Can alternators get better?

Intermittently bad battery (internal shorts) lead to death of the first

Is it safe to assume that the battery that was replaced was the original?

sim> Here's my story:

No, the battery in the car now is number 3. After three years of use, the original battery was replaced four years ago. And then that battery just got replaced.

I'm curious as to why my battery light is now not lit up (indicating no problem.) To be on the safe side, should I get a new alternator because it failed the recent test?

And is the battery being charged at the moment by the alternator, or just partially, or am I just running off the battery?

Thanks, Simon.

Approximately 11/11/03 09:48, simonc uttered for posterity:

No. However, it may not be the alternator. From replacing the battery to multiple replacing the alternator, sounds like you've been the victim of "swap and pray" troubleshooting.

In LA there are all sorts of good automotive electricals specialty shops. Head for one and get your cables checked, your alternator checked, your battery checked, your voltage regulator checked [if not built in to the alternator], and anything else in your charging control system checked. Don't let your current shop continue to just piecemeal it. The shop should be willing to drop in a test battery if needed to test your alternator and complete charging control system across the full rpm range, and specially at low rpm.

I had a Volvo that actually had an open circuit behind the dash and went thru similar sorts of gyrations with battery, alternator, etc. until my shop sent me to the electrical shop on the Lomita/Torrance border. Took them a coupla hours, but they found and fixed it and it never failed after.

Approximately 11/11/03 11:41, simonc uttered for posterity:

The person making the test may have been a doofus.

Go to Radio Shack and buy an inexpensive voltmeter. With your engine running at about 1500 rpm, you should see 14.7 volts across the battery terminals...and those terminals and cables should be clean and tight.

Then drop the rpm to idle, you should still see charging. If not, your battery is slowly gonna go dead in LA traffic.

Anyone check the belt?

because it

battery light

brighter.

Do yourself a favor and go to a junkyard. Find a similiar car (Geo Prizm of same year for example). Or, just about any Toyota that uses the 7AFE 1.8L engine. Yank out the OE alternator which is a Nippon Denso. Drop it in and be on your way for 200,000+ miles. If the battery light comes on, get new brushes for $7 and be on your merry way.

These so-called "mechanics" are the absolute scum of the earth.

-Tim

Indeed, every city has it's gems. I had a problem with a 1981 Ford Escort. Thing would not charge. Finally in frustration I took it to a little place called the Battery Exchange. Turns out one of the belts was bad.

True. The dashboard light is lit when the alternator regulator tells it to come on - if the alternator regulator thinks it's putting out power OK, it won't light the lamp.

It might be working, just not enough to keep up with the load.

You will get a voltage drop whenever you are sitting at idle, since the alternator doesn't put out it's full power output until the engine is above 1,200 to 1,800 RPM.

In almost all cars, sitting at idle is break-even on battery charge during the day with no accessory loads on, and a slow battery draw if the AC and/or the headlights are on. Sit at curb idle long enough with the headlights, wipers, and air or heat on, with your foot on the brakes (brake lights on), and the battery will go dead.

But the voltage should hold at above 12 to 12.5 volts for a while, as the alternator is trying to keep up but the battery has to put out a little power. If it drops to 11.5 volts or below, either the alternator is barely working, or the battery has a dead cell. It happens, even on brand new batteries.

Once the light turns green and you get moving, the battery will charge back up.

-->--

Stop allowing mechanics to take guesses with your car. A voltmeter will tell you everything you need to know.

Assuming that the belt is good, I'd say all you ever really needed was a good rebuilt alternator or one from a junkyard. Sounds to me like they put in junk rebuilt alternators (i.e. - Pep Boys, Autozone, etc.).

They don't call them "idiot lights" for nothing. Lights are notoriously inaccurate. A voltmeter (or better still an ammeter) would tell conclusively if the alternator is keeping up with the electrical load, and in the case of the ammeter will tell whether it is charging the battery or if the battery is supplying current to run the electrical loads. Ammeters are difficult to wire in, though, and that's part of the reason that no one except Chrysler used them in the past 30 years, and Chrysler quit quite a few years ago also.

You're probably running off the battery.

In news: snipped-for-privacy@texas.net, Steve being of bellicose mind posted:

An "idiot light" could more accurately be described in today's vernacular as a "threshold indicator."

Ammeters followed the DC generator into obscurity, regardless of manufacturer.

A voltmeter would suggest that condition as soon as the voltmeter displayed less than nominal battery voltage of 12.6v.

Too bad. 1989 was the last year Chrysler offered them, IIRC.

The biggest drawback was that you had to run heavy-guage wiring to and from the ammeter, and that in itself added an extra failure point.

Quite true. But an ammeter tells you the instant that the failure occurs, because the needle immediately swings toward "discharge."

There is no need to run the heavy gage cable from the alternator to an ammeter and then to the battery. Standard practice for such installation is a 14-16 guage wire in parallel.

Which would distress most people until they came to ignor the thing. There are people out there who couldn't accept the fact that oil pressure varies so ....Ford (for one) on some models made the oil pressure meter read mid scale when pressure was above 9 psi .... no fluctuations ever UNLESS.... the pressure dropped below 9 psi, then the meter would read zero.

Probably another part of the reason they're gone. Much is the pity, once again we have to settle for "lowest common denominator" crap.

Yep. An 'idiot guage'. Worse than an idiot light, because at LEAST the light grabs your attention quickly.