alternatorquestion of what is the max and min amps?

[ryan_pope]

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

[Bob]

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.

[bob k. mando]

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.

[ryan_pope]

I have a Fluke 77 , series II multimeter. It looks like it can measure up to 10 amps, not completely sure about that though.

[bob k. mando]

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/digi...ultimeter.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.

[bob k. mando]

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.

[ryan_pope]

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.

[ryan_pope]

Testing , trying to add signature picture, testing

[65specialconvert]

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?

[guyopel]

Most Alt. will charge at 85% of their Amp rating and you can find the amp rating marking on the Alternator housing.
HTH
John