skishop69 Posted October 25, 2012 Share Posted October 25, 2012 Ok, I'm cranky and tired so forgive me. WRONG again!! He is talking about length in rergards to using a fuse.WRONGWRONGWRONGWRONGWRONG! You are correct in that you use length and gauge to rate it's amperage capacity and the SIZE of fuse to use factoring the load of the device being powered. It doesn't matter if it's 2" away, you use a fuse, PERIOD. Length, routing, etc means NOTHING! Fuses are there for a reason. Argue semantics all you want, this is what I do for a living. Now I know why GD responds the way he does when you guys think you know what you're talking about... Link to comment Share on other sites More sharing options...
Idasho Posted October 25, 2012 Share Posted October 25, 2012 Sure, but if the capacity of said wire far exceeds the device it is powering, a fuse is not needed. You already have a few of these under the hood on a STOCK car. Link to comment Share on other sites More sharing options...
skishop69 Posted October 25, 2012 Share Posted October 25, 2012 Nope. Fuse is there for not only circuit protection, but DEVICE protection. If the wire capacity exceeds the device load, this is especially important! A dead short in the device with no fuse will cause wiring to melt and possibly cause a fire. The manufacturer doesn't put them there because they are pretty! Link to comment Share on other sites More sharing options...
skishop69 Posted October 25, 2012 Share Posted October 25, 2012 Battery cables are the only non-fused lines under the hood anymore. The reason was fire, safety and liability. Link to comment Share on other sites More sharing options...
Idasho Posted October 25, 2012 Share Posted October 25, 2012 Battery cables are the only non-fused lines under the hood anymore. Want to bet? :-p Link to comment Share on other sites More sharing options...
skishop69 Posted October 25, 2012 Share Posted October 25, 2012 Yep. Battery to starter and to UBEC has no fuse. At the UBEC, you have a 125A or similar sized fuse depending on the manufacturer. Inside the UBEC main lines go through the maxi fuses then either out to components or to the dash mounted fuse blocks or to the mini fuses in the UBEC and out to the devices. Careful.... 20 years experience, degree, repair and engineering experience. (yes, I am being light hearted lol) Link to comment Share on other sites More sharing options...
skishop69 Posted October 25, 2012 Share Posted October 25, 2012 UBEC = underhood bussed electrical center Link to comment Share on other sites More sharing options...
sikend667 Posted October 25, 2012 Share Posted October 25, 2012 gauge of wire determines fuse size there is draw down on LONGER runs but the shorter the less resistance less resistance=more amps. at least thats what im deciphering from what ive read. im no electrical expert but i know fused wires are better than no fuse if you want you can do a little expriment at home to prove this. grab a pair of 9v batteries out of the junk drawer, 2 peices of small gauge wire, a 1 amp fuse, set of gloves, soldering iron, solder, and a fire extiguisher. take one wire cut it in half, solder the fuse between the two halves then take the ends and short the battery. fuse should blow fast and remember how hot the wire got. now grab the gloves, the other battery, the other chunk of wire (without the fuse), and make sure the fire extiquisher is close by. with the gloves on short this battery see how hot the wire gets. dont do it for long dont want the battery to split, or the gloves to catch on fire! this will basically prove the need for a fuse no matter how short or how long the wire is you will get the same result. ohh and when you are done do us all a favor READ THE QUESTIONS BEFORE YOU SPIT YOUR OPINION! i just wanted to know what size fuse i should use not whether or not a 2004 chevy tahoe has every circut fused and whether that upsets you because :Flame:you dont need no fuses for yer rig:Flame: i like to be safe personally so ill be fusing mine if you have a suggestion as to what size fuse should be used i appriciate it if you want to try to justfy your unsafe setup save it for the next idiot. ok now that im done ranting..... GD thank you for your direction to the proper information but unfortunatly it is all greek to me. i have a spare 4 gauge about 22" long i was going to use. according to the charts ive read itll sustain 110a but with the maximum output being 90a logic to me says slap a 90a fuse in there and call it a day but that doesnt seem right..... any advice would be appriciated 1 Link to comment Share on other sites More sharing options...
skishop69 Posted October 25, 2012 Share Posted October 25, 2012 If the wire is rated ay 110A surge, and the nominal is 90, there is roughly a 10% suge on initial flow (it gan be much higher, but shouldn't be on the alt). If the alternator output is 90A, you need a 100A fuse to avoid blowing it during the initial surge at max power. This will also put you below the wire threshold to minimize any circuit damage should it blow. Link to comment Share on other sites More sharing options...
sikend667 Posted October 25, 2012 Share Posted October 25, 2012 thank you for the sound advice ill report back when its done Link to comment Share on other sites More sharing options...
GeneralDisorder Posted October 26, 2012 Author Share Posted October 26, 2012 To be completely accurate there is typically a single large cable from the battery positive feeding the starter solenoid and another ~8-10 AWG wire that feeds the fuse/link panel. Neither of these runs are typically fused. Ideally they would be but the manufacturers don't seem to feel its needed on a very short, very large wire run. Adding an additional run from the alt to the battery to handle heavy draw is important and you should fuse it for the wire size that you use. Remember the load will be shared with the existing wiring so you still fuse it for the wire size even though that may be less than the full amperage capacity of the alt. GD Link to comment Share on other sites More sharing options...
rain_man_rich Posted January 24, 2013 Share Posted January 24, 2013 GD, did you delete your pictures on your pic hosting site? I can't see them and I'd like to look at some of the spacer pics. Link to comment Share on other sites More sharing options...
Tofutti Posted March 2, 2013 Share Posted March 2, 2013 Sorry to be that guy that revives an old thread, but I feel this one is not only worthy of reviving, but should be sticky'd somewhere, maybe in the "how to's" as it helped me immensely. Plus, I had to dig around forever just to find it.. Trying to clean up my pictures and hosting.... here's the pics for this thread:GD In response to rain_man_rich above, He re-hosted his pics on page 6 of this thread (But here they are again, above) Welp, I got a 94 Nissan Maxima alternator, built by duralast - part # 14661 at autozone. It doesnt fit, there's some bushing in the mount that wont fit into mah car. I would consider filing it to fit except the plug is wrong as well and well, this is looking bleak.pic of the offending part: in summery- the 94 year model alternator seems to be a no go. After seeing this particular post, I wasn't sure my new alt was going to work in my '92 Loyale because I was scared of this same insert on the new alt. In my case, it fit just fine, except I had to add a washer between the outside of this offending part and the original alternator mount bracket to close up a gap that was there.OP (GD), I absolutely love this thread, and I thank you so very much for finding/making this upgrade so clear. I was reading several posts about this and still wasn't sure this would work with my non-turbo EA82 Loyal, as I do have A/C and a single pulley alt.It took me longer just to get the pulleys off the alternators than it did to do the rest of the very minor modifications required for this upgrade project AND install the whole thing. *Note to other Loyale owners:I found that in my particular model of car, this new alt will hit the mounting bracket when you try to rotate it down, at about the midway-point of the adjuster bracket, thus not allowing you very much slack in the belt. When putting a NEW belt on, you will have to remove the upper bolt and try to drop the top end of the new alt down a bit. Once the belt is on, wiggle it back up and install the upper bolt, THEN tension the belt as normal and tighten the lower bolt. I went from crap To great! Link to comment Share on other sites More sharing options...
Tofutti Posted March 2, 2013 Share Posted March 2, 2013 Just to try and clarify even further for the first-timers (like me, last week): Sorry, you may have to find a way to zoom in for the pic..What I did here was mechanically and electrically sound, but it was still temporary. This will get you on the road again safely, but you will probably still want to find the alternator pigtail connector from the Nissan alt at some point, just so water doesn't wreak havoc in there (puddling inside the cup of the connectors on the new alt).On a side note, I've seen people talking about having to split the ring on the main connector of the alt charging post.. I too, found the original ring terminal to be too small to fit on the post of the new alt, but, not by much. I used an old trick. Take a flat-blade (regular) screwdriver and use it to "drill" the connector out a bit. Go a little bit on one side, then flip connector over and go from the other side. Doing this will help you to not over-enlarge the hole quite so easily, and will still do a neat job. Link to comment Share on other sites More sharing options...
Corvid Posted May 27, 2013 Share Posted May 27, 2013 Hey GD, I was reading on other threads here, and I think it was you that posted links to madelectrical.com's writeup on 3-wire alt. setups. That writeup was great, but I came away from it with the impression that direct wiring between the alt and the battery is likely to fast-charge and damage a low battery. I came away from this thread with the impression that after upgrading the alternator, the charge wire running from the main junction box to the battery should be upgraded, and that an additional fused wire should be added between the alternator main output post and the battery. To explore this or clear it up in plain english, have I misunderstood either your advice, or the advice of the madelectrical.com writeup? If I understand both sets of advice, could you speak about the difference of opinions? Why would a person not simply upgrade the charge wire from the main junction to the battery, and add an appropriate fuse? Thanks for all your time on this project and your advice. 1 Link to comment Share on other sites More sharing options...
l75eya Posted June 15, 2013 Share Posted June 15, 2013 Another successful install here. Why has this not been stickied yet? From the "What have you done to your subaru" thread:Maxima alternator.Pretty straightforward installation. Took a bit of creativity to get the pulleys off though, without an impact.Slightlydisappointed, but at the same time impressed. I no longer have voltagedrop when the bass hits through my system anymore, but I've noticed thatmy no load volt reading on the in dash voltmeter is lower now than itwas with the original alt. Also, at idle with a full load (high beams,flashers, rear defroster, heater on full blast, interior lights on) myvolt meter drops down to about 10 volts. My idle is high already, (1,000rpm) so it's not that. Any ideas?So like I said, both good and bad things. Link to comment Share on other sites More sharing options...
Corvid Posted June 28, 2013 Share Posted June 28, 2013 I now have a working modified Maxima alt all ready to drop in, just trying to bump this to see if I can get some info on this previous question before I wire it up. Hey GD, I was reading on other threads here, and I think it was you that posted links to madelectrical.com's writeup on 3-wire alt. setups. That writeup was great, but I came away from it with the impression that direct wiring between the alt and the battery is likely to fast-charge and damage a low battery. I came away from this thread with the impression that after upgrading the alternator, the charge wire running from the main junction box to the battery should be upgraded, and that an additional fused wire should be added between the alternator main output post and the battery. To explore this or clear it up in plain english, have I misunderstood either your advice, or the advice of the madelectrical.com writeup? If I understand both sets of advice, could you speak about the difference of opinions? Why would a person not simply upgrade the charge wire from the main junction to the battery, and add an appropriate fuse? Thanks for all your time on this project and your advice. Link to comment Share on other sites More sharing options...
Crazyeights Posted June 29, 2013 Share Posted June 29, 2013 (edited) In my opinion it's important to look at or upgrade/repair the high current circuit at the alternator on ANY car that age. This is a great place to start a meltdown. Increasing the amperage capacity of an alternator does not make it charge any more than your old one did though, unless you add accessories (stereo, lights, winch, ect). With the car running and the accessories on you can check for voltage drop. Try hooking the positive lead of your volt meter to the + alternator large terminal and the negative lead to the positive terminal right at the battery. The voltage reading should be less than about 0.3 or so. Any higher indicates a poor connection or a high resistance situation which will generate heat. Edited June 29, 2013 by Crazyeights Link to comment Share on other sites More sharing options...
mikaleda Posted June 29, 2013 Share Posted June 29, 2013 When I upgraded my alt in my 80 (95 impreza alt) I re wired the charge lead with a heavier duty wire. From my experiences with Subaru I've noticed they tend to make their wiring too small and after 20-30 years it tends to degrade, I would say it would be a good idea to re wire the charge lead with a heavier wire that is less likely to fail. Link to comment Share on other sites More sharing options...
Vegablade Posted December 18, 2013 Share Posted December 18, 2013 Just did the swap. Working great. Voltage never drops below 12 unless bogging it way down. I cheated and cut the connector from the Maxima and then just put two male spades on the end which I inserted into the stock Subaru connector. Will clean up the install later. Don't mind the WCSS mud. Oh also bump. 1 Link to comment Share on other sites More sharing options...
Gloyale Posted December 18, 2013 Share Posted December 18, 2013 Just to be clear when you upgrade....you DEFINATELY should add a new wire from Alt. to Batt. BUT it needs to be protected. IF the ALT shorts internally, it will melt the wire, and then the battery will catch fire........yes......that's what will happen so the circuit needs protection.....got it? In the factory configuration this wire goes through a "FUSIBLE LINK" not a fuse. Newer Legacy, etc....use "Slow Blow" high amp fuses....kinda the same. You don't want a standard "fuse" that will blow suddenly during a spike of the rated amperage. If you use say a 100 AMP.....it might pop during a max. output situation from a spike. You'll blow it often if you have a big stereo or turn on lots of offroad lights while using defrost and blower and then radiator fan kicks in see what I'm sayin? You want it to be "fusible link" wire or a Slow Blow fuse that will only melt after a prolonged(3-15 secs) high amp draw. A 2" length of 10ga fusible link wire will provide 100-130 amps of protection. Place this as close to the battery as possible. 1 Link to comment Share on other sites More sharing options...
Tofutti Posted December 19, 2013 Share Posted December 19, 2013 Just to be clear when you upgrade....you DEFINATELY should add a new wire from Alt. to Batt. BUT it needs to be protected. IF the ALT shorts internally, it will melt the wire, and then the battery will catch fire........yes......that's what will happen so the circuit needs protection.....got it? In the factory configuration this wire goes through a "FUSIBLE LINK" not a fuse. Newer Legacy, etc....use "Slow Blow" high amp fuses....kinda the same. You don't want a standard "fuse" that will blow suddenly during a spike of the rated amperage. If you use say a 100 AMP.....it might pop during a max. output situation from a spike. You'll blow it often if you have a big stereo or turn on lots of offroad lights while using defrost and blower and then radiator fan kicks in see what I'm sayin? You want it to be "fusible link" wire or a Slow Blow fuse that will only melt after a prolonged(3-15 secs) high amp draw. A 2" length of 10ga fusible link wire will provide 100-130 amps of protection. Place this as close to the battery as possible. If one were to upgrade the alt, but still use the original wires, then the wire still goes through a FUSIBLE LINK, as per your second paragraph above. So, if the new alt shorts, it's still protected. I'm not disputing the fact that if one upgrades the alt, then one SHOULD ideally update the wiring (age of the vehicle, degradation, etc.). However, as long as one does not go crazy with adding other electrical loads, one should be fine using the factory wiring, as it was originally set up from the factory with fusible links for protection. An alternator will only provide the amperage it needs to to overcome the load. Luckily, a good battery can overcome the sudden need for lots of amperage in a short burst, and if it can't, folks add a capacitor (This is why the battery cables are much larger than the main charge wire from alt to battery). But the alt still does it's thing, providing a steady flow of current to charge the battery. If the battery can't handle the amperage draw consistently, thus is discharging, THEN the load gets pulled from the alt. That becomes an issue. Just because the new alt is CAPABLE of 90 amps, doesn't mean it will constantly throw 90 amps in to the system if there is no 90 amp draw. I've been running with my alt for 9 months now. I still haven't cleaned up my connections any from my pics above. However, my car had no other electrical issues to begin with. But, I've added a 900 watt amp and band-pass sub set up (running separate lead direct from battery (8 gauge POS and Grounded to chassis with 8 gauge) without upgrading factory alt wires, nor upgrading factory ground wires from Bat to chassis. I almost always have audio turned up, thus, the amp will draw amps. No issues yet. No dimming lights. No nothing. I'm just stating that this has been MY case. And Gloyale, I absolutely agree with the differences you stated regarding slow-blow fuses, fusible links and normal standard fuses. In my opinion it's important to look at or upgrade/repair the high current circuit at the alternator on ANY car that age. This is a great place to start a meltdown. Increasing the amperage capacity of an alternator does not make it charge any more than your old one did though, unless you add accessories (stereo, lights, winch, ect). With the car running and the accessories on you can check for voltage drop. Try hooking the positive lead of your volt meter to the + alternator large terminal and the negative lead to the positive terminal right at the battery. The voltage reading should be less than about 0.3 or so. Any higher indicates a poor connection or a high resistance situation which will generate heat. ^^ This guy is right on the ball. Link to comment Share on other sites More sharing options...
86 Wonder Wedge Posted December 20, 2013 Share Posted December 20, 2013 I've been running this swap for about a year now, approx 15K miles with no problems (with the setup. The alternators however, aren't holding-up well. 3 total in the last year. One had a stripped ear and the other one VR failed. Remans, what are you going to do...) One thing you MUST be careful of is to get the SOHC VQ30DE alternator. Pre-91 Maximas all had the SOHC. 92 and up had the SOHC and DOHC. The DOHC had different plug location and is a royal PITA to plug-in and wire. And while yes, this CAN produce more amperage, I did the swap for higher production at lower RPMs AND off the shelf replacement. Around here, an EA82 alternator is an order item and even then, you have to swap the pulley because they're only supplying 2x pullies on the remans now. And it's a only a few bucks cheaper. The Maxima? Every parts house has one on the shelf. And will for a while because the 90s maximas are 1M times more prevalent then the EA82.. 1 Link to comment Share on other sites More sharing options...
eulogious Posted December 31, 2013 Share Posted December 31, 2013 So I just noticed that there was a little discussion that I apparently missed regarding how I don't fuse the wire from the batt to the alt and I just want to add some facts (not anecdotal evidence of "this is my job, trust me because I say so") based off of the IASCA rules that back up what I said. Page 12, at the bottom of this PDF says it all: http://iasca.com/download/sq/IQC%20Rules%202013%20full%20page.pdf You need to fuse anything within 18" of the battery. So one can naturally infer that anything that is within 18" is safe by these standards. Otherwise they would say 6", or the rule would be right of the battery, not 18". So one can assume that anything under 18" doesn't need to be fused. Further to back this up, the Note on the bottom of page 12 states that between batteries if the wire is 18" or under, there does not need to be a fuse. If these guys say it's ok to do this, then I would pretty much agree with them. These are the guys that judge and regulate bass drags for years. If it was an issue, then these cars that put out massive bass at shows would be catching on fire and burning to the ground on a regular basis, and I would think they would have changed the rules long before 2013. Of course it doesn't hurt to fuse it, but it's not needed, to be technical. Oh, and you only fuse based on the wire, not the device. This is industry standard. I don't know where anyone would get the idea that you need to fuse for the device. The device should be fused itself, therefore there is no need to fuse the wire based on the device as the device is already protected by a fuse. All my amps are fused, and if they aren't I add a fuse within 18" of the amp I don't fuse the wire based on my the device, that's totally overkill and not needed. The only reason to add a fuse to a wire is to protect the wire from catching on fire, period. No other reason. 1 Link to comment Share on other sites More sharing options...
spazomatic Posted December 31, 2013 Share Posted December 31, 2013 Wrong dude. Wire length and wire size are both used when determining the capacity of a wire. Length most certainly matters. But the circuit still needs to be fused, even if less than 18"...which was skishop69s point I think. And all this is presuming we are using wires up to the task anyway. Fuses should be sized to the component in the circuit 1 Link to comment Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in
Sign In Now