konak85

iTrader: (10)

hey guys. My battery dies very quickly. It seems weak, but i'm not sure if its the alternator or battery. Whats the proper way to check them?

deezo

iTrader: (3)

If the car dies while you're driving, then it's the alternator. Your lights will get dim and the car will drive horribly due to lack of the proper electrical power. If the battery is bad, it will not hold a charge even after running a charge on it.

cardana24

iTrader: (81)

crank your car, once it is running pull the negative cable off the battery....if it dies then its the alt. if it continues to run it is the battery....same theory as ^^^, this is just and easy way to check it.

konak85

iTrader: (10)

is it supposed to die right away or a minute or two afterwards. thanks for the responses.

mzmtg

iTrader: (11)

DO NOT DO THIS.

It is very very bad for your electrical system and can cause major damage.

From what you have described, your alternator is dead. Once you get it replaced, you may also need to replace the batt. Repeated total discharges can damage it.

kaji

Go to a good mechanic and have them test the battery and alternator.

cardana24

iTrader: (81)

how can this hurt a car? What am I missing? This is how a car runs after start up. I am not trying to argue with you I just do not understand how this is bad for your car.

I can speak from personal experience. I have used this method many times and I have never had a very bad electrical problem as a result...maybe I got lucky?

kormax97

In my understanding, all your computer equipment, ie, your ecu runs on battery. It would be like holding down on your power on button for your PC at home to turn it off while it's reading/writing etc, instead of using "shut down windows" command. I'm sure that's bad....

MAXRB8

iTrader: (19)

The alternator supplies AC (ALTERNATING Current) the battery acts as a large capacitor. Disconnecting the Neg lead and running only on the Alternator means your feeding your system only alternating current which causes current spikes and that's not good for computer run vehicles! The alternator is used to recharge the battery that is constantly being drawn from by the electrical components (ECU, lights etc etc). So I would say it's not a good thing to disconnect your neg cable.!

You also said " I have never had a very bad electrical problem as a result" did you have a not so bad result?

cardana24

iTrader: (81)

Thanks for the reply. I guess I should stop using this method , and no, I have never had any problems related to doing this.

MAXRB8

iTrader: (19)

You're welcome, nice color Max BTW! That's a helluva wing you have on there!

cardana24

iTrader: (81)

Thanks man, check page 7 on my cardomain page...that is what the car looks like now. No more wing and a bunch of other changes.

MAXRB8

iTrader: (19)

Thats looks waaay better! Sweet! What kind of CF trunk is that? How the fit etc?

cardana24

iTrader: (81)

fit is just as good as OEM....I got it from Paradox Systems

konak85

iTrader: (10)

I don't think i explained my problem well. When i leave the ignition in the ON position where the ABS light and others come on(without engine running) for about 10-20 minutes, the car wont crank the engine but there is still enough power to roll up windows and use the radio. When the engine is running i have no power problems.

does autozone test batteries and alternators for free?

killcrap

iTrader: (3)

that is completely wrong. depending on if the voltage reg is on the battery side or the ground side, your alternator is producing 3 phase AC voltage. it then sends the voltage to a rectifier(diodes) to allow only DC voltage to pass. from there, it goes to the battery. when your car is running the electronics draw power from the Alternator. when its needs more current it draws it from the battery. your battery has 4 functions.

1)starting
2)providing voltage to the rotor inside the alternator
3)providing amperage to the electronics if needed.
4)acting like a voltage regulator. keeping the system voltage around 12.68v.

if you take that battery signal away, the voltage will jump up above 15V, and electroncis dont like anything over 15V and WILL fry.

killcrap

iTrader: (3)

so your basiclly saying("i'm draining the battery by turning the ignition switch to on, and leaving it there for 10-20mins")

seems like you answered your own question. STOP DOING THIS

konak85

iTrader: (10)

i mean it shouldn't die so quick like that. or is it supposed to?
even if i leave the radio on without the engine running for about 10-20 min. it won't crankup the engine. So whatdo you think the problem is? anyone?

JoeB

My Alternator died on me the other day. The battery light on the dash lit up whenever the engine was below 3k rpm's. Funny thing is the brake light also lit up along with the battery light. Must be a jap thing because I had a Toyota that did the same thing.

Wetballoon

Autozone does do checks, although you may have to remove your own parts. You can test with a multimeter that you battery has about 12 volts with the engine not running and around 14 at 3000 RPM. If there is no voltage increase you probably have a bad alternator. Also, with a faulty alternator, you will not get very far befor stalling once you get running. Unplug it and see how far you get with all of your lights on. Sounds to me like your battery isn't taking the charge.

Dubaimax

i had the same problem just when i got the car..
checked the voltage of the alternator, was fine..
got a new battery, pulled off the (-)ve cable off the battery, the car was still running(the alternator was fine) still the battery was drained in some time, i got the alternator bearings changed, no more problems.
23120-58S01(1pc)
23120-97E00(1pc)
i sell each of these at around $9.50
((((if the bearings are out, the alternator won't charge the battery, thus, it dies...))))

Mrbizness1

The first thing you should check is the alternator belt. For some reason this is easily over looked. I had my alt and battery light on for months. The alt was charging correctly, cleaning the connections did nothing. I installed the foam pads (bought from Walmart) under the battery terminals and the next day the lights went out for good. Can't figure it out but it worked.
You can buy a battery and alt tester for under $10.

zagato27

You might want to have the dealer check to see if your Max was listed in an alternator recall. My 97 SE was covered and the dealer changed it out. May not be the problem but a new alternator for free...can't beat it. Cheers

mindlessoath

iTrader: (1)

what kind of batteiry do you guys prefer? also if you had the money what would you have got? im looking for a new battery.

Wetballoon

I have a Duralast gold from Autozone (part no 34DT-DLG). It isn't supposed to fit but it does and pushes about 1000 amps in the sun and 800 cold. Also, I have heard good things about the optima batteries. If you leave the electrics on with the engine off on a regular basis, you should probably look into deep cycle batts.

zagato27

I've got an Interstate but wish I had gotten an Optima.....no water, no water. Cheers

C3nthusiast

iTrader: (3)

So, what happens when an alternator goes bad? Well, at first, nothing. That is because the battery has some reserve power in it, enough to keep the engine running for quite some time, many many miles in fact. So a bad alternator doesn't necessarily mean a tow truck should be called right away. As long as energy is conserved elsewhere, like turning off the blower motor, the rear window de-fogger, the stereo and the headlights (if possible), you could make it for some distance on just the battery reserve alone.

Most of the time the alternator fails in stages. The alternator gets its name from the fact that it generates alternating current (AC). Well the battery can't use alternating current so the alternator output is fed into what are called diodes, which convert the AC into DC. The alternator has a unique feature in that it is able to generate a relatively high voltage while the engine is at idle. The alternator can do this since it is really three alternators in one body. Each of the three sections of the alternator generates its voltage out of phase with the other two sections. Since the complete cycle (one revolution) of the alternator is 360 degrees, each phase is shifted by 120 degrees from the next phase. So in one revolution of the alternator it puts out three separate voltages.

Each of the three phases has its own windings in the alternator and each of the windings has its own pair of diodes. Each of these windings and/or diodes can fail, one set at a time. If this happens the alternator can still charge the battery, but only with a limited current, approximately 2/3 of its original capacity if one system fails. If two systems fail, then it puts out only 1/3 of its rated capacity. What that means to you is that you can go a long time on a limping alternator. Chances are if you don't need headlights or air conditioning or other high current using accessories, you would never know that the alternator was in the process of failing! The time you will find out is when it is 10 below zero and you wear down the battery by cranking the starter, then put the fan on high for heat, and then drive in the dark.

So, how can you tell if the alternator is failing without taking it apart and doing some measuring inside the alternator? It's really pretty simple. You will need a simple voltmeter. You can get one at Radio Shack for under ten dollars. Here's what you do - start the car, make sure all the accessories are off and rev up the motor to a fast idle. Set the Voltmeter to the DC scale (not AC or Ohms). Measure the voltage across the battery terminals - red lead of the voltmeter on the positive terminal, black on the negative (ground in most cars). The voltage should, and probably will, read around 14 volts. If it reads less than 12 volts you may indeed have a failed alternator and you can skip the next step. Next, turn on the heater, the rear window de-fogger, the radio, the headlights and anything else that draws power. Now rev up the motor and watch the voltmeter. It should still be reading around 14 volts. If it reads lower than 13 volts the chances are that your alternator is not up to snuff.

One last failure mode is of course noise. The rotor inside the alternator rotates on bearings, normally very high precision needle bearings, and these can fail. When they do you will hear a loud grinding noise associated with the alternator. To isolate the noise take a length of tubing, heater hose will do fine, put one end to your ear and move the other around in the vicinity of the alternator. The noise will be much louder when you point it at the alternator if that is the culprit. Other possibilities are the water pump and the power steering pump which are also driven by the engine belt. To further isolate the noise disconnect the drive belt and spin the alternator by hand. If you hear a rumble or grinding noise then the bearings are shot. If you don't hear a noise the problem may still be in the alternator since the bearing might be quiet without the loading of the drive belt tension. Check for side play in the pulley. If you are pretty certain the noise came from the alternator it is a relatively simple task to take it apart and visually inspect the bearings, else swap it in for a rebuilt. Your auto supply store will normally bench test the alternator free of charge and can tell you at that time if the bearings are noisy.

Before you go running down to the parts store for a new alternator make sure to check the connections at the battery terminals and also check to see that the voltage is the same at the alternator terminal (the big fat one with the heavy wire attached). Check to make sure the belts are tight and not slipping. Replace them if they are cracked or shiny on the side that faces the alternator pulley.

One final thing to check - the field voltage. In order for the alternator to generate electricity it must be supplied with a field voltage. If you know which wire is the one that supplies the field (normally labeled 'F') then simply check with a voltmeter to see if there is 12 volts at the field. Another check is to use a hacksaw blade or a lightweight screwdriver , anything magnetic, and hold it near the side of the alternator with the ignition switch turned in the on position. If there is a field voltage present then the metal will be attracted magnetically to the side of the alternator, not very strongly, but you will feel it pull the metal to the side of the alternator.

So, what are you going to ask the stealership when he tells you that you need a new alternator?

1. Did you perform a load test on the alternator? If you did, what were the voltage readings? Were they all below specification?? (mechanics will use a load testing machine instead of turning on all the accessories.)

2. Did you check to see if the belts were old and cracked or possibly slipping?

3. Did you measure the voltage at the alternator connector or at the battery? Were the readings the same at both places or is there a voltage drop somewhere in the system. You can tell him the "Dead Battery" story if you want to.

4. Finally, did you check the price on a rebuilt as well as a new alternator? (rebuilt alternators are just as good as new if they are done correctly and usually cost about 1/3 as much)

Well try not to get shafted!!!!!

Wetballoon

Excellent tale of how to test an alternator. Move it to the stickies.

maximamaybe74

Just buy an alternator battery tester for like 10 bux form radio shack and you will quickly know what your problem is.