Alternator, battery, or amp meter?

[dwinters14]

** EDIT: I curiously went back to the alternator listing and right there it mentions using a smaller belt. I am not currently. So first thing I am going to do is get a shorter belt and see if that tightens things up**
My lights flicker (ext and int) with my bass and it's time to fix it. I have been dealing with this gremlin for quite awhile and I'm asking for some thoughts because it's making my truck un-driveable at night. Before I upgrade my headlights I need to know why they are flickering. It did it with the stock alternator/battery/headlights and wiring and it's doing it now with all newly changed parts. I did a CCA test a few months ago on the battery it came back healthy although it may be due again. Someone recommended a CAP but that is a bandaid, and I want to fix the problem.

Mods:
- Big 3 (0 gauge OFC)
- New OE negative battery terminal
- Interstate battery
- eBay high output alternator

Issues:
-Corrosion on negative battery terminal (about a teaspoon after 5 months)
- Lights flickering when bass hits
- Voltage drops when bass hits

I'm leaning towards the alternator being the problem, but I have also read that "regular" batteries cannot handle the draw of a sound system. I would need to upgrade to an XS or something similar. I don't want to swap the alt and it ends up being the battery or vice-versa. Any help or tests I can do to narrow down my problem would be greatly appreciated.

 

[Doubeleive]

** EDIT: I curiously went back to the alternator listing and right there it mentions using a smaller belt. I am not currently. So first thing I am going to do is get a shorter belt and see if that tightens things up**
My lights flicker (ext and int) with my bass and it's time to fix it. I have been dealing with this gremlin for quite awhile and I'm asking for some thoughts because it's making my truck un-driveable at night. Before I upgrade my headlights I need to know why they are flickering. It did it with the stock alternator/battery/headlights and wiring and it's doing it now with all newly changed parts. I did a CCA test a few months ago on the battery it came back healthy although it may be due again. Someone recommended a CAP but that is a bandaid, and I want to fix the problem.

Mods:
- Big 3 (0 gauge OFC)
- New OE negative battery terminal
- Interstate battery
- eBay high output alternator

Issues:
-Corrosion on negative battery terminal (about a teaspoon after 5 months)
- Lights flickering when bass hits
- Voltage drops when bass hits

I'm leaning towards the alternator being the problem, but I have also read that "regular" batteries cannot handle the draw of a sound system. I would need to upgrade to an XS or something similar. I don't want to swap the alt and it ends up being the battery or vice-versa. Any help or tests I can do to narrow down my problem would be greatly appreciated.

I would do some.troubleshooting
As in get a meter and start testing
See where the draw or poor ground is stemming from.
You may need new battery cables (not just a terminal)
The amp may need to be rewired with a very good power and ground cable and ground location
An amp even if it's not a very big one should have 0 gauge direct to the battery and grounded to the body with o gauge also at the closest location
Amp wiring should be ohm.tested
Battery cables should be ohm tested

 

[swathdiver]

Flickering lights is usually a battery problem, a weak battery.

These trucks have a maximum discharge of about 55 amps or so in stock form. The batteries are rated for between 70 and 80 amp hours of discharge (depending on model). Plenty for a stock system, not so much for you audiophiles.

Ebay alternator? What does that mean? Mechman is what you get when you are serious about such things. Wes has one or two in his rigs. @Doubeleive

 

[Joseph Garcia]

** EDIT: I curiously went back to the alternator listing and right there it mentions using a smaller belt. I am not currently. So first thing I am going to do is get a shorter belt and see if that tightens things up**
My lights flicker (ext and int) with my bass and it's time to fix it. I have been dealing with this gremlin for quite awhile and I'm asking for some thoughts because it's making my truck un-driveable at night. Before I upgrade my headlights I need to know why they are flickering. It did it with the stock alternator/battery/headlights and wiring and it's doing it now with all newly changed parts. I did a CCA test a few months ago on the battery it came back healthy although it may be due again. Someone recommended a CAP but that is a bandaid, and I want to fix the problem.

Mods:
- Big 3 (0 gauge OFC)
- New OE negative battery terminal
- Interstate battery
- eBay high output alternator

Issues:
-Corrosion on negative battery terminal (about a teaspoon after 5 months)
- Lights flickering when bass hits
- Voltage drops when bass hits

I'm leaning towards the alternator being the problem, but I have also read that "regular" batteries cannot handle the draw of a sound system. I would need to upgrade to an XS or something similar. I don't want to swap the alt and it ends up being the battery or vice-versa. Any help or tests I can do to narrow down my problem would be greatly appreciated.

What size amp are you running for your bass output. My system has 2 amps totaling 800 watts, and my lights never flicker. I also have just a stock battery. I am assuming that you have a direct connection from your power amp to the battery with the appropriate size wire and fuse.

As @Doubeleive recommended, first do some checking of your wiring and connections to ensure that you do not have a connectivity issue. If you can confirm that you have no connectivity or ground issues, then I'd say that your eBay alternator may be the source of your issue.

 

[dwinters14]

I would do some.troubleshooting
As in get a meter and start testing
See where the draw or poor ground is stemming from.
You may need new battery cables (not just a terminal)
The amp may need to be rewired with a very good power and ground cable and ground location
An amp even if it's not a very big one should have 0 gauge direct to the battery and grounded to the body with o gauge also at the closest location
Amp wiring should be ohm.tested
Battery cables should be ohm tested

I redid my negative cables. Alt to body, battery to body and battery to engine. All 0 gauge OFC. My alt is running 0 gauge straight to the battery for power as well.

My amp wiring could definitely be the culprit as I installed it a few years ago when I was more of an electrical novice and to top it off it's a really crappy "marine" clarion amp with non-standard plugs and connectors. The first one burnt up and this one has a dead channel.

What size amp are you running for your bass output. My system has 2 amps totaling 800 watts, and my lights never flicker. I also have just a stock battery. I am assuming that you have a direct connection from your power amp to the battery with the appropriate size wire and fuse.

As @Doubeleive recommended, first do some checking of your wiring and connections to ensure that you do not have a connectivity issue. If you can confirm that you have no connectivity or ground issues, then I'd say that your eBay alternator may be the source of your issue.

I think it's a 1000w clarion marine amp. Nothing special. Between my two amps I'm definitely less than 1500watts. I have a 4 gauge OFC with a 175a fuse.

I think I will wire in a fuse block from the battery just under the dash, with 0 gauge OFC power and a ground up somewhere on the firewall. Then run fresh wiring from that block to the amps and see how things go.

 

[Doubeleive]

I redid my negative cables. Alt to body, battery to body and battery to engine. All 0 gauge OFC. My alt is running 0 gauge straight to the battery for power as well.

My amp wiring could definitely be the culprit as I installed it a few years ago when I was more of an electrical novice and to top it off it's a really crappy "marine" clarion amp with non-standard plugs and connectors. The first one burnt up and this one has a dead channel.



I think it's a 1000w clarion marine amp. Nothing special. Between my two amps I'm definitely less than 1500watts. I have a 4 gauge OFC with a 175a fuse.

I think I will wire in a fuse block from the battery just under the dash, with 0 gauge OFC power and a ground up somewhere on the firewall. Then run fresh wiring from that block to the amps and see how things go.

you should be able to check the voltage the amp is pulling at the at amp, if it is abnormally high or abnormally low then that would indicate a poor connection somewhere.
I was checking mine one time and it was showing 15-16v and I was like what the heck? I mean you would think wow cool, but turned out the fuse connection was loose as hell and it was barely connected, so it was fibbing and probably pulling high voltage but low amps. fixed that and it went back to normal. Another time I had a bad ground and the ground wire was getting cooked pretty good because of it, moved it to a seat mounting bolt and that fixed it right up.
I would crank up the noise with the engine running, take the meter and read the voltage at the battery post's then compare that what it reads at the amp connections, there should be very little difference if you are running 0 gauge.

 

[dwinters14]

After doing some research I think my RVC is the problem not my battery, alternator or amplifiers. It seems the headlight diming is an issue regardless of OE vs aftermarket with these trucks. My alternator definitely works properly as it fluctuates from 12.7v - 13.8v depending on load. Without the sound system on the lights flicker every so slightly and more so with the bass.

Before I start tearing anything apart I'm going to do a an RVC bypass with this component from mechman

https://www.mechman.com/mm-vc1-2005-gm-2pin-rvc-voltage-controller/

and see if I can crank my voltage up. Even IF my alt was slipping or isn't good, 12.7v isn't enough for my sound system. I notice a significant drop in sound quality as they're designed to push the most wattage @14v+.

If at that point my issues persist I will invest in a mechman alternator as I will already have all the infrastructure to support it.

 

[j91z28d1]

bit off topic but I'm curious, with the rvc system measuring amps all the time. would hooking the amp up to the battery bypass that measurement and the ecm not know what's up?


on another not, doesn't running the headlights and or wipers send the rvc into max voltage mode? could be a easy test before bypassing it


as for alt, a new design 6 dioid 220amp alt low mileage take off can be had on ebay for a 100$ ish shipped. it's a direct bolt on. I'd personally try that before dropping 600$ plus on a aftermarket alt. they don't need to be over driven to put out that power either.

 

[dwinters14]

bit off topic but I'm curious, with the rvc system measuring amps all the time. would hooking the amp up to the battery bypass that measurement and the ecm not know what's up?


on another not, doesn't running the headlights and or wipers send the rvc into max voltage mode? could be a easy test before bypassing it


as for alt, a new design 6 dioid 220amp alt low mileage take off can be had on ebay for a 100$ ish shipped. it's a direct bolt on. I'd personally try that before dropping 600$ plus on a aftermarket alt. they don't need to be over driven to put out that power either.

Regardless of where the power draw comes from, all power goes to ground. That's why the rvc is on the negative wire.

As to your question about the voltage, yes. With no load besides driving and audio my volts are around 12.7v-13.1v. With headlights on it jumps up to about 13.4v-13.8v. I'm sure if I loaded the truck down with wipers and other electronics I'd get over 14v. It will periodically get up to about 14.4v to 14.7v which I assume is it charging.

I agree with you about the alternators as well which is why I want to give the one I bought off ebay a fighting chance to fully power my system. If I still get flicker, I'm going to throw an amp clamp on to see the draw myself and compare that with what the alternator should be putting out.

 

[Doubeleive]

Regardless of where the power draw comes from, all power goes to ground. That's why the rvc is on the negative wire.

As to your question about the voltage, yes. With no load besides driving and audio my volts are around 12.7v-13.1v. With headlights on it jumps up to about 13.4v-13.8v. I'm sure if I loaded the truck down with wipers and other electronics I'd get over 14v. It will periodically get up to about 14.4v to 14.7v which I assume is it charging.

I agree with you about the alternators as well which is why I want to give the one I bought off ebay a fighting chance to fully power my system. If I still get flicker, I'm going to throw an amp clamp on to see the draw myself and compare that with what the alternator should be putting out.

it's pretty unlikely your RVC causing the issue, if it was there would be a code for it.
IF you really suspect the RVC simply unplug the sensor, this will make everything default
Also if you are using a Tech2 or any other scanner capable of reading the RVC status, then you can test it for functionality.
been down this road already, pretty deeply actually. I suspected the same at one point but it was a bad battery which caused the RVC system to not operate as designed.
determined this after fairy extensive testing, new cables, new rvc sensor, etc,etc. The battery had a bad cell would charge up but would drain pretty quickly and caused the RVC system to think all was hunky dory, it made the RVC think the battery was fully charged and would stay in "economy mode" even if I had every single possible thing turned on that could be turned on
been down the bad alternator road too, the "ebay" alternators I bought in the past were garbage

 

[Doubeleive]

historically speaking my own personal experience with "flickering lights" has been "weak battery" with the one exception of a poor headlight ground one time which was remedied pretty easily by grounding the headlight ground right to the frame

 

[dwinters14]

Two very interesting and insightful posts. Thank you for them. Currently the headlights AND my interior lights dim, so it's definitely through the entire system. I am going to unplug the RVC and go for a drive and see what happens. This is why you don't buy crap parts because I have a lot of question marks and not a lot of answers! I will report back with my findings.

 

[dwinters14]

Alright here's my report on a ~20 minute drive after unplugging the RVC.

Volts were steady between 14.4 - 14.7. Headlights flickered heavily for the first 5 minutes, then almost completely went away for the rest of the drive. Overall about 70% better but still not eradicated entirely. Volts would drop about .4 with the bass. Had the music cranked. The lower the volume, the less the flickering. So the amp draw is 100% causing it, but I'm still unsure of the problem being the battery or the alternator.

 

[Joseph Garcia]

One item to note is that the alternator does not increase amp output for increased truck amp demand instantaneously. When a pulse current draw request comes from the truck (in this case, a bass note that generates an amp surge to move the subwoofer), that pulse is handled by the battery (assuming that correct size power cables are used everywhere). If the battery cannot handle the current request, the lights dim, as the instantaneous voltage of the system drops, due to the current demand. You won't see that voltage drop with a multimeter, since it is a pulse of very short duration, but you would see it on an oscilloscope.

So, if there is a light dimming with bass notes, there is an issue either with the battery itself or some greater-than-zero Ohm resistance electrical connection, such as a ground point. Your opening statement says that the battery was replaced. Have you subsequently removed the battery and taken it to an auto shop and have it bench load tested? If not, I suggest the you do so first, in order to eliminate the battery as a source of your issue. As @Doubeleive stated, a battery issue is not always readily apparent, unless it is bench load tested.

If bench load testing eliminates the battery as a source of your issue, the next steps would be a re-inspection of all of your electrical connections and ground points.

 

[Doubeleive]

Alright here's my report on a ~20 minute drive after unplugging the RVC.

Volts were steady between 14.4 - 14.7. Headlights flickered heavily for the first 5 minutes, then almost completely went away for the rest of the drive. Overall about 70% better but still not eradicated entirely. Volts would drop about .4 with the bass. Had the music cranked. The lower the volume, the less the flickering. So the amp draw is 100% causing it, but I'm still unsure of the problem being the battery or the alternator.

the battery should be able to keep the voltage fairly steady, presuming power and ground are good with very little to no restriction.
if you feel everything is good and the amp is not very efficient you could try going with adding a cap and see if that resolves the dimming.
you can find used ones pretty cheap

Tsunami 1.2 Farad 20VDC car audio speaker capacitor Cap Digital Readout USED | eBay

The product is a Tsunami 1.2 Farad 20VDC car audio speaker capacitor with a digital readout. It is used for enhancing the audio performance in a car entertainment system. The capacitor helps in providing a steady power supply to the speakers for improved sound quality.

www.ebay.com

 

[Doubeleive]

One item to note is that the alternator does not increase amp output for increased truck amp demand instantaneously. When a pulse current draw request comes from the truck (in this case, a bass note that generates an amp surge to move the subwoofer), that pulse is handled by the battery (assuming that correct size power cables are used everywhere). If the battery cannot handle the current request, the lights dim, as the instantaneous voltage of the system drops, due to the current demand. You won't see that voltage drop with a multimeter, since it is a pulse of very short duration, but you would see it on an oscilloscope.

So, if there is a light dimming with bass notes, there is an issue either with the battery itself or some greater-than-zero Ohm resistance electrical connection, such as a ground point. Your opening statement says that the battery was replaced. Have you subsequently removed the battery and taken it to an auto shop and have it bench load tested? If not, I suggest the you do so first, in order to eliminate the battery as a source of your issue. As @Doubeleive stated, a battery issue is not always readily apparent, unless it is bench load tested.

If bench load testing eliminates the battery as a source of your issue, the next steps would be a re-inspection of all of your electrical connections and ground points.

you sort of can see the voltage dipping if you have it turned up and have the meter on the amp, that's why I stated to check at the battery post's and then compare that to the amp connections. this would tell you if there is a significant voltage drop in between. i.e. poor ground, poor power
if the power is dipping much more at the amp that's your sign

 

[dwinters14]

One item to note is that the alternator does not increase amp output for increased truck amp demand instantaneously. When a pulse current draw request comes from the truck (in this case, a bass note that generates an amp surge to move the subwoofer), that pulse is handled by the battery (assuming that correct size power cables are used everywhere). If the battery cannot handle the current request, the lights dim, as the instantaneous voltage of the system drops, due to the current demand. You won't see that voltage drop with a multimeter, since it is a pulse of very short duration, but you would see it on an oscilloscope.

So, if there is a light dimming with bass notes, there is an issue either with the battery itself or some greater-than-zero Ohm resistance electrical connection, such as a ground point. Your opening statement says that the battery was replaced. Have you subsequently removed the battery and taken it to an auto shop and have it bench load tested? If not, I suggest the you do so first, in order to eliminate the battery as a source of your issue. As @Doubeleive stated, a battery issue is not always readily apparent, unless it is bench load tested.

If bench load testing eliminates the battery as a source of your issue, the next steps would be a re-inspection of all of your electrical connections and ground points.

The battery is about 2 years old right now, and I have had to clean corrosion off of it at least 3 times. The first 2 times was pretty bad and what prompted me to upgrade my ground wires and terminal.

I purchased a foxwell battery tester that can test the battery under multiple conditions as well as the alternator. I will hook that up and see what it says. If it's inconclusive I will physically inspect the cells in the battery and test the acid to see what's going on before I move on to wiring and then the alternator.

 

[Joseph Garcia]

The battery is about 2 years old right now, and I have had to clean corrosion off of it at least 3 times. The first 2 times was pretty bad and what prompted me to upgrade my ground wires and terminal.

I purchased a foxwell battery tester that can test the battery under multiple conditions as well as the alternator. I will hook that up and see what it says. If it's inconclusive I will physically inspect the cells in the battery and test the acid to see what's going on before I move on to wiring and then the alternator.

IMO, the only true test for a battery is the bench load test. I don't believe that your Foxwell battery tester can perform this load test, as a HUGE high wattage resistor is used in the bench load test, which is larger than your entire Foxwell battery tester case. Just my 2 cents worth for battery testing, particularly in troubleshooting your specific issue.

 

[dwinters14]

After an exhaustive couple of days I think I have detangled the mess of my electrical system. It all started when I did my system initially. I did my big 3 the old fashioned way, NOT properly incorporating the RVC unit. I also didn't use a smaller serpentine belt. As a result I think I fried the ebay alternator I bought and in the process have stressed the battery really hard. Although it still seems to be good.

What I am going to do is run a ground wire from the alternator through the RVC as well as the headlight ground while keeping all the OEM ground connections (battery to chasis, battery to engine and battery to lights) I am also going to remove the alternator to chassis ground that I put in. I hear this can cause alt wine, and it also splits the amps away from the RVC.

We'll see how that performs, but I anticipate needing to purchase another high output alternator and if so, JS as mechman is just out of my price range. Next will be an AGM battery, and a complete re-wire (just for cleanliness and future upgradeability's sake) of my amps. I plan on replacing them anyway as I would like to expand my system. I will report back with my findings once I properly incorporate the RVC just to see what changes.

 

[j91z28d1]

just my experience load testing batteries fairly often at work with one of those new style Snap-on testers. They usually read much higher than the factory rating on brand new batteries. so say an 800 cold cranking battery will show a thousand on there when new. so if you see say 600 cca test from a 800cca battery, it's pretty weak compared to new. now that's just our testers, yours might do a better job. load test a brand new one out curiosity if you can.


back when I added electric fans to my 96 Tahoe, it would drag the smaller stock alt down to battery voltage at hot idle max ac type of rush hour traffic. at killed batteries every 2 years and went thru a few alts. once I found the large case diesel version fit in the bracket and was still 99$. all that was fixed and batteries lasted 5 plus years again and the alt was still on the truck 15 years later when I sold it. so I think you're right under driving it at high load wasn't good for either one.