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Re: Question: "low voltage at idle" deal [Re: Mattax] #2714858
11/11/19 04:27 PM
11/11/19 04:27 PM
Joined: Oct 2006
Posts: 7,358
Iowa
burdar Offline
Owen's Dad
burdar  Offline
Owen's Dad

Joined: Oct 2006
Posts: 7,358
Iowa
Quote
Burdar I put in new flasher dealies for both turn signals and hazard.


Did you install the original kind or the full electronic ones? When I got my Challenger on the road, the turn signals only worked half the time. I replace the flashers with new "original" style units and got the turn signals to work all the time. However, when coming to a stop, they would flash really slow. The full electronic flashers fixed that issue and they now flash at a consistent rate. You may have other issues but the electronic flashers are a good upgrade IMO. Good luck!

Re: Question: "low voltage at idle" deal [Re: hemienvy] #2715014
11/12/19 04:38 AM
11/12/19 04:38 AM
Joined: Jan 2003
Posts: 3,122
Auburn WA
Dave_J Offline
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Auburn WA
And a cheap 12 volt test light is your friend when working on these old Mopars.

A glass fuse may look good but I gave a few in my tool box that look solid but one end under the cap was disconnected. A test light will show if the fuse is good. If it lights on one side but not the other, toss it.

Stanwood is a 82 mile ride. Thats only 3 gallons of gas ROUND trip on my scooter. wink

I will be going thru my wiring on my 78 LRT soon. The bulkhead connector is all green. I'll also be doing the Alternator feed straight to the battery and back feeding the AMP meter.


Retired, US ARMY 1973-1994
ASE mechanic, Electrical 1994-1997
Retired GTE/VERIZON/FRONTIER 1997-2015


Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.

03 Suzuki Burgman 650(Burger King) Scooter
65 Formula S Cuda
78 Little Red Express Truck
98 Buick Regal (wifes car)
Re: Question: "low voltage at idle" deal [Re: Dave_J] #2715037
11/12/19 09:55 AM
11/12/19 09:55 AM
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax Offline
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Phila. Pa.
Originally Posted by Dave_J
the Alternator feed straight to the battery and back feeding the AMP meter.

The alternator's 2nd job should be to recharge the battery.
The alternator should connect as direct as possible with the power distribution point(s).

Do not back feed an ammeter:
(a) it then becomes meaningless
(b) the circuit can become overloaded.

The ammeter is for the battery only. It should not also carry the power to be distributed to the rest of the equipment.

Ammeter-zero-Master-Tech1960.pngBasic-Power-diagram6x-p.pngBasic-Power-diagram6x-p-running.png
Re: Question: "low voltage at idle" deal [Re: Mattax] #2715041
11/12/19 10:06 AM
11/12/19 10:06 AM
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax Offline
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If you want to run a wire direct from the alternator output to the ammeter, attach it to the same side as the main splice.
If keeping the original wires, then there are two parallel lines (as shown below). So the load is shared.
If not keeping the original run through the bulkhead, check the size of the wire from the ammeter to main splice. Might be worth taking the unused/ damaged wire out of the bulkead and putting a ring terminal on it. So then there is new heavy (8 or 10 gage wire) to terminal stud, and two older 12 gage wires to the main splice.

Basic-Power-diagram6x-p-running-pll-.png
Re: Question: "low voltage at idle" deal [Re: Mattax] #2715102
11/12/19 12:29 PM
11/12/19 12:29 PM
Joined: Sep 2003
Posts: 19,239
north of coder
moparx Offline
"Butt Crack Bob"
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could the parallel line diagram you posted be used to install an ammeter where there was none ?
TIA. bow
beer

Re: Question: "low voltage at idle" deal [Re: moparx] #2715135
11/12/19 01:57 PM
11/12/19 01:57 PM
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Phila. Pa.
Mattax Offline
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Originally Posted by moparx
could the parallel line diagram you posted be used to install an ammeter where there was none ?
TIA. bow
beer

As long as no other equipment is between it and the battery, sure!

Re: Question: "low voltage at idle" deal [Re: Mattax] #2715370
11/13/19 11:23 AM
11/13/19 11:23 AM
Joined: Sep 2003
Posts: 19,239
north of coder
moparx Offline
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what would that show ? in other words, would it be worthwhile to do this ?
beer

Re: Question: "low voltage at idle" deal [Re: moparx] #2715466
11/13/19 04:37 PM
11/13/19 04:37 PM
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Phila. Pa.
Mattax Offline
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Whether it would be worthwhile depends on the person! laugh2
Witness how many owners don't know what the ammeter shows.

If you want to see whether the battery is getting charged, how much it is being charged and for how long; and whether it is discharging, how much it is discharging and for how long, then this type of ammeter is useful.

Not every car company offered ammeters on their baseline cars and trucks. Some used 'idiot lights' which arguably may grab a driver's attention when something is wrong. In contrast, a gage pointing to any particular point, or even an extreme has to be interpreted as to whether it is normal, abnormal or even dangerous conditions. There's at least one post on the IFSJA forum where TWICE the owner left something on, needed a jump start. The second time he attempted to drive home even while ammeter (which goes to 60 amps) was pegged to charge and he could tell the wires was sizzling. He got lucky and the fusible link finally melted before something flammable lit up.

Now here's the thing. An ammeter alone doesn't tell the whole story.
If we see what appears to be excessive charging, we still need a voltmeter to help us narrow down the cause.
If the voltage across the battery was in normal rangewhile the ammeter is showing this, its probably due to the battery excessively low condition.
In this scenario, we'd ant to try to get the battery on a charger, and if not available, keep the rpms as low as possible so the battery doesnt get hot. (or the wires!)
On the other hand, if the voltage across the battery is at say 16 Volts, then excessive current to the battery would be due to the high voltage driving it. Something is wrong on the regulation side. Either the regulator is getting bad info or its not working properly.

So a dashboard voltmeter shows potential being maintained by the battery or the alternator.
and a dashboard ammeter shows whether battery charging or discharging is occuring.

Hope that makes sense.

Re: Question: "low voltage at idle" deal [Re: Mattax] #2715710
11/14/19 01:15 PM
11/14/19 01:15 PM
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north of coder
moparx Offline
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yes it does.
however, using a large amp alternator, the biggest [highest ?] rated amp gauge i have seen has been only 60 amps.
how would this figure into the equation ?
beer

Re: Question: "low voltage at idle" deal [Re: moparx] #2715728
11/14/19 01:55 PM
11/14/19 01:55 PM
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Auburn WA
Dave_J Offline
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I had a major issue when I was running a 120 Amp cop car alternator. It would PEG the dash Amp meter after every start for 1-2 minuets or so. So IF you run not much over the factory old school 45 Amp alternator you are fine but....
What is really needed is a "look-a-like" Mili-Amp meter that has a shunt in the back. When you run say a 90/120 amp alternator only a small portion of the amperage goes thru the miliamp meter but the major amps bypass it thru the shunt.

If you are still wanting to run the factory 60 Amp MAX amp meter with a HUGE amp alternator, you could somehow figure out a by-pass shunt wire to strap across the amp meter so it will still see a discharge/charge. Run a 6 gauge red wire from the alternator to the shunted amp meter with maybe the shunt wire being a 16 gauge and then a 6 gauge black wire to the battery. This will not be 100% accurate but it should work.

Or just bypass the amp meter like what I have done in the past. None of my daily drivers will ever go go a 'POINTS' car show so I run a 2 gauge pod under the dash with a Oil pressure and a volt meter.


Retired, US ARMY 1973-1994
ASE mechanic, Electrical 1994-1997
Retired GTE/VERIZON/FRONTIER 1997-2015


Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.

03 Suzuki Burgman 650(Burger King) Scooter
65 Formula S Cuda
78 Little Red Express Truck
98 Buick Regal (wifes car)
Re: Question: "low voltage at idle" deal [Re: moparx] #2716027
11/15/19 09:43 AM
11/15/19 09:43 AM
Joined: Feb 2010
Posts: 1,645
Phila. Pa.
Mattax Offline
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Originally Posted by moparx
the biggest [highest ?] rated amp gauge i have seen has been only 60 amps.


Probably because if there's more than 40 amps going to the battery there's a problem - at least in a normal setup.

Originally Posted by moparx
however, using a large amp alternator,
how would this figure into the equation ?
beer

It depends on the alternator; But if its capable of producing more power, then its more likely to provide a high charging current to a low battery.
Some examples of alternator curves in these two posts
https://board.moparts.org/ubbthread...ories-amp-gauge-re-wire.html#Post2714603

You've probably observed that batteries draws more current when more heavily discharged.
And the closer it gets to full charge, the less current it draws.
This is true as long as the power is available, and the voltage its available at is unchanged.
About 1/2 way down this thread I post a sequence of charging photos with timestamps.
https://www.forabodiesonly.com/mopar/threads/charging-battery-with-alternator-warning.424783/
Notice in the beginning, I manually reduce the power available, dropping the voltage from the charger.

Re: Question: "low voltage at idle" deal [Re: Mattax] #2716330
11/16/19 10:57 AM
11/16/19 10:57 AM
Joined: Sep 2003
Posts: 19,239
north of coder
moparx Offline
"Butt Crack Bob"
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i understand the amperage needed in a totally [or almost totally] discharged battery will be very high, [your graphs are good by the way] and as you approach 40 amps charging, you are closing in on dangerous territory as far as charging goes, but i think my main question is, can you safely use a 60amp gauge on a say, 100amp alternator system ?
this, of course, is using the bypass diagram you posted above, and your wiring system is in good working order.

for the last many, many years, all my wiring [original harness and from scratch] has been centered on using a volt gauge only, [in creating a new harness] and disconnecting the original amp gauge, or converting it to a volt gauge in an original or reproduction harness. now, high amperage alternators are a common addition, and for one of my own projects, i would like to run an amp gauge as well as a volt gauge, but was somewhat concerned about the available amp gauges only coming in at 60 amps. [if a guy has a draw or input of that amount, you have problems ! eek]

comments ?
beer

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