dougielx Posted November 21, 2012 Report Share Posted November 21, 2012 I plan to run a 4guage wire to my alternator. My question is can I run it directly to the positive terminal on the battery. Thanks . 1998 Olds 3.1 Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 21, 2012 Report Share Posted November 21, 2012 you run it TO the alternator? don't you mean FROM the alternator? do you have a cutlass or something? there should be a AUX hub that distributes power to everything including the battery. I would go to there. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted November 21, 2012 Report Share Posted November 21, 2012 yeah, much easier than attempting to hack another wire into the side terminal connectors. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 22, 2012 Report Share Posted November 22, 2012 easier yet the proper approach to powering the running vehicle, the primary function of the alternator. secondary function is maintaining battery voltage. Quote Link to comment Share on other sites More sharing options...
ron350 Posted November 22, 2012 Report Share Posted November 22, 2012 The large factory wire (on my 96) runs from the alternator nut to the starter solenoid positive terminal. The large wire from the positive battery terminal also runs to the starter solenoid positive terminal. If I were going to add a parallel wire to the alternator I would run it the same way the factory did. I would leave the Remote Battery Stud alone it has enough problems built in to its design. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 22, 2012 Report Share Posted November 22, 2012 (edited) 4-gauge wire from alternator output is humorously enormous. In the same way that a 4+ inch diameter exhaust tip connecting to sub-2-inch exhaust pipe is: A sure sign that something "ain't right". How big is the output stud? Why would you need substantially more copper in the wire than the diameter of the stud? First Guess: 8-gauge would be PLENTY. OEM is...10-gauge??? Perhaps 12-gauge? Have you even bothered to measure voltage drop along the existing wire? Have you tried cleaning the terminals at each end? Is there a problem with VD to begin with? Don't get me wrong, the car manufacturers are not known for being generous with copper. The 16-gauge fuel pump wiring of my Lumina is provably four sizes too small based on electrical-industry-standards for allowable voltage drop considering wire length and amperage draw. Even so...FOUR GAUGE alternator output wire? Most folks around here buy 6-gauge jumper cables. Edited November 22, 2012 by Schurkey Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 22, 2012 Report Share Posted November 22, 2012 4-gauge wire from alternator output is humorously enormous. In the same way that a 4+ inch diameter exhaust tip connecting to sub-2-inch exhaust pipe is: A sure sign that something "ain't right". How big is the output stud? Why would you need substantially more copper in the wire than the diameter of the stud? First Guess: 8-gauge would be PLENTY. OEM is...10-gauge??? Perhaps 12-gauge? Have you even bothered to measure voltage drop along the existing wire? Have you tried cleaning the terminals at each end? Is there a problem with VD to begin with? Don't get me wrong, the car manufacturers are not known for being generous with copper. The 16-gauge fuel pump wiring of my Lumina is provably four sizes too small based on electrical-industry-standards for allowable voltage drop considering wire length and amperage draw. Even so...FOUR GAUGE alternator output wire? Most folks around here buy 6-gauge jumper cables. jumper cable size is irrelevant. this is for one of the most important wires in your car. continuous duty not jumping a car but RUNNING the car and charging the battery. 8 gauge would be weak as f----. 0 gauge is what you should use. go to the starter if you must and you think you need to charge the starter with the alternator. don't make sense, but you would need to tear in to the harness and replace the pencil thin charge wire with something worth a damn. might look a little cleaner, that's about it. Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted November 22, 2012 Report Share Posted November 22, 2012 ...... all of my factory alternator wires have been 8 guage.... i'm sure that's plenty for the 100 amps the factory alt will push out. start moving up to higher amp alts and i can see it being an issue though. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 22, 2012 Report Share Posted November 22, 2012 are you sure it does not get hot when ALL the accessories are running for hours at a time on rainy days. or on a 95 degree day and average system bumping, or even stock stereo, and AC running on high, with those big radiator fans kicking on and off non stop in a traffic jam? then it gets dark and the headlights come on, still 90 outside? about 200 under the hood? will that 8 gauge heat up at all? Quote Link to comment Share on other sites More sharing options...
RobertISaar Posted November 22, 2012 Report Share Posted November 22, 2012 heat up? definitely. enough to cause voltage drop, probably. enough to make me worry, probably not. i'm sure in those situations, the alternator is being quite a limiting factor as well. http://genuinedealz.com/voltage-drop.html a guess based on that, at 80 amps of load with an 8 foot alt wire, roughly a 7% voltage loss. probably not accounting for a heated wire, but still, at 14 volts, that's still ~13.1 volts. not great, but certainly something i could live with. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 22, 2012 Report Share Posted November 22, 2012 (edited) jumper cable size is irrelevant. Jumper cable size is COMPLETELY relavant. Jumper cable transmits ~200--250 amps when the dead vehicle is cranking. Alternator cable transmits half that, usually much less. this is for one of the most important wires in your car. continuous duty not jumping a car but RUNNING the car and charging the battery. 8 gauge would be weak as f----. 0 gauge is what you should use. The cable that powers the starter--on these cars probably a 150 amp draw, maybe more--is not 0 gauge. Probably four gauge, maybe six. You think the alternator output needs to be zero gauge? Woof. Again--LOOK AT THE ALTERNATOR OUTPUT STUD. Why do you need two, three, four times the diameter in copper than the stud itself? The stud will burn off LONG before you get to the limits of the copper cable. go to the starter if you must and you think you need to charge the starter with the alternator. don't make sense, but you would need to tear in to the harness and replace the pencil thin charge wire with something worth a damn. might look a little cleaner, that's about it. You're not trying to "charge the starter", you're powering the CAR's ENTIRE ELECTRICAL SYSTEM with the alternator. The starter connection is just a semi-convenient distribution block, a central location that then supplies power to the various loads--and one that doesn't require any additional parts that aren't already needed for another purpose. Earlier GM cars used the horn relay as a distribution point. Go direct to the battery with the alternator output cable, and the interior--including the fusebox, lights, HVAC--may have increased voltage drop (less available voltage) due to longer cable path. The battery may have increased voltage, but the headlights aren't as bright. GM is OFTEN tight (cheap) but they're rarely stupid. Edited November 22, 2012 by Schurkey Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 22, 2012 Report Share Posted November 22, 2012 you are not going to power the entire car electrical system until the end of the line which is the AUX post from the starter anyway. didn't mean to make you start yelling. lol Quote Link to comment Share on other sites More sharing options...
white4d96 Posted November 22, 2012 Report Share Posted November 22, 2012 To answer OP's question, yes, it is fine to run straight from alt to batt. That is how mine is ran. Make sure to fuse it (~100A for a true 4 gauge wire) and if you have an issue with getting the lug into the terminal, you can pick up a terminal screw meant to hold extra wiring. Something like this: http://www.ebay.com/itm/RAPTOR-GM-CHEVROLET-CAR-TRUCK-GOLD-SIDE-MOUNT-POST-BATTERY-TERMINAL-CHEVY-GMC-/360457612943?pt=US_Car_Audio_Video_Connectors_Terminals&hash=item53ecf2ae8f You should also beef up your grounds too if you're trying to stabilize and/or up your voltage. Quote Link to comment Share on other sites More sharing options...
dougielx Posted November 22, 2012 Author Report Share Posted November 22, 2012 Looks like I opened a can of worms! The power cable FROM the alternator on my car was spliced at some point and the wires just look too small to me, even the original, so why not upgrade the size. I just wanted to make sure I wasn't doing anything stupid by running it straight to the battery because I did not trace it out. Thanks for the replies. Doug - 1998 Olds Achieva Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 22, 2012 Report Share Posted November 22, 2012 Make sure to fuse it (~100A for a true 4 gauge wire) What happens if the fuse pops? The alternator has a voltage surge that can wipe out the electronic circuitry, particularly the diodes. It would be no different from disconnecting the output wire while the engine is running. Alternator may--or may not--survive. The more loaded the alternator, the less likely it is to survive being disconnected from the load. GM does not fuse the output wire. They route the wire properly, protect it where needed with plastic loom and routing clips, and keep it reasonably short before the first junction. Yet another reason to NOT go directly to the battery. Quote Link to comment Share on other sites More sharing options...
EviLette Posted November 22, 2012 Report Share Posted November 22, 2012 Thanks for this post. It's something I am looking into as well. A lightning capacitor is a band-aid for a weak electrical system, I've always heard, and I beat HARD when I beat. Two 12" subs (400 watt amp - very efficient MTX speakers, but still) I have ALWAYS had issues with the lights dimming when I pressed the brakes. I need to know exactly what is needed to upgrade the wiring on my electrical system. It wouldn't be a bad idea to do it while the car is stone dead with her battery sitting on the kitchen table. (By her, I mean Precious). Just soaking up the knowledge, not asking for info or trying to derail. Thanks. Quote Link to comment Share on other sites More sharing options...
dougielx Posted November 24, 2012 Author Report Share Posted November 24, 2012 What happens if the fuse pops? The alternator has a voltage surge that can wipe out the electronic circuitry, particularly the diodes. It would be no different from disconnecting the output wire while the engine is running. Alternator may--or may not--survive. The more loaded the alternator, the less likely it is to survive being disconnected from the load. GM does not fuse the output wire. They route the wire properly, protect it where needed with plastic loom and routing clips, and keep it reasonably short before the first junction. Yet another reason to NOT go directly to the battery. I plan to leave the original wire intact, just add the 4ga to the battery. Overkill I know. Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted November 24, 2012 Report Share Posted November 24, 2012 I plan to leave the original wire intact, just add the 4ga to the battery. Overkill I know. not a good idea. but it will work. you will just have a big loop of resistance. Quote Link to comment Share on other sites More sharing options...
Schurkey Posted November 24, 2012 Report Share Posted November 24, 2012 I plan to leave the original wire intact, just add the 4ga to the battery. Overkill I know. So you enjoy spending time, money, effort, and enthusiasm on something that's going to have no benefit to the way the car runs/drives? Aside from adding the additional weight of the cable, what do you hope to gain from this waste? Quote Link to comment Share on other sites More sharing options...
80's tech Posted December 4, 2012 Report Share Posted December 4, 2012 I WOULD NOT ADVISE IT, 4 GAUGE IS IS FAIRLY LARGE WIRE FOR A CHARGE LINE (SOME VEHICLES USE 4 GAUGE WIRE FOR STARTING). MOST GM VEHICLES CHARGE LINES RUN TO THE STARTER (THINK OF BAT TERM OF STARTER AS A JUNCTION), ALSO ADEQUATE CIRCUIT PROTECTION IS REQUIRED. IF I MAY ASK ,WHY SUCH A LARGE CABLE FOR A CHARGE LINE? Quote Link to comment Share on other sites More sharing options...
Garrett Powered Posted December 5, 2012 Report Share Posted December 5, 2012 YUmadbro? Quote Link to comment Share on other sites More sharing options...
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