The Jalopy Journal
Discussion in 'The Hokey Ass Message Board' started by Roothawg, Jun 15, 2014.
I think we are on to something here fellas.....I'll check it after work.
OK boys and girls, it gets more confusing now. I checked the voltage not running 13.3 V. Running 14.5 V at the battery. The only thing I haven't done is to turn on the lights etc. The fan and fuel pump draw the most amperage.
I did order the pigtail to add the sense line, should be here by the weekend.
Even if the battery was bad, wouldn't the alternator be able to put out enough to keep everything running until I killed the ignition?
uh....it's hard to fix things that aren't broken.
I don't know. How old is the battery? What exactly are the symptoms? It's pretty confusing from this end.
Just a WAG here, but maybe the coil is overheating due to the high charging voltage. Then it quits until it cools off.
I never had an HEI do that, but it's plausible to me.
Jim please read post number 1. It explains everything in detail. If you think you are confused, you should see it from my point of view.
I realize the battery is going dead, but there's possibly other things going on because of that issue.
You say the battery went dead and the engine quit, but did you measure the voltage from your "dead" battery" after the engine stopped.
Or did you simply observe that it wouldn't crank over and conclude that the battery was dead.?
OK, here's what happened, the engine would start to run rough and the GPS would act like it was losing a power source etc. So, I would pull over and hook the battery up to a set of jumper cables and let it charge for 15 minutes, jump in and fire it right up. It would last for another 40 miles approx. and then the symptoms would arise again. When I did check the battery with my meter, when it was dead or close to it, it read 12.2V.
Man a car should run OK on 12.2 volts.
The only time I saw my charging system go full bore, but my battery went down instead of up, the ground cable had come loose at the battery, while the car was running.
I had an ammeter and it was peggin' out.
I think the same thing can happen if a cell-to-cell connector in the battery goes bad, but then it usually won't charge.
Unless it's opening up when the battery gets hot, and closing back up when the battery's cooled off. I've seen that before. Car starts fine then dies later. Cools off & starts again. After a couple days of this the battery went completely.
But that's not likely, because you changed the battery, right? (Unless you got two bad ones in a row.)
It's possible that I got a bad one. I'm wondering if the battery can be too small? This battery was an experiment. Sometimes reinventing the wheel can be a bad idea. It's a gel cell and I have only had one other, an Optima red top, but it is 10 years old and never had an issue with it. This one was going to go in the 1/4 panel and be hidden, but that never happened. That's why I opted or a sealed lead acid, so I didn't have to worry about venting issues.
I'm going to go out and test it with it running and lights on etc. see what the voltage does.
Guys , i think we are overlooking the problem and thats the system amp draw.
My vote is that the fans equip etc are eating the battery alive !!!! I just checked one for a friend and they drew 72 amps !!!!!!!!!
So my question would be : Whats the amp draw of the system ?????
Did you ever hook up the voltage sensing wire? I would not trust anyone who told me it isn't necessary or shouldn't be hooked up even if they built the wiring harness. Unless you have a one wire alternator. GMC bubba may be onto something too. Try running with out the fans hooked up, Or wire them on a switch so you can turn them on at a light or in stop and go, at least for the purpose of testing.
The battery is only 28 amp hours....that's pretty dang small.
Although the battery capacity should not affect how well the alternator keeps up with the electrical load. It mostly determines how long you can crank the starter.
You said the battery voltage is over 14 v when the engine is running. If that's the case when you're driving the car, then the battery should not be running down. Is there more load on the system when driving? can you connect a test meter to power inside the car, and see what it does when you're moving? and fans etc are all running?
I'm assuming all the wiring is up to snuff, and power is getting from the alternator, to the battery, and all the electrical loads.
Yeah, my motorcycle has a 24 amp in it. but the ratings on Optimas are different as I recall.
The thing is that once the car started it shouldn't matter, unless it's just not getting charged.
I haven't heard of a "sense" wire on an alternator, but if it's the idiot light wire, I'd hook it up. It'll be handy if you're only running a voltmeter and no ammeter. If it is required to balance the internal regulator, then problem solved.
The "sense" wire is what tells the regulator how much voltage the battery has. It's not the same as the "exciter" wire, which is usually what connects to the idiot light in a GM.
OK, here's the skinny. I just went out and turned on everything that I could…headlights, blower fan, turn signals, electric cooling fan. I have no way to test the amperage (yet) but the voltage followed the load.
The sense wire plug is on order. I didn't make a home made jumper yet.
The wiring is brand new and all grounds are to bare, clean metal. I even have a ground to the case of the alternator…..
I have no idea what the draw on this elec fan is. It came on the car. It's just a generic 15" puller fan. I don't have any stereo stuff….pretty basic.
Here's the alternator I bought.
I am no electrical engineer, that's obvious.
What is the lowest the voltage drops to with the engine and everything else running? is it higher than the resting (everything turned off) battery voltage?
Well clearly I'm clueless about the new alternators.
1970s-80s technology is a bitch.
While running, it never drops below 12.8 V……
It's a 105 A 1994 Suburban alternator.
Nah, just none of mine ever failed. I haven't had to fix one in a long time.
Don't disconnect an an excited alternator with the engine running. It is a good way to ruin one.
12.8 means it's not charging the battery. Sounds like the alternator is not keeping up with the load.
I have a pc925 running in an OT '92 olds with a 3.8 supercharged. No problems with keeping up with that electrical load at all. dual electric fans, super duper fuel pump, full electronics PCM , EFI heated O2s.
I'm wondering if your issue is actually a "heat over time" issue and the resting period is camouflaged by thinking the battery is being charged.
The thing with the GPS kinda belies that.
It is if the battery's only 12.2 volts.
That doesn't mean it's charging correctly though, unless that 12.8 is just at idle.
But before he was getting over 15 volts right?
Sealed lead acid batteries usually rest at about 13.2v after being charged. If it's not well over 13 volts with the engine running, something's wrong with the charging system.
Yep, but without the sense wire the alternator really has no idea that it's not doing its job.
Any charging trouble shooting chart will have "check wiring" as one of the first things to look at. Sooo if there is a need to run without the sense wire there's a need to reinvent the charging wheel on this one. GM 1 wire and different brackets
It could be the lack of the sense wire. I haven't messed with these "modern" alternators (CS type). I always connect the sense wire on the earlier 10SI alternators.
The 12.8 was at idle. When I would rev the engine, it (voltage) would climb accordingly.
When I checked the battery after sitting all night, it was at 13.3 V.
Do you think a fusible link could actually open if it got hot enough and then close when it cooled down?
Good input here guys. I like seeing the meeting of the minds.
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