY

USE LOTS OF SPLIT LOOM

You can use a 100A fuse. I would try 80A. The lower the better. Turn on the headlights, blower, stereo, and everything electrical, then start the car and see if it blows the 80A. Use a good quality fuse and fuse holder. There's a sticky about fuse holders.

More importantly, how are you going to ground the battery?

You are using a sealed battery and/or battery box, correct?

 

"Don't even think about running it out in the open."

Why not?

"DO NOT REST THE WIRE AGAINST ANY METAL EDGE"

You mean any edge that is perpendicular to the wire?

"More importantly, how are you going to ground the battery?"

negative terminal to fuse to cable that runs to some nearby bolt. I think it's better to put the fuse on the - terminal.

"You are using a sealed battery and/or battery box, correct?"

sealed

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beanbag &raquo;</TD></TR><TR><TD CLASS="quote">"Don't even think about running it out in the open."

Why not?</TD></TR></TABLE> Just don't.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beanbag &raquo;</TD></TR><TR><TD CLASS="quote">"DO NOT REST THE WIRE AGAINST ANY METAL EDGE"

You mean any edge that is perpendicular to the wire?</TD></TR></TABLE> He probably means any edge that could "abraid" it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beanbag &raquo;</TD></TR><TR><TD CLASS="quote">"More importantly, how are you going to ground the battery?"

negative terminal to fuse to cable that runs to some nearby bolt. I think it's better to put the fuse on the - terminal.</TD></TR></TABLE> It is not. Put the fuse on the pos.(+) line, [within 18"] running from the batt. to the starter motor.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beanbag &raquo;</TD></TR><TR><TD CLASS="quote">"You are using a sealed battery and/or battery box, correct?"

sealed</TD></TR></TABLE> Use both, the sealed batt. in a batt. box solidly mounted. 94

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fcm &raquo;</TD></TR><TR><TD CLASS="quote"> Just don't.

He probably means any edge that could "abraid" it.

It is not. Put the fuse on the pos.(+) line, [within 18"] running from the batt. to the starter motor.

Use both, the sealed batt. in a batt. box solidly mounted. 94</TD></TR></TABLE>

OK, I know you have mentioned before to use the fuse on the + terminal. Could you please explain why this is better? What are the possible failure modes in which a fuse on the + is better?

The reason I want to use the fuse on the - is that it seems to protect against more possible failure modes. For example, if something were to touch the actual + terminal of the battery, the fuse on the - would still blow out.

 

Put the fuse as close to the (+) battery terminal as possible. You don't install fuses at the end of the circuit dude. This is common knowledge.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by White Smoke &raquo;</TD></TR><TR><TD CLASS="quote">Put the fuse as close to the (+) battery terminal as possible. You don't install fuses at the end of the circuit dude. This is common knowledge.</TD></TR></TABLE>

How is the - terminal the "end of the circuit"?

Still nobody has mentioned what bad thing will happen if the fuse is on the - terminal.

How is this different from the advice that when working on your car, you disconnect the - terminal of the battery and not the +?

 

If the fuse is on the negative terminal, and there's a short on the positive wire somewhere, there's nothing stopping from that wire heating up and starting a fire.

Now you have three people telling you to fuse the positive lead. If you choose to fuse the negative lead, and you have an issue, please don't post about it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by B18C_EJ8 &raquo;</TD></TR><TR><TD CLASS="quote">If the fuse is on the negative terminal, and there's a short on the positive wire somewhere, there's nothing stopping from that wire heating up and starting a fire.

Now you have three people telling you to fuse the positive lead. If you choose to fuse the negative lead, and you have an issue, please don't post about it.</TD></TR></TABLE>

If there is a short on the + wire, then the fuse on the - terminal will blow out, preventing any more current flow.

 

If you say so. I wouldn't risk a car fire because I wanted to be an "expert".

 

DC current flows from + to -
Beanbag your just wrong on this... I think you need to go do some more research on DC voltage before you come in here and start telling us how things work. The people who have posted in here including myself have been doing this for many, many years.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by White Smoke &raquo;</TD></TR><TR><TD CLASS="quote">DC current flows from + to -
Beanbag your just wrong on this... I think you need to go do some more research on DC voltage before you come in here and start telling us how things work. The people who have posted in here including myself have been doing this for many, many years.</TD></TR></TABLE>

I'm afraid to say that I don't think you know how a circuit works.

Circuit, means something that goes round and round. Current goes out the +, thru whatever, and due to the principle of charge conservation, goes back in thru the -. So if you short out something on the +, the temporary excess current that goes out the + means that an equal current goes back in the -. This will blow out the fuse on the - terminal, the "circuit" is broken and no current flows. Does this make sense?

I'm not telling you how to do things. I don't really care if you've done the same thing for years. I'm looking for a correct reason why putting the fuse on the - is wrong, and so far, no good reason has been mentioned.

Tell you what, I'll stop asking if you can name one situation where it is better to have the fuse on the + than on the minus. Just one.

No, wait, you'll have to name two. Because I already thought of one situation where it is better to have the fuse on the -.

 

I'm done with this thread. This person obviously possesses knowledge superior to all of us, so therefore, it's not necessary for anyone to further comment.

Good luck, sir.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by beanbag &raquo;</TD></TR><TR><TD CLASS="quote">No, wait, you'll have to name two. Because I already thought of one situation where it is better to have the fuse on the -.</TD></TR></TABLE> That would be what?

Let me ask you this...
1 - Do you know any car manufacturer that fuses the neg.(-) side of the circuit?
2 - What will happen if the fused neg.(-) line shorts out?

I will give you one good reason, your car is a common ground, the neg.(-) side of all circuits are common the cars chassis is the neg.(-) side of the circuit.

It was us you asked, take our advice or not, that's up to you, but don't tell us we do not know how things work, I am pretty sure after more then 30 years of working with 12VDC, I know how a 12VDC circuit works. nuff said. 94

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fcm &raquo;</TD></TR><TR><TD CLASS="quote"> That would be what?
</TD></TR></TABLE>
That would be the same reason that you disconnect the - terminal of the battery when working on your car. Because it is safe to "short" out the minus side, but not the plus. Consider the below scenarios: Your car gets rear-ended or there is a loose piece of metal in the trunk that bumps up against the battery.
Case 1: fuse on positive terminal:
1a: metal touches - terminal. Result: nothing
1b: metal touches + terminal. Result: fire

Case 2: fuse on - terminal:
2a: result: nothing
2b: result: fuse blows out.


<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fcm &raquo;</TD></TR><TR><TD CLASS="quote">
Let me ask you this...
1 - Do you know any car manufacturer that fuses the neg.(-) side of the circuit?
2 - What will happen if the fused neg.(-) line shorts out?
</TD></TR></TABLE>

1. No. Reason one being that the negative is already connected to case so there is nowhere to put a fuse anyway. Reason two being that if there is a return wire, and you put the fuse on the - return path and it blows out, the rest of that device still floats at 12v. But this is for individual devices, and not the entire battery.
2. If it is on the chassis side of the fuse, nothing. If it is on the battery side of the fuse, nothing also, except that the fuse doesn't protect any more.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fcm &raquo;</TD></TR><TR><TD CLASS="quote">
I will give you one good reason, your car is a common ground, the neg.(-) side of all circuits are common the cars chassis is the neg.(-) side of the circuit.
</TD></TR></TABLE>
Yes, I know that the rest of the car is common. This stops becoming relevant once the battery fuse blows out and no additional current flow is possible. This is in contrast to having a negative fuse on a particular device, where if the fuse blows out current flow is still possible if you short something.

Let me put it this way: Suppose I put both the battery and fuse inside a battery box. Only a + and - wire come out. Can you tell, without opening the box, which terminal has the fuse on it? Because if you can't tell, then it doesn't matter. If there is in fact any way that it matters, then that is the info I am looking for.

Now going on to the next case, suppose the fuse is outside the box, but within 18". The only difference with the previous case is that you now have the option of shorting the segment of wire between the battery terminal and fuse. I've already spelled out what will happen above. If there are any additional scenarios, then I would like to know of them.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fcm &raquo;</TD></TR><TR><TD CLASS="quote">
It was us you asked, take our advice or not, that's up to you, but don't tell us we do not know how things work, I am pretty sure after more then 30 years of working with 12VDC, I know how a 12VDC circuit works. nuff said. 94</TD></TR></TABLE>

I'll have you know that I only insulted one person with respect to their knowledge, and that was in a polite and pedantic manner. I didn't come in here to tell you anything, rather I asked if there was any specific reason why something will not work. Now I appreciate your time in answering this post, but I would still like to see one specific example where having the fuse on the - is bad.

 

I'm locking this thread. The original question has been answered and it's only going to go down hill from here.

The entire point of a fuse is to protect the circuit following it from damage.
Just read the fist sentence here: http://www.calex.com/pdf/9fuse_size.pdf
Putting the fuse at the end of the circuit is pointless because there is nothing left to protect. Sure it may still blow if you have a good direct short to ground and all current is not dissipated elsewhere. But at that point all your electronics in the car would be garbage.

Beanbag if you want to argue your take on fuse placement in a DC circuit I encourage you to join an electronics form like the12volt.com and protest there. Fell free to PM me with a link once you have done so to prove us all wrong.

EDIT: Beanbag sent me this link: http://groups.google.com/group...9c889