i have a 100amp breaker becuase that is the largest the autoparts store had. it has never tripped even after cranking for 20 seconds. if it starts tripping ill just order a 150 amp breaker.

 

So tell me...
How do I run 199A of current through an automotive electrical system?
The largest current draw is the starter.
There is nothing else that even comes close to drawing that kind of current.
If you don't believe me, look at the fuses - what's the biggest one?
There is nothing over 30A / 40A.

And, if you didn't know, if you manage to run 199A of current, the 200A rated circuit breaker WILL eventually trip.
I'll let you do the research on why this is so.

Another technicality, I've never advocated the use of 4AWG wire for the battery relocation.
I've always recommended 2AWG.
Go look at my posts and my battery relocation write-up on my website.

What does the alternator have to do with the circuit breaker rating???


See above.
We're talking about AUTOMOTIVE APPLICATIONS, not a &**()^#$)(*# boat.
If we were on a marine forum, I'd conceded...but we're not.
Sure, the marine stuff is overkill, but you're trying to impose your marine standard on the wrong application.

Again, see above...
I don't see how your boating experience has anything to do with our automotive application.
Yes, it's overkill, and it will work, but it's NOT necessary.

Also, your grasp of DC electronics still hasn't been shown.
There is a huge spike in electrical current anytime to first start any (DC) electrical motor.
This current spike is several times the constant duty current draw - duh.
The stock starter is rated under 100A of current draw, but I have personally seen the bitch current spike over 150A on the test bench.
So, can your "100A" rated circuit breaker handle this current spike?
That's the million dollar question...

I've seen 150A circuit breakers trip after 3 to 4 hits to the starter.
This is MY experience.
Approximate 5 seconds of cranking per cranking event - never fails to trip the circuit breaker.
We needed to let the electricals rest a few minutes before trying again - if we immediately try after the initial trip, it'll trip again on the first try.
This is trying to clear a flood on a freshly rebuilt motor while adjusting the Haltech E6K - not the best scenario, but you get the picture.
Now, picture this...you're in a getto part of town, and the engine floods - do you really want to be sitting there while your circuit breaker cools off?
It's you're life...


-Ted

 

A circuit breaker works on the same principal as a fuse. HEAT. (unless running an electromagnetic type circuit breaker) Once the heat going through the breaker reaches a certain temp, the bimettalic material will bend, thus opening the circuit. Depending on what type of breaker your using, the time to trip can vary.

As far as cranking and cranking an engine, I have popped fuses for the starter while diaging an issue. I have also seen 200 amp breakers in cars that are so equipped trip upon extended cranking. All because of drawing enough amps through it and creating enough heat to trip or blow the breaker or fuse.

 

Ohh, and lets get back to thie OP's questions please. We really need to stop all the **** being slung on the forums and get back to what its really here for. (this is directed to no one in particular, just dont want to see this forum go down like the protege forums did)

 

is marine grade battery cable wire any better than standard wire? I have some extra 2 AWG marine wire laying around and have been thinking for doing a battery relocation.

 

I can't comment on marine grade stuff, but copper is a better conductor than tin is - see any conductivity metal chart, and it'll confirm that.
The tin coating actually drops conductivity, but it gives you added corrosion resistance.
So unless you live and drive by salt water all the time, it's really unnecessary to run tin'd wiring.

I personally use 1/0 weldding cable on my car.
This is my battery relocation page...
http://fc3spro.com/TECH/HOWTO/BATTRELO/battrelo.html

I don't use anything smaller than 2AWG (i.e. welding cable) on customer cars
Typical power cable run from engine bay to rear for the battery relocation is around 15 feet to 20 feet.
Check the recommendation charts, and 2AWG is minimum recommended for that length.


-Ted

 

I appreciate the attempted redirect, but I already figured out the problem on Pg.2.

 

Simple, you short that big wire you just ran. Route a wire wrong, have a clamp break whatever the case may be. I'd rather have the lowest breaker NEEDED to break the connection in the shortest amount of time. I've only NEEDED a 150A


Than why am I an "expletive" idiot for saying the same thing?

I live in the NE, they salt the roads. I also live 1/2 a block from Long Island Sound and worked at a marina & a Yacht Club. I think I have a a few more corrosion concerns than most. I've never had a corrosion problem but I have seen cars that have had cable completely chewed through.

All of that about spike and constant draw, believe me I get. Diesels are very promenient in the marine world, you want to talk about current spike, think about the spike that's needed to start turning a V-8 CAT. My 150A has never tripped. Even after cranking the motor for 5-10 seconds a few times in a row. That has been MY experience. I personally would NOT go to a 200A becuase I don't need to. Why would I? In MY experience, there is no need to. Also, I would never park my FC in a ghetto part of town, that's what my black 5% tint Cherokee is for. & even if I did and the bitch wouldn't start, I wouldn't worry & I have my reasons for that.

If you've needed a 200A breaker, so be it. I haven't.

Crazy Driver - Marine cable is WAY better than autocable in MY opinion. The name brand stuff, Ancor makes some really nice cables. Look at the inerds of the cable and compare it to some automotive stuff. The strands are ALOT thinner and they are tinned. This does a few things, both good and bad. The thinner strands are more flexible, the cable itself is much more flexible and easier to route. The thinner strands means more strand count/ given gauge, since the current flows ontop and not through, more strands means more current, or so I've been taught. However, the Ancor stuff is tinned, every single strand is tinned. As I pointed out earlier & RETed just re-iterated, the tinning creates resistance, ALOT of resistance. So for a given load @ a given length the marine stuff will probably have to be upped a ga size. But, when you solder on a tinned battery lug and heat-shink it, you have a VERY corrosion resistant connection.

When running heavy gauge wire, I personally will never use anything BUT marine grade stuff. All of the 14ga/18ga though is pure copper Painless Performance Wire.

 

That's a myth. In a DC circuit, current flow is through the entire conductor. Only in high frequency AC applications does current exhibit the skin effect.

See references to Litz conductor in http://www.aaroncake.net/rx-7/grounding.htm

 

Well than, thanks for clearing that up. Can't remember where I learned that, but I remember it being in a discussion about wire, strand count, current, resistance, voltage drop, etc etc. Basically things to consider when picking your ga.

Thanks for the complement too.

-B

 

how much black and how much red will i need going by teds link??

it just says

 

Sorry it wasn't more specific...
I typically use welding cable, which is not usually color coded.

20 feet is more than enough to run the power from the engine bay back to the rear of the car.
18" is the maximum safe length for ground cables according to IASCA, so I use that standard.

So 20 feet red and 2 feet black should be more than enough to take care of this relocation.


-Ted

 

Summary of Below:
Circut Breaker: 100 amp slow blow would be ideal, dunno if that exists
original poster's question: He already figured it out, don't worry about it.
marine cable & tinning, corossion, electrical resistance: A larger size will completely get rid of the extra electrical resistance.
cable size: Use 8 AWG or bigger. I'd get bigger to help it last. Multi-stranded of course for flexibility. 2 AWG seems pretty ridiculous though, unless you like cranking your starter for several minutes at a time.

Longer Explanation:
Circut Breakers: As some one pointed out, there are slow blowing circuit breakers and fast blowing circuit breakers. You can blow a 150 amp fast blowing circuit breaker with a 200 amp spike while the same spike won't blow a 100 amp slow blowing circuit breaker. Ideally for safety purposes you want the lowest ampage that won't blow during continuous use and a slow blowing circuit breaker so it won't blow during that initial current spike. Isn't the main fuse only 70A? In that case a 100 amp slow blowing breaker is plenty. A short circuit will blow any fuse in an instant, btw, so no worries there. And if you don't have a short circuit, your electric components and wires will be able to last several seconds without overheating, so no worries there either. Disclaimer: There are components such as electronics that are sensitive to current spikes. Correct me if I am mistaken in recommending a slow blowing fuse b/c of such and such a component (but not b/c you feel like it, not b/c you wish to imagine into existance such an unfused electronic component, etc.).

original poster's question: Already answered a while ago. He connected his ground better and it worked. This thread has been off-topic for a while. But the OP is fine.

marine cable & tinning, corossion, electrical resistance: You can comletely make up for the lower conductivity with fatter cable. In fact, if you wanted to save weight aluminum gives better conductivity per pound than copper. Just use fatter cable and you'll have both less weight and better conductivity. That's why hanging power lines are aluminum (underground lines are copper, I think, b/c weight isn't a factor). Do you need the extra corossion resistance from marine cable? Maybe not. Copper is already pretty good at resisting corossion. But saltwater is extremely corossive, hence the tinning.

cable size: The goal is to prevent wire overheating and voltage drops. I just changed my alternator, so I happen to know that the voltage drops of about 0.3V are okay when powering the blower and headlights (~20A plus other components). Based on AF_H1VLTG3's table (https://www.rx7club.com/showthread.p...6&page=1&pp=15), you could probably get away with 10 gauge if voltage drop were your only concern. Then there's wire overheating. Wire overheating can only happen from continuous current. Current spikes won't do it. According to some handbook referenced at http://www.powerstream.com/Wire_Size.htm, 8 gauge is good for up to 73A. Again, this is continuous current. Current spikes won't melt your wire and don't mean diddly squat. So is there a reason to bother with the larger sizes? Well, a lower voltage drop might save that 2% of power that used to go to heating the wires. At 35A, that translates into about 0.01HP. OTOH if your wires degrade the extra bulk provides a bit of a safety net. But in that case, IMO, I'd also want extra corossion resistance too. What's the point of nice wire if your contacts get corroded?

 

I had lots of 0/3 from an electic car I found at the junkyard, so in mine I have a 0/1 for the + from the back to the starter, a 0/3 from the battery to the chassis in the rear, then to a lug on the trans, then to the chassis in the front, and a seprate 4 gauge wire from the alternator to the battery, with a 200 amp breaker in the back to the starter, and a 100 amp fuse on each side of the alternator. The breaker is bieng used a a switch with a piece of aluminum rod drilled through the tail light to make it legal for racing.

 

Does anybody have any pictures of the engine bay w/o the huge clutch fan (with an efan) and the batter relocated? Does it looks super clean?

 

thanks my friend!

 

after researching a price range here (NAPA and such) i found they wanted as much as $80+ for 25 feet of 2AWG!!
i found this site (http://www.wiringproducts.com/?targe...FRAvhgodqFdsWA) showing $48.50 for 25 feet of one color. i guess im going to keep looking locally so i wont get hit with shipping. what do you guys pay for the wiring? im going to try welding shops to see if they can hook me up i guess.

 

Try welding shops...
It's typically about $1 / foot.


-Ted

 

This was my thought, too. Can't average car batteries push at least a few hundred COLD cranking amps? There's a reason they do. Also, just to be sure (and I'm not sure on this myself), there might be a difference between a 150A AC breaker and a 150A DC breaker. Make sure if there's a difference you use a DC breaker.

 

The average car battery will be able to push at least 500A into a short. When you start talking about the "performance batteries" like the Deka Intimidator, we get into around 1000A.

 

But under normal use they aren't going to "push" more than the starter will pull.

I just checked www.westmarine.com $5.99/FOOT! DAYUM! That has come close to doubling if memory serves. I seem to remember paying ~$5/ft for 1/0, but that was also wholesale. How about their 4/0 for over $20/ft. Ridiculous
http://www.westmarine.com/webapp/wcs...0001/123/120/9

 

is this the one i need guys, 150 amps (lifetime warranty)

 

That's true, but why would battery manufacturers make them so powerful? If you keep a stock setup without adding a powerful sound system, you're not going to pull any more than the starter does at startup, so it would make sense that there are normal circumstances under which more than 150A would be drawn.

 

There is good information in here.

Love the arguing.

Its funny when people talk about marine cable being tinned and how tinning adds resistance which creates heat, and then they talk about how you will burn up a certain gauge wire and never relate the two but they try to tell you that the same effect will happen on automotive wire or non-tinned stranded wire which has less resistance.

 

So are you saying you want me to drive to NH & kick you in the *****?

Or should I link all the instances when you've been owned, banned, cursed out and laughed at? Keep egging me on....

You still have problems reading & comprehending.

It still has resistance, not as much, meaning Marine has more, can you understand that concept? I know I mentioned it. Run 100A though non-tinned 18ga and tell me what happens. Constantly, meaning change a few wires in your car, say the main alt wire, maybe the starter wire too. Gauge sizing is important, this has been talked about. I know I mentioned that due to the tinning, one must generally up the size when dealing w/marine cable. I know I mentioned grabbing a West Marine catalog as they have in the past had the Amp vs Lenght in an X vs Y format so you can easily gauge what gauge you need.

Furthermore, You need to understand a concept known as citeris paribus (sp??) Simply meaning change one thing at a time. If you simply change to marine grade from auto grade and keep the ga the same, there will be more reisitance..... wait, wait wait for it........ yup, I know I mentioned upping the size. Go back and read.

Keep egging me on .... I dare you.