Red this on the JL audio facebook page lately........

[dwnrodeo]

For the "Big 3" I prefer to run upgraded positive and negative wires from the alt to the battery and then run a dedicated power and ground to the amp(s). I then ground the headunit and any other accessories directly to the battery, same goes for positive. That way the alt directly feeds the battery (no chassis or engine block grounding necessary) and the battery directly feeds everything else. I know it's not necessary to do it this way, but it makes me feel better knowing everything is powered from a single point source.

[shawn k]

Shawn I believe the debate is not fusing in general, but fusing at the alt in addition to at the battery.
Protection from both ends, so if alt cable comes off the battery terminal a fuse at the alt will protect it from shorting against the chassis.

I hear you, however I still fail to see why anyone would want a fuse holder directly at the alternator. It's really just not necessary.

Placing a fuse on the charge line "at the battery" makes sense. Even though this is still the charge line, it's the location that is different.

I think there's a misconseption by a few people here that an alternator has enough current dumping capability to "fry up" a heavy guage charge line if the line was somehow shorted. That just isn't so. That's why I stated before that the charging "system" had to be designed properly.. which mostly means providing a charge cable of sufficient size. You could theoretically bolt the output of an alternator directly to ground via heavy guage cable, and that cable still would not burn up. Sure the alt. would be working at its full capacity (most current fow), but the cable would still be fine (within SOA) since the alt simply cannot dump enough current to cause the cable to overheat.


A battery does have the capability to burn up almost any size cable, therefore fusing at the battery makes sense. This is pretty much what almost every vehicle manufacturer does now. I'm also sure that if fusing at the alternator was of great importance, then these manufacturers would indeed have fuses there, yet they don't.

[ttocs]

again what if it is a HO alt?

[shawn k]

again what if it is a HO alt?

If it's a HO alt from the manufacturer, then they would provide a charge cable of the correct size (larger than average)

If someone were to upgrade his own alt, then I would like to believe that he would upgrade his charge line (larger guage cable) at the same time. It really would otherwise be pointless to upgrade the alt.

It goes back to: "properly designed system"

[ttocs]

I do have properly sized wire/cables ran but why would I risk my ho alt/voltage regulator by saving a $10 fuse holder? Why would anyone risk their alt to save a $10 fuse?

[shawn k]

The way I look at it is.. Why put another voltage drop inline? Each and every fuse/holder does resist current even if it's only a little. You should already have a fuse for the charge line at the battery no matter what, but I just don't see the necessity to add another one at the alt itself, especially considering that a short on a charge line is VERY unlikely.

I'd like to see pics of your alt & fuse holder installed. Just how close to the alt do you really think you'll be able to mount the fuse holder?

[ttocs]

so no damage will occure to the HO alt/voltage regulator with the charge lead on the alt grounding out? My fuse might be about a foot downline from teh alt. I guess if the ceramic coated anderson powere pipe were to heat up enough suddenly it might be able to melt the insulation prior to the fuse.

[shawn k]

so no damage will occure to the HO alt/voltage regulator with the charge lead on the alt grounding out? My fuse might be about a foot downline from teh alt. I guess if the ceramic coated anderson powere pipe were to heat up enough suddenly it might be able to melt the insulation prior to the fuse.

Over time (who knows exactly just how long) I'm sure it could damage an alt by causing the alt itself to overheat and destroy the diodes. But it should be able to handle the load for a little. Hopefully long enough to realize you have something significantly wrong happening under your hood! If the short was somehow "fused" to ground (again extremely unlikely) I'm sure the alt would become extremly difficult to turn possibly causing the belt to slip and I'm sure you would hear, smell, see what's wrong right away. None of this however, should EVER be an issue with proper installation of a charge cable.

[Eric D]

Fusing at the alternator sounds like a good idea to me. Not only would it be nice to have a fuse there in the event that the cable came off the battery and shorted to ground, but consider the opposite possibility...

If the alternator or rectifier failed in such a way as to short out, the battery would dump enough current into it to potentially cause a fire. With a fuse it would just blow, and possibly save further damage.

But, I like to use a lot of fuses. Any voltage drop from a fuse may be important to the SPL guys out there, but to anyone in SQ, more fuses is not going to affect their goal.

I am sure plenty of people don't plan on a cable ever coming off of their battery, and I felt the same until last year when the whole battery post fell off my battery. The lead had rotted out internally and eventually the side post with all my connections on it fell off. The battery itself, and all the connections looked as good as new, so I was pretty surprised by the whole event. Lucky for me the post fell out when I went to start the vehicle, so it was never running to have the alternator short out on anything.

[ttocs]

with as much as I will have into that pg/balmar set there will still be a fuse on mine.

[audiophyle_247]

I'm just saying if fusing at the alt could potentially save the alt from self destructing if it's charge wire does short to ground, it may be worth consideration. I wouldn't think the cable would melt, but the alt maybe? Not something I'll loose any sleep over though.

Fusing at the alternator sounds like a good idea to me. Not only would it be nice to have a fuse there in the event that the cable came off the battery and shorted to ground, but consider the opposite possibility...

If the alternator or rectifier failed in such a way as to short out, the battery would dump enough current into it to potentially cause a fire. With a fuse it would just blow, and possibly save further damage.

In this situation the fuse at the batt would blow to protect the battery, even if there were 2 fuses in the charge line the one at the batt would be the first to exceed rating which is why it's there in the first place. The only thing the fuse at the alt end would do is potentially protect the alt from seeing a dead short on the charge wire.

[shawn k]

Hey, if you guys think it's a good idea then by all means have at it. However I'd be willing to bet that if I were to take a peak under Eric's hood today, I wouldn't see a fuse at his alternator (even after proclaiming to have a very odd incident as he described)

Now TTOCS is "planning" on installing a fuse near his alt and I believe him. But at the same time his example presicely explains why it's really pointless.... You guys are claiming that there's a "possibility" of the charge cable comming loose somehow. Sure, I guess it's plausible, but take a look at what TTOCS had said earlier.. he's installing the fuse holder approximately "1 ft" away from the alt. Now whouldn't it be just as feasible for that 1ft of cable going from the alt to the fuse holder to somehow come loose as well?? And couldn't that 1ft of cable somehow short to ground in the event it came loose?? It's really no different than what you guys are claiming "could" happen up at the battery. In which case, I'll stick with my guns and say it's a waist of time to add a fuse at the alt.

The only scenario that I would see it being legit (adding a fuse at the alt) would be if the fuse holder itself was somehow fabricated as part of the alt's chassis. In other words, no lead wire to the fuseholder. The connection from the alt to the fuse would be done internally, and the other side of the fuse would then have a lead feeding the battery. If any of you would were to go this far in fabrication, then and only then would I see it justifiable and I would be impressed. I'm NOT saying anyone needs to impress me, I now none of you give a shit what I say anyway.....lol... I'm just saying

[Eric D]

I'm just saying if fusing at the alt could potentially save the alt from self destructing if it's charge wire does short to ground, it may be worth consideration. I wouldn't think the cable would melt, but the alt maybe? Not something I'll loose any sleep over though.

Fusing at the alternator sounds like a good idea to me. Not only would it be nice to have a fuse there in the event that the cable came off the battery and shorted to ground, but consider the opposite possibility...

If the alternator or rectifier failed in such a way as to short out, the battery would dump enough current into it to potentially cause a fire. With a fuse it would just blow, and possibly save further damage.

In this situation the fuse at the batt would blow to protect the battery, even if there were 2 fuses in the charge line the one at the batt would be the first to exceed rating which is why it's there in the first place. The only thing the fuse at the alt end would do is potentially protect the alt from seeing a dead short on the charge wire.

If something in the alternator failed and shorted, the fuse on the battery would not blow, unless I am missing something. In my vehicle for example, there is a solid wire from the alternator to the battery (+) post. There is a solid wire from the battery (-) to the chassis. The only fuse is the one I installed, which is on my power wire and is after the battery. If the alternator failed, and shorted, it would complete a circuit from the battery through to ground, which would probably cause a fire.

Also, Shawn is correct, I do not have a fuse on my alternator. But, I have a 100% stock electrical system also, other than the addition of a power wire on my battery for my stereo.

[audiophyle_247]

Eric, the discussion was on fused charge cables, as part of the big 3, where you would be introducing a new charge cable and if both ends should be fused or not. Both of my old Civics (92 & 93's) ran the charge cable to the fuse panel, not the battery, so they were protected. I think my Element runs the charge cable straight to the battery without a fuse. That's part of why I think the alts must have some kind of protection circuit inside, but I also don't think an alt will ever short to ground unless serious mechanical failure. If the internal rectifiers or diodes short closed the alt just stops producing DC power & introduces more AC to the battery.

[stipud]

Stock wiring usually has a fusible link for the alternator, so if upgrading the wire, it should be fused IMO. My last alt burned up really bad without a fuse... I'm glad it didn't ignite anything else in the engine bay!

[shawn k]

Stock wiring usually has a fusible link for the alternator, so if upgrading the wire, it should be fused IMO. My last alt burned up really bad without a fuse... I'm glad it didn't ignite anything else in the engine bay!

Usually it does... Yes. And the fuse is located at the battery, not the alt.

[Eric D]

Eric, the discussion was on fused charge cables, as part of the big 3, where you would be introducing a new charge cable and if both ends should be fused or not. Both of my old Civics (92 & 93's) ran the charge cable to the fuse panel, not the battery, so they were protected. I think my Element runs the charge cable straight to the battery without a fuse. That's part of why I think the alts must have some kind of protection circuit inside, but I also don't think an alt will ever short to ground unless serious mechanical failure. If the internal rectifiers or diodes short closed the alt just stops producing DC power & introduces more AC to the battery.

In my vehicle the charge line is about 24in long. There currently is no fuse on it (stock). If I were to put a fuse on it, I would put it 6in from the battery (closest place to mount it), which would leave me 18in un-fused from the alternator. I see no point in putting a second fuse 12 more inches down the line. If I managed to cut the alternator line in that 18in and shorted it out, I would have other things to worry about, as it would likely mean I was in a head on collision.

[Eric D]

Apparently I missed the part where the discussion started covering putting two (2) fuses on the line between the alternator and the battery.

Unless the line is longer than a few feet, I don't see much point in doing it. With a vehicle which has its battery located in the rear, then there could be some benefits to having two separate fuses, one up front, and one in the rear.

[ttocs]

hey shawn I know how you can settle this for us right now.

go out and start your car and then short out your charge cable. A vid is a must-have....... I mean it should be able to take the load right? Put your money where your mouth is and if you don't have to buy a new alt I will salute you.

[shawn k]

hey shawn I know how you can settle this for us right now.

go out and start your car and then short out your charge cable. A vid is a must-have....... I mean it should be able to take the load right? Put your money where your mouth is and if you don't have to buy a new alt I will salute you.

You first!

[shawn k]

In my vehicle the charge line is about 24in long. There currently is no fuse on it (stock). If I were to put a fuse on it, I would put it 6in from the battery (closest place to mount it), which would leave me 18in un-fused from the alternator. I see no point in putting a second fuse 12 more inches down the line. If I managed to cut the alternator line in that 18in and shorted it out, I would have other things to worry about, as it would likely mean I was in a head on collision.

That is essentially the point I have been making this whole time

[ttocs]

so no damage will occure to the HO alt/voltage regulator with the charge lead on the alt grounding out? My fuse might be about a foot downline from teh alt. I guess if the ceramic coated anderson powere pipe were to heat up enough suddenly it might be able to melt the insulation prior to the fuse.

Over time (who knows exactly just how long) I'm sure it could damage an alt by causing the alt itself to overheat and destroy the diodes. But it should be able to handle the load for a little. Hopefully long enough to realize you have something significantly wrong happening under your hood! If the short was somehow "fused" to ground (again extremely unlikely) I'm sure the alt would become extremly difficult to turn possibly causing the belt to slip and I'm sure you would hear, smell, see what's wrong right away. None of this however, should EVER be an issue with proper installation of a charge cable.

Ah c'mon now you said above here that in a properly designed system it should be able to handle it for a short time at least? Long enough for you to realize something is significantly wrong under the hood right? Figure 10 secs to watch the volt gauge and see that something is definitly up, 5-10 secs to pull over to the side of the road, 15 secs to pop the hood and look under and see what is wrong(assuming you are fast to get out, quick to open the hood and then can easily see what is wrong). No not counting the time to run back and turn off the motor that is only 30 secs right? So why would you be afraid to go short the charge lead for 30 secs to show us that you are right? I would be happy to go show what a large amperage fuse looks like when it blows on mine if you really have to see it but we all know mine is safe. Safer then yours.............

[Eric D]

hey shawn I know how you can settle this for us right now.

go out and start your car and then short out your charge cable. A vid is a must-have....... I mean it should be able to take the load right? Put your money where your mouth is and if you don't have to buy a new alt I will salute you.

This would make for a good video. Probably get some high YouTube hits as well...

[ttocs]

would also settle this debate both on here and other sites where I have seen it.

[shawn k]

hey shawn I know how you can settle this for us right now.

go out and start your car and then short out your charge cable. A vid is a must-have....... I mean it should be able to take the load right? Put your money where your mouth is and if you don't have to buy a new alt I will salute you.

This would make for a good video. Probably get some high YouTube hits as well...

Yes.... Yes it would!