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voltage regulation issue...*check my summit order before I order it*

Avery4jc

Avery4jc

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ok so here is my problem...about a month ago my amp that powers my subs slowly faded out and was gone for about two seconds then came back. It did this maybe once a week at random times and I never worried about it...

The other day it cut completely out for a couple minutes so when I got home I took out the connections, soldered new connectors on and screwed them back in so that I was positive everything was making a good connection...

Now for the past few days whenever I am driving the amp shuts off and goes into protection mode and my tach freaks out. When I am sitting there idling (or turn the key to accesssory) its fine and never cuts out. But when the alt. starts spinning up as the engine comes up in the 1500+ rpm range the amp goes into protection mode (assuming from too much power...voltage spike of some sort and my tach freaks out).

I put it in park tonight and got into the throttle and sure enough as soon as it got up past about 1500 (but really after 2,000) it goes into protection mode...then when the rpm's come back down it kicks right back on.


I took it over to Sears b/c they do free battery tests and alternator tests if your battery was ok.
They hooked it up and tested my battery and said it was fine then I mentioned that the amp is what tipped me off to the possible problem b/c it keeps protecting itself from the spikes and he went off on some stupid tangent about how I need a cap and he doesn't know how people think that you can install electronics and not get problems...blah blah blah and he wouldn't test my alternator b/c he said the battery was fine. So long story short I left b/c he was being an idiot.


I would look into a cap if I was having power issues (lights dimming, etc.) when the subs are hitting but I'm not. Plus even if I turn the subs off through the head unit the amp will still kick off to protect itself once I get going.


Sooooo hopefully a few of you read all of that and are still with me :) I was wondering is there some sort of voltage regulator in our trucks that could have gone bad? Or is there something built into the alternator that keeps it from over charging or something?
 
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voltage regulator on these is built into the alternator. take it to an auto parts store, most can test them on or off the vehicle.
 
see thats what I was saying and this guy was like, "well the battery tested fine so your alternator is working properly", and I tried to explain that of course it'd be fine now its when I'm running that causes the issues.

So if that regulator goes bad will it overcharge the battery...or cause the battery to put out more than 12ish volts?
 
yea it can overcharge if it goes bad. it would just keep putting out max power till it quits all together.
 
ok...tomorrow after I get off of work I'll run it by pep boys and have them check the alternator.
 
Might also have some bad diodes, so it's sending a little AC current instead of all DC current out to your accessories.

The bench check should be able to determine that.

If you have a DVOM, you can check the output voltage when it's spiking your amp.
 
yeah I thought about that...if I hook up the volt meter then have someone get in the truck and bring the rpm's up I'd be able to see what its doing to the battery's voltage.
 
Double check all grounds, is the amp grounded to the batt or frame? If it is a big amp I would ground it to the batt, but make sure you have a big ground from the batt to frame/body/and eng. If your tac is acting up when the amp does it may be a ground.
 
yeah I thought about grounds but I ruled that out because if it was a ground it would do it all the time (or intermittenly) this is 100% of the time when I go past about 2k rpm which is why I think its a voltage issue...I just got home from work so I'm going to head over to pep boys and let them run a test on the alternator so I can at least start ruling stuff out.
 
Grrrr

So I took it to Pep Boys b/c they have done work for me in the past and have always been great. They hooked it up to their computer and ran a test w/o accessories and just starting, running w/o accessories, running w/ accessories, lights, etc. and took it through the rpm's up to 3k or so and said that the computer kicked it out as the battery. That it didn't have enough amps to push everything so they said that they need to replace it.
So I had them put in an Optima Red top...910 cranking amps...should be good to go.
They were closing so the office guy got my stuff wrapped up and I paid for it then went outside and hopped in. The lights were brighter and I could tell a huge difference over my old battery.
So I go home and when I get back in the driveway I go through and re-set my head unit, turn the pre-amp out for the subs back on and they are hitting like they should be and then I bring the rpm's up and it does it again! what the heck!

So now I have to take it back and have them test it with the new battery. I guess they can't test the alternator if the computer kicks out a bad battery so now that I have a brand new battery in there they are going to have to test it again.

shesh...never dull I tell ya!
 
How old are your battery cables? I've had old battery cables do funny things on me in the past before.

Try a different store like auto zone.

Or get yourself a volt gauge and watch it while you drive. Or do the thing you said before with a multimeter and have someone rev up the truck.

How about, as you climb in RPMs do your headlights get brighter? If you aren''t sure park in front of a wall while its dark and rev it a little see it they get brighter or stay the same.
 
no they don't get brighter (at least that I can notice)...maybe slightly but definately not noticable (although I haven't been paying attention to it).

The cables are who knows how old...I know that I've had the truck for about two years and I've never replaced them. But how would that make sense...normally it would but I'm still set on the alternator b/c it only happens when I am bringing the rpm's up. I ruled out wiring b/c it works perfectly fine (subs, lights, etc.) when I'm sub 2k ish rpm or when its on accessory so iono.

I just went outside and changed the ground for my amp...I can't think of one reason why that would be the problem but I figure why not rule it out. I originally had it grounded to the body behind the seat.
Now I have it grounded to the bolt that holds the seat belt down. I backed it off a bit, sanded the metal then slid it in and bolted it back down really tight. It worked but its late so I didn't rev it or take it for a test drive.
I'll see what it does tomorrow on the way to school.

This is so weird!
 
On my 85 due to it having no computer, i can unhook the battery after its started. If the alt is good it will stay running. might think about giving this a try. It is a quick easy way to test out an alternator. be sure to be careful with the cables though cause if your alt is working there will be voltage there. Though, i dont think this rules out a flakey diode pack. one of the guys had mentioned that with the diodes bad you could be seeing a little bit of AC. you can check your ripple by switching a multimeter to ac. the value should be a couple hundred millivolts or less. mines at 60mV.

I recently had charging issues with my rig turned out that the plug going into the alt that is for the exciter was broken. so the alt was not putting out any voltage.
 
where is this diode pack? All the diode pack does is make sure only DC power goes through the lines or does it have another purpose?
 
The diode pack is inside the alternator. The diode pack is the rectifier that takes the AC voltage and makes it more like DC so our DC electronics can use it. you can also replace the pack on most alternators.
 
ok...tomorrow I'll check it with a volt guage and then switch it to AC and see what I get. If I get more than 60ish Mv I'll look into replacing the diodes.
 
Avery4jc said:
ok...tomorrow I'll check it with a volt guage and then switch it to AC and see what I get. If I get more than 60ish Mv I'll look into replacing the diodes.
Click to expand...
Avery,

I have all my alternators and starters rebuilt by a friend of mine. Mine was doing about the same thing yours is seeing here, and even when testing the voltage regulator and alternator tested good. I pulled it and found the diode trio (activates the alternator at low rpm) was bad. The diodes themselves were fine, and the voltage regulator tested good outside the alternator. We replaced the diode trio, and I still had the same problem. Voltage at idle was around 12.8 rev the motor up and it would spike to 15 volts. I highly recommend having a comptent auto electrical shop look at it and rebuild it. The alternators are cheap enough to just buy a new one as well. Everything I have seen in this post points to a faulty regulator, even if it tests good.

Just so you know, there was no difference in my lighting, stereo, or anything obvious outside of the OE voltmeter on the dash.
 
Just so you know, when the engine is running the normal opporating range is between 13.5v and 15.5v. The more accessories you turn on the voltage may drop some, but the important part is that no matter what RPM the voltage should always be constant.
 
Chevy305 said:
Just so you know, when the engine is running the normal opporating range is between 13.5v and 15.5v. The more accessories you turn on the voltage may drop some, but the important part is that no matter what RPM the voltage should always be constant.
Click to expand...

To that end, you might want to make sure your alternator is wired properly. If the PO was digging around in there, there's no telling what might be bass-ackwards. Go here and read everything:

http://www.madelectrical.com/electrical-tech.shtml
 
Ok I took off from work early and went back over to Pep Boys to have a chat with them. They hooked it back up to the tester and we ran it through a series of tests all of which said it was perfectly fine.
The guy I was working with was really cool and brought me outside and let me watch the machine...it was at about 14.2v-14.4v when I had the engine up at 3,000rpm (my highway speed) and dropped a little when it was at an idle.

He said that his guess would be the diodes or a possible jumping brush and that although he didn't want to turn away business he said I would really be better off taking it over to Star rebuilders or electric labs (two alternator/starter rebuild shops here in town). So I took off and headed over to Electric Labs and had a great chat with one of the guys there.

He said that they can't get to it today but that they could in the morning. He said that they can hook up a machine that will test how much ac is running through the lines as well as test the regulator.

Here is my issue though...Electric Labs is $92 an hour (so the minimum they'll charge is $92...even if it takes less time to figure out whats wrong).

I asked about a higher output alternator and he said that the stock one is probably 65 or so and that I could step up to something in the 100amp range for a couple hundred.

Do you think that I'd be better off just taking it in and having them replace it with a 100a alternator and not even messing with this old one? Especially if its going to be $92 just to test it.

Right now I'm going to go and pull the amp out and see if I can figure out whats going on...maybe its just a fluke and my tach and amp died at the same time. Its just sooooo strange that the amp only shuts off past a certain rpm so thats why I'm 99.9% sure its something with the alternator.
 
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