Confusing Amp Meter

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   Hey Guys-

I recently took my 78'SN in for alternator service because it was not charging the battery correctly.  They fixed that (missing ground wire) but the amp gauge is still reading -20 DIS while running. I know the battery is charging as a handheld volt meter showed 14+ volts.  

Any ideas on a fix?  Mixed up wiring somewhere? When I first cold start the motor the amp meter reads +10 CHG then quickly drops to the -20 DIS side and stays there.

Thanks-

NM

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Nautique Mike Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-20-2006 Location: United States Status: Offline Points: 147	Post Options Post Reply Quote Nautique Mike Report Post Thanks(0) Quote Reply Topic: Confusing Amp Meter Posted: August-19-2006 at 12:31pm
	Hey Guys- I recently took my 78'SN in for alternator service because it was not charging the battery correctly. They fixed that (missing ground wire) but the amp gauge is still reading -20 DIS while running. I know the battery is charging as a handheld volt meter showed 14+ volts. Any ideas on a fix? Mixed up wiring somewhere? When I first cold start the motor the amp meter reads +10 CHG then quickly drops to the -20 DIS side and stays there. Thanks- NM
	Nautique Mike

JEFF KOSTIS Members Profile Send Private Message Find Members Posts Add to Buddy List Gold Member Joined: April-19-2005 Location: United States Status: Offline Points: 817	Post Options Post Reply Quote JEFF KOSTIS Report Post Thanks(0) Quote Reply Posted: August-19-2006 at 8:31pm
	Does the meter read zero with nothing on and the engine off?? Does it go to Discharge about 10 amps or so if the just blower is turned on with the engine off? Jeff...
	MUSTANG COUNTRY 1974 Mustang 17 1976 Mustang 17

David F Members Profile Send Private Message Find Members Posts Add to Buddy List Platinum Member Joined: June-11-2004 Location: United States Status: Offline Points: 1770	Post Options Post Reply Quote David F Report Post Thanks(0) Quote Reply Posted: August-21-2006 at 10:14am
	Kind of sounds like the amp meter is wired backwards. Is that even possible?

JEFF KOSTIS Members Profile Send Private Message Find Members Posts Add to Buddy List Gold Member Joined: April-19-2005 Location: United States Status: Offline Points: 817	Post Options Post Reply Quote JEFF KOSTIS Report Post Thanks(0) Quote Reply Posted: August-21-2006 at 9:43pm
	Dave yes it is, my 76 reads -25 all the time due to the new engine wiring. I havent had the time to put in a voltmeter as I cant use the ammeter due to insufficient wire size to the dash. (new alt is 60A ) It is kinda cool to know how much I am drawing while running. Jeff....
	MUSTANG COUNTRY 1974 Mustang 17 1976 Mustang 17

Nautique Mike Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: June-20-2006 Location: United States Status: Offline Points: 147	Post Options Post Reply Quote Nautique Mike Report Post Thanks(0) Quote Reply Posted: August-23-2006 at 8:07am
	Jeff and Gang- If my wiring is reversed where do I make the correction? In the engine compartment or at the meter? My meter is original and the wiring looks as if it has never been touched under there (sealed liquid electrical tape on all the leads). My new altenator is the one SKIDIM recommended for my 78' SN 351 commander. It is Item #RA097006 Alternator 51A w/reg. It was installed by my local marina who removed the elxternal regulator. I don't know if this is related but they also did a electronic conversion to the distributer at the same time. There they removed the external resistor. The marina didn't know what to do with the amp meter so any help would be great! Thanks- NM
	Nautique Mike

79nautique Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872	Post Options Post Reply Quote 79nautique Report Post Thanks(0) Quote Reply Posted: August-23-2006 at 9:33am
	I would bet that they have it wired for a volt meter and not an amp gauge. When I changed mine out with a new alternator and wiring harness Vince forgot to send me the diagram for the amp meter wiring which is a little different so if one of the orange or red leads (forget which) isn't taped off and un-used it's not wired right for an ampmeter application.

77stang Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: May-19-2004 Location: United States Status: Offline Points: 342	Post Options Post Reply Quote 77stang Report Post Thanks(0) Quote Reply Posted: August-23-2006 at 11:21am
	your correct 79 and its the orange wire that needs to be terminated.
	'77 Mustang 17

oldskiboat Members Profile Send Private Message Find Members Posts Visit Members Homepage Add to Buddy List Groupie Joined: June-16-2006 Location: United States Status: Offline Points: 92	Post Options Post Reply Quote oldskiboat Report Post Thanks(0) Quote Reply Posted: August-23-2006 at 11:41am
	An Amp meter is wired in series with the load and a volt meter is wired from positive to negative. If you wired an amp meter like a volt meter it would burn out. The actual meter movement is about the same but the amp meter has a shunt that carries most of the current. Most of the current does not go through the meter movement it shunts across it. Check to see if the meter reads anything with everything off. Then turn to key to acc and turn on a blower or blow the horn. You should see a minus reading. If it is plus you have something wired backwards. It could be changed at the meter, but I would suggest it is done at the source. It sounds like the positive and negative is reversed some where. By the way you would normally see a discharge at start and then a charge when the alternator starts charging.
	Gary The Villages Fl. 75Southwind 20

79nautique Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872	Post Options Post Reply Quote 79nautique Report Post Thanks(0) Quote Reply Posted: August-23-2006 at 1:25pm
	that's fine if you added one and wiring it from scratch. but in this case it existing not adding, it is not changing anything under the dash or changing any of the wiring at the gauge or dash it has to do with the way the engine wiring harness is and the leads from the factory that are there and the way they have to be wired when up grade to a new internal regulated alternator and eliminating the voltage regulator. Jerry and I know exactly what we are talking about and we are telling them what has to be done. We don't need anymore cla$$room basic wiring leasons, we get plenty of that for a couple of others on the basics of wiring. This is a specific application that me and several others have done on 80's and older boat when the alternator goes out and a new higher amp unit is installed.

JEFF KOSTIS Members Profile Send Private Message Find Members Posts Add to Buddy List Gold Member Joined: April-19-2005 Location: United States Status: Offline Points: 817	Post Options Post Reply Quote JEFF KOSTIS Report Post Thanks(0) Quote Reply Posted: August-23-2006 at 10:21pm
	Sounds like the alternator output got jumpered to the starter solenoid stud. A 50A alt would pin the ammeter and is a bit much for the #10 wire. See if they ran a wire from the alt output stud to the starter solenoid stud or the big circuit breaker. Factory wiring is to go from the alternator to the ammeter, then back to the Large breaker at the engine. My suggetion would be to get a voltmeter for it since you have a 50A alt. Jeff....
	MUSTANG COUNTRY 1974 Mustang 17 1976 Mustang 17

79nautique Members Profile Send Private Message Find Members Posts Add to Buddy List Grand Poobah Joined: January-27-2004 Location: United States Status: Offline Points: 7872	Post Options Post Reply Quote 79nautique Report Post Thanks(0) Quote Reply Posted: August-23-2006 at 10:49pm
	the issue is the way the leads that went to the regulator, relay and curcuit breaker are now wired. I'll see if I still have the diagram somewhere to tell you exactly what to do to fix the problem. Or you could just call vince at skidim and ask him to fax it to you and you'll have the problem fixed in 15 minutes.

Confusing Amp Meter

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