Moparts

Ammeter Reading Question

Posted By: YO7_A66

Ammeter Reading Question - 09/29/12 02:16 PM

I don't drive the car much with the lights on so I don't have much of a reference. I was driving this morning with the headlights on and the ammeter was showing the same position at a cruise and in N. The attached shows what it was reading in both situations with the headlights on. Is this a typical ammeter reading for this situation?
The voltage was dead on 14v with no movement both at a cruise and at idle. This picture was taken in N for ref. The ammeter goes back to straight up as soon as the lights are off.

Thanks allot.

Attached picture 7399245-N+headlights.png
Posted By: Supercuda

Re: Ammeter Reading Question - 09/29/12 03:43 PM

Are your head lights wired stock? Or do you have them on a relay powered from the battery?

If the relay setup it's "normal", if stock it's not normal.
Posted By: YO7_A66

Re: Ammeter Reading Question - 09/29/12 04:34 PM

The headlights are setup on a relay.
Posted By: cjskotni

Re: Ammeter Reading Question - 09/29/12 04:46 PM

Quote:

The headlights are setup on a relay.




With what you are describing, you must have the relay powered from the battery side which will work but it will "trick" your ammeter into showing a charge when the headlights are on when there could be really no charging (breaking even from alternator) or even a discharge (from battery).

A better solution would be to take the power from the alternator stud or at least from that side of the ammeter. In that case, when your headlight relays are pulling juice, it will keep the ammeter honest so it won't be as confusing. What's worse, if this is the case, you are pulling that load through the ammeter whenever your headlights are on which is not the best idea with the well-known Mopar wiring (or lack thereof).

To get around this, move the relays to the alternator side of the charging circuit and/or do the ammeter bypass.
Posted By: YO7_A66

Re: Ammeter Reading Question - 09/29/12 05:15 PM

I have the parallel bypass around the bulkhead and I want to keep the ammeter. I will look into moving the power source. Can I just go straight to the alternator stud?

Thanks!!
Posted By: cjskotni

Re: Ammeter Reading Question - 09/29/12 05:31 PM

Quote:

I have the parallel bypass around the bulkhead and I want to keep the ammeter. I will look into moving the power source. Can I just go straight to the alternator stud?

Thanks!!




Yes, that's where I tappedd in for my fan relays...right on the stud!

If you have the parallel ammeter bypass, this will eliminate most of the need to stay on the alternator side as the bypass will take the lion's share of the current. However moving the power tapping point will make the ammeter more honest.

Good Luck
Posted By: YO7_A66

Re: Ammeter Reading Question - 09/29/12 08:17 PM

I swapped the power lead from the battery to the alt stud. I will test drive it tomorrow with the light on again.

Thanks a bunch.
Posted By: YO7_A66

Re: Ammeter Reading Question - 09/30/12 05:15 PM

I test drove the car today with the lights on and the ammeter still shows into the "+" while cruising but not as far to the right. At a stop, the ammeter now fluctuates from straight up to where it shows at cruise, fairly fast, back and fourth.
I now have the headlights powered off of the alt stud.
Are there any issues with this?

Thanks
Posted By: DAYCLONA

Re: Ammeter Reading Question - 09/30/12 05:43 PM

Are the headlights protected with a circuit breaker?...hope so


what alternator are you running?...recent upgrades/changes to the charging system?
Posted By: YO7_A66

Re: Ammeter Reading Question - 09/30/12 05:54 PM

I have a 30a breaker on the alt feed wire. Is that enough?
Power master 60a idle, 99a max alt. I have the bulkhead parallel wire byppass wiring upgrade.

Thanks
Posted By: NachoRT74

Re: Ammeter Reading Question - 09/30/12 07:38 PM

Quote:

I test drove the car today with the lights on and the ammeter still shows into the "+" while cruising but not as far to the right. At a stop, the ammeter now fluctuates from straight up to where it shows at cruise, fairly fast, back and fourth.
I now have the headlights powered off of the alt stud.
Are there any issues with this?

Thanks




well, you have an honest reading now, and alt output is not enough. More time stopped at iddle, more fluctuations will have on a low capacity alt. It takes longer to charge what it takes to discharge
Posted By: RapidRobert

Re: Ammeter Reading Question - 09/30/12 07:49 PM

Quote:

At a stop, the ammeter now fluctuates from straight up to where it shows at cruise, fairly fast, back and fourth. I now have the headlights powered off of the alt stud.
Are there any issues with this?
Thanks


I'm wondering if there is an issue with the alt or what Nacho said it's just underpowered. yes I'd keep the lights (& any other major draw) on the alt side
Posted By: YO7_A66

Re: Ammeter Reading Question - 09/30/12 07:53 PM

I would have thought that 60a at idle would be plenty for my car. At idle in D (this is when I found the fluctuation), I had my brakes applied, headlights on, my MSD 5, and my 2 O2 sensor kits. That is it! Does this sound like 60amps?

Thanks Nacho.
Posted By: Supercuda

Re: Ammeter Reading Question - 09/30/12 08:15 PM

Someone want to explain how the ammeter showing + (charging) somehow means it is low on output?

If it showed - (discharging) then yeah.

Do you have anything else being powered directly from the battery, such as an electric fuel pump?

Fluctuations means it's cycling the charge to the battery, assuming there is nothing wired to the battery non-stock.
Posted By: YO7_A66

Re: Ammeter Reading Question - 09/30/12 08:29 PM

""Do you have anything else being powered directly from the battery""

My MSD 5 and both of my O2 sensor kits are wired to the battery.

Thanks
Posted By: cjskotni

Re: Ammeter Reading Question - 09/30/12 08:30 PM

Quote:

Someone want to explain how the ammeter showing + (charging) somehow means it is low on output?

If it showed - (discharging) then yeah.

Do you have anything else being powered directly from the battery, such as an electric fuel pump?

Fluctuations means it's cycling the charge to the battery, assuming there is nothing wired to the battery non-stock.




If alternator output was enough not to ever discharge the battery, the ONLY time the ammeter would register charge would be right after cranking the car (to refill battery from starter motor).

If the ammeter is reading charging while driving, this means that at some point (maybe at idle) there was a discharge from battery which must be replenished when the engine/alt is at higher rev's.

I can see this all the time with my ammeter...slightly discharging at idle when at a light then pegs the charging side for a few secs after taking off due to replenshing the charge used to fill the shortcomings at idle.

If it shows charging regularly off and on during driving (esp after idling for a while), you are losing dicharging. This could also be falsely read if there is some other non-stock load on the battery side of the ammeter.

As the guy above mentioned, anything else drawing from battey? Fuel pump maybe? If not, you are discharging slighly at idle.
Posted By: Supercuda

Re: Ammeter Reading Question - 09/30/12 08:42 PM

Quote:

""Do you have anything else being powered directly from the battery""

My MSD 5 and both of my O2 sensor kits are wired to the battery.

Thanks




As I mentioned earlier in the thread, ANYTHING wired directly to the battery will draw from the battery and show a + condition on your ammeter. Stock wiring excepted.

Move all your battery powered loads to the alternator output stud.
Posted By: NachoRT74

Re: Ammeter Reading Question - 09/30/12 09:24 PM

http://www.dodgecharger.com/forum/index.php/topic,33574.0.html

Ammeter showing charge it means alt is sourceing back the batt to getting all the chemical balance. If you got a discharge, will demand be charged back like any device on car demanding juice.

If you have a charge reading is because batt got discharged sometime. If your alt is not able to source all the car ( at any RPM ) the batt will provide the juice the alt is not able to source, so got a discharge.

MOSTLY of constant charging readings came out because your car at iddle &/or low RPMs wasn't able to source everything and got discharge on those moments for long time.

You need to save the discharge much as posible to keep power sourcing balanced.

The ammeter reads what batt gains ( just because lost ) or loose ( because alt is not able to give ) IS NOT AN ALTERNATOR GAUGE, thats a missundertood created by most of the labels on clusters. Of course will give you an alt status reading, but just if you understand how to read it, but really is an STRAIGHT BATT STATUS READING

You don't get ever a discharged alternator, because the alternator is not an acumulator able to loose power.

there are many ways to understand this, but just one way to fix it if you pretend to keep the balance on your cars, and make it work like stock SAFELLY. If you change the charge system design, then there is another story

is pretty much normal get battery power loose on ANY car, DON'T BE AFRAID of get small ammounts of discharge readings, but try to keep them smaller and quicker as posible, to get it back charged again as soon as posible...

ammeters gives you an INSTANTLY status, voltimeters gives you a proportional "reflection" of the charge status.

Quote:

Someone want to explain how the ammeter showing + (charging) somehow means it is low on output?

If it showed - (discharging) then yeah.




everything depend WHEN is giving charge... revving up? any alt is able to feed all the car revving up, and even get back the juice to the batt... but what about iddling or low RPMs ? thats the reason why you are getting charge when revving up, because your alt is not powerfull enough when spinning low
Posted By: NachoRT74

Re: Ammeter Reading Question - 09/30/12 09:31 PM

we can say also on this way.

you need to push ( or pull ) a car. How many men you need to do it ?

More men, will mean less effort made from each man

But you'll need ALLWAYS to push ( or pull ) 4K lbs.

well the totall effort made to push the car is the volts.

the AMOUNT OF MEN needed is the AMPERES. More "amperes", less effort by each man... less stress on the "force generator"

sounds good ? I tried to make it more basic as posible
Posted By: Supercuda

Re: Ammeter Reading Question - 09/30/12 10:52 PM

Quote:

we can say also on this way.

you need to push ( or pull ) a car. How many men you need to do it ?

More men, will mean less effort made from each man

But you'll need ALLWAYS to push ( or pull ) 4K lbs.

well the totall effort made to push the car is the volts.

the AMOUNT OF MEN needed is the AMPERES. More "amperes", less effort by each man... less stress on the "force generator"

sounds good ? I tried to make it more basic as posible




I been working on electronics since 1983.

Basic is this, he has additional loads wired directly to the battery. I do not care if your alternator puts out a billion amps at idle, it will show a + on the ammeter wired like that.

The cycling could very well be the heater circuits on his O2 sensors turning on and off, if they have them.
Posted By: NachoRT74

Re: Ammeter Reading Question - 10/01/12 01:00 AM

Quote:



Basic is this, he has additional loads wired directly to the battery. I do not care if your alternator puts out a billion amps at idle, it will show a + on the ammeter wired like that.






yeap, definitelly, that's because the power will go through the ammeter, without NEED for that if you hook it correctly to alt stud. But need a GOOD alt to source it from there and not require power from batt, getting the ammeter in play reading discharge, no matter if alt is still working, but not enough
Posted By: YO7_A66

Re: Ammeter Reading Question - 10/01/12 01:16 AM

Thanks allot for the replies. I started moving my two O2 sensors over to power off of the alternator. I should have that finished tomorrow. I will then test drive the car to see if the ammeter changes.
I have a feeling that this issue is with the two O2 sensors though. If I remember correctly, my idle ammeter readings started acting funny after I wired in the second unit. I already have a 30a fuse to protect the two sensors per FAST. So swapping the main feed will be quick.

My MSD5 unit only pulls .7a per 1000rpms, so I assume that this is not the issue.

Thanks again.
© 2024 Moparts Forums