alternator whine

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=103080
Printed Date: April 30, 2024 at 11:36 AM

Topic: alternator whine

Posted By: edaddee
Subject: alternator whine
Date Posted: March 15, 2008 at 1:33 AM

3 months ago I installed a system into a 2005 scion xb that consisted of :
Kenwood 7019, ARC audio components in front, Alpine type S rear coax, 4-12" Diamond audio D3's,1-phoenix gold 4 channel (unsure of model) for front/rear speakers, Elemental Designs 9.1 for subs, 1/0 gauge wiring to 2.5 farad cap, dist blocks to 4 gauge to amps, 1/0 ground upgrade @ 12 volt source.
At that point, and for the last 2 months everything was fine, sounded great w/no probs. Within the last month, the vehicle has had an extremely bad charging prob to the point of battery deep cycle over a 8hr period. The vehicle was put into a storage facility due to window shattered for a 1-1.5 week period. After that term, the owner was driving the vehicle one day, apparently hit a bump, extremely bumpy do to an air ride suspension, and so it began with a heavy alternator whine. Once funds allowed, it was brought back for upgrades that include high output alt, and hc1400 kinetic cell.
The main reason for this post is to ask more experienced opinions if the cause would be more from the bad alt, possible pinched wire, or shorted RCA from the extremely bumpy ride, etc.
I am awaiting back surgery, so un-needed searching for the prob unless once the alt, and batt arrive, the prob doesn't dissipate. Anyone care to give their advice or thoughts?

Replies:

Posted By: edaddee
Date Posted: March 15, 2008 at 5:08 PM

please tell me someone has a clue, idea, suggestion, something. This is the second or third time I have posted a question and had no reply or help when needed. Someone please give a little insight??????

Posted By: audioman2007
Date Posted: March 16, 2008 at 9:42 AM

Several things could have happened. First you need to listen to where the whine is coming from. Is it coming from the speakers, subs, or what? Then after knowing where the sound is coming from, then you go and check the amps ground. For instance if the sound is coming from the speakers ONLY, then simply check that amps ground. Also, check those RCA's. Same goes for if the subs are making that sound. If both are making the sound, then check both amps grounds PLUS check the headunits ground. It is very possible that one of the grounds worked loose and isnt making a solid ground now causing the sound. Oh yea, the sound you are hearing is called a ground loop. Its caused when a certain grounding point has too high of a resistence which causes the alt noise to carry into the ground to the amp. Also check the location of the RCA's in comparision to the power wire. Never run both along the same side of the vehicle. The power wire being so big in gauge will cause the alt noise to transfer from it to the RCA's. I always run my power wires down the driver side and the RCA's down the passenger side. Another thing that could be the problem is the upgraded alt. You might have had a ground loop problem before but was small to where you couldnt hear it. Between the big power wire and the bigger alt, you could have magnified it to where you can now hear it. But I would first listen to where the noise is coming from. If its coming from the 4 channel amp but only the front or back, then its those RCA's not the ground thats causing the problem. Also you can use a DMM to check the resistence on each grounding point. Those readings for each should not be anymore than 1/2 ohm. If one or more are, then theres the problem and you need to find a new grounding point for that wire. If after you have done all this you STILL have the problem, then they do make ground loop isolators. They are basically band aids which go in line with your RCA's and filter out the noise so you cant hear it. I have those on 1 of my amps because I just cant seem to fix the problem. They work great but are only to be used if you have no other choice. Hope this helps.

Posted By: edaddee
Date Posted: March 16, 2008 at 1:01 PM

audioman2007 wrote:

Several things could have happened. First you need to listen to where the whine is coming from. Is it coming from the speakers, subs, or what? Then after knowing where the sound is coming from, then you go and check the amps ground. For instance if the sound is coming from the speakers ONLY, then simply check that amps ground. Also, check those RCA's. Same goes for if the subs are making that sound. If both are making the sound, then check both amps grounds PLUS check the headunits ground. It is very possible that one of the grounds worked loose and isnt making a solid ground now causing the sound. Oh yea, the sound you are hearing is called a ground loop. Its caused when a certain grounding point has too high of a resistence which causes the alt noise to carry into the ground to the amp. Also check the location of the RCA's in comparision to the power wire. Never run both along the same side of the vehicle. The power wire being so big in gauge will cause the alt noise to transfer from it to the RCA's. I always run my power wires down the driver side and the RCA's down the passenger side. Another thing that could be the problem is the upgraded alt. You might have had a ground loop problem before but was small to where you couldnt hear it. Between the big power wire and the bigger alt, you could have magnified it to where you can now hear it. But I would first listen to where the noise is coming from. If its coming from the 4 channel amp but only the front or back, then its those RCA's not the ground thats causing the problem. Also you can use a DMM to check the resistence on each grounding point. Those readings for each should not be anymore than 1/2 ohm. If one or more are, then theres the problem and you need to find a new grounding point for that wire. If after you have done all this you STILL have the problem, then they do make ground loop isolators. They are basically band aids which go in line with your RCA's and filter out the noise so you cant hear it. I have those on 1 of my amps because I just cant seem to fix the problem. They work great but are only to be used if you have no other choice. Hope this helps.

I def appreciate the reply, and here's a bit more info, just to further explain. The upgraded alt, and kinetic haven't been installed as of yet, we are still awaiting the delivery on those to get them in. As far as the ground loop, yeah I know the terminology of what I'm looking for was a little off, alt whine vs. ground loop, but I def understand as I went to school down in daytona for mobile electronics, where they def schooled me on terminology, and a vast array of other in depth knowledge. Thats why I wanted to present this question to people that have more experience than myself at actually troubleshooting than I do. The 1/0 gauge is routed solely down the drivers side, RCA's on the pass. Made every effort possible for those not to even come close to crossing paths, as for the ground, both amps share the same grounding point as it goes from the ground (start washer included)to the cap, dist, to amps. I'll still probe the shared ground with a dmm, just to see what the reading says, and hope that isn't the problem, as it is located directly under the box. The h/u ground is still possible, along with the RCA's, as the owner admitted to pulling the h/u out to fiddle with another part of the dash.
Update, while checking the RCA's, even though it only quieted part of it down, once I unplugged the RCA's from the amps front input, the noise subsided to about half the tone. Nothing more with any other set, but at least partial. Also, after I turned the stereo up over the half way mark, there was almost like a distant popping sound that came through the f/r speakers only.
I guess bad back or not, I have to see what I can do. Again, I appreciate the help, any other input, feel free to post it up, otherwise I'll post up what the prob was after the find/fix

Posted By: audioman2007
Date Posted: March 16, 2008 at 1:55 PM

You might have a faulty RCA. I would use another RCA and test it running it from the headunit back to the amp. You just need to fiddle around and test different things. Check all grounding points again.

Posted By: edaddee
Date Posted: March 16, 2008 at 2:04 PM

will do, I have the car running/charging currently so I have some sort of battery life while trying to track down this prob. After another 15 minutes or so, i'll pull it back in, and start the process. Thanks again for your help, and please continue to check this topic till I find the prob, as at this point you are my only help with this one. Thanks again

Posted By: edaddee
Date Posted: March 16, 2008 at 2:05 PM

Posted By: edaddee
Date Posted: March 16, 2008 at 2:39 PM

something else interesting, maybe might lead to a diff suggestion, not sure though. Upon starting the car, and listening for the whine, I couldn't hear it at all. Once I turned it up a little over half volume, and turned it back to less than a quarter volume, I could again hear the noise. Let it sit @ idle for apprx 30 minutes, long enough to get the last reply, went back out to pull it in, volume had been sitting at the same spot, lower than a quarter of full volume, and no whine once I went to pull it back in. Turned it up again, and the whine was again present. Would this give more of an indication that once the alt and or battery goes under a heavier load, that due to failure in one or another or both, that it is creating this whine? I have no problem checking all possibilities, but unless I have the volume up high for a majority of the time, I won't be able to tell whether it be alt/batt failure, pinched RCA, bad ground, etc.

Posted By: audioman2007
Date Posted: March 16, 2008 at 2:53 PM

Try this.... Turn the car to accessorie (car off) and see if you hear anything. Then turn the car on and turn the volume down to 0. If the whine is no present, then its not a ground loop problem. A ground loop problem is there reguardless if the volume is at half, max or muted but wont be present when the car is off but radio is on.

Posted By: edaddee
Date Posted: March 16, 2008 at 4:03 PM

if its not present during all of the stereo functions of mute, half, close to max, then am i correct in the assumption of the alt, or batt being the cause. Also, what would the explanation be of the prob not being there upon starting, and low volume, but becoming noticeable only when half volume or higher, and then turning down

Posted By: audioman2007
Date Posted: March 16, 2008 at 5:05 PM

Ok let me try and get this straight. It only happens when you turn the volume up to half and above, but then keeps happening after you turn the volume back down, or does it only happen at half and above period? Does this sound change when you rev the engine? A ground loop problem will change pitch when the engine is quickly reved, then drop back down to a constant level when car is idling.

Posted By: edaddee
Date Posted: March 16, 2008 at 7:17 PM

audioman2007 wrote:

Ok let me try and get this straight. It only happens when you turn the volume up to half and above, but then keeps happening after you turn the volume back down, or does it only happen at half and above period? Does this sound change when you rev the engine? A ground loop problem will change pitch when the engine is quickly reved, then drop back down to a constant level when car is idling.

Exactly on the first, its not there when the car is first started, or at low volume, once mid and above volume happens, the noise becomes evident, even if you turn it down, or muted for a time period of less than 30 minutes. Within that time period,at least 30 min or less it goes away. Again, to me, it seems like its only happening once the charging system/battery is under a heavier load, such as the draw from both amps.
I spoke with the owner, and he said he noticed it in a few diff instances. The first being that he said the alt was squealing rather bad, and when that would happen, it would start. Once the car hit a significant bump, due to the harsh ride of an air ride equipped vehicle. Also after driving for a period of 45 min or more, turning the vehicle off for a short period of time, then again upon restart.
When I spoke with him, I told him the issue I was having with trying to track the noise to the source of the prob vs not knowing the time period of which the noise dissipates on its own. I have never heard of any prob like this even remotely similar, that of which its not whining all the time, only select moments, etc which again puts me back to square 1 of thinking that the heavier current load is torturing an already old and tired alt, which is giving an adverse effect.
I'm going to keep trying on this 1, its 1 of those problems that needs to be found, just for future ref if it happens to anyone else