alternatorquestion of what is the max and min amps?

R

ryan_pope

Member
Howdy, did you get enough turkey?

My question is for my alternator on my 1964 Buick Riviera, what is the minimum and maximum amps that I should read with a multimeter or amp meter at the positive and negative battery posts when the car engine is idling (and no lights and no a/c is running) ?

Oh, this is a forum question: how do I print out a thread (it is many pages in length) ? I want to reference the thread postings while standing at the car and doing the described work on the engine in the thread. Thanks in advance.

God Bless
 
Most multi meters will not do what you are asking. What make and model are you using?

If you are actually meaning volts, at an idle it may be well below 12, and when idled up, it should climb to over 14 to show satisfactory charging.

To print out a multi page thread, you will have to print out each page separately. Using Internet Explorer, you can just right click on the page and look down for print, or print preview.
 
Oh, this is a forum question: how do I print out a thread


there is a thread specific toolbar at the upper right. this is what shows in mine ( i have access to mod tools, so yours won't look exactly like this )

Thread Tools Administrative Search Thread Rate This Thread Inline Mod


click on "Thread Tools" and then "Show Printable Version". it may still run to several pages, but it will be WAY better than trying to printscreen the normal browser page.


Bob is correct about the multimeter; most of them will NOT be rated to take a large current draw ( normal handheld multis max out in the tenths of an amp ) and should NOT be used to read amperage to/from a car battery. you'll almost certainly fry the meter.

note that you measure current in series with the battery ( disconnect one of the battery leads from the terminal, then use the multimeter to complete the open circuit ) while voltage is measured in parallel ( leave all cables and wires on the car connected in 'normal operation' configuration, connect the positive lead from the multimeter to the +12 side of the battery and the negative meter lead to the ground side of the battery. )


normal lead-acid auto batteries will show ~12.6v with the ignition off. glass matt batteries ( like Optima ) may be under 12.0. with the engine and alternator running, you should show over 13v.
 
my multimeter is Fluke 77

I have a Fluke 77 , series II multimeter. It looks like it can measure up to 10 amps, not completely sure about that though.
 
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Fluke is *the* name brand in high quality multimeters and the 77 is indeed rated at 10 amps continuous / 20 amps short term.

http://en-us.fluke.com/products/digital-multimeters/fluke-77-iv-digital-multimeter.html

perhaps you'd better look at the largest fuse or fusible link in your car? 30 amp fuses are quite common, i've got 60 amp fuses in my truck. i think the main fuse ( which protects the whole fuse block ) on my 95 Ford Probe is 100 amp. and that's a dinky little v6 car.

whatever you do, i most sincerely recommend AGAINST starting the car while checking current.

to think of it another way, look at the gauge of the cable ( usually a 2-6ga ) going to the + and - sides of the battery.

now look at the gauge of your test leads. are those test leads even as big as 12ga speaker wire? 18ga?

IF you don't blow the fuse out of the Fluke ( which it should )
THEN it will burn all the insulation off of those leads.

don't mess with testing the main batt current unless you've got an auto tech test station that is designed for these current loads. 99.99% of the time, if you're getting the correct VOLTAGE readings, you're not going to have any problems.

the ONLY time i would recommend testing auto current is if the car is killing the battery overnights and you were testing leakage currents WITH THE CAR TURNED OFF. you'll still have minor draws like for running the dash clock, but it should be minimal.
 
if you're that concerned about the alternator output, pull it off the car and drag it into your local parts store. many of them have test stands in the store for starters / alternators and you can test them right there for free.

obviously, call around to find the store that has one of these before you bother pulling the alt.
 
I won't test the ampere with my Fluke, thanks, I understand. appreciated it, Sirs.

hey, the auto parts guy told me while testing my Battery,...that if I start the car using my now confirmed good Battery, then with the car idling .... pull and remove the battery positive cable from the battery .... the car engine should remain idling BUT if the engine stops running ....Then the alternator is bad. He is suggesting that a engine will run without a battery connection and the engine will run only using a Good alternator.

Is That true, and Correct about a good alternator? If so that is a quick and easy test for my alternator.
 
Absolutely do not pull the cable on a running car! That parts guy has no clue what he's telling you to do.I've seen everything from exploding batteries to blowing every bulb in the car from doing that.
Like the OP said,test the voltage,you want above 14 at a fast idle with the headlights on.
What exactly is your concern about the alternator?
 
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Most Alt. will charge at 85% of their Amp rating and you can find the amp rating marking on the Alternator housing.
HTH
John
 
My battery went dead and I had it checked at auto parts store and the battery is good....So I am thinking it is my alternator. My belts is tight and after I drive the car and it is put safely away for the night, I disconnect the negative battery cable. Why, you may ask, well because usually I don't know knew the next time I will drive the car again and that could be a month or more in time.
 
I disconnect the negative battery cable.



this is what you do with a car that has excessive current drain with the ignition switch off. and, of course, any car that sits for months at a time should either be on a trickle charger or have the batt disconnected.

like i pointed out earlier, things like the car clock have to draw current constantly or the clock can't keep time. that's hard on a battery that doesn't get regular charging.
 
not the battery and not the alternator: What next?

While idling in the garage I had opportunity to check my charging system. I am having a dead battery. I checked the battery at auto parts store and it is Okay. And I checked it in my Chevelle yesterday and while chevelle is idling the voltage across positive and negative terminal of battery is 14 volts.

So, I checked the Riviera voltage at idle and only read 12.1 volts at the battery posts. Thus, I took my alternator off and just got back from auto parts store where they tested the alternator, Good. It passed the test.

Thus, where do I go from here?? I noted that while idling in the garage, I heard a low and quiet buzz from the voltage regulator. It would start a buzz then stop and then start again, and repeat.

The voltage regular has a four pin connector and another single pin connector . The single pin connect is attached to what looks to me like a condenser. {if I am correct, a ignition condenser}

A) How do I proceed?
B) The voltage regulator is expensive and non-returnable. $55.00 Can I test mine that I have now in the Riviera ?
C) Should the voltage regulator be making a buzzing noise?


My belt alternator belt was Tight. My connection at the alternator were clean and tight, too.
 
Help

ryan_pope said:
I know it is sunday morning and we are all busy, however, anybody got an idea for my charging issue? please
Click to expand...

Ryan, I believe it is time to take your baby to the Doctor. You need to find a shop that specializes i auto electrics. They will be able to locate your problem.

Ben
 
firstofeight is probably right. You are probably going to need some help. It sounds as though something is drawing too much while the engine is off.

To solve these types of problem MAY be a challenge. You first need a wiring diagram. I just checked, the site does not have one, nor do I have one in my reference. You can do things like pull all your fuses and see if the drain is still there. If not, replace them one at a time. Your testing can be done at the battery by disconnecting a battery cable and noting the spark when it comes in contact with the post. When you are on the bad circuit it will be brighter.

If you wish to risk your Fluke, you can connect it in series with the battery terminal with all options turned off. When the offending circuit is closed, you will get a much higher reading, perhaps right off the scale!

Your problem could be located right in a harness. These are the hardest to find. They are usually caused by an old overheat issue which has compromised the insulation and allows two wires to come in poor contact with each other.
 
Ryan, I recommend not using your Fluke for testing for a drain on your battery while it sits over night. Do you have a test probe? It has a sharp point on one end, a light in the handle and a length of wire and a clip on the end of the wire. They are cheap and can be used for looking for the drain on your battery. First off test out you tool by touching the clip end to either terminal of the battery and the other pointed end to the other terminal on the battery, the light in the handle should show bright. You can reverse ends on the battery and the light should still be bright. For this test to work all the lights have to be off, the doors closed and the engine not running and the ignition switch off. Remove the negative terminal on the battery. Take your test probe light, attach the clip to the negative battery cable and touch the probe to the negative terminal on the battery in series, if the light comes on you have a drain. If the light is bright like in your initial test of the tool you have a big drain, if it is fainter you have a smaller drain. Your fuse block is divided into two sections, one section is controlled by the ignition switch and is only "hot" when the switch is turned on, the other section is "hot" all the time, like your horn, lighter, interior lights and head lights. With your negative lead attached to your battery find a good shinny piece of metal to attach the clip to and touch the end of the fuses to get familiar with how your fuse block is organized. One section (end) should be hot all the time and the other section should get hot when you turn on the ignition switch to the run position. Assuming your initial test at the battery showed you have a drain remove the neg. terminal and hook up your test probe in series start removing fuses (the ones that are hot all the time) one at a time till the light on your test probe goes out. This should get you started, now you are gaining experience to understand how electrical system operates. You just have to keep eliminating circuits till you find the culprit.
 
Mr. Suntreemcanic and Mr. Bob,

Thank you for your comments. I have work to do here to find the issue. For now I am determined to find and fix it . (I can't live with this issue)!!!

Do you have comments about the voltage regulator, also? Should it make a constant low small noise if working properly? Or No noise at all if working properly? Or intermittent (start and stop noise) if working properly? Which is correct?, please.

Tonight and tomorrow tonight I plan to re-install the alternator. I recheck voltage at the battery post while car is idling (voltage only not trying to get an Amp reading, I don't want to blow up my Fluke. I do have a test probe light, so I will work through the test described ( I printed out the comment to read again and again AT the Car.

I also want to disconnect and clean the connection at the voltage regulator and also check for a Good electrical ground to the "wheel well" metal, too.

{{To everyone, I really enjoy using this website, thanks to the administers for this website !!}}
 
It works: 13 to 14 volts at the battery

What is the difference 12.1 volts and 13.8 volts in a car charging system? SUCCESS

I replaced the voltage regulator and the ignition condenser. And Success, the charging system is working!

Thanks everyone for your comments.

God Bless
And
Merry Christmas
:hurray:
 
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