Battery Losing Power

JBaez · JBaez's Garage

I might have a bad battery or a bad voltage regulator but am not sure. I replaced the battery last night since as I drove, the car would eventually get to the point that it would lose power and then die. The car was lightly used over 3 years and the battery sat so I figured it could be bad. When I bought the car the seller informed me he had to put the battery on charger. A friend of mine told me it could be the voltage regulator. The alternator was replaced over the last 2 years so I believe that should be good and only has about 10k miles since the new one. Do you know how I can see if it is a voltage regulator problem? None of the red lights on the dash come on when the car dies and if I figured if they did that would show that the alternator was failing.

Any insight you could provide would be fantastic!

Thanks all!

pwd72s · 01-10-2004, 08:55 AM

If I'm not mistaken, an '86 has the internal V. regulator...meaning you'd have to pull the alternator anyway...maybe Warren (earlySman) will choose to weigh in on this.

ruf-porsche · ruf-porsche's Garage

unless someone back dated the alternator and VR, your system should have the internal regulator. If it needs to be replaced you need to remove the alternator.

Our host has the internal regulator.

Lorenfb · 01-10-2004, 09:00 AM

You need to put a voltmeter on the battery and start the car. The typical
3.2 alternator puts out about 14.2 volts at the battery. It's not the low
10K miles which would indicate a good alt., but the quality of the rebuilt
unit.

If the car restarts after it dies, then the battery is probably O.K. You
need to provide more info.

Good Luck
Loren
'88 3.2

JBaez · JBaez's Garage

The car would get to the point where it would idle barely and the even the clock on the radio would go out. When it died, the battery was totally dead. Thanks for the tip. Any idea what the cost of a voltometer is?

Por_sha911 · Por_sha911's Garage

Shouldn't it be able to run straight off the alternator without the battery?

Lorenfb · 01-10-2004, 09:13 AM

Not a good idea, especially if the alternator overvoltages the system.
If the alt. & reg. are good, you can disconnect the battery and hold
the idle at 1200 to 1500 RPMs. A good alt. will run the car in this
manner. Remember, the battery is only there for starting and to
"buffer" the alt. for load changes and at low RPMs when the alt. output
is low.

Good Luck
Loren
'88 3.2

pwd72s · 01-10-2004, 09:18 AM

Quote:

Originally posted by JBaez
The car would get to the point where it would idle barely and the even the clock on the radio would go out. When it died, the battery was totally dead. Thanks for the tip. Any idea what the cost of a voltometer is?

A cheap temporary volt meter can be rigged with a low cost multimeter. A friend gave me this tip...wire a male cigarette lighter plug to a multimeter set to read VDC, set it on the passenger seat, and you can monitor as you drive.

Wil Ferch · 01-10-2004, 09:40 AM

A nice pocket sized multi-meter..digital...from Radio Shack is about $28 and I checked mine against a very $ Fluke meter and they both read the same...
--Wil Ferch

vash · vash's Garage

i bought a cool multimeter from sears for 28 bucks. it came with a free thermocoupler. i dont even know what to use a thermocoupler for except testing the frying pan for proper temp before i put the pancake batter in.

maybe measuring cylinder temps?

JBaez · JBaez's Garage

Does anyone think that the battery could be bad enough to where it is not cycling a charge? If the car ran and then lost the ability to even run the headlights and clock lights, could this be due to a bad battery?

Early_S_Man · 01-10-2004, 11:32 AM

Does the alternator warning lamp come on when the ignition is switched on, before you start the engine?

Did you charge the new battery before installing in the car and trying to use it?

From your description ... both battery and alternator capacity are too low to operate the DME reliably. The cause for the lack of alternator output can't be determined here from data you have supplied.

JBaez · JBaez's Garage

the warning light for the alternator never comes on while the car is running and comes on normally as a check light when the ignition is first turned. If I disconnect the negative cable from the battery and the car shuts off, is this a sign of a bad alternator?

ruf-porsche · ruf-porsche's Garage

Pep girl or Auto Zone should be able to test your battery to determine if you have a bad cell. How old is the battery? Not using the car is harder on a battery than using the car. I have to replace the batteries in the Lotuses every two years because they just sulfate themselves from sitting.

If you want to DIY you gotta spend some money on some basic tools and test equipment. I brought a digital meter at Sears for $20 bucks.
Just as good as the Fluke that my brother has.

JBaez · JBaez's Garage

I bought a bosch yesterday so I have not had the chance to test this battery for an extended period. I think that could be the cause but when I disconnected the neg lead of the battery the car shut down. Was I suppose to disconnect the positive to see if the charging system is working?

JBaez · JBaez's Garage

On a second check, it turns out the battery light is NOT coming on. Is it supposed to do this? If I turn the ignition, but don't start the car it does not come on. I tested the bulb and it seems to be fine. Does anyone know if an '86 is supposed to have the battery light come on when you turn on the ignition key?

Thanks!

ruf-porsche · ruf-porsche's Garage

If the alternator light does not come on when you turn the ignition switch you have a bad alternator, either an open field or bad brushes.

Just had my alternator rebuilt when I had the same problem, engine dying and radio dying at the same time. Ended up buying a new battery also, cheaper than getting the car towed back to my house.

JBaez · JBaez's Garage

where did you have the alternator rebuilt and what did it cost?
Thanks!

vash · vash's Garage

hey baez, do you have a gauge yet? you are going at it all wrong if you dont. you have to measure if you battery is dead first. you need better than 12V. then if you get the car started, how many volts are you seeing at the battery? better than 14V? electrical probs are a big pain in the arse, you HAVE to approach it systematically? i think the light bulb is wired inline from the alt. if it doesnt come on, you are not getting a charge.

Lorenfb · 01-10-2004, 01:39 PM

Yes! It goes out once the engine starts. Possibilities:

1. bad connection to alt.
2. bad regulator on alt.
3. open slip rings in alt.
4. no +12 volts to one side of alt. light

You going to have to pull the alt. out and ground the blue wire (to light).
If the light then comes on, then #2, or #3.