# voltage drop after big 3



## slow2.2sonoma (Jul 9, 2006)

I got the alternator postive to battery upgraded and the battery to ground upgraded. I started it up and got past 14 volts initially and it pretty much stayed there. After a few hours I saw it go back down and now its back to where it usually is. I will admit it does no doubt sound different. My main concern is that I'm only getting 13.5 volts now and nothing aside from touching the wires brings it back up...


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## CMR22 (Feb 10, 2007)

slow2.2sonoma said:


> I got the alternator postive to battery upgraded and the battery to ground upgraded. I started it up and got past 14 volts initially and it pretty much stayed there. After a few hours I saw it go back down and now its back to where it usually is. I will admit it does no doubt sound different. My main concern is that I'm only getting 13.5 volts now and *nothing aside from touching the wires brings it back up...*


Possibily a bad connection somewhere?


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## Fast Hot Rod (Apr 19, 2007)

Was it 14 volts consistently before the big three?

I would think that 13.5 volts is more than sufficient. That's 2.25 volts per cell... which I think is right on the money.

Does your vehicle have temperature compensation built into the voltage control circuit?

Mark


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## Exalted512 (Jul 23, 2006)

do you have a solid ground to the chassis? Ive seen people do it where they ground to the body instead of the chassis, they arent the same....
-Cody


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## chad (Jun 30, 2005)

lemme get this straight, you touch the wiring and the voltage goes up?

What are you metering this voltage with?


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## SteveLPfreak (Sep 26, 2005)

Did you add your new Big 3 connections over top the stock wiring, keeping the stock connections or did you remove the stock connections and add all new?

Adding beefier wiring/connections over the originals should not increase the voltage drop.


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## 02bluesuperroo (Oct 31, 2006)

What was voltage before the big 3? If the only drop you're experiencing is from when you first started it up until a few minutes after that is normal. If your battery was slightly discharged the alternator will charge it a little harder initially to get it full charged. 13.4 - 13.6 volts is normal. If you were contantly at or above 14 volts I think _that_ is something to be worried about.


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## chad (Jun 30, 2005)

02bluesuperroo said:


> What was voltage before the big 3? If the only drop you're experiencing is from when you first started it up until a few minutes after that is normal. If your battery was slightly discharged the alternator will charge it a little harder initially to get it full charged. 13.4 - 13.6 volts is normal. If you were contantly at or above 14 volts I think _that_ is something to be worried about.


X2

I feel it's at the PROPER voltage.

The question is: If under load, if your drop is less than before, if it is then...

Mission accomplished!


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## slow2.2sonoma (Jul 9, 2006)

I use a DMM at the battery and amps. I added the new wires over top the old ones. If I tighten the alternator bolt slightly it almost always pops back upto 14 volts when I restart and then falls back to 13 after a few restarts or after I put a load onto it from the system. I haven't upgraded the most important cable which is the block to chassis ground yet, but so far I'm somewhat happy. I was really hoping to get a constant 14 volts after I did the upgrade.


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## Lightninghoof (Aug 6, 2006)

Did you upgrade all 3 wires?

1) Alt (+) to battery (+). (should be fused)
2) Chassis (-) to battery (-).
3) Engine block (-) to battery (-).


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## fej (Feb 8, 2006)

How old is the battery? Sometimes that is the culprit. I think it also has a lot to do with the type of car, whether there is traction control/active handling or other "pulsing" electrical checks that the car performs regularly.

I run 13.9-14.2 in the vette (Optima Redtop 1 yr old) without the big 3, although I can get the lights to dim (lights on 13.8, big bass hits drops it to 12.2) on only 600w. Too damn much electrical stuff going on, I need to motivate and handle the big 3 on that car  

The truck with a brand new Yellow Top runs 13.8-14.0 pretty consistently with only the alt to batt connection upgraded (1/0). Need to get some more terminals to finish up the big 3, but zero light dim or voltage drop on that car with 1400w. At startup it is up around 14.2 generally and around 13.6 with the ac/stereo cranking.


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## CGG318 (Apr 9, 2007)

I'm guessing by your name you have a GMC Sonoma? I have an 07 Siverado and the voltage meter seems to randomly go from 14+ to around 13 +/-. This seems to happen for no reason at all, regardless of what is running, lights on/off, a/c, stereo cranked or off......


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## ogahyellow (Apr 16, 2007)

Were you running the car the whole time? I believe voltage drops as the alternator gets hotter. 



slow2.2sonoma said:


> I got the alternator postive to battery upgraded and the battery to ground upgraded. *I started it up* and got past 14 volts initially and it pretty much stayed there. *After a few hours I saw it go back down* and now its back to where it usually is. I will admit it does no doubt sound different. My main concern is that I'm only getting 13.5 volts now and nothing aside from touching the wires brings it back up...


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## slow2.2sonoma (Jul 9, 2006)

It is always moving around. If I play system for a little while it seems to drop and never really fully recover. I am going to do the engine block to chassis ground asap after I find a wrench big enough to remove the bolt holding the wire for the stock ground. I think the chassis will be sufficient when grounding the block and I will probably simply add the 1/0 to the factory location.


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## Lanson (Jan 9, 2007)

what year is the sonoma? I'll look up the issue on identifix.


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## slow2.2sonoma (Jul 9, 2006)

1999 4 cylinder


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## Lanson (Jan 9, 2007)

Just so you know (and it doesn't mean this is why you are having troubles, but you should at least look at them

Identifix has many articles on the 2.2 motor and Sonomas in general, with battery and charging issues. Here are some of the critical ones.

The 2.2 came with a notoriously weak alternator. Hundreds and hundreds of cases of this alternator failing, or producing weak output are reported.

There is a potential problem with vehicle wiring shorting to ground, or shorting to each other, under the front seats. A known problem is for some of these to rub together, and fail. Check under the carpet to make sure you don't have a frayed stock wire anywhere. Very common.

Your BCM (Body Control Module) pulls a lot of current. It can pull enough to drop the output voltage of the alternator to a fair degree. 

The ignition lock, and lock cylinder have been known to cause excessive current draw, which could also lead to a low charging rate.

MY bet however, is that the alternator isn't sufficient for power anymore. I recommend replacing with an aftermarket, HIGH QUALITY, audio-related alternator.


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## slow2.2sonoma (Jul 9, 2006)

Where did you find all of that? The alternator charges fine it's just that the voltage isn't always where I'd like. Thanks for all the information, I'm definately going to check it out more in depth when I get some time. Can you give me tips on where to find these things and if possible how to fix them?

The only real problem I've ever had was when a motor mount heat shield which I bent so it would quit rattling broke off and managed to hit the hot wire of the starter and grounded through my brake line. It seriously stalled my truck after a few seconds and then after I restarted it. I didn't know what was happening so I kept trying to restart it and eventually it blew the Starter fuse and melted the inside of the brake line. All I had to do was brake the rest of the heat shield off and have a new brake line made. Also had to replace the fuse  Cost me a whopping $35 and one bad day.


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## Pb2theMax (Aug 26, 2005)

Alternator voltage regulators usually do that. Put out 14v at first and then drop to 13.5. 

For having a stock alternator, your voltage numbers seem normal to me.


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## bass_lover1 (Dec 10, 2005)

Since you haven't done the engine to chassis ground yet, if location allows it, try grounding the engine directly to the battery. Obviously the stock location is fine, but if it's feasible to ground to the battery, there's no reason NOT to.


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## slow2.2sonoma (Jul 9, 2006)

I have a dual 1/0 awg terminal on the negative so I will probably try to.

I also noticed today that my voltmeter fluxuates when I use my blinker as in the voltage goes up and down a little with every blink. That seems kind of weak imo...


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## Lanson (Jan 9, 2007)

slow2.2sonoma said:


> Where did you find all of that? The alternator charges fine it's just that the voltage isn't always where I'd like. Thanks for all the information, I'm definately going to check it out more in depth when I get some time. Can you give me tips on where to find these things and if possible how to fix them?


 
Identifix is a website made for techs. I sell the service to shops. Thats my thing. Fixing them isn't really hard. Its just knowing that they exist thats the hard part.


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## Oliver (Jun 25, 2007)

Go to a auto parts store that has a lifetime warranty on their alternators and batteries.

Then buy some.


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## Lanson (Jan 9, 2007)

NO! Most aftermarket alternators are in worse shape then the factory piece. It is in your best interest to get all the wiring up to par, then install a quality, audo-focused alternator.


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## slow2.2sonoma (Jul 9, 2006)

The headlights on my truck come on automatically once E-Brake is released. I noticed the voltage is guaranteed to drop 1 volt when this happens. I also noticed my voltage flucuates with the blinker. I'm seriously thinking of checking out all of my lighting wires etc to make sure they are fine especially considering that my blinker used to come on when the horn was honked.

Can you please take a screen shot of the identifix page so I can get some more detailed information. Thanks!


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## Lanson (Jan 9, 2007)

slow2.2sonoma said:


> The headlights on my truck come on automatically once E-Brake is released. I noticed the voltage is guaranteed to drop 1 volt when this happens. I also noticed my voltage flucuates with the blinker. I'm seriously thinking of checking out all of my lighting wires etc to make sure they are fine especially considering that my blinker used to come on when the horn was honked.
> 
> Can you please take a screen shot of the identifix page so I can get some more detailed information. Thanks!


Sorry, can't do it. I'm not supposed to post fixes and all that, but I take care of my community brothers. I can't screen-shoot however. Trust me, this car has electrical gremlins. Time to take out a DMM and test all the grounds you can find, and check continuity everywhere.


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