Alternator

elpuas3000 · 11-06-2009, 05:33 PM

how do u check the alternator?

i think i know 1 way and that would be by disconnecting the battery and if the car dies it means the alternator is bad right?
is there another way?

99alerogirl · 11-06-2009, 05:40 PM

take it to autozone!

a4d2a0m · 11-06-2009, 05:44 PM

A quick way is to get a multi-meter.. start the car and check and see if the batt. voltage is dropping(slowly). If it is... get a new alt.

elpuas3000 · 11-06-2009, 06:57 PM

my radio has a a program that reads the voltage of the battery...
today mornign it dindt want to start but later it did and when i check the voltage of the battery it was very low... it read 10.00...

so what i did was i disconnect the battery when car was running and car died.... so am guessing the alternator is bad... am i right or wrong?

DansGen1Alero · 11-06-2009, 07:53 PM

to my knowledge disconnecting the battery while car is on will die regardless, the alternator charges the battery but the car is still drawing the power from the battery, no battery no power. Can anyone back up my logic??

a4d2a0m · 11-06-2009, 08:04 PM

Yes... battery needs to be connected! a few question...

1. Is it an accurate voltage display?? (showing tenth of a volt?)

2. what did it do when "it didnt want to start"???

3.When it read 10v was the car running??

elpuas3000 · 11-06-2009, 09:19 PM

1. yes
2. it didnt do anything... no noise no nothing.... the power completely die when i turn the key

3. yes the car was running ....

Nate's Alero · 11-06-2009, 09:42 PM

Quote:

Originally Posted by elpuas3000

1. yes
2. it didnt do anything... no noise no nothing.... the power completely die when i turn the key

3. yes the car was running ....

replace alt, and see what happens

DansGen1Alero · 11-06-2009, 10:07 PM

That would be blinding diagnosing. I think the point is to not to spend the money unless it is for sure.

Let the car run parked and monitor the voltage

widbyj · 11-06-2009, 10:12 PM

Do yourself a favor and charge the battery before installing the new alternator. Since the battery is already near-death you'd need a jump at least to get going anyhow. If your new alternator sees a dead battery first thing it will go into 'stress' mode and possibly be damaged/overheat right away. All new parts prefer a bit of 'break in' before being fully stressed. IIRC these alts can put out up to 140 amps at full ability which is a lot for an older battery to take.

Trying a different battery that you know is good would be easier to do and allow you to check things also, if the voltage goes down once the engine is started the alternator is not charging. And yes, almost any parts source can test your alternator, usually for free.

a4d2a0m · 11-06-2009, 10:25 PM

Yep, monitor the voltage first.. after running for 2-3 min. it should drop around 1-2 volts if the alt isnt charging.

When you say the power completely died... did the power return to the lights/interior when you turned the key back?

[ion] C2 · 11-06-2009, 11:53 PM

autozone dude i'll check your battery with our new AutoMeter starting/charging/battery system tester lol

Gr1m · 11-07-2009, 01:48 AM

if you dont want to take the alt off the car, you are going to need a clamp on amp meter which can run anywhere up to $250, more then the price of a new one, but if you disconnect everything and take it to autozone they are test it for you

jayson_waltz · 11-07-2009, 02:59 AM

just use a voltage meter. with the car off the batt should be at about 12 volts. with the car running it should be about 14 volts. only method you need to know. if the batt doesn't read about 14 volts with the car running, the alt is shot. plain and simple.

CBLOHM3400 · 11-07-2009, 08:36 AM

running voltage @ battery should be between 13.5 and 14.5
never unhook battery with car running
the battery is a storage and also and equillzer for the cahrging system and when you un hook the alt it goes in high rate mode and with out the battery there to equillize the sytem it can send voltage spike thru the system thus frying electrical componets
battery is powering everything when the key is on and the engine is off
alt takes over after the car is started thus powering everything
(now on old no computer cars that was the fastest way to check alt , by unhooking it)
hth
chris

elpuas3000 · 11-07-2009, 03:29 PM

ok i took the battery to be charge... i connected the new battery and the voltage was 12.60 with the key turn (car was not running)...
when i turned on the car the voltage was 12.10...

so am guessing the alternator is not working at all... so am going to take the altenator tomorrow to autozone so they can check it

jayson_waltz · 11-07-2009, 11:28 PM

yep the alt is bad.

[ion] C2 · 11-07-2009, 11:42 PM

Quote:

Originally Posted by elpuas3000

so am guessing the alternator is not working at all... so am going to take the altenator tomorrow to autozone so they can check it

You can get both checked ON the car by the way....

99alerogirl · 11-08-2009, 02:18 AM

Quote:

Originally Posted by [ion] C2

You can get both checked ON the car by the way....

man aren't you our nice little AZ rep

GO SELL SOME CHECKOUT CHALLENGE

Afugy · 11-08-2009, 07:24 AM

I'd just like to add that if you have not done the Big 3 you really should. For safe measure any time that you add an amp to a car you should do the big 3.