bad car battery?

[Sniper82]

Car doesn't seem to charge right. Took it to advance and had it tested and tested bad. Took the alternator out to have it rebuilt and the guy put it on a tester and said it tested fine throwing 14amps. Well then since the belt on my car makes squeaking noises often I figured I would change it since its cheap anyway. Well the belt fixes the squeaking sound but not the alternator problem. So now I am thinking the battery might be bad?

I have a tester myself and with the A/C and headlights on it tests anywhere from 40-60 percent out of 100. I put the same tester on my sisters mustang with A/C on and headlights and it stayed above 90 percent. Could it be that the battery although it seems fine? Could have a dead cell or something? The green LED on it shows green and my tester shows it throwing 12v.

Any ideas? Its a Pontiac Grand Am SE 2000 model. BTW if nothing is on(A/C,ect) my testers shows around 80 or so. Also the engine sounds bad with the A/C on like its not getting enough power.

 

[SilverTorch]

Wiring?

 

[Sniper82]

I looked over the wiring from the alternator to the battery and didn't see anything wrong. What else should I look for on the wiring? I've owned it for a couple years now and have never changed the battery so I am probably assuming it could be the original battery that was in it.

 

[AmdEmAll]

With a tester the battery can look fine but once its put under load the voltage can drop below normal. Have the battery tested.

 

[Sniper82]

Originally posted by: AmdEmAll
With a tester the battery can look fine but once its put under load the voltage can drop below normal. Have the battery tested.

Can Advance test the battery under load to see if its bad?

 

[farmercal]

Auto Zone and Advance Auto can check you battery for free and tell you whether it is bad or not.

 

[Sniper82]

I'll have it checked out

 

[SilverTorch]

I think the battery tests that places do (at least Murray's) just tests how well and what charge the battery has.

I was under the impression that the battery is there just to start the car, everything else from that point is run off the alternator.

 

[feralkid]

Originally posted by: Sniper82
Car doesn't seem to charge right. Took it to advance and had it tested and tested bad. Took the alternator out to have it rebuilt and the guy put it on a tester and said it tested fine throwing 14amps.




How many Amps is it supposed to put out?

14 seems a bit anemic.

 

[Sniper82]

Originally posted by: feralkid

Originally posted by: Sniper82
Car doesn't seem to charge right. Took it to advance and had it tested and tested bad. Took the alternator out to have it rebuilt and the guy put it on a tester and said it tested fine throwing 14amps.




How many Amps is it supposed to put out?

14 seems a bit anemic.

From what I heard anything less than 13 amps with lights,A/C,ect on isn't to good. I think a alterntor is suppose to run around 14 amps. But thats what I heard.

Silvertorch I am not sure if thats the only thing the battery is used for. But again I heard everything runs off the battery and the alternator just keeps the battery fully charged and they sorta work together? Feel free to correct me car experts.

 

[cavemanmoron]

Originally posted by: Sniper82

Originally posted by: feralkid

Originally posted by: Sniper82
Car doesn't seem to charge right. Took it to advance and had it tested and tested bad. Took the alternator out to have it rebuilt and the guy put it on a tester and said it tested fine throwing 14amps.




How many Amps is it supposed to put out?

14 seems a bit anemic.

14 VOLTS.

you want at least 40 AMps. @ 13.6 VOLTS.



From what I heard anything less than 13 amps with lights,A/C,ect on isn't to good. I think a alterntor is suppose to run around 14 amps. But thats what I heard.

 

[PowerEngineer]

How old is that battery?

If it's more than 3 years old, just go ahead and replace it. Odds are very good that it's causing the problem. If it's not, you'd have had to replace the battery soon anyway; and then you can start looking for some other less probable cause.

Good luck!

 

[EyeMWing]

Originally posted by: Sniper82

Originally posted by: feralkid

Originally posted by: Sniper82
Car doesn't seem to charge right. Took it to advance and had it tested and tested bad. Took the alternator out to have it rebuilt and the guy put it on a tester and said it tested fine throwing 14amps.




How many Amps is it supposed to put out?

14 seems a bit anemic.

From what I heard anything less than 13 amps with lights,A/C,ect on isn't to good. I think a alterntor is suppose to run around 14 amps. But thats what I heard.

Silvertorch I am not sure if thats the only thing the battery is used for. But again I heard everything runs off the battery and the alternator just keeps the battery fully charged and they sorta work together? Feel free to correct me car experts.

It could be wired either way.

 

[sao123]

Alternator is supposed to run at 14 amps, but that doesnt mean it isnt bad. Its performance could drop when temp goes up, etc... have both battery and alternator checkeed at advanced auto (its free). Also be sure your battery contacts and rings are clean.

 

[Sniper82]

took it to advanced and had both the alternator and battery tested. Alternator tested fine but not the battery. Well I bought a battery that was recommended for the car and all seems well. The car sounded good at idle even with A/C on. Well after my GF made a trip in it and got it back I hooked my tester up to it with the same results as it did with the bad battery. Also with A/C on the engine bogs down some and doesn't sound as smooth. Anyone have any other ideas? Or is it possible my tester is just faulty?

BTW all the testing I done was at idle. Should I have revved the engine up some to around 2k for a reading?

 

[Eli]

Originally posted by: Sniper82
took it to advanced and had both the alternator and battery tested. Alternator tested fine but not the battery. Well I bought a battery that was recommended for the car and all seems well. The car sounded good at idle even with A/C on. Well after my GF made a trip in it and got it back I hooked my tester up to it with the same results as it did with the bad battery. Also with A/C on the engine bogs down some and doesn't sound as smooth. Anyone have any other ideas? Or is it possible my tester is just faulty?

BTW all the testing I done was at idle. Should I have revved the engine up some to around 2k for a reading?

Your battery and alternator has nothing to do with the sound of your car at idle or your A/C.

What exactly are you testing? What are the "results"?

 

[Kalvin00]

Originally posted by: SilverTorch
I was under the impression that the battery is there just to start the car, everything else from that point is run off the alternator.

Everything runs off the battery.

The alternator merely keeps it charged.

 

[Sniper82]

Originally posted by: Eli

Originally posted by: Sniper82
took it to advanced and had both the alternator and battery tested. Alternator tested fine but not the battery. Well I bought a battery that was recommended for the car and all seems well. The car sounded good at idle even with A/C on. Well after my GF made a trip in it and got it back I hooked my tester up to it with the same results as it did with the bad battery. Also with A/C on the engine bogs down some and doesn't sound as smooth. Anyone have any other ideas? Or is it possible my tester is just faulty?

BTW all the testing I done was at idle. Should I have revved the engine up some to around 2k for a reading?

Your battery and alternator has nothing to do with the sound of your car at idle or your A/C.

What exactly are you testing? What are the "results"?

I have a battery/alternator tester and am using it to test the battery and alternator. I explained it to the guy at advanced and he said where the battery is bad when I turn my A/C on the motor isn't getting all the power it needs or something. Doesn't the condenser fan,blower motor,ect need power to run? It needs to get it from somewhere(battery/alternator)

I think I was getting little over 12v on the new battery and 13.4 to 13.6 with the A/C on, on the alternator. Maybe I need to just buy a multimeter since it would probably be more accurate?

But the engine has a slight pecking sound with the A/C on and goes aways when off. A/C work good.

This is what I am using:
http://www.batterychargers.com/details.cfm?prodid=SC%2D1200A&catid=2

 

[Eli]

Originally posted by: Sniper82

Originally posted by: Eli

Originally posted by: Sniper82
took it to advanced and had both the alternator and battery tested. Alternator tested fine but not the battery. Well I bought a battery that was recommended for the car and all seems well. The car sounded good at idle even with A/C on. Well after my GF made a trip in it and got it back I hooked my tester up to it with the same results as it did with the bad battery. Also with A/C on the engine bogs down some and doesn't sound as smooth. Anyone have any other ideas? Or is it possible my tester is just faulty?

BTW all the testing I done was at idle. Should I have revved the engine up some to around 2k for a reading?

Your battery and alternator has nothing to do with the sound of your car at idle or your A/C.

What exactly are you testing? What are the "results"?

I have a battery/alternator tester and am using it to test the battery and alternator. I explained it to the guy at advanced and he said where the battery is bad when I turn my A/C on the motor isn't getting all the power it needs or something. Doesn't the condenser fan,blower motor,ect need power to run? It needs to get it from somewhere(battery/alternator)

I think I was getting little over 12v on the new battery and 13.4 to 13.6 with the A/C on, on the alternator. Maybe I need to just buy a multimeter since it would probably be more accurate?

But the engine has a slight pecking sound with the A/C on and goes aways when off. A/C work good.

This is what I am using:
http://www.batterychargers.com/details.cfm?prodid=SC%2D1200A&catid=2

Neat, heh.

13.4 - 13.8V is what an alternator is supposed to output.

A lead acid battery, after sitting for ~8 hours to dissipate residual charge voltage, should read 12.7 - 13.2V.

I'm still not understanding what the problem is.

If the voltage sags significantly when you turn all your lights and accessories on, there is a problem. Otherwise, it sounds like everything is OK.

The engine is supposed to change pitch when you turn the A/C on.. It is a significant load.

 

[conehead433]

External voltage regulator?

That is to say, the regulator is not inside the alternator. Many cars have external regulators. The alternator can be OK, but a bad regualtor could keep the car from charging properly.

 

[Sniper82]

Originally posted by: Eli

Originally posted by: Sniper82

Originally posted by: Eli

Originally posted by: Sniper82
took it to advanced and had both the alternator and battery tested. Alternator tested fine but not the battery. Well I bought a battery that was recommended for the car and all seems well. The car sounded good at idle even with A/C on. Well after my GF made a trip in it and got it back I hooked my tester up to it with the same results as it did with the bad battery. Also with A/C on the engine bogs down some and doesn't sound as smooth. Anyone have any other ideas? Or is it possible my tester is just faulty?

BTW all the testing I done was at idle. Should I have revved the engine up some to around 2k for a reading?

Your battery and alternator has nothing to do with the sound of your car at idle or your A/C.

What exactly are you testing? What are the "results"?

I have a battery/alternator tester and am using it to test the battery and alternator. I explained it to the guy at advanced and he said where the battery is bad when I turn my A/C on the motor isn't getting all the power it needs or something. Doesn't the condenser fan,blower motor,ect need power to run? It needs to get it from somewhere(battery/alternator)

I think I was getting little over 12v on the new battery and 13.4 to 13.6 with the A/C on, on the alternator. Maybe I need to just buy a multimeter since it would probably be more accurate?

But the engine has a slight pecking sound with the A/C on and goes aways when off. A/C work good.

This is what I am using:
http://www.batterychargers.com/details.cfm?prodid=SC%2D1200A&catid=2

Neat, heh.

13.4 - 13.8V is what an alternator is supposed to output.

A lead acid battery, after sitting for ~8 hours to dissipate residual charge voltage, should read 12.7 - 13.2V.

I'm still not understanding what the problem is.

If the voltage sags significantly when you turn all your lights and accessories on, there is a problem. Otherwise, it sounds like everything is OK.

The engine is supposed to change pitch when you turn the A/C on.. It is a significant load.

But is it suppose to have a noticeable pecking sound when the A/C is on? It doesn't sound good IMO. But that isn't the reason I tested the car to begin with. I had the old battery fail on me a couple times when starting. BTW this tester shows a percentage of 0-100. When the tester shows above 80 or so the charge light comes on meaning everything is fine. If it drops below around 50 the check light comes on saying something is wrong with the alternator and that is what I am getting once A/C,lights,ect is turned on(25-50 percent). Maybe that feature on this needs to be overlooked and is faulty?

I think I will buy a multimeter soon for testing as I need one anyway. Anyone recommend a cheap but fairly accurate one?

Thx for the help all

Originally posted by: conehead433
External voltage regulator?

That is to say, the regulator is not inside the alternator. Many cars have external regulators. The alternator can be OK, but a bad regualtor could keep the car from charging properly.

Any idea where that might be located and how it can be tested(if it can).

 

[Analog]

14A? My minivan's alternator is rated at 140 Amps! My minivan's computer uses pulse width modulation to control the field voltage of the alternator to regulate it's output voltage, based on the load ('95 pontiac). If yours is similar, then you may have a bad PCM - which is giving a weak feedback signal to the alternator to maintain voltage under load. I would still have the battery checked.

 

[Eli]

Originally posted by: Sniper82

Originally posted by: Eli

Originally posted by: Sniper82

Originally posted by: Eli

Originally posted by: Sniper82
took it to advanced and had both the alternator and battery tested. Alternator tested fine but not the battery. Well I bought a battery that was recommended for the car and all seems well. The car sounded good at idle even with A/C on. Well after my GF made a trip in it and got it back I hooked my tester up to it with the same results as it did with the bad battery. Also with A/C on the engine bogs down some and doesn't sound as smooth. Anyone have any other ideas? Or is it possible my tester is just faulty?

BTW all the testing I done was at idle. Should I have revved the engine up some to around 2k for a reading?

Your battery and alternator has nothing to do with the sound of your car at idle or your A/C.

What exactly are you testing? What are the "results"?

I have a battery/alternator tester and am using it to test the battery and alternator. I explained it to the guy at advanced and he said where the battery is bad when I turn my A/C on the motor isn't getting all the power it needs or something. Doesn't the condenser fan,blower motor,ect need power to run? It needs to get it from somewhere(battery/alternator)

I think I was getting little over 12v on the new battery and 13.4 to 13.6 with the A/C on, on the alternator. Maybe I need to just buy a multimeter since it would probably be more accurate?

But the engine has a slight pecking sound with the A/C on and goes aways when off. A/C work good.

This is what I am using:
http://www.batterychargers.com/details.cfm?prodid=SC%2D1200A&catid=2

Neat, heh.

13.4 - 13.8V is what an alternator is supposed to output.

A lead acid battery, after sitting for ~8 hours to dissipate residual charge voltage, should read 12.7 - 13.2V.

I'm still not understanding what the problem is.

If the voltage sags significantly when you turn all your lights and accessories on, there is a problem. Otherwise, it sounds like everything is OK.

The engine is supposed to change pitch when you turn the A/C on.. It is a significant load.

But is it suppose to have a noticeable pecking sound when the A/C is on? It doesn't sound good IMO. But that isn't the reason I tested the car to begin with. I had the old battery fail on me a couple times when starting. BTW this tester shows a percentage of 0-100. When the tester shows above 80 or so the charge light comes on meaning everything is fine. If it drops below around 50 the check light comes on saying something is wrong with the alternator and that is what I am getting once A/C,lights,ect is turned on(25-50 percent). Maybe that feature on this needs to be overlooked and is faulty?

I think I will buy a multimeter soon for testing as I need one anyway. Anyone recommend a cheap but fairly accurate one?

Thx for the help all

Originally posted by: conehead433
External voltage regulator?

That is to say, the regulator is not inside the alternator. Many cars have external regulators. The alternator can be OK, but a bad regualtor could keep the car from charging properly.

Any idea where that might be located and how it can be tested(if it can).

Any pecuilar noises should be checked out..

But a ticking/pecking noise from your A/C wouldn't have anything to do with your battery or charging system. 😉

Without knowing the tester, I can't say for certain.. but if that percentage drops when you turn everything on, it's probably indicating a low voltage situation.. in which case, something is wrong with the charging system.

But that's totally independant of your A/C as far as noises and stuff go..... the only thing the A/C needs power for is to lock up the compressor's clutch, and for the condesor fan.

 

[Sniper82]

the ticking/pecking is the engine not the A/C in my situation. It completely goes away and sounds fine with A/C off. But maybe thats normal on a car that has 120k miles with the A/C on.

 

[Minjin]

Unbelievable amount of misinformation in this thread...

Easiest way for a shade tree mechanic to test the alternator and wiring:

1. Check battery voltage with car off, should be in the 12-13v range. While you are there, check the terminals for corrosion and make sure they are tight.
2. Start up the car and check voltage at the battery again. Should be around 13.5v. As the car warms up and tops up the battery, it might move as high as 14-14.5v. GM cars tend to charge at a very high voltage.
3. Turn on your headlights. Turn on the radio. Turn on the rear defroster. Turn your blower motor to high. Now check your voltage again. It will most likely sag but it shouldn't go below 13v, 12.5v at the worst.

THAT is a load test. Its more difficult to do a battery load test at home because you need a special tester thats basically a toaster with a switch and a voltmeter on it. They will definitely have one of these at your auto parts store.

Go from there.

And yes, bad wiring can be a problem as well. Rodents can chew at wires. Heat from exhaust can melt the insulation causing corrosion on the strands. To test wiring, your best bet is check the voltage at the back of the alternator AND at the battery under load. If the two numbers are very different, then that shows that you have more resistance than you should have. If you can't do that, disconnecting the battery and checking the resistance between those two spots will tell you what you need to know.

Mark