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Re: Mopar Action article
[Re: John_Kunkel]
#624752
03/01/10 06:52 PM
03/01/10 06:52 PM
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Joined: Jun 2008
Posts: 1,822
Colorado
denfireguy
top fuel
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top fuel
Joined: Jun 2008
Posts: 1,822
Colorado
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Judging by the number 8 cables, I would say that it is not shunt driven.
I have often wondered about calibrating a voltmeter to the current drop across the alternator lead to use it as a shunt. The wire should have around .01 ohms from end to end. Then you could have the best of both worlds.
Craig
2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado
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Re: Mopar Action article
[Re: denfireguy]
#624753
03/01/10 09:13 PM
03/01/10 09:13 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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There is substantial misinformation about ammeters.
ALL an ammeter reads is current to, or from, the battery. NOTHING else. If you have a 120A alternator and you are pumping 120A into the battery you have substantially more problems than a "40 year old" ammeter to worry about.
If you put in a thumping sound system and you wire it on the battery side of the ammeter then you need to step away from the soldering iron cause you are over your head.
Voltmeters and ammeters measure two different things in an electrical system. To use the water flow example, it's like a pressure guage (voltmeter) and a flow guage (ammeter). Both have their places and an ammeter will tell you things a voltmeter won't.
For example, if you have both hooked up and your voltmeter shows a nice 13.8V but your ammeter shows 75A being pushed into the battery you have a problem, one a voltmeter will not show.
Another issue with a voltmeter is that it is buffered, to an extent, by the battery. When the alternator dies your voltmeter will still show battery voltage as it drops (rate of drop depends on the load), an ammeter will an instantaneous discharge.
The factory draws almost all the electrical load (except the starter) from the alternator side of the ammeter. One should never draw a load from the battery side of the ammeter, except for the battery obviously. Then it really doesn't matter how many amps your pulling cause none of the load passed thru the ammeter unless the charging system isn't working (engine off, for example).
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: Mopar Action article
[Re: John_Kunkel]
#624754
03/01/10 09:19 PM
03/01/10 09:19 PM
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Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
@#$%&*!
New user name, Same old jerk!
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New user name, Same old jerk!
Joined: May 2008
Posts: 1,131
Thigh-Gap Junction
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Quote:
Why do you need to know how much current is being drawn by the system? A voltmeter will tell you the system voltage, if the system voltage is above the battery's "engine off" voltage the battery is being charged.
A voltmeter tells you the voltage 'state' of the system while the ammeter tells you what is actually happening right now, charge or discharge. If your charging system dies you might not know it for a while with a voltmeter while the ammeter tells you immediately that it's not charging.
Quote:
So Dragstripper, are you saying that, if all the connections are clean and in good working order, that using the stock ammeter is not a danger to the wiring harness nor the car?
All of my cars are still stock in the ammeter department. The problem is that some of the internal connections aren't easily maintained and as the metals oxidize over the years the resistance of the connections go up. Resistance and high current generates heat. You could troubleshoot the system by exercising the charging system and then feeling the various connections for high temps, carefully! Any instrument rebuilder worth using will set you up and have your gauges working as good as new. I've never been a fan of the charging system current going through those light-duty bulkhead connectors but mine are all still hooked up that way, except for the bracket car which is totally custom.
Quote:
Judging by the number 8 cables, I would say that it is not shunt driven.
I have often wondered about calibrating a voltmeter to the current drop across the alternator lead to use it as a shunt. The wire should have around .01 ohms from end to end. Then you could have the best of both worlds.
Craig
You could certainly sever the factory ammeter internally and run modest gage wires to a section of the circuit elsewhere as long as the resistance between the connection points of the new wires is precisely the same as the internal resistance of the factory ammeter. That's basically what a shunt setup is. Maybe a section of fusible link calibrated to simulate the resistance of the factory ammeter, keeping the charging current under the hood, straight from the alternator to the battery.
Cory
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Re: Mopar Action article
[Re: 70duster340]
#624757
03/01/10 11:36 PM
03/01/10 11:36 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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There is no debate. Ammeters, in stock applications, work one way. All else is misinformation.
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: Mopar Action article
[Re: ahy]
#624758
03/02/10 10:31 AM
03/02/10 10:31 AM
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Joined: Jun 2008
Posts: 1,822
Colorado
denfireguy
top fuel
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top fuel
Joined: Jun 2008
Posts: 1,822
Colorado
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Quote:
I did the ammeter to voltmeter conversion on a Challenger ralley dash... or more precisly I had a shop do it. They set it up so the needle was just about centered at normal charged battery voltage - around 12.5 volts. Higher voltage went the the charge side and lower voltage went to the discharge side.
It has been a very useful instrument; At a glance when running if the needle is a bit to the left of center, all is well. If its centered or to the right that means problems. I won't get into the debate on which is better, ammeter or voltmeter, but I can say this setup has worked well for me. Keeping the ammeter wasn't really an option for me due to heavy non-stock electrical loads and the requirement for a bigger alternator.
That said, I've delt with problems on stock MOPAR's with the standard setup and am glad to get away from it. The heavily loaded charge wire on the bulkhead connector especially.
I agree that a heavily loaded bulkhead connector is bad news. See the above post about police and taxi versions. Not a lot of us are running overhead lights and a Federal Q siren so that should not be an issue. The 30 amp two ways are also history. Halogen headlights draw less current than the old tungsten lamps. All in all, current loads in cars have dropped. GPS, car stereo, CB, and dvd player only add around 5 or ten amps total to current draw.
I worked for 4 years in the '70s for a city fleet management shop with a fleet of 85 Plymouth police cars and battalion chief cars. I took care of the radios, sirens, radar, Vascar and consoles. I wound up doing lots of charging systems since the mechanics always blamed the electronics for all electrical issues. The ammeter system was never an issue. A lot of that is because none of them was more than 5 years old so the oxidation had not set in.
To keep my 'Cuda in shape, I just drop the radio out of the dash (two bolts, one nut and the antenna connector). Laying on the floor I can see the ammeter connections. I back off the nuts with a nut driver then retighten them. I do this as part of every oil change. Five minutes of work but good insurance. The bulkhead connector is packed with dielectric grease to keep water and green cancer away. The seals are available from Detroit Muscle and have been replaced. Dielectic grease also helps hold the gasket in place when mounting the connector from the inside.
Craig
2014 Ram 1500 Laramie, 73 Cuda
Previous mopars: 62 Valiant, 65 Fury III, 68 Fury III, 72 Satellite, 74 Satellite, 89 Acclaim, 98 Caravan, 2003 Durango
Only previous Non-Mopar: Schwinn Tornado
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Re: Mopar Action article
[Re: denfireguy]
#624759
03/02/10 10:46 AM
03/02/10 10:46 AM
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Joined: Jan 2003
Posts: 1,443
70duster340
OP
pro stock
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OP
pro stock
Joined: Jan 2003
Posts: 1,443
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Thanks, Craig. I intend to keep the stock ammeter working, I'm just not sure right now how to wire it in. When I installed the Painless fuse block, it effectively did away with the ammeter. The red power wire from the bulkhead connector is not routed to the fuse block, as is the black wire from the alternator. I just need to figure out how to wire in the ammeter. I thought it was a good idea to install the fuse block, as the stock fuse block was looking a bit suspect. And, where I live, the glass type fuses are becoming more difficult to find. This fuse block includes the horn relay, and flashers for both the turn signals and the emergency flashers, among many other things.
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