Im running two fosgate punch 200 trans anna amps each one is bridged to a duel voice coil 12 in alpine type r so two amps two subs. I just upgraded to a 3 wire 100 amp alt but when the bass hits the voltage holds at 14 volts for a sec or two then drope below 13 volts and will continue to drop when im at idle is there a fix or do i need to find an even bigger alt?
CK5
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amperage drop
- Thread starter Thumbs75
- Start date
The voltage is dropping,not the amps,evidently...unless you have both a voltmeter and ammeter and can watch both drop together...
You might not have a large enough wire from the alternator to the battery if the altenator is working OK--.I would think 100 amps should power just about anything,but I'm not a wizard when it comes to high powered amps and stereos--maybe they can draw more than that?..
Did you upgrade the stock red wire that goes to the stud on the alternator to the wiring harness,or add another 8 or 10 gauge wire from the stud ,directly to the positive battery terminal?--if not,you should..that stock wire in the harness is only a 12 or 10 gauge and was designed for a lower amp alternator if its an older square body truck,like a 63 amp one--it wont like having over 100 amps pumped through it,especially if its old and corroded some..the path it takes thru the original harness is pretty long,before it gets back to the battery,and can cause voltage and amperage drop..adding a thick gauge wire right from the alternator to the battery helps get more amps and volts to the battery..
You might not have a large enough wire from the alternator to the battery if the altenator is working OK--.I would think 100 amps should power just about anything,but I'm not a wizard when it comes to high powered amps and stereos--maybe they can draw more than that?..
Did you upgrade the stock red wire that goes to the stud on the alternator to the wiring harness,or add another 8 or 10 gauge wire from the stud ,directly to the positive battery terminal?--if not,you should..that stock wire in the harness is only a 12 or 10 gauge and was designed for a lower amp alternator if its an older square body truck,like a 63 amp one--it wont like having over 100 amps pumped through it,especially if its old and corroded some..the path it takes thru the original harness is pretty long,before it gets back to the battery,and can cause voltage and amperage drop..adding a thick gauge wire right from the alternator to the battery helps get more amps and volts to the battery..
Rtull32
1/2 ton status
Google the big 3 upgrade... that'd be where I'd start
Running another wire to the battery positive from the main alternator output stud wont harm anything...it helps it-- by eliminating the long distance and added resistance of the existing factory wiring harness..
Now, If you had hooked full 12V to the field or #2 terminal on the two wire plug on the alternator (assuming your using a 10 SI alternator from a '73-87 GM ) ,then you could harm it "maybe",because the alternator will then put out maximum amps and voltage all the time--the factory wires in the "ALT" idiot lamp (or a resistor on ammeter equipped vehicles) in line with the field or #2 wire terminal ,to reduce the amount of current energizing the field coils in the alternator--less current going to them, reduces the output..--this allows it to "sense" the voltage better,and determine if the battery needs more charge or to cut back on it..
GM alternators are pretty beefy and can be run "full fielded" for long periods,that is how they made them into welders--but they also take the regulator and diode trio out of the circuit too when modified to be used as a welder--those parts,and the battery,can be fried pretty rapidly if you ran one full fielded for long...
Now, If you had hooked full 12V to the field or #2 terminal on the two wire plug on the alternator (assuming your using a 10 SI alternator from a '73-87 GM ) ,then you could harm it "maybe",because the alternator will then put out maximum amps and voltage all the time--the factory wires in the "ALT" idiot lamp (or a resistor on ammeter equipped vehicles) in line with the field or #2 wire terminal ,to reduce the amount of current energizing the field coils in the alternator--less current going to them, reduces the output..--this allows it to "sense" the voltage better,and determine if the battery needs more charge or to cut back on it..
GM alternators are pretty beefy and can be run "full fielded" for long periods,that is how they made them into welders--but they also take the regulator and diode trio out of the circuit too when modified to be used as a welder--those parts,and the battery,can be fried pretty rapidly if you ran one full fielded for long...
For car audio stuff, you definitely want to run directly to the battery. Alternator won't hurt, but any "reserve" needed out of the battery is only linked by the "charge" wire between the alt and battery.
First, look up what wire size is recommended for those amps. 10ga sounds WAY small. I'm running 2 gauge to a distribution block in mine, then 6 or 8 gauge to the amps in my truck. I'm running 1/0 to all my boat amps.
Run AT LEAST the recommended wire size. Not sure of the power ratings of the amps, but i often use the largest size the amp will accept.
Then, run both those directly to the battery. Make sure you have a GOOD ground wire from the amps to the body, of at least the same size as the power wires.
From there, add additional grounds from battery to engine block, engine block to body, and battery to body. These should also match the amp wire in size.
This SHOULD fix your problem. If not, you need to look into capacitors, not alternator upgrades.
First, look up what wire size is recommended for those amps. 10ga sounds WAY small. I'm running 2 gauge to a distribution block in mine, then 6 or 8 gauge to the amps in my truck. I'm running 1/0 to all my boat amps.
Run AT LEAST the recommended wire size. Not sure of the power ratings of the amps, but i often use the largest size the amp will accept.
Then, run both those directly to the battery. Make sure you have a GOOD ground wire from the amps to the body, of at least the same size as the power wires.
From there, add additional grounds from battery to engine block, engine block to body, and battery to body. These should also match the amp wire in size.
This SHOULD fix your problem. If not, you need to look into capacitors, not alternator upgrades.
The wiring to the amps is not an issue ive got 6 gauge running the amps its a charging voltage drop issue the voltage gauge drops drasticly at idle with anything loud enough to vibrate the mirors and i noticed when i turn the lights on it will drop to just below 13 volts without the radio on so im thinking its a ground issue or a the battery is going bad. Im pulling enough power through the battery to blow a 40 amp fuse at high volune
Ok now i know for shure its a bad wire some where whent for food at halftime and when i made a turn volts droped to zero and lights when almost all the way out a second later it all came back on now i just need to find it
I'd look at the thick red wires with the fusible links at the starter solenoid --one runs to the junction block near the brake booster (on square body trucks),and it also branches off in a "T" splice in the harness behind the engine and goes to the main alternator stud terminal..those wires carry all the current from the alternator to power the rest of the truck..
Gonna have to trace those wires today cause now there is a new simptom im losing almost all power wile driving everything all lights and radio shut off but when i hit a small bump in the road it all come back on
