First....the wire size has nothing to do with the amount of current the alternator is able to produce. If your alternator can make 80 amps it will make 80 amps with a 18ga or 0ga..the 18ga will burn up. The 0ga wire allows more current to flow and provides less resistance.

You are proably getting the pulsing because either the voltage regulator is going bad inside the alternator or the ECM is making the alterntor turn on and off. I would pull the alternator and have it tested at an alternator shop.

Adding a second battery to an already overdrawn system is very bad. The stock alternator is designed to run the car and it's stock electrical components. Anything after that is a stressor on the alternator. Yes your alternator will work but it will not last as long or provide enough current. Why does he want to use two batteries?

 

Electricity follows the path of least resistance.

Run the BIG wire to the amps. If the headlights start to dim while the stereo is cranked, you need a bigger alternator........THEN possibly a bigger wire between the alternator and the battery.

 

EatRice... you confirmed my thinking. I figured the alt. would put out rated amperage regardless of wire size. Like you said, you might burn up 16 ga wiring but that alt. will put out rated power. I have been grasping at straws to get any answer for the pulsing.

Jake's alt. is an upgrade from the stock (90 amp I believe) size. His current alt. is 105 amp. There was provisions for dual batteries from the factory for his year Tahoe. I believe Jake said he was going to try having his alt. tested so I will let you know what comes of that.

65Hardnoks... The headlights do dim somewhat. Jake is running big wire to the amps (0 ga). Jake has upgraded the alt. from the stock size (90 amps I believe) to 105 amp. Now he is trying to upgrade the wire between the alt. and battery having done the upgraded size grounds. This is where the problem has started (the big wire between alt. and battery).

 

Find out if GM did this on Jake's Tahoe.. I know newer vehicles have this.

my Uplander is one and it pulses liek you mention from the factory..

 

I think what EatRice said clears that up.
But if not, pretend the altenator is a full bucket of water. Pretend the battery is an empty bucket. Hook up a small (stock wire) and large (0-guage) hose to that full bucket. Which hose will let the water flow easier out of the full bucket to the empty bucket? Of coarse, the large hose (0-guage) will. Thus the 0-guage is the best choice to transfer the amps from the altenator to the battery. The altenator (full bucket) was the same for both hoses. The fullness is the amount of amps the altenator can put out. The full bucket doesn't care what hose is hooked up, the bucket just wants to give it's fullness (105 amps). The empty bucket (battery) does care which hose is used. The empty bucket wants to get filled as quickly as possible since other hoses (your stereo, A/C, etc.) are hooked up the the empty bucket trying to drain it.
Does any of that make sense? I know I'm a retard but I'm trying to explain my thoughts to help you guys to understand how those things work.


Your amps might have fuse rating of 170 amps but that doesn't mean they are pulling 170 amps, even at full volume. When you crank the stereo up and the amplifiers are drawing more than the altenator can provide, then it is the batteries job to provide the extra current. Caps do pretty much the same as batteries but just quicker. Again, the larger hose will let that water flow easier.


Back to the topic at hand. I honestly don't know what going on with the voltage fluctuations when the 0-guage is used. My guess is that there is some type of feedback to the regulator from the stock wire and the battery. With the 0-guage hooked up, the regulator gets feedback of different voltages and then the regulator gets confused. I would not bet $.02 on that guess though. Please post what you find

 

KnewBlew...good explanation of the hose and buckets.

Jake was able to get a load test done on the alternator and also get the current flow measured. It took some time to find a meter capable of doing current flow for DC. Anyways, with the stereo up high, the high beams on, wipers going, defroster running, etc. the current flow was 159 amps.

Jake confirmed his alt. is 120 peak amps (nominal was around 105 amps). He has since noticed that the pulsing of lights was occuring with the stock small wire in place and the big wire disconnected.

Jake got the alt. replaced (under warranty) with the same size as before. It is working better and no pulsing any more but there are still voltage drops with big bass hits. Best guess was that the voltage regulator (internal) was going bad on the old alt.

Current thought is to buy a larger alternator. Does this seem like a good idea?

 

An old racing saying comes to mind:

You want to play you have to pay.

He is trying to do too much with the stock upgraded alternator's output vs what his stereo is capable of pulling. IMO upgrading the alternator is the correct choice to provide more juice for ALL of the vehicles electronics and draws along with the upgraded stereo.

Is this an ex-police tahoe? Might be able to source a high output alternator that way ...

Fej

 

It's not an ex-police Tahoe...but Jake did tell me he looked into that. He said those alt's were 140 amp. He is looking at 200 or 250 amp alt. so that he can do it once, do it right.

 

Yeah, a high output alt will do the job. If the battery is old he might want to think about a Optima yellow top too. If the new alt can prevent the lights from dimming when the bass hits, the bass should be louder since the amps will still be gettting the high voltage

 

He has a newer Yellow Optima in there. I believe he put the battery in this spring/summer. I think the bigger alt. is the cure. He has been shopping around and I suspect will have it pretty soon.

 

O.K., I spoke to Jeff at Boyle future tech and he said That they are probably picking up a sensing wire for the regulator off the factory wire. With the new wire, voltage will take the path of least resistance and the sense wire might not be sending enough power and is confusing the regulator. Does this wire go straight from the alt to the batt with no other taps in it?

 

Adown,

Not sure off hand. I will talk to Jake and find out from him. I'll update this post once I know.

 

Dave is Jake running a CAP? It my be time to look into one for the sub amp...