Car Alternator / battery problem

[random]

Battery loses power over time. When this happens, car jumps ok and seems to run fine after starting. Disconnecting the battery while running, it stops after 2-3 seconds.

Main suspicion is a bad alternator. I don't want to pull it and end up it's something else though - anything else I should consider first?

 

[skeets]

Does the amp meter show it is charging? What kind of car/truck how old ect, But that would be my first guess atuo zone will check it I think that can even do it in the car

 

[85Hokie]

Battery loses power over time. When this happens, car jumps ok and seems to run fine after starting. Disconnecting the battery while running, it stops after 2-3 seconds.

Main suspicion is a bad alternator. I don't want to pull it and end up it's something else though - anything else I should consider first?

Ohm meter set to DC volts .....

Battery - +/- and see what battery reads - SHOULD be about 12.7 volts ..... betcha yours is low 12's or even 11ish or worse.

Start - jump if need be - while running what is voltage now at battery?????? IF not above 13.5 or closer to 14 then you have a charging problem.

Do not remove the battery while running...... but I assume you are removing the jumping battery?

A voltage test on the battery will tell a story - bad connections are another problem too.

Clean all connections bright and tight!

 

[Ikc1990]

Also ground wires to ! a bad ground is as bad as a bad power.

 

[North Idaho Wolfman]

Pull the battery and have it load tested.
If it's good, then your more than likely looking at an alternator/ regulator issue.

 

[armylifer]

Older cars such as the Fords had voltage regulators that could go bad. So, it is really important that you tell us the year and model of the car. I know that there are some older folks on this site that have experience with almost every American made car.

 

[random]

So far all seems to be still pointing the same way. Thanks for the tips on the voltage checks! Armylifer it's a 1996 Kia Sephia.

If it continues to point that way, I'll see if they can test it in the car, did't think that was a possibility.

 

[armylifer]

A quick search shows that the voltage regulator for that car is integral to the alternator. A new alternator for that car is about $75.00 at several sources online or around $100.00 in parts stores.

 

[BruceP]

Disconnecting the battery while engine is running is a BAD IDEA... I have seen this INSTANTLY kill the diodes within the regulator.

Instead, just use voltmeter to measure voltage at BATTERY TERMINALS (not the connectors) while engine is running. If not over 14.8 volts, suspect the alternator is not charging. (not necessarily a bad alternator)

*) If NOT >14.8 volts, you need to troubleshoot to determine WHY the alternator is not charging. (could be connections, diodes, regulator, brushes, sliprings, slipping belt....etc)

*)If IS >14.8 volts, you have a parasitic current draw which is draining battery whilst parked.

 

[Daren Todd]

Start your vehicle and check your battery voltage with the engine running. It should show 13.5 to 14.5 volts.

If it is reading in between those voltages then your alternator is working fine.

You can have a parasitic drain from numerous locations. Could be the alternator, starter, relay sticking, ect.....

Or you could have a bad cell (short in the battery) that is causing the battery to lose charge over a period of time.

To check if it's the battery, make sure your vehicle is off. Then disconnect the ground cable from the battery.

Let the battery sit for 5 minutes or so and check the voltage. For example it could read around 12.5 volts. Check periodically over the next hour. If the voltage holds steady at the original reading then the battery is good.

If it's still dropping slowly after an hour then the battery is bad.

Note: The electronic testers at the auto parts store can't always tell you a battery is bad. I've had them test a known bad battery with one and tell me it was good. I then put my old trusty analog tester on it and proved them wrong.

 

[lugbolt]

kinda 'car' is this that we're dealing with??

Any automotive alternator produced since about 1985 at the latest is internally regulated. The reg "senses" voltage and adjusts it's output accordingly. With that, newer alternators sensing circuit is controlled via ecu, which means there is possibility of much more involved issues....which is why I asked what kinda "car" are we dealing with?

could be:
bad batt
bad alt
bad wiring
bad ground
bad ecu
bad can
fuse
gauge
charge indicator bulb (yes that'll cause it too on some cars)
and a host of other things

 

[armylifer]

kinda 'car' is this that we're dealing with??

Any automotive alternator produced since about 1985 at the latest is internally regulated. The reg "senses" voltage and adjusts it's output accordingly. With that, newer alternators sensing circuit is controlled via ecu, which means there is possibility of much more involved issues....which is why I asked what kinda "car" are we dealing with?

could be:
bad batt
bad alt
bad wiring
bad ground
bad ecu
bad can
fuse
gauge
charge indicator bulb (yes that'll cause it too on some cars)
and a host of other things

See post #7. He said that it is a 1996 KIA Sephia.

 

[random]

Yeah, just learned about the battery thing - apparently has a possibility of a surge that can damage components. I think maybe that wasn't an issue in the past? (70's or so?) I guess my info is pretty outdated.

Going to try the suggestions here as soon as I have a chance.

 

[RCW]

Yeah, just learned about the battery thing - apparently has a possibility of a surge that can damage components. I think maybe that wasn't an issue in the past? (70's or so?) I guess my info is pretty outdated.

Going to try the suggestions here as soon as I have a chance.

Not a good practice, but much less risk in the <'70's vehicles.

 

[JimmyJazz]

We have a AAA auto club membership. I think they are available nationwide. It cost about $100 per year. I got it a year ago when my daughter started to drive. Very handy. They will come out "for free" and test your battery. If its no good they will replace it on the spot at a reasonable price. A good deal for those of us not fully comfortable with ohm meters and such. Lock your keys in the car? No problem. They "bust into it" in about 3 minutes. Godlike. You would have to see it to believe it. I salute them when I see them. I recommend AAA.

 

[armylifer]

Now they need a AAA for tractors.

 

[Tooljunkie]

One sure fire test, park car with battery disconnected. Say for 2 days. Reconnect battery, if it starts, its not the battery.
it isnt easy to track down a parasitic drain, unless its constant. And a multimeter with amp capability is required.
knowing the amount of draw is helpful too.
glove box or dome lights, rear wiper motors, power antennas are things that are overlooked.
if the alternator is drawing power it will be making heat. So a charger overnight with everything connected, and before starting reach in and see if alternator is warmer than surrounding components. An infra-red camera is an awesome tool for this,as a quick scan will identify a warm spot.

 

[GreensvilleJay]

One possible problem are the actuall batery cable to posts connections. Over time they'll oxidize and form an 'insulator' between battery and cable ( telltale' is a whitish fuzz.....)
reading the cable will show 14.5,so alt is fine, but the fuzz keeps the battery from fully charging.
Every since 'maintenance free' batteries came out ,nearly nobody CHECKS the battery anymore....

 

[random]

Finally got a chance to get back to this.

Terminals and connections are clean.

After a few days, the battery is checking about 6.7vdc unconnected to anything, not sure what it was checking previously. I jumped it and after disconnecting the jumper cables, got a read of 14.4vdc across the terminals. Turned it off and disconnected the battery cables, read just over 12vdc across the terminals.

Here's where it gets interesting:

After 15 minutes or so, remaining disconnected, it read 11.85vdc. Ambient temp about 50 degrees F, so I don't think it would be due to that. I'll check again tomorrow. THAT suggests the battery isn't holding a charge.

But ALSO, checking resistance across the connectors (still keeping it disconnected) with the doors shut and key out of the ignition gives me a steady reading around 2000 ohms. That suggests a parasitic draw, right?

So maybe it's BOTH?

Could a draw like that screw up the battery to a point it won't keep a charge? 2k seems a pretty low resistance when you're expecting an open circuit. Doesn't make sense to replace the battery until the draw is fixed...

ETA:
Ah, looking things over some more, looks like maybe I should have been checking for amps? Still that doesn't seem right on the resistance for everything off...
I'll check amps tomorrow. Too dark out anymore today.

 

[random]

it isnt easy to track down a parasitic drain, unless its constant. And a multimeter with amp capability is required.
knowing the amount of draw is helpful too.
glove box or dome lights, rear wiper motors, power antennas are things that are overlooked.

Any tips on how to use amps to help determine the drain source?