Engine block to chassis ground

[TwoJ's]

Yeah, my EE prof. told me that 200mA can kill a person. And I have accidentally touched both terminals on a battery with a wrench and it gave me a good jolt. If I had held it there, it very well could have stopped my heart.

[Jean]

200A? :o Is it even possible for our alternators to put out that much current? That is huge current. That shit would kill a person quickly.

And also, what is the point of the ground from the hood to the body? Is there any point to this? Mine is broken, but seeing as the hood bolts to the body, and there is nothing electric on the hood, I have never replaced it.

You don't need 200a to kill a person, giving high enough voltage even 1/4a will do. I can sit there all day with my hands on a 12 volt source with 100amp and not worry about a damn thing in the world ;)

[StereoInstaller1]

Basically, with a rear mount battery the capacitors inside the amp will recharge so quickly that it won't make much difference...thus my idea that it is pointless.

A cap does deliver current far quicker than a battery will, especially if the amp is connected to 15 feet of 4 gauge. If you only have 3 feet, I think the battery is adequate as long as you are not using a straight current dump amplifier.

My Exile 600.2 is fairly tightly regulated class A/B, more biased towards A. I am going to be running a 2 farad cap on it, but only because I want the look...I do sell this shit, so I need the looks. Besides, it is the cheapest way of putting a voltage meter in my car!

When I say this crap ($200 RCA's, Monster Cable 00 gauge, 2 redtops with $100 battery terminals, etc) are for bragging rights, I really do mean it. I do not believe it helps performance at all.

Luke

[TwoJ's]

12 isnt a measurement of caps, or anything for that matter its just a number
just before he replies you may want to edit

I know. It's not just a number, it's a number that represents the capacitence of the capacitor. I forgot the F.

It very well may be a 1.2F cap. 12 Farads is way beyond what would be necessary, but that's what I thought I remembered it being. Capacitors not only maintain current for slightly longer periods, but they can also deliver current much faster.

Why do you say they're meaningless in a car with rear mounted battery? The losses in 2 ga wire from the bay to the the trunk would be very minimal. 2 ga wire has resistance of .16 ohms per 1000ft. So if the wire from battery to trunk was ten feet, it would only have a resistance of 16 mili-ohms. How is it different if it's a 3 foot cable to the battery?

And I am in no way trying to challenge you, you are the pro here, I'm just trying to get an understanding.

[StereoInstaller1]

He likely has a 1.2F cap.

Caps store energy for a couple of seconds. Basically intended to maintain bass impact after the first few initial "beats"...meaningless in a rear mounted battery vehicle.

Multiple batteries are ONLY for being able to maintain voltage with the car not running.

A GM 140A alternator will blow a 150A circuit breaker in 2 or 3 seconds of high volume listening on a 3800 watt system (ask me how I know).

The circuit breaker is ONLY to protect in case of collision or fire.

Yup.

Luke

[NC325iC]

12 isnt a measurement of caps, or anything for that matter its just a number
just before he replies you may want to edit

[TwoJ's]

And also Luke, do you think that a large cap (I've got a 12 rockford one) would suffice instead of running dual batteries? And when you use two batteries, you wire them in parallel, not in series, correct?

[TwoJ's]

The first thing to upgrade is the charge wire. Run a nice chunk of 4 gauge from the alternators output over to the battery...but I would do a 200A circuit breaker for protection, personally.

200A? :o Is it even possible for our alternators to put out that much current? That is huge current. That shit would kill a person quickly.

And also, what is the point of the ground from the hood to the body? Is there any point to this? Mine is broken, but seeing as the hood bolts to the body, and there is nothing electric on the hood, I have never replaced it.

[StereoInstaller1]

Luke...

You're crazy.

Thanks all.

-Addis

I'm Crazy? Tell me that to my face at the 2008 picnic!


:)


600 watts A/B on bass is why I need more power...hungry amps rool.

Factory rear harness is 0 ga, so I am going to replace it with Monster, NBD.

2 redtops are for bragging rights, y0! 140A alternator is just enough, as you know.

Luke

[Addissimo]

I've got a 140 amp alternator, stock wiring to the front of the car, a new cheap battery and its all doing just fine for about 1000 watts, 600 on class d bass, the rest on a/b. I personally think all that wiring is over-kill, but whatever.

Isn't the stock wiring from the battery to the power distribution about 4 awg? I don't see much of a point in replacing it unless its with 0awg, and with that, have fun running it, and its only necessary for 3kw systems...

Luke...

You're crazy.

Thanks all.

-Addis

[StereoInstaller1]

It's anything lighted in the car, dash lights, buttons, headlights, interior lights, everything pulses.

I didn't realize the big 3 was supposed to make your car smoother or faster. I was just doing it as I planned on adding another 800 watt amp to a system already pushing 400 watts, I already had it, and I don't want to buy a new alternator or blue top if I don't have to. If the stock BMW wiring is already 4 guage or higher then I guess there would be no point to adding the 4 guage wiring I have available. Although plenty of people install 0 guage, and I know the stock wiring is not that large. Any particular reason you do not think it is a good upgrade?

Also, I have a vert, my battery is located under the hood. What would you suggest as a grounding point in the trunk?

As a power upgrade for stereo, I would agree 100% that better ground and better charge wire is a necessity. I am doing much the same, only I put my alternator upgrade on hold until after the motor swap.

The first thing to upgrade is the charge wire. Run a nice chunk of 4 gauge from the alternators output over to the battery...but I would do a 200A circuit breaker for protection, personally.

I have heard that the E28s and early E34 (m20 powered) had bigger alternators...and I know for a fact that some E34 had a cooling duct for the alternator (!).

The whole "big 3" thing is what all the Honda and Eclipse guys do thinking it will make the sensors more accurate, thus more HP (y0!). If you are doing it for audio power, WTF, give it a shot and let us know!

Do me a quick favor though...pull the trunk liner on the right rear, as in where normal 6 banger E30s have their batteries...look for a sheetmetal attachment for the stock battery location.

Have you thought about running 2 batteries? I will be doing 2 redtops and a minimum of 140A alternator, using 00 gauge Monster for main power, and I only have 600 watts on bass.

Luke

[soul rebel]

Go get a half-farad cap and install it on your headlights.

Big 3 won't do shit on our cars...ricer crap only.

It's anything lighted in the car, dash lights, buttons, headlights, interior lights, everything pulses.

I didn't realize the big 3 was supposed to make your car smoother or faster. I was just doing it as I planned on adding another 800 watt amp to a system already pushing 400 watts, I already had it, and I don't want to buy a new alternator or blue top if I don't have to. If the stock BMW wiring is already 4 guage or higher then I guess there would be no point to adding the 4 guage wiring I have available. Although plenty of people install 0 guage, and I know the stock wiring is not that large. Any particular reason you do not think it is a good upgrade?

Also, I have a vert, my battery is located under the hood. What would you suggest as a grounding point in the trunk?

[AndrewBird]

No settling needed. I'm not the type to get my panties in a wad over a question on the internet.

I saw it on Josh's car when we swapped his oil pan. It could be that a previous owner replaced it with a hood ground strap. (?)

Either way, it is in the place I said it was. ;)

[Rigmaster]

The one I am thinking of I KNOW is uninsulated. It looks just like the one connecting the hood to the body. Flat and braided.

I'm not disputing that you've seen one- so settle down.... ;)


I've never seen one like you mention on any E30. 2002's and E21's, yes- but not on an E30.


Do you remember what kind of E30 it was? I've got a bunch of cars, and all of them I checked today had the insulated ground cable.



Bret.

[shiboujin]

So the guy on the slidewayz (y0!) page is replacing a fucking bas ass groundstrap with a cheezball 4 gauge ground and expects it to be an improvement?

I don't think so Bob.

I know my block ground is just fine.

I later replaced it with audio grade wiring but it wasnt supposed to be an improvement. It was a fix for the starter not grounding enough to kick over the motor as a result of the dead stock wiring. It might not last 20 years but the stock one obviously didnt either.