I searched quickly and didn't see other posts with a similar problem, hope you guys can help. I am having a problem where the alternator is charging when I first start the car but as it warms up, it quits charging. The first few times it happened, I took the alt out and had it checked and it checked out fine. I installed a volt gauge which is when I discovered the symptoms above. This week, it was not charging at all, so I had the alt checked again and sure enough, now it is dead dead. Brand new alt went in today, same problem. Starting strong at 13.8 volts then dropped off to not charging as car warmed up (11.5 volts on gauge). I have checked it with a hand held Fluke meter at the battery, fuse block, and at alt, same readings as volt meter.

Quick background...replaced entire electrical system during rebuild with an American Autowire kit (awesome kit by the way). I race it so the battery is in the bed, and has a master cut-off switch. Converted to internal regulated alt, a Powermaster 105 amp p/n 17294, wired as 3 wire. To meet NHRA rules, the alt charge wire (4 gauge weld cable) is routed back to the battery side of the master cut-off switch. 0 gauge cables back up to ford solenoid. 0 gauge cable to starter. A 8 gauge wire feeds the fuse block from the upstream side of the ford solenoid. The red sensing wire to the alt feeds from the fuse block battery connection, brown trigger wire to the ignition switch power connection. My goal was to sense and maintain voltage at the fuse block at 13.8V. Volt meter reads voltage at the fuse block as well. When I first got the car running, I initially had trouble with the battery holding charge. Turned out to be a battery problem, it wouldn't hold a charge for more than 2 days even when removed from the car. New battery solved it. With the large cables, I saw no significant voltage drop from alt to battery to fuse block, with all normal loads on. However, over the last couple months, I am experiencing this new problem. All cable connections are crimped and soldered. I have 0 gauge cable ground from engine block directly back to battery, motor plates so engine is definitely grounded to frame as well, multiple grounds from body to frame, battery neg term to body and frame. I have checked every electrical connection in the car, all clean and tight.

Any ideas, please.

R/ Dave

Quick background...replaced entire electrical system during rebuild with an American Autowire kit
Did you use a gauge dash harness or a idiot light dash harness?

brown trigger wire to the ignition switch power connection.

Any ideas, please.

R/ Dave

Since this a race car im going to assume it doesn't have much "run" time on it, like a street car would......

The wire is supposed to have some resistance, either from the GEN light or a resistance wire. This limits current to the field. If it is wired directly to a IGN power source, it can cause you to kill alternators.

You indicate that you can remove the alternator have it tested and it is good. You have a new battery so either the sense is open, the alternator is not grounding properly through the mounting brackets to the block or the brown wire has little or no power.

Fluke meters are not the best way to check wire continuity. The best way is to take a 10 ohm 10 watt resistor (Radio Shack) and put it in series with a 12V battery and force a current down the wire (in this case 1.2 amps) to see if the connection is good. A Fluke meter on the 10A current scale will show you how "good" the wire is. If the current is constant (the resistor will get quite hot during this test) then the wire is good. If the current starts dropping more than 0.1 A from the initial reading then the wire has a problem somewhere, usually at one end or the other where a connection to a terminal occurs. Sometimes though the wire has been crushed by a bracket that was bolted down or the hood was slammed on it etc. The wire did not short to ground but it is not good at conducting current anymore.

Let me know if this is understandable. If not I could draw a diagram of the set up.

Ron

Greg, I used part of the gauge dash harness, mostly to power the gauge lights. I have all aftermarket gauges, and all but the tranny temp, fuel level and voltmeter are mechanical. No idiot lights. I do drive it on the street as it is a street/strip deal. That is how I first found the problem. The battery would get drained while out driving around. I'd pull the alternator, have it tested, it would be good. I'd trickle charge the battery back up, start the car, check voltage right away with a handheld and it would show 13.5-13.8 at the alt, battery, and fuse block. SO I finally put a volt meter in and that's when I saw that voltage would go away after 4-5 minutes of running, and start draining the battery. The electrical diagrams with the kit show the alt. brown wire wired directly to the ignition switch, no resistors or notes mentioning resistance shown. I used the wire directly from the kit as supplied. I've never heard of there being a resistance required in that line and it seems to contradict other input I am getting, but that doesn't necessarily mean too much. How much resistance are you suggesting needs to be there? and do you have a source for that info I can research into more?

Ron, the sense wire is not open, at least not completely. It shows full system voltage at the plug when I check it (car not running). I've checked numerous times now and the wires are not being pinched or rubbed anywhere that I can see. I spent a LOT of time to re-route and hide the wiring in the engine compartment, running them in places where they could not be seen but also not pinched or rubbed or otherwise bothered. The alt. ground is something I'll try adding as I did not attach a separate ground initially. I assumed grounding thru the mounting would be sufficient since it always worked before, but it certainly won't hurt anything so it will be done. I talked to a nephew later last night and we also ended up discussing the ignition switch and brown wire feed. He said he has seen many ignition switches cause problems (heat up, adding too much resistance, etc). He suggested I remove the brown wire from the switch and jumper a hot source to it to try and identify or eliminate the switch as a potential problem. If that doesn't help, I'll look into your resistor check of the wires. I believe I understand your method and that sounds like a good idea as well.

Thanks guys, I'll let ya know if I find something. Other ideas still welcome.

Regards/ Dave

Greg, I used part of the gauge dash harness, mostly to power the gauge lights. The gauge dash harness should have the resistance wire (from the IGN switch to the firewall bulkhead connector).

I'd trickle charge the battery back up, start the car, check voltage right away with a handheld and it would show 13.5-13.8 at the alt, battery, and fuse block. SO I finally put a volt meter in and that's when I saw that voltage would go away after 4-5 minutes of running, and start draining the battery. 13.5 at alternator is a little low. As a test did you try wiring as a 1 wire? After 4-5 minutes of running, check to see if alternator is hot. High current draw can also cause low voltage.


The electrical diagrams with the kit show the alt. brown wire wired directly to the ignition switch, no resistors or notes mentioning resistance shown. I used the wire directly from the kit as supplied. I've never heard of there being a resistance required in that line and it seems to contradict other input I am getting, but that doesn't necessarily mean too much. How much resistance are you suggesting needs to be there? and do you have a source for that info I can research into more?
See my posts here, w/link
http://www.camaros.net/forums/showthread.php?t=115803

Dave, I looked at the Powermaster website and did not see much technical help.

I suggest you look at:

http://www.madelectrical.com/electricaltech/remotevoltagesensing.shtml

to see why you are not getting the alternator to regulate. I suggested actually running current down all the wire to check them as I have observed many times some one coming to me saying "I checked all the wiring and it is fine" only to go through a diagnostic procedure and discover that it was wiring and the part that was bad got missed.

Ron

Ah HA...I think Greg's link shined the light I was needing. That is some good tech info I had not seen before. In retrospect, I think the reading material and diagrams I have looked at so far assume the idiot light is still being used since mine was originally equipped with one, and none of them talk to the resistance function of the light. Or I just plain missed it... I customized my dash a little bit (see pic below) and eliminated the alt. light that was acting as the resistor without realizing the "rest of the story". I just wired per the diagrams ( but eliminating factory gauges or lights) and never gave it a thought. Just goes to show that after 22 years with the SAME car, there is still always something new to learn. Thanks Greg, I appreciate the info and your patience. I printed it off so I could read the whole thing SLOWLY:) The only thing I don't understand still is why it seemed to work fine for a while (couple months) and THEN started this. I was driving it during that time...but oh well. It needs to get fixed right either way.

Ron, Yeah I had already scoured the Powermaster, MAD Electrical, and some other sites, books, magazines, etc. I have factory manuals for 65s and went through them twice. Like I had mentioned, I have been chasing after this for a while. Don't really know why I waited so long to post here but I guess I was busy trying to hunt it down on my own.

I'm still going to add the case ground, and re-check the wires and switch connections, and now figure out where to add a light or resistor. Thanks for the great info guys.

R/ Dave

Dash pic:
http://i243.photobucket.com/albums/ff97/65Camino/Interior2.jpg

OK guys, alt case ground direct to block is installed. I re-installed the original alternator light which uses a GE 1895 light bulb in the excitation line from the ignition switch. I measure 0.23 amps current through that line with the light on and there was no change after 5 minutes of current draw through that line. I hooked everything back up to the alt and same deal. Start the car it shows me 13.8 volts at the alt, battery, and on the installed volt meter. Alt light is out. As car warms up I start fans and voltage goes away. The more loads you turn on, it drops further. Radiator fan sees biggest drop. Turn loads off, voltage comes back slowly but not fully. Revving the engine has no affect. I checked again for grounded wires, can't find anything. Took alt to auto parts store, they said it checks out just fine. I watched and agree it looked fine. I asked how much load it applied and he didn't know, only that it only pulls a load for 3 secs. Voltage was at 14.0 or so and never wavered during his test. Greg, Ron any other ideas?

R/ Dave

Another update. Just spent 20 minutes on the phone with Powermaster Tech Support, described all the symptoms and checks, and he was stumped too. Particularly the checks indicating the voltage measurements being the same at all points in the system but the alt won't carry any load. He asked me to bring in the alt and let them look at it and load check it. He said the parts store checks put very little load on the alternator at all so it would not detect an alternator that won't carry more than a few amps load. That is, the alt may still be bad.

A side note for Greg, I was asking him about the resistance requirements in the excitation line. He replied that while stock systems and alternators DO require that, the particular alt I have (Powermaster P/N 17294) does not require any in-line resistance. He says it is fine either way because it is built to run as 1 wire OR 3 wire and that I shouldn't have had a problem with this particular model alt from the way it was wired. I didn't ask how that works but it is interesting to note. BTW, I intend to run the light anyway.

Any other ideas guys? I'm almost bald now:)

R/ Dave

What is the alternator pulley to crank pulley ratio? Did you check to see if the alternator was very hot after a few min of running?

Dave,
Sometimes these things are hard to find. You say you always measure 13.8V all around the system.
What are you using to do the measurement? A DVM? Analog meter?
And next question, where do you place the negative probe?

Ron

Crank pully 6" dia, alt pulley 2.75" dia. Ratio=2.18:1 ? Engine idles at 1000rpm so alt rpm is about 2200. The alt is warm to the touch after running but not hot.

I use a Craftsman digital multi-meter. Looks near identical to Flukes used at work. Can check Voltage, current up to 10 amps, resistance, AC and DC. I place the ground probe on the nearest frame or body ground connection. I have numerous ground connection points around the car. In my head, I think it would show a wire or connection that was building resistance in line. Volt meter in the car is a Autometer Sport-Comp #3391. The 13.8 is upon first starting the car. As the voltage drops off, it drops off evenly at all measured points meaning it always measures the same at the various points checked. When the alt was checked at the auto parts store, it also only went to 13.8-14.0. I was a needle read out so I couldn't see an exact reading myself.

R/ Dave

Dave,
Check the voltage between grounding points, like from the engine block to alternator body, engine block to battery negative terminal, battery terminal to body (the small wire on the negative battery cable assembly and you should see a few tenths of a volt at most. IF not you have an open ground return.

You should also check, after the engine is warm and the voltage from the alternator starts to drop off, to see that you have current into the field control wire to the alternator. You should measure the current and see if powermaster thinks that the value of current is correct.

Otherwise I think you will have to start using the resistor current source trick to check wires...pain in the behind..

Ron