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Ammeter problem?
https://slantsix.org/forum/viewtopic.php?t=26877		 Page 1 of 1
Author:  polkat [ Sun Jan 27, 2008 5:17 pm ]
Post subject:  Ammeter problem?
Just got this '73 Dart (318) which is stock. Had to fix the fuel gauge (it was the sender). I've noticed that whenever the engine is idling (around 700rpm) the ammeter reads low. When I'm stopped with the lights on and the defroster on (rains a lot here), the ammeter goes completely to the left (-40)!! If I rev it up to about 1000rpm the ammeter comes back to normal. Oddly, the battery is always very strong!!
Is there a fix for this?
Thanks!
________
7Y
Author:  dudley [ Sun Jan 27, 2008 5:54 pm ]
Post subject: 
You might try running a ground wire from the body of the alternator to the body of the voltage regulator and from the body of the voltage regulator to the battery ground.

http://www.slantsix.org/forum/viewtopic.php?t=24993

http://www.slantsix.org/forum/viewtopic.php?t=25708

http://www.slantsix.org/forum/viewtopic.php?t=12891
Author:  polkat [ Sun Jan 27, 2008 7:45 pm ]
Post subject: 
I might try running that ground wire. But I don't have any of the problems in the links. My headlights stay bright when the ammeter dips. In fact, everything keeps working as normal, just the ammeter dips at idle or goes clear left if the lights are on, but again, the lights don't dim. Weird problem I know. Actually, I think I'm gonna chuck the ammeter and put in a voltmeter.
________
marijuana vaporizer
Author:  dakight [ Mon Jan 28, 2008 4:12 am ]
Post subject: 
Chucking the ammeter might be akin to the ostrich putting his head in the sand to avoid danger. You need to find and fix the problem sausing the current swings. It sounds like possible issues with the alternator and/or regulator to me. ALso, some discharge at idle is normal, particularly with older designs, but -40 amps seems extreme to me. Don't get me wrong, I'm not dissing the voltmeter; virtually all modern cars use them, but there are things an ammeter will tell you that a voltmeter won't.
Author:  66aCUDA [ Mon Jan 28, 2008 7:41 am ]
Post subject: 
I personaly believe the ampmeter is reading corectly. Remember that our old cars didnt have a lot of current available to start out with. And the old alts didnt like slow speeds like todays alts.
My.02
Frank
Author:  boredskater [ Mon Jan 28, 2008 9:28 pm ]
Post subject:  regardless...
ditching the ammeter is more than a sound idea. having dealt with wiring issues on more than one /six as a result of the wiring setup leading to it, just ditch the thing if you're not stuck on being an absolute purist.

the connections, and circuit board it's involved in, combined with the power of modern electrical systems as i'm sure by this point you've got a newer alternator and at least a handful of newer components, are trouble waiting to happen.

having the entire under dash bundle slowly melt together into one mass unbeknown to you as a result of the ammeter jumping is not fun, particularly if you're paying someone else to rewire. I enjoyed the complete rewire of my valiant on my own as a result of this, but would have enjoyed putting the same money and man hours into suspension and engine components and just driving the thing around.

It's antiquated tech. and even with other problems going on it will encourage you to trouble shoot down the line and get the whole system in check. If you're having problems now, there's more on the way even if they're minor, and there'll be a reduced chance if you just replace or get rid of the thing and start working down the line.

while this isn't the answer to your problems, or problematic for everyone, it will eliminate a lot more issues in the future to just bypass or put a better insulated voltmeter in it's place. If you're maintaining your car regularly as a classic requires, there's not a whole lot more your ammeter is gonna tell you that you aren't recognizing from daily performance anyway.
Author:  polkat [ Mon Jan 28, 2008 11:06 pm ]
Post subject: 
There is an ammeter bypass circuit mod offered on the M.A.D. website. I know that there are guys here that don't like that site, but will the circuit offered there actually work? There's a part of the finished circuit that puzzles me....when completed, the red and black wires are both carrying current to the "welded splice" that feeds the instruments. This seems redundant to me. Seems one of these wires could be eliminated. This would make for a slightly cleaner setup. Or am I missing something here?
Thanks!
________
Motor Manufacturing Texas
Author:  KBB_of_TMC [ Thu Jan 31, 2008 9:54 am ]
Post subject: 
Could you please post the URL of the circuit you're describing? It'd be easire to comment on it if I can take a look at it.
Author:  polkat [ Thu Jan 31, 2008 11:04 am ]
Post subject: 
Yes, the circuit mod I've been looking at can be found here:

http://www.madelectrical.com/electrical ... uges.shtml

It's in 2 pages with the modified circuit on pg. 2.

I'm wondering how well it will work, and if there's redundency in the red/black wires now feeding the dash.
Thanks!
________
Toyota GR engine
Author:  slantvaliant [ Thu Jan 31, 2008 11:27 am ]
Post subject:  Re: regardless...
Quote:
ditching the ammeter is more than a sound idea ... just ditch the thing if you're not stuck on being an absolute purist.
I'm a long way from being a purist, but I'll keep the ammeter, thank you.
Quote:
the connections, and circuit board it's involved in ... are trouble waiting to happen.
Why not fix the atual problems? Specifically, the firewall connector can be bypassed for the ammeter feed fairly easily and the leads replaced with heavier wire. If you have truly high amps passing through, a shunt ammeter system has been discussed before.
Quote:
having the entire under dash bundle slowly melt together into one mass unbeknown to you as a result of the ammeter jumping is not fun.


The ammeter almost always jumps in response to changes in the charging rate - that's what ammeters are designed to do - not because of a fault in the ammeter itself. If your charging system has a problem, fix the problem, not the indicator.
My car suffered a wiring melt because of inexperienced but well intentioned actions of a teenager and his mom, and it was not fun to fix. The ammeter was not the cause. But the new connectors and upgraded wiring are much appreciated.
Quote:
It's antiquated tech.
So is the Slant Six. So? :wink:
Author:  SlantSixDan [ Thu Jan 31, 2008 1:12 pm ]
Post subject: 
MAD electrical = a bunch of half-baked advice from a Chevy-head pretending to know something about Mopars. :roll:

http://www.slantsix.org/forum/viewtopic ... ht=#153636

http://www.slantsix.org/forum/viewtopic ... ht=#121080

http://www.slantsix.org/forum/viewtopic ... ht=#121269
Author:  polkat [ Thu Jan 31, 2008 1:44 pm ]
Post subject: 
Okay, let me see if I have this straight. A voltmeter shows the voltage at any given time being produced by the alternator, but doesn't show how much the battery is being charged, while the ammeter shows exactly what's happening with the battery now! Right? If so, then yes, it seems the ammeter is the better choice.

As far as safety goes, would be a better idea to bypass the bulkhead connector, and just run the ammeters wires straight through the firewall (or through holes drilled in the bulkhead).

Am I close on this?
Thanks!
________
one vaporizer
Author:  slantvaliant [ Thu Jan 31, 2008 2:47 pm ]
Post subject: 
Quote:
Okay, let me see if I have this straight. A voltmeter shows the voltage at any given time being produced by the alternator, but doesn't show how much the battery is being charged, while the ammeter shows exactly what's happening with the battery now!
Pretty much. Both give real-time information, and both require some interpretation. The voltmeter indicates the voltage difference between its positive and negative reference points. Make sure you know where those are. The ammeter indicates the current flow through the ammeter circuit. Same caveat. Neither is perfect, both give good information when understood, and either is better than nothing.

I prefer an ammeter, and it is largely a personal preference. I wouldn't remove a voltmeter just to install an ammeter, either.
Quote:
As far as safety goes, would be a better idea to bypass the bulkhead connector, and just run the ammeters wires straight through the firewall (or through holes drilled in the bulkhead).
Yes. Make sure you at least use a good grommet to prevent chafing on the hole in the firewall. Insulated bulkhead connectors are also available.
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