I've been having issues with my charging system for a while now, but yesterday I went out to my car and the battery was dead! It's a four month old Optima red top!

Anyways...When you start the car and nothing is running like the fans or blower motor, it's charging just fine. When the fans kick on, it does drop the voltage a little, but it still stays right around 13V. BUT, if I've got to turn on the lights, or worse yet, the lights and the heater, the voltage is sitting around 10-11v, and won't increase to save it's life even while flying down the freeway. Now, I've put a set of SPAL fans in, but I did put in a 140 amp powermaster alternator to compensate. I've also noticed that when I've got my turn signal on and have stopped, the tach bounces with the light. I've looked for a short in that wiring, but can't come up with anything. I've also checked all the grounds. What's the deal with this thing?

 

have both your battery and alternator tested at a place like pep boys, autozone.

something is not working right

 

I suspected that the alternator wasn't working just right. I had it tested and it wasn't. Four month old Powermaster 140 amp!!! So, I got a stock replacement one from Autozone and got a new Optima since it was still under warranty. The car acts the same way! Everything is fine until you start turning on accessories like the heater or the lights. This combined with the electric fans sucks the power down especially when you're stopped at a light. What should I be looking for to fix this???

 

anybody got any ideas?

 

Maybe if I give some more history on the car someone can give me an idea? When I got the car, someone had taken out the dual fan setup and put in a single. The single fan was about to die, so I replaced it with a SPAL dual fan setup. When I went to wire it up, I saw the wiring was a little 'christmas treed', so I put it all back to stock and wired in the fans. The fans work as they should. I noticed that when I would come to a stop at a light with the trans in drive, the voltage would drop down to just above the 1st hash mark..maybe 11v or so? Well, everything is fine if the fans aren't running. If the car is warm and the fans are on, then the problem happens, although while driving it seems to be ok, charging at or just below 13v. The headlights also put a huge drain on the car. These two things combined give even more drain, and put the needle directly to the hash mark.

I did do something stupid while changing manifold gaskets. I put everything back together and left the field wire for the powermaster alt off and started the car. When I saw what I had done, I didn't disconnect the negative cable, and tried to connect it anyway. Of course, it slipped out of my hand and grounded to the valve cover. It cooked off the negative battery cable satellite wire, and the ground wire in the 8? wire weatherpak next to the battery. I replaced the cable, and wired a new ground around the weatherpack.

Also, I was using stock 14 guage wire for where the field wire contacts the positive side of the battery. I had put a fusible link in, a 30 amp one, that it fried. So, I got a blade style fusible link. It didn't cook the fuse, but it cooked the connection points for the fuse. I bought a cylinder style fuse link, and the same thing happened. The fuse was fine, but the holder was fried! Just before the powermaster died, I was running a straight, unchecked wire. The housing had become bubbled, presumably from heat, and the wire inside had become brittle. It melted one of the 'twist-loc' connectors I had put in to splice the wires. I replaced this with a 10 guage wire, and haven't noticed any heat issues yet.

Do you have any ideas why the voltage is acting the way it is? I think it should act just like a normal car, since even a stock 105 amp alternator should be able to keep up with the draw of the SPAL fans. What should I be doing to remedy all this?

I really appreciate any help you could give!

 

Are you using at least an AWG 6 from the alternator output stud to the battery?

 

I'm using the stock wire that came with the car. It appears to be about 6 guage.

When I had my idiot moment and shorted out that wire, could I have cooked it inside the housing and not be able to see from the outside?

 

I have an 89 5.7 with a 140 amp alt, load up the system with headlights, defroster, rear defroster and the same thing will happen. You will notice it at idle in drive. The tach will bounce to the tune of the turn signals. Unfortunately, it's normal and I'll explain why. Basically at a certain point of high current load and low rpm the alt essentially turns off. You are running strictly off the battery, factor in voltage drop in the wiring etc and the dash guage will drop down to the first line off the bottom red. Thats why they have such a large spread before either red area. Simply put, the alt cannot supply all the current to run the car without overheating the rectifier pack. The best way to check the charging system is on a cold start in the morning with no load on the alt(everything off except engine) and measure the voltage across the battery. At fast idle it should read between 14-15 volts. If it does, the alt and charging system is OK. You cannot use a standard fuse for a link type, it will always melt. Always replace a link with a link and make sure it's soldered and not just crimped or it too will fail prematurely. Another thing to keep in mind is that at low idle a higher output alt put's out LESS than a lower one. The Si and CS alternators protect themselves pretty well, if they sense an overcurrent condition they will throttle back. The later GM CS-130D alternators have a different charging curve and not so prone to this problem because they moved the diode pack to the outside if the alt for better cooling. There is a lot of misunderstanding about alternators and what they do, they are not battery chargers but more of a battery maintainer. The alt will only keep they battery at around 70-80% of capacity. The only thing that keeps the battery at full capacity is periodic trickle charging. I do it once a month. The only thing I might suggest is that once you fix the wiring replace both battery cables. They will develop some degree of resistance over time.[ Any type inline fuse holder will melt, it's a resistance issue they can't handle the heat]. Typical guage readings are kind of like this, cold start no accessories the guage should run right at or pretty close to the top line, 7-8 minutes of driving half way between the 13 and top line, with all stuff running at night slightly above the 13 mark until you stop, then it will nosedive. If it's in the red area you DO have a problem, otherwise that's the way they work. I have rebuilt quite a few delco alt's and the CS 130's are the worst as far as heat. The rectifier pack copper mounting to the frame gets so discolored it looks like it was hit with a blowtorch, sometimes the stator leads where they connect to the rectifier have drops of melted solder. That's why they cut back output, they simply cannot handle it. The CS-144 is a better unit if you can find one, www.alternatorparts.com had then but last time I checked they were out of stock. It's what the police package came with, they have much more idle output and better cooling. PM me if you want more info, Dan One thing to keep in mind is that you fix everything make sure the battery is fully charged before testing, not just a 10 min hot-shot but a good overnight trickle. Many alt problems can be traced to a funky battery.

 

That's an awesome explanation, Danno. Thanks for that info! I think that the thing I should have to do immediately, and I don't know why it didn't occur to me in the first place, is to take a look at the field wire in the back of the alternator. The wiring was jacked when I first got the car in that area, and I think I've found one problem. The field wire is about 6 ga. at least, running from the back of the alternator ALMOST to the battery. About 3 inches from the battery, it gets 'twist-loc'd' into a 10 ga. wire continuing to the positive terminal of the battery. This has got to offer a ton of resistance, which might explain why the new alternator didn't last more than two days.

I had to kind of cut and paste with the wires to make everything work because of their previous condition. I don't use the side terminals, I use the top posts after converting the ends of the battery cables. The fan relay power comes directly from the post, not any satellite wire on the positive cable.

So, if I run the 6 ga. wire all the way directly to the battery, that should help out with the resistance and keep the alternator more cool. Using other connectors at the battery post is how I should connect all the other wires. Does this all make sense, or should I just shut up and take it to a non-idiot?!?!

 

Don't put youself down, most mechanics don't fully understand the fine points of an auto charging system. The output lead from the back post of the alt should go down towards the positive battery post, that twist lock you describe is where you should have the fusible link. The one or two wires at the alt plug are the field supply and sense wires. Both should be controlled by the ignition key. The heavier of the two on the plug is the field supply wire, it should read exactly what the battery reads within a 10th of a volt(wiring resistance in vehicle) and the sense wire should read about a half to 3/4 of a volt lower. The sense wire intentionally has resistance in it to keep inside accessories up at 13-14 volts to compensate for wiring voltage drop. If the sense wire is directly connected to the battery the alt will put out very little output. Connecting other things to the battery post is usually a bad idea, only because they will corrode in time and create problems due to battery outgassing. Coating the connections with silicone die-electric grease will help but you might want to pick up a single post tie and mount it near the battery on the side inner fender. It is a plastic block with a big post and nut then you tie all the stulff you want to it. Some even have a plastic cap to keep out water. It keeps the wires away from the battery and prevents corrosion. Make sure your fan relay hot feed also has a fuse link. I helped one of the local kids with an 86, it was hacked up pretty bad. A little time and perseverence and you'll get it right. If you make wire splices, use a non insulated butt connector, crimp then solder it with 60/40 electronic solder. A good solder joint will look shiny and will sort of "wet" the metal. Before you connect them together and crimp get some heat shrink tubing and after everyting is done coat the joint with die-electric grease slide the heatshrink over the splice then heat it with a lighter or hair dryer. I usually then run some decent tape up and down over the shrink tubing for extra insurance. LOL, keep us posted.

 

Thanks Danno. Well, the wiring was a little hacked when I got the car. The output lead does run from the back of the alternator towards the battery. I put in the 10 ga wire myself, since the stock wiring was shot. I had problems with the fan relay lead. No matter how I tried to splice into that alternator lead, it would always melt the connector I used. So, I put it directly on the battery post. It seems that the alternator now will work when it's cool and there are no accessories on. I did disconnect one fan at the relay, allowing one fan to operate as it should. Even this power drain brings the voltage below 13v, and it won't rise above even while driving. Adding the lights to this equation drops the voltage even further. I am just at a loss here, and I think I better have someone look at it with a more extensive knowledge than my own.

 

Ok, it seems that the short, wherever it is, drains the battery overnight as well. I put a new Optima in, and it killed the battery in less than 24 hours. Anybody have a similar situation like this and can give me some insight as to where to look? Is there a relay that normally fails causing this? The starter is only about a month old, and I doubt the short is there.

 

Get a voltmeter capable of measuring current to at least 10 amps, hook it in series with the battery and measure parasitic current or "draw" with everything off. Make sure the doors are closed and the hood light if equipped is off. GM rates most vehicles at 15< milliamps parasitic drain. If it's more than that (a + or- 10% will NOT drain a battery overnight) then start pulling fuses one by one until the drain is within spec. I suspect that from what you say if the battery is fully charged and good you probably have at least a 2 amp or greater drain. If that does not locate the drain fully disconnect the alt, the plug and the lead at the rear. Also, make darn sure both voltages at the alt plug go off with the key. The rear high current lead has power all the time. Let me know what you find.

 

Did you ever get this fixed? I have a similar situation but believe I have just linked it with the fan circuit.

 

Yeah, so I brought this one back from the dead. Hey-I'm just getting around to rebuilding the damn car!!!

RMK, what did you find with your fan circuit??? I put those SPAL fans in, and maybe my car is having the same issue!