Alternator / Regulator issue?

[kyalami]

I took my 87 Targa Carrera out of the garage today to celebrate the near arrival of spring. Car has been on a trickle charger all winter. Started right up. Drove car about 60 miles with three stops. At the third stop the battery was dead and wouldn't turn car over. Just prior to stopping I noticed that the stereo was acting strange and cutting in and out. Got a jump start and went to my local station. Their charge meter showed the battery at about 11-12 volts with the engine running. Obviously not charging. But, the charge light was not showing a no charge condition.

I am operating on the assumption that the alternator or regulator are shot and need to be looked at in spite of the fact that the dash light isn't on. I checked the belts...all tight with minimal slack and no slippage.

Are my assumptions correct? Probably taking it in to have the pros look at it this week.

[pete3799]

You might get lucky and just need a new bulb in the alt. light.
I think the bulb is necessary for the alt. to work.

[DRACO A5OG]

what brand of trickle charger is it?

+1 check bulb and connectors, may be over the winter they may have built up some corrosion.

I thought my alt was out but it turned out to be my positive side connector, wiggled it a bit then saw the voltage increase to normal 14.1 at idle

[kyalami]

Hmmmm...I'll check to see if the bulb is working tomorrow by turning the key halfway. My positive side connectors were a little loose but have been tightened....still not a high enough charge voltage when running.

[kyalami]

Didn't realize the bulb was an active part of the charge circuit...

[wwest]

The current flow through the bulb (and parallel resistor if present) only provides a (slight) "jump start" current flow to the alternator rotor. If the alternator/regulator is working correctly it then begins supplying its own rotor current internally.

With weeks of storage I would first check for loose or poor, oxidized, electrical connections, special attention to the battery posts/conenctors.

[kyalami]

So,

I can now confirm that the charge light on the dash does NOT illuminate at all. Does that mean that the alternator will not charge the car regardless?

[pete3799]

Pull one of the other ( working) bulbs and swap them to see if it's the bulb or the wiring.

[kidrock]

what a coincidence...my alternator just started acting up last night. Alternator bulb works fine, and my cigar plug ampmeter reads 13.6-13.9 during a 25-mile freeway drive, but drops down to 11.5-12 v when pulling into the garage. Sound like a replacement is due soon?

[wwest]

Originally Posted by kidrock

what a coincidence...my alternator just started acting up last night. Alternator bulb works fine, and my cigar plug ampmeter reads 13.6-13.9 during a 25-mile freeway drive, but drops down to 11.5-12 v when pulling into the garage. Sound like a replacement is due soon?

Sounds most like a battery that will not accept a charge....

[James Brown]

even on a trickle charge, the battery can expire. if over 2 years old i would change that first. An alternator needs voltage (from a battery) to make voltage (as in a electromagnet) to work, load test the battery first

[kyalami]

In my case, the battery takes a full charge from my AC charger. It just appears that it is powering the car when driving since it's not getting charged....eventually it runs out of juice...as I said earlier, my alternator light appears to be dead....checking the bulb next

[Joe Bob]

Test and/or replace the bulb, check for proper function when back in the circuit and check voltages AFTER the battery has been charged by an outside source.

Battery should be 12.5 at rest, 13+ at idle and under 14 at 2500 rpm.

[kyalami]

Good advice. I have now had the opportunity to read the dozens of posts on this subject from the past and now understand the purpose of the bulb in the charging circuit and how it is necessary for the bulb to work to get the alternator started. Hopefully this is a $2 fix.

Thanks Pelicans!

[DRACO A5OG]

Originally Posted by aaaaeahk

I thought my alt was out but it turned out to be my positive side connector

how did you determine this?

I found when I play with the accessories connectors on the terminal connector I would get a good and bad connection via voltage readings

tia,

Jim

[Don Ivey]

What if you're getting about 14.8 at 2500rpm's. Is that too high? My battery keeps losing charge, andit is not even a year old. Thanks,

Originally Posted by Joe Bob

Test and/or replace the bulb, check for proper function when back in the circuit and check voltages AFTER the battery has been charged by an outside source.

Battery should be 12.5 at rest, 13+ at idle and under 14 at 2500 rpm.

[Joe Bob]

That is a bit high....I would suspect that the regulator is a bit wonky and you may have overcharged the battery.

If the battery has access to the cells, check for fluid level. High volts can boil out fluid.

If the battery voltage level is low after a drive and you see that 14+ volt input when running......the battery is likely in need of replacement AFTER you diagnose the high voltage from the alternator.

If the battery is discharging. How do you start it?

[kyalami]

Checked the Charge bulb. It's good. So this will be a little more complicated and expensive than the cost of the bulb.

[Joe Bob]

But the bulb isn't working.....so could be diodes. Are you a competent wrench? Pull the alternator and take it to a local rebuilder. DO NOT buy a reman/exchange, they suck.

[kyalami]

Understood. Read that same opinion several times in other posts that I found...Rebuild, not Reman!