Battery or Alternator? NF

[John Bacon]

I am having problems starting my 1996 Aerostar. When I did get it going, the volt meter had a very low reading. It did increase when I turned the air conditioner off but still remained below normal, even on the 401. The reading dropped to zero when I left it idling. It continued to run but I couldn't restart it once I turned it off. Thankfully I had the foresight not to turn it off until I had it parked at home ;-).

 

I am hoping that it is just the battery but I am concerned that it may be a faulty alternator.

 

If I had a properly functioning alternator would I get a normal reading on the volt meter regardless of the condition of the battery? Or, would a dead battery cause a low voltage reading even with a properly functioning alternator?

[Roy]

I'm afraid it's your battery.

[banger]

While your Car is running, unhook your Battery cable ( positive+) if it still runs with the power calble off.Most likely your alternator is still good.

 

 

 

The alternator "should " be able to keep the car running without the Battery hooked up.( for a short time).

 

 

IS the Battery the same one, when the car was new???

 

If so... you got some long life outta it. And It's time to get a new one.

[aplumma]

If you have a volt meter you can check a few things .....

 

With the engine off a charged battery should read around 12.56 volts.

 

With the engine running above 800 rpms the reading at the battery should be around 14.40 volts.

 

If your battery reads less than 14 volts at 800 rpm's then you are not charging the battery. The alternator has gone bad or the regulator which in most cars now adays are inside of the alternator.

 

As an alternator dies it puts more and more of a load on the battery and could cause it also to be bad. It is not that they both went bad at the same time it is that you did not catch the first failed component before it killed the battery.

 

Replace the alternator and put a charger on the battery to see if it will charge up to the 12.56 volts. If it does drive it around for 20 min and then recheck the battery volts it should be fully charged. then while idleing turn on the head lights and the a/c with fan on high the volts should remain above 12.25 if not replace the battery it will not hold a charge to keep ahead of the load.If you want to save some future headaches then replace the 11 year old battery before it stresses the new alternator into an early death.

 

 

Art

[Fisherman]

While your Car is running, unhook your Battery cable ( positive+) if it still runs with the power calble off.Most likely your alternator is still good.

The alternator "should " be able to keep the car running without the Battery hooked up.( for a short time).

IS the Battery the same one, when the car was new???

 

If so... you got some long life outta it. And It's time to get a new one.

A lot of mfgr's don't recommend doing that, a sure way to screw the alternator and the other electronics. You might be able to do that with a 1960'70's car or truck, but not the newer ones.

Edited August 5, 2007 by Fisherman

[banger]

A lot of mfgr's don't recommend doing that, a sure way to screw the alternator and the other electronics. You might be able to do that with a 1960'70's car or truck, but not the newer ones.

 

 

 

 

I'm sorry, Your RIght.

 

Have'nt had my coffee yet.

This was & is an old school trick for checking this prob, on late model vehicles.

Just like jumping the old man's Mustang with a long scewdriver.

 

 

 

 

 

 

Never mind.

Edited August 5, 2007 by banger

[John Bacon]

Thanks for the tips. I was hoping that it was the battery (I assume that a battery is cheaper than an alternator and I can replace it myself); but the evidence is starting to lean more toward an alternator problem.

 

I was able to start the van after hooking up the charge for a couple of hours. Plus, the charger is now indicating that the battery is fully charge. This would seem to indicate that the battery is capable of holding a charge, it just isn't getting charged. If my logic is wrong, please let me know.

 

How much will I have to pay for a new alternator including installation?

[Fisherman]

I would tend to believe your diagnostic is correct, alternator is going FUBAR. Take off the battery cables, positive and negative, slacken off the belt or serpentine belt, remove the alternator. Draw a diagram to show where the wires go, something like Murphy's Law will make you forget how to reinstall them correctly. Take said suspicious alternator to your local Canadian Tire, for NO Charge, they will put it on the test machine, give it a spin and tell you within a minute or less if it's still up to specs. I had to replace one on my '91 Jetta, $69, my long gone POS '94 Chev, $160, and they come with a good warranty, KEEP THE RECEIPT...Like Hop Singh says "No tikky, No laundry" Installation costs, a couple of dirty hands, bruised knuckles if you're a real cave man with no finesse, go find a buddy that can play with nuts...and bolts. And lastly, RTFI, it says, install ALL the wires on the alternator BEFORE replacing the battery cables, there's a reason for this. You may well fry the diodes if you don't, and that's not covered. Go forth and wrench...

[John Bacon]

I would tend to believe your diagnostic is correct, alternator is going FUBAR. Take off the battery cables, positive and negative, slacken off the belt or serpentine belt, remove the alternator. Draw a diagram to show where the wires go, something like Murphy's Law will make you forget how to reinstall them correctly. Take said suspicious alternator to your local Canadian Tire, for NO Charge, they will put it on the test machine, give it a spin and tell you within a minute or less if it's still up to specs. I had to replace one on my '91 Jetta, $69, my long gone POS '94 Chev, $160, and they come with a good warranty, KEEP THE RECEIPT...Like Hop Singh says "No tikky, No laundry" Installation costs, a couple of dirty hands, bruised knuckles if you're a real cave man with no finesse, go find a buddy that can play with nuts...and bolts. And lastly, RTFI, it says, install ALL the wires on the alternator BEFORE replacing the battery cables, there's a reason for this. You may well fry the diodes if you don't, and that's not covered. Go forth and wrench...

 

 

Thanks again... maybe I can replace an Alternator myself after all. Unfortunately, the engine compartment of an Aerostar does not have a lot of room to work with.

[Marko]

pull the battery out and take to canadian tire and they`ll test it for you for free.

ITs easier then pulling your alternator out, they would test it out for free overthere too.

[John Bacon]

Thanks for all of the advice.

 

I ended up buying a new Pontiac Wave rather than fix the ailing Aerostar. A little less cargo space, but it should be easier to park and better on gas.

[JerseyDog]

WOW! That was a radical fix for a crappy alternator.

 

Congrats. One more for the General!

[irishfield]

So, if I put a new battery in the car, and unhook the positive cable, and the car dies, it's the alternator?

 

Not unless it's a '69 Dodge! Old GM's wouldn't run with the battery pulled, but dodges and fords would! New stuff ain't gonna run at all without a battery hooked up.

 

Paul...were do you find the time to go thru these old threads?

[Deano]

Definitely was the altenator, the battery keeps the motor running till it drained enough, then it will stall and not start. If a vehicle will stay running(forever) after it is started (even with a boost to get it started), it's gonna be the battery. No need to disconnect the battery.

[Deano]

To make it a little easier to understand, here's what you can do

 

Test

So you get the engine running (boost if necessary) and turn on heat, radio and lights to drain battery. If engine stalls in a little while (1/2 hour), you know it's the alternator, if engine keeps running, it's gonna be the battery. Hope that helps.

 

I know the problem was solved by purchasing another vehicle, but this info can be used for reference.

[Fisherman]

Or, provided you don't live out in the sticks, take your suspected alternator to your local CTC and they'll diagnose it for free in about 30 seconds. Some of the other auto repair centers will also do it for free.

[Deano]

Clamp-it: Yours problem seems like the alternator. Especially if you got the alternator from Canadian Tire. Your new battery because it's fully charged will take quite some time to die. See if your alternator is still under warranty, and bring it back to where you got it, they'll test it and replace it. But check all connections first to rule out loose or corroded wiring.

[Sinker]

Clamp-it: Yours problem seems like the alternator. Especially if you got the alternator from Canadian Tire. Your new battery because it's fully charged will take quite some time to die. See if your alternator is still under warranty, and bring it back to where you got it, they'll test it and replace it. But check all connections first to rule out loose or corroded wiring.

 

Make sure you really check over the connections. If the light goes out when you rev it up, that tells me there is a loose connection somewhere, and its only working when the alternator is making peak power.

 

I would say its your alternator though, your battery sounds fine, and the light wouldn't come on if your battery was dying. Your old battery might still be good too....did you have it checked? If you had it checked and it was bad, that's prolly what fried your alternator. CTC will test the battery and alternator for free!

 

Sinker

[Tybo]

When your batt, light comes on . it's your alt. If the car dies it's your batt.

 

I have driven for over a hour when the alt, has died with the heater and lights on.

 

When changing your alt, you should change your belt also.

Most of the belts now days will not squeal when it's dry out.

 

There is only one belt on the market. and that is GATES.

You don't use GATES you deserve what can happen.

 

I change my belt every 2 years. To much is ride on something so simple.

[irishfield]

It may very well just be his non-gates belt slipping as well..

[Zib]

Not unless it's a '69 Dodge! Old GM's wouldn't run with the battery pulled, but dodges and fords would! New stuff ain't gonna run at all without a battery hooked up.

 

Paul...were do you find the time to go thru these old threads?

 

My old '73 Pontiac Lemans ran after the battery was pulled as did my '79 GMC Jimmy.

[Fisherman]

Well, I am the proud owner of a new battery, and re-mfg alternator, (3 yr warrantee).

Cost, $434.00 Battery, $134.00, Alternator, $ 298.00 (Tax incl).

 

I bought the battery in error because I figured since the alternator was purchased last year, it couldn't be that, but I was wrong.

Lord liftin C, $134 for a battery and $298 for an alternator, what are you driving?

[sonny]

If you look behind the air filter box. there you will find a connector that is part ot the alternator wiring,,,it is a coomon problem for that connector to go bad causing the alternator to not charge the vehicles battery,,,the wa to check that is to do a voltage drop test across the connector or from the alt to the battery,,,if there is a problem with the plug just cut it out and wire direct with solder and heat shrink,,,,you may have just masked the problem with a new battery but if there is a problem it'll catch you at the worst time!

[douG]

I agree with Roy *snort*.