Charging issues

[Beekeeper]

Hey guys, could use some advice on a problem I've had for years with my battery going dead and not charging. I took the alternator and had it bench tested. It's good. Engine wiring harness is new and the correct one for car. I've tried two different voltage regulators but no change.

The ammeter in the dash shows positive 20 amps but nothing is going to the battery. When the car is off but I turn something on like lights, I can see the ammeter go into the negative until the car is started.

Am terrible with electrical stuff. I'd rather tackle any problem but this which is why I've ignored it for years and only used the car on short trips. I was always under the belief that if the ammeter showed positive that the battery was getting charged. Obviously I'm wrong.

Is it possible for the problem to be under the dash? I cringe at the thought of trying to trace everything down wire by wire but I'm not sure where to begin.

[blown motor]

Welcome to the site Beekeeper. I'm not the best one to answer your question but someone will chime in here and set you straight. You've come to the right place.

[sassygreen]

check for an amp draw while the car is shut off. The only thing that should be drawing any juice is the clock on your aftermarket radio or the factory clock. In order to check for this current draw remove the positive or negative battery wire and install a test light in series with the lead you removed. The light will burn as long as there is a current draw on the battery. While the light is still on, start pulling fuses out of the fuse panel and leave them out until the light goes out. Then you can reinstall the fuses, one at a time, until the light comes back on. That is the circuit that is draining the battery. I hope this helps.

[Chryco Psycho]

Sounds like a bad battery , if it is above the middle of the gauge it is charging , a simple volt meter will tell you what is going on  connect a volt meter across the battery it should read 13.2 v once the car is started if it reads higher than 13.2 it is charging .
 So what are you running for accessories , it is possible that you have more amperage used than being created causing the battery to discharge while running & requiring more amperage output from a better alternator .
 

[Beekeeper]

No drain other than the factory clock and that is tiny. The battery doesn't go dead from sitting, it goes dead from driving it week after week. I try to throw a charger on it now and then but at some point, I drain it to nothing, ruin the battery, and put it a replacement. I typically go through a battery every year.

When I start the car, the voltage measured at the battery does not increase. It remains the same as before I started it. Usually in the mid 12 volt range until I charge it externally.

Today, I had a guy at a shop check the battery while it was running with a special tester and he confirmed what I already thought, the battery is receiving no charge.

The car is restored and there are no hack jobs under the dash. I am considering a couple ideas:

1) when I had the gauge cluster out, maybe I connected the ammeter up wrong. It looks like it works but since the battery is not receiving a charge, maybe I hooked it up wrong?

2) maybe there is some sort of bad connection at the firewall bulk connector? I seem to recall reading that basically the charging circuit goes to the dash first then back out to the battery.

I'm generally very good at trouble shooting problems but I'm quite ignorant of electrical stuff so it's harder to reason my way through the problem.

[Strawdawg]

What is the voltage at the alternator when it is running?

[sassygreen]

I think a thin piece of metal will stick to the back of the alternator if it is charging. If you don't have a meter.

[Beekeeper]

Ok, so I charged the battery all night. It had 12.4 volts yesterday and today it's 13.09 volts (with ignition off and terminals disconnected).

I checked the drain by measuring between the positive battery post and the positive cable while it was off. Negative was still on. The reading was 63.4 milliamperes. I am guessing this is right since all I have is a clock which is converted to Quartz and probably uses less power than the original unit. Furthermore, I can lightly touch the positive cable to the positive post and I see no spark whatsoever. I've seen cars with shorting problems have a small spark when you do this.

I checked voltage at the alternator with the engine running around 2000 rims. It is 15.2 volts. When I check the voltage at the battery while it's running, it's still the same as before I started the engine. This tells me the battery is receiving no charge and will slowly drain which is what I have seen before.

On a side note, yesterday when the battery was low, the ammeter read 20 amps in the positive as the engine ran. Today with a charged battery, it read only 5 amps while running.

My experience with other Mopars is that the gauge reads high after starting then comes down to around 3-5 after a few moments. I always understood this to mean the alternator quickly tops off the battery and once fully charged, the reading shows only what you are currently using which is around 3-5 amps for the ignition system.

Bart suggested to me that the problem might lie in the ammeter gauge because he had a similar problem once before. It sounds logical to me so I was planning to try and disconnect the gauge and bypass it to see if the problem goes away.

[Strawdawg]

Just do the bypass that we usually suggest to avoid ammeter fires, burnt terminals in the bulkhead connector, etc.  Just run an 8 ga wire from the large post on the alternator to the terminal on the starter relay that goes to battery plus

[Chryco Psycho]

Bypassing the ammeter is as simple as connecting both wire to one post on the gauge

[sassygreen]

I would run a new wire to the starter relay as suggested to eliminate the possibility of a faulty bulk head connecter.

[4 speed fish]

I had a alternator bench tested once.They said it was good.I bought a new one anyway.Problems solve with new alternator.

[Beekeeper]

So I went through everything looking for loose connections. I found nothing but now everything seems good. The ammeter needle comes down to almost zero after a few minutes of run time and when I checked the battery with a volt meter, I am getting almost 15 volts. So my question now is, what is a normal charging voltage? I have an extra voltage regulator if this one isn't bringing it down enough.

I am strongly considering the 8 ga. bypass wire to the starter relay just for safety and peace of mind. I could care less if I lose my ammeter anyway. If i do this, is the voltage to the battery no longer regulated? I don't want to cook the battery.

Appreciate the input guys! I know so little of electrical stuff it's embarrassing.

[brads70]

So I went through everything looking for loose connections. I found nothing but now everything seems good. The ammeter needle comes down to almost zero after a few minutes of run time and when I checked the battery with a volt meter, I am getting almost 15 volts. So my question now is, what is a normal charging voltage? I have an extra voltage regulator if this one isn't bringing it down enough.

I am strongly considering the 8 ga. bypass wire to the starter relay just for safety and peace of mind. I could care less if I lose my ammeter anyway. If i do this, is the voltage to the battery no longer regulated? I don't want to cook the battery.

Appreciate the input guys! I know so little of electrical stuff it's embarrassing.

No you won't harm the battery from running the bypass. I REALLY recommend doing it though. Your voltage sound good. Something is telling me your alternator is giving you a warning shot though? Or you had a bad connection somewhere?

[Strawdawg]

14.5v at the battery is pretty much ideal...above 15.0v consistently is on the high side.

What normally happens is that the voltage sensing feed to the alternator is reading a lower voltage due to bad resistance connnections which may be on either the input side or output side going thru the bulkhead connectors, or at the ammeter/ignition switch.

Let's say that it is reading 13.5 at the volt sensing connection point so the regulator tells the alternator to charge harder and we get 15.0, or higher,  coming out of the alternator.

If we install a by pass directly to the battery so that the alternator output goes directly to the battery as suggested above, then we still have the voltage sensing connection reading a lower voltage due to high resistance connections between the battery, the bulkhead connector, the ammeter and/or the connector on the column that goes thru the ignition switch.

I cut the factory wiring out and rewired mine because the resistance had generated so much heat that the ammeter was fried and that took a lot of surrounding wiring with it.