Alternator?

[jfirios]

OK so I am still trying to track down that power drain on my system. I have a new yellow top battery and all my after market equipment I installed seems to turn off when the key is removed. LEDs Stereo, Amp those things. Now what I am noticing and more so today, there is a drain on the system, But When I have a underpowered battery, being drained down to under 10 amps the car wont start. I jump it with my charger and the engine comes right to life. Problem. Engine runs fine, drove for over half hour, volt gauge on the car reads that it is sending just under 13v. As soon as I turn the car off, I wont be able to start the car again, the battery will read back under the 10v mark. or at least hover around 8v on the dash panel. So I am thinking that it must be the alternator, either bad ground in it, or something is bad that it is no longer sending voltage to the battery. I have read that if the battery light in the dash doesn't work the battery will not be charged from the alternator. When I start the car, the battery light does come on so I assume it is working. Just wondering what your thoughts might be.

Though on a cool note. Was gassing up at the costco here in san fernando and randomly met another delorean owner from sylmar. Though you wouldnt know it seeing the mustang he was sporting :) But it is always nice to meet another D owner.

[WelmoedJ]

OK so I am still trying to track down that power drain on my system. I have a new yellow top battery and all my after market equipment I installed seems to turn off when the key is removed. LEDs Stereo, Amp those things. Now what I am noticing and more so today, there is a drain on the system, But When I have a underpowered battery, being drained down to under 10 amps the car wont start. I jump it with my charger and the engine comes right to life. Problem. Engine runs fine, drove for over half hour, volt gauge on the car reads that it is sending just under 13v. As soon as I turn the car off, I wont be able to start the car again, the battery will read back under the 10v mark. or at least hover around 8v on the dash panel. So I am thinking that it must be the alternator, either bad ground in it, or something is bad that it is no longer sending voltage to the battery. I have read that if the battery light in the dash doesn't work the battery will not be charged from the alternator. When I start the car, the battery light does come on so I assume it is working. Just wondering what your thoughts might be.

The voltage gauge should read at least 13V, better near the next line above 13V when running.
Around 13V after turning the ignition key to ON.

With the engine and ignition key off, you should test at the battery for a drain current.
With the engine running you should test the voltage from the alternator.
These figures ought to give you the necessary information on the status of the alternator and power leaks in the electrical system.

Power is maintained to clock and IIRC also the radio.
You should check your relay compartment and its wiring for damages and possible shorts (the ones that causes drain, but do not blow a fuse).
The drain could also be caused by your door lock module as it is continuously powered.
Bad grounds can add to the problem, so check these too (all over the car).

Switch lights on: if there is a considerable drop on the voltmeter, this is not good.
Also test with A/C (fans coming on), wiper and all together, for drops in power.
Power should stay over 13V, with a momentary drop if a device starts, but has to return to where the needle was previously.

Success.

[Bitsyncmaster]

Sounds like the battery is not charging. You need to get a voltmeter and read the voltage on the jumper terminal to the engine block. It should be about 14 volts with the engine at idle.

Common battery drain (a day or two) is mostly caused by a light not shutting off. Pull your #12 fuse (courtesy lights) and if that stops the drain, a light is not shutting off.

[jfirios]

I already had the #12 fuse pulled due to the plunger switches not hitting the door propperly when closed and since I have been working on it so much and leaving the doors open. So I know that isnt a problem. I do though know that the door lock modules are starting to go. And all this started in junction I believe with the Hit and run I was in where my head lights got smashed out.
It is just confusing to me, and I agree that it seems that the battery isnt recieving any charge. When the car is running I have turned the ac on and let the radiator fans kick in and everything is fine, just when I turn the car off, it seems that the battery is still dead.
I am thinking of getting a new alternator and ground cable system just to make sure. The one i have now is who knows how old. I would say at least 15 years old. and for 200 bucks might as well take that out of the equation anyway.

[WelmoedJ]

May I advise to buy 2 groundstrips?
Put one on each side (left and right) at the motor mounts.
Double your options to keep a solid ground.

[David T]

Even if you have already made up your mind to replace the alternator and/or the battery, you really should troubleshoot the problem so you know what the root cause is otherwise after replacing the parts you believe to be bad, you will still have the original problem. It seems to me the alternator is not charging. That can be caused by things other than just a bad alternator. Many parts stores will test your battery and alternator for free. If the battery is over 5 years old just replace it.
David Teitelbaum

[Ron]

It sounds as if it is not charging to me as well...forget the gauge and use a multimeter to be sure. Having the battery and alternator checked first is a good route to take...either can be the cause of a drain. If you don't have a Amp Meter, you can stick a small bulb (eg 1156) in series with either battery cable and its post/terminal and if there is a significant drain, it will glow or light (or simply blow if a huge drain is present). Then start disconnecting things until the bulb goes out.
...I would start with everything off and shut, except the passenger door (unplug either one of its switch wires). Then, watching the light, pull fuse 17, the Door Lock relay/module, fuses 6, 7, 12 (always one at a time and leave out). This should cover anything factory that remains powered at all times, IIRC. If not, keep pulling fuses. If you happen to run out of fuses to pull, then you'll have to start disconnecting the feed wires off of the main positive (+) cable to narrow it down any further...

[jfirios]

I will try that test again. I have already replaced the battery when I started with the new stereo system. So I know the battery isnt the issue. Another reason I would like to change the alternator is that it is the last major piece other than the clutch and the main water pump that hasn't been replaced in the engine. I would like to have as many new/ updated components as I can. but something is definitely leading me to either something with the headlights since the accident or the door lock module. Danny down at DMC Cali was going to change it out saying that it might be going bad, but at the time didn't have any replacement ones.

[David T]

One way to check for battery drains is to hook a test light in series with one of the battery terminals (or a multi-meter set on amps). Keep disconnecting things until the light goes out or you are drawing less than 50 MA. Common drains are:
Door lock module
cigarette lighter
Plunger switches on the doors missing the rubber tips and not shutting off the courtesy lights
Non-original wiring, alarms, etc.
Bad alternator diodes
David Teitelbaum

[ccurzio]

If nobody minds, I'm going to correct the horrible spelling in the title so that others can find this thread down the road.

[jfirios]

thanks for the spelling correction.

[jfirios]

okay test results. I tested the battery at full charge, and then turned the car on. I should be getting on my yellow top, a reading while the car is running, between 13.4-13.8v I am reading 13.1 and dropping. I switched my meter to AC and it should be below 0.25 I am reading 0.005. I am thinking that the alternator is starting to go bad. I already had the fuse for the door lights pulled so I know that isnt pulling anything, and I pulled the #17 fuse for the cigar lighter and clock, of which i removed both of them in the redesign anyway. But it seems that it was still pulling power, even though the wires were cut and taped off. It was drawing though only .025v so I am not sure that it was the cause. Either way I can leave that fuse out since I am no longer using those components. Unless that fuse does more than just supply power for the clock and lighter. The last one I checked with my test light was the second fuse on the top row, engine control. That is drawing power too while the car is off. Is that normal?
What do you all think?

[Exolis]

okay test results. I tested the battery at full charge, and then turned the car on. I should be getting on my yellow top, a reading while the car is running, between 13.4-13.8v I am reading 13.1 and dropping. I switched my meter to AC and it should be below 0.25 I am reading 0.005. I am thinking that the alternator is starting to go bad. I already had the fuse for the door lights pulled so I know that isnt pulling anything, and I pulled the #17 fuse for the cigar lighter and clock, of which i removed both of them in the redesign anyway. But it seems that it was still pulling power, even though the wires were cut and taped off. It was drawing though only .025v so I am not sure that it was the cause. Either way I can leave that fuse out since I am no longer using those components. Unless that fuse does more than just supply power for the clock and lighter. The last one I checked with my test light was the second fuse on the top row, engine control. That is drawing power too while the car is off. Is that normal?
What do you all think?

13.1 Does sound a bit low for an Alternator with No C-Terminal. Two things I recommend; 1. You don't need to use AC on Battery System unless you are checking for Alternator Ripple (which is primarily used for Testing of electrical component and state of charge of the battery). 2. Not sure if you are, but when Charging a battery, let it sit for 30-60mins, this will allow the battery to stabilize so you do not get misreadings with a surface charge.

13.1 is still too high to determine if the Alternator is bad or not. So I would recommend charging it again, let it sit and test again. Then check voltage with Battery connected and vehicle off, then IGN ON, then ENG ON. I would also recommend cleaning terminal connections to/from engine and body and Alternator.

As for checking drain, easiest way to check is to get a switch, connect it from ground terminal to harness and connect an Ammeter in parallel. Once everything is connected and off, open the switch and like was said earlier, current should be like 50mA or lower(Ideally, I don't know the exact specs for the DeLorean Dark Current or avg dark current amount for vehicles back in early 80s). And becareful no loads are on and settings are on highest current ratings when opening switch as it can blow the fuse to ammeter if not done correctly.

EDIT: Also check Ground float, put positive side of voltmeter on engine block(near alternator) and the negative on Negative battery terminal.

[Ron]

... Either way I can leave that fuse out since I am no longer using those components. Unless that fuse does more than just supply power for the clock and lighter. The last one I checked with my test light was the second fuse on the top row, engine control. That is drawing power too while the car is off. Is that normal?
What do you all think?
#17 feeds the Clock, Lighter and Radio Memory.
#7 (second fuse on the top row) feeds power to the RPM Relay and the Main Fuel/Lambda Relay when the key is off and they they can pass power on to the Lambda Control Unit, Frequency Valve, and Control Pressure Regulator (CPR/WUR). Try pulling these two relays one at a time...

[jfirios]

Well I pulled the cigarette lighter fuse. I don't care about the radio memory since I created a new electric harness just for the stereo. So I can leave that out. I still think though i should just get a new alt and ground wire kit from Harvey. I know Alternator tech has advanced in the past 20 years. At least i will have new grounds and main power wires and a more efficent alternator.
But I am still checking other issues.

[jfirios]

So i bought a test light. I removed the positive wire from the battery and put the test light in like from the battery to the power wire. From what I understand if there is a power draw then the light should glow. With everything hooked up there is no glow from the light. Though just to test it when I re plug in the fuse for the door lights with the door open, the light glows just barely. So I know there is then power going through that circuit. So can I assume that since there is no power being drained by either my stereo or the main harness, that the alternator might be the culprit?

[Bitsyncmaster]

Now you replace that test light with a milliammeter. Do the same test and it will show lower current draws than the lamp will. I think you can buy a meter for $10 at home improvment centers. You need to know how much current is being drawn when the car is parked. It should be about 20 ma. with a stock car.