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Re: I need a reason why this happenend - Electrical
[Re: 70Coronet500Vert]
#891117
12/31/10 11:08 AM
12/31/10 11:08 AM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
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West Coast, USA
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If you haven't done the bulkhead & amp guage bypass, there is a too large current flow through the original bulkhead connections to feed the amps and charge the battery via the stock wiring arrangement etc.
The stock bulkhead connections are just not up to that kind of an additional load. They were not even up to the original load. You should take corrective actions as soon as possible.
Have you read the information available at Mad Electric regarding these cars and their issues?
Last edited by jbc426; 12/31/10 11:12 AM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: Evil Monkey]
#891118
12/31/10 08:49 PM
12/31/10 08:49 PM
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Joined: Jan 2003
Posts: 5,441
So Cal
Sinitro
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So Cal
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Quote:
Quote:
Run a power lead from the battery, starter relay lug, or alternator output lug to a distribution block.
There's a huge difference between pulling the power for a distribution block from the battery/starter relay lug and from the alternator output lug. You want to make sure to pull the power from the alternator output lug, for this reason:
If you pull from the alternator output lug, you are getting the power directly from the source (the alternator), without anything else in between, and the power to the distribution block all stays under the hood.
If you pull the power from the battery or from the starter relay lug, the power comes from its source (the alternator), then has to go through the bulkhead connector to the interior, through the ammeter, back through the bulkhead connector and into the underhood area (where it started from anyway), and then finally to the point you are drawing the power from (the battery or starter relay lug).
Drawing power for a distribution block that powers a large amplifier (or any other high powered devices) from your battery or starter relay lug puts a huge amount of current through the bulkhead connector and ammeter, which could fry either one, unless you have made other electrical system modifications, like bypassing the bulkhead connector and ammeter by running a large gauge wire from the alternator output lug to the battery or starter relay lug. Mopars in the latter half of the 70s, like the '78 Aspen I owned, had a wire running directly from the alternator to the battery from the factory, and you could connect high power accessories or distribution blocks directly to the battery without issues. Earlier cars (like my 74 Cuda) do not have that direct connection between the alternator and battery, and should have high powered accessories or distribution blocks connected to the alternator side of the electrical system, before the power goes through the bulkhead connector.
The solution for high current drawing accessories including stereo power amplifiers is to run their 12V + and ground directly to the battery. No need to run through the bulkhead or somewhere else, as the power amplifier has a built-in power relay triggered by the remote lead. Run the remote lead to a Turn-On switch and you are good to go, note that the Turn-On draws only about 50Ma (0.05 Amps).
Just my $0.02... 
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Re: I need a reason why this happenend - Electrical
[Re: Sinitro]
#891119
12/31/10 09:33 PM
12/31/10 09:33 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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master
Joined: Mar 2007
Posts: 3,277
West Coast, USA
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Quote:
Quote:
Quote:
Run a power lead from the battery, starter relay lug, or alternator output lug to a distribution block.
There's a huge difference between pulling the power for a distribution block from the battery/starter relay lug and from the alternator output lug. You want to make sure to pull the power from the alternator output lug, for this reason:
If you pull from the alternator output lug, you are getting the power directly from the source (the alternator), without anything else in between, and the power to the distribution block all stays under the hood.
If you pull the power from the battery or from the starter relay lug, the power comes from its source (the alternator), then has to go through the bulkhead connector to the interior, through the ammeter, back through the bulkhead connector and into the underhood area (where it started from anyway), and then finally to the point you are drawing the power from (the battery or starter relay lug).
Drawing power for a distribution block that powers a large amplifier (or any other high powered devices) from your battery or starter relay lug puts a huge amount of current through the bulkhead connector and ammeter, which could fry either one, unless you have made other electrical system modifications, like bypassing the bulkhead connector and ammeter by running a large gauge wire from the alternator output lug to the battery or starter relay lug. Mopars in the latter half of the 70s, like the '78 Aspen I owned, had a wire running directly from the alternator to the battery from the factory, and you could connect high power accessories or distribution blocks directly to the battery without issues. Earlier cars (like my 74 Cuda) do not have that direct connection between the alternator and battery, and should have high powered accessories or distribution blocks connected to the alternator side of the electrical system, before the power goes through the bulkhead connector.
The solution for high current drawing accessories including stereo power amplifiers is to run their 12V + and ground directly to the battery. No need to run through the bulkhead or somewhere else, as the power amplifier has a built-in power relay triggered by the remote lead. Run the remote lead to a Turn-On switch and you are good to go, note that the Turn-On draws only about 50Ma (0.05 Amps).
Just my $0.02...
He has it wired like you're suggesting, now. His problem is that his charging system is stock and still going through the bulkhead before making it's way to the battery to feed the amp.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: Sinitro]
#891120
01/01/11 02:46 AM
01/01/11 02:46 AM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
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Posts: 14,889
up yours
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Quote:
The solution for high current drawing accessories including stereo power amplifiers is to run their 12V + and ground directly to the battery. No need to run through the bulkhead or somewhere else, as the power amplifier has a built-in power relay triggered by the remote lead. Run the remote lead to a Turn-On switch and you are good to go, note that the Turn-On draws only about 50Ma (0.05 Amps).
Just my $0.02...
No, not in a system with a non-shunted ammeter and even with a shunted ammeter it will indicate a drain giving the ammeter to read falsely.
An ammeter reads current flow. In an OEM design electrical system with an ammeter ALL running loads are drawn off the alternator side of the ammeter circuit EXCEPT for the battery charge current.
That is why after you start an engine the ammeter will read on the + side, then taper off to 0. When the running loads exceed the alternators capacity, or the alternator dies, then you get a - reading on the ammeter. If you wire ANY current draw to the battery you will always read - on the ammter, how much depends on the load. If it is not a shunted ammeter circuit then all that current draw will go thru the ammeter and the associated wiring, bulkhead connectors and all.
It should be wired to the alternator output, not the battery unless you have a voltmeter only, or an idiot light and even then you have best make sure you wiring from the alternator to battery is capable of handling it.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: I need a reason why this happenend - Electrical
[Re: Sinitro]
#891121
01/01/11 03:22 AM
01/01/11 03:22 AM
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Joined: Mar 2010
Posts: 357
Lake Elmo, MN
Evil Monkey
enthusiast
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enthusiast
Joined: Mar 2010
Posts: 357
Lake Elmo, MN
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Quote:
Quote:
Quote:
Run a power lead from the battery, starter relay lug, or alternator output lug to a distribution block.
There's a huge difference between pulling the power for a distribution block from the battery/starter relay lug and from the alternator output lug. You want to make sure to pull the power from the alternator output lug, for this reason:
If you pull from the alternator output lug, you are getting the power directly from the source (the alternator), without anything else in between, and the power to the distribution block all stays under the hood.
If you pull the power from the battery or from the starter relay lug, the power comes from its source (the alternator), then has to go through the bulkhead connector to the interior, through the ammeter, back through the bulkhead connector and into the underhood area (where it started from anyway), and then finally to the point you are drawing the power from (the battery or starter relay lug).
Drawing power for a distribution block that powers a large amplifier (or any other high powered devices) from your battery or starter relay lug puts a huge amount of current through the bulkhead connector and ammeter, which could fry either one, unless you have made other electrical system modifications, like bypassing the bulkhead connector and ammeter by running a large gauge wire from the alternator output lug to the battery or starter relay lug. Mopars in the latter half of the 70s, like the '78 Aspen I owned, had a wire running directly from the alternator to the battery from the factory, and you could connect high power accessories or distribution blocks directly to the battery without issues. Earlier cars (like my 74 Cuda) do not have that direct connection between the alternator and battery, and should have high powered accessories or distribution blocks connected to the alternator side of the electrical system, before the power goes through the bulkhead connector.
The solution for high current drawing accessories including stereo power amplifiers is to run their 12V + and ground directly to the battery. No need to run through the bulkhead or somewhere else, as the power amplifier has a built-in power relay triggered by the remote lead. Run the remote lead to a Turn-On switch and you are good to go, note that the Turn-On draws only about 50Ma (0.05 Amps).
Just my $0.02...
The problem is, when something is wired directly to the battery in a stock electrical system, the power WILL go through the bulkhead. It's not a matter of running it through the bulkhead or not running it through the bulkhead, wiring directly to the battery FORCES it through the bulkhead.
You need to remember, in a running car the battery is not the source of power, the source of power is the alternator, and the battery is just a storage device so that you have power when the engine is not running so that it can be started. It is only when the car is not running that the battery becomes the source of power.
If the stock electrical system has been upgraded with a heavy gauge wire directly connecting the alternator and the battery, then you can connect anything you want to the battery and it will be directly connected to the power source (the alternator) through that wire. Without that wire, though, the only way for power to get from the alternator to the battery is to go through the bulkhead connector and ammeter, so anything connected directly to the battery gets its power through that route, or else it drains the battery when no power is available through that route.
1974 'Cuda 360/TKO
1990 Ram Van
1998 Neon
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Re: I need a reason why this happenend - Electrical
[Re: Evil Monkey]
#891122
01/01/11 11:41 AM
01/01/11 11:41 AM
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Joined: Dec 2010
Posts: 4
Virginia,USA
74Bcuda
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member
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Virginia,USA
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Thanks for this post, I just got a new sound system from Santa and I was needing this information as well. A long time ago my amp gauge went out and I put the wire in from my alternator to the battery to "bypass" the gauge. Last year I finally got a new gauge and removed the large "bypass" wire. SO, now with this new system going to be installed I guess I will need to put the wire back OR did i read right in that I can just run my system to my alternator?. The only problem I can see with "bypass" wire is (as before) my amp gauge will no longer read at all. 
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Re: I need a reason why this happenend - Electrical
[Re: 74Bcuda]
#891124
01/01/11 12:27 PM
01/01/11 12:27 PM
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Joined: Mar 2007
Posts: 3,277
West Coast, USA
jbc426
master
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Joined: Mar 2007
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Quote:
.... A long time ago my amp gauge went out and I put the wire in from my alternator to the battery to "bypass" the gauge. Last year I finally got a new gauge and removed the large "bypass" wire....
Adding this single (fuse etc. protected) wire from the alternator directly to the starter lug and subsequently the battery is a great idea, but until you unbolt the red and black wires from the amp gauge and connect them together in a secure manner, even if you just move one of the wires so they are on the same lug, you amp guage is not bypassed and remains a potentially weak link.
You can get away with just adding the single wire like you describe if you don't add any extra load on that side of the circuit, BUT only add extra loadS to the starter lug/distribution lug side using relays and fused circuits IF YOU HAVE TAKEN CARE OF THE BULKHEAD AND AMP GAUGE ISSUES FIRST), Rn bypasses and make sure the remaining connections at the bulkhead are clean and filled with dielectric grease, which can help reduce future corrosion and disipate some of the heat.
I like amp meters too, but will be running an aftermarket volt meter along with aftermarket oil pressure and oil temperature gauges. There are some amp gauges available with various heavier duty shunts that are designed to have much more current passing through them with out going into thermal overload. The problem for me is that they just don't fit into the stock dash location with out extensive modification, and I believe you have to be pretty exact in matching them with the amp load they will end up carrying in order to be able to choose the right one.
Last edited by jbc426; 01/01/11 06:28 PM.
1970 Plymouth 'Cuda #'s 440-6(block in storage)currently 493" 6 pack, Shaker, 5 speed Passon, 4.10's
1968 Plymouth Barracuda Convertible 408 Magnum EFI with 4 speed automatic overdrive, 3800 stall lock-up converter and 4.30's (closest thing to an automatic 5 speed going)
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Re: I need a reason why this happenend - Electrical
[Re: Supercuda]
#891125
01/01/11 06:19 PM
01/01/11 06:19 PM
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Joined: Jan 2003
Posts: 5,441
So Cal
Sinitro
master
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master
Joined: Jan 2003
Posts: 5,441
So Cal
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Quote:
Quote:
The solution for high current drawing accessories including stereo power amplifiers is to run their 12V + and ground directly to the battery. No need to run through the bulkhead or somewhere else, as the power amplifier has a built-in power relay triggered by the remote lead. Run the remote lead to a Turn-On switch and you are good to go, note that the Turn-On draws only about 50Ma (0.05 Amps).
Just my $0.02...
No, not in a system with a non-shunted ammeter and even with a shunted ammeter it will indicate a drain giving the ammeter to read falsely.
An ammeter reads current flow. In an OEM design electrical system with an ammeter ALL running loads are drawn off the alternator side of the ammeter circuit EXCEPT for the battery charge current.
That is why after you start an engine the ammeter will read on the + side, then taper off to 0. When the running loads exceed the alternators capacity, or the alternator dies, then you get a - reading on the ammeter. If you wire ANY current draw to the battery you will always read - on the ammter, how much depends on the load. If it is not a shunted ammeter circuit then all that current draw will go thru the ammeter and the associated wiring, bulkhead connectors and all.
It should be wired to the alternator output, not the battery unless you have a voltmeter only, or an idiot light and even then you have best make sure you wiring from the alternator to battery is capable of handling it.
Oh really..
Then why does MSD tell you to connect their box directly to the battery..
Below is a direct lift form their install instructions..
Power Wires
There are two heavier gauge wires on the MSD, a Red and Black. The heavy red wire needs to be connected to the positive side of the battery. Connecting it to the battery side of the starter solenoid is also okay, but the directly to the battery positive terminal is ideal.
Next, confirm that the heavy black wire is connected to the negative side of the battery, or directly to engine ground on the head or block.
As previously mentioned for the car amplifier install, its primary 12V should be direct to the battery not the alternator output. One disadvantage of connecting directly to the alternator output is that if the amplifier is used when the engine is off, there is a loss(voltage drop) between the alternator output connection back to the battery.
Another advantage of connecting directly to the battery is that it acts as shunt for noise pickup such as alternator output whine.
To me the key point is to determine what is going to be connected within the system. And then one needs to determine the best hardware and setup. For example, our 40 year Mopars were designed with a typical electrical capacity of about 50 Amps.. If one is installing electric fans, fuel pump, subwoofer amplifiers and ignition boxes the a careful layout should be done in advance. As all of these components can easily draw upwards of 100 amps when adding the headlites as well.
The biggest weakness of our old Mopar electrical systems is age and lack of maintence especially for the bulkhead connectors.
Just my $0.02...
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Re: I need a reason why this happenend - Electrical
[Re: Sinitro]
#891126
01/01/11 08:07 PM
01/01/11 08:07 PM
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Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
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About to go away
Joined: Sep 2007
Posts: 14,889
up yours
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MSD tells you to do that because they are thinking RACE car, many of which don't even use an alternator at all. Hooking directly to the source, in this case it's the battery only, is always best. If the engines running and it has an alternator the output of the alternator is best.
HOWEVER, in a street car with an ammeter what I said above is still correct.
As for the Amp setup answer this, which happens most? Amp on and engine running or amp on and engine off? Bet it's amp on and engine running which means if you set it up to the battery then your current will go thru the wiring it cautions you against most of the time. Set it up my way and it doesn't.
As for the shunt claim, it's bogus and noise isn't suppressed by the battery, you'd use a noise suppression capacitor hooked to the alternator output or coil, depending on noise source.
I been screwing with electronics and instrumentation, especially noise suppression for about 25 years now.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
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Re: I need a reason why this happenend - Electrical
[Re: Sinitro]
#891127
01/02/11 03:41 AM
01/02/11 03:41 AM
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Joined: Mar 2010
Posts: 357
Lake Elmo, MN
Evil Monkey
enthusiast
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Lake Elmo, MN
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Quote:
As previously mentioned for the car amplifier install, its primary 12V should be direct to the battery not the alternator output. One disadvantage of connecting directly to the alternator output is that if the amplifier is used when the engine is off, there is a loss(voltage drop) between the alternator output connection back to the battery.
So, when you're all done listening to your high powered amplifier with the engine off, how do you plan on starting the car? Running that high powered amplifier for the last 45 minutes has just drained your battery to the point where it will no longer turn your engine over. Better have some jumper cables sitting in the trunk next to the amplifier.
In my eyes, it's much more realistic to look at what's happening when the engine is running - that covers the 99 percent of the time that you will be running the amplifier, rather than looking at what's happening when the engine is off, which covers the other 1 percent of the time that you will be running the amplifier. Besides, there is already a voltage drop to the amplifier when you shut the engine off - your electrical system is at around 14 volts (or more) with the engine running, and drops to 12.6 volts with the engine off. Does it really matter if it drops another .2 volts or so when the engine is off by pulling the power from the alternator side?
And, you're not even considering that you will get that exact same voltage loss by connecting to the battery (instead of the alternator) when the engine is running - the power is going through the exact same wiring going from the alternator to the battery when the engine is running that, as you are pointing out, is causing a voltage loss when the engine is off. Same wiring, same voltage loss. When you connect directly to the battery, that voltage loss happens 99 percent of the time the amplifier is running, but when you connect to the alternator, the loss happens only 1 percent of the time it's running.
Quote:
Another advantage of connecting directly to the battery is that it acts as shunt for noise pickup such as alternator output whine.
That's what a filter capacitor is for - you want to connect a filter capacitor as close as possible to the amplifier to eliminate noise. Yes, the battery will act as a filter also, but then you have a 15 or 20 foot line running from the battery to the trunk where the amplifier is located, and that line can pick up alternator noise, or noise from fans, plugs, MSD boxes, turn signal flashers, etc. So, even if you draw your power directly from the battery, you would still need a filter cap near the amplifier to eliminate noise.
Oh, and those MSD directions, they were written by MSD, not by Ma Mopar. I've seen plenty of directions written by third parties that are not correct - the directions might get their product to work, but can cause problems overall with the equipment you are installing their product on (this is true with any piece of equipment, not just cars). I take all third party instructions with a grain of salt, and use them as general guidelines to help determine how to make their product work. To determine the actual configuration that I will use when I add a third party product, the most important thing to consider is how it will affect the equipment I add it to, and I alter the instructions based on what is best for the equipment I'm adding it to, and not based on what is best for that third party product. After all, even after an MSD installation, I'm still driving the car, not the MSD box.
1974 'Cuda 360/TKO
1990 Ram Van
1998 Neon
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Re: I need a reason why this happenend - Electrical
[Re: Evil Monkey]
#891128
01/03/11 11:26 PM
01/03/11 11:26 PM
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Joined: Jan 2003
Posts: 5,441
So Cal
Sinitro
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So Cal
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Quote:
Quote:
As previously mentioned for the car amplifier install, its primary 12V should be direct to the battery not the alternator output. One disadvantage of connecting directly to the alternator output is that if the amplifier is used when the engine is off, there is a loss(voltage drop) between the alternator output connection back to the battery.
So, when you're all done listening to your high powered amplifier with the engine off, how do you plan on starting the car? Running that high powered amplifier for the last 45 minutes has just drained your battery to the point where it will no longer turn your engine over. Better have some jumper cables sitting in the trunk next to the amplifier.
In my eyes, it's much more realistic to look at what's happening when the engine is running - that covers the 99 percent of the time that you will be running the amplifier, rather than looking at what's happening when the engine is off, which covers the other 1 percent of the time that you will be running the amplifier. Besides, there is already a voltage drop to the amplifier when you shut the engine off - your electrical system is at around 14 volts (or more) with the engine running, and drops to 12.6 volts with the engine off. Does it really matter if it drops another .2 volts or so when the engine is off by pulling the power from the alternator side?
And, you're not even considering that you will get that exact same voltage loss by connecting to the battery (instead of the alternator) when the engine is running - the power is going through the exact same wiring going from the alternator to the battery when the engine is running that, as you are pointing out, is causing a voltage loss when the engine is off. Same wiring, same voltage loss. When you connect directly to the battery, that voltage loss happens 99 percent of the time the amplifier is running, but when you connect to the alternator, the loss happens only 1 percent of the time it's running.
Quote:
Another advantage of connecting directly to the battery is that it acts as shunt for noise pickup such as alternator output whine.
That's what a filter capacitor is for - you want to connect a filter capacitor as close as possible to the amplifier to eliminate noise. Yes, the battery will act as a filter also, but then you have a 15 or 20 foot line running from the battery to the trunk where the amplifier is located, and that line can pick up alternator noise, or noise from fans, plugs, MSD boxes, turn signal flashers, etc. So, even if you draw your power directly from the battery, you would still need a filter cap near the amplifier to eliminate noise.
Oh, and those MSD directions, they were written by MSD, not by Ma Mopar. I've seen plenty of directions written by third parties that are not correct - the directions might get their product to work, but can cause problems overall with the equipment you are installing their product on (this is true with any piece of equipment, not just cars). I take all third party instructions with a grain of salt, and use them as general guidelines to help determine how to make their product work. To determine the actual configuration that I will use when I add a third party product, the most important thing to consider is how it will affect the equipment I add it to, and I alter the instructions based on what is best for the equipment I'm adding it to, and not based on what is best for that third party product. After all, even after an MSD installation, I'm still driving the car, not the MSD box.
Well...
Since we have been building show cars for major trade shows such as CES and SEMA, as well as certain auto performance magazines for the last 35 years, we do know a little about this subject... 
Also we are MECP certified as well..
Before we install any device, we carefully read the instructions even if we have installed their products previously...
Check out the boards and you will find many reports of defective MSD boxes, yet after being tested @ MSD 95% of these function fine.. 
The MSD boxes especially the earlier ones needed a strong/solid 12V with stable current capability. If the voltage source was marginal and dropped below a certain point the MSD box would stop working.
Regarding audio/video systems, note how the systems are played today often when the car is parked. Thats why we typically install additional batteries to deliver more current capability.
Bottom line..
The car's 12V system should be matched to what is connected. Again read the boards and note the number of problems and fingerpointing @ the bulkhead connectors in our 40-50 year old Mopars. Next ask when was the last time the bulkhead connectors were serviced... 
The original Mopar electrical system did just fine within its 50 Amps capability, install more stuff such as halogen lites, electric cooling fans, subwoofer amplifier or electric fuel pump more current is required..
Which requires a bigger alternator, bigger battery, and revised electrical harnesses.
Just my $0.02..
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