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On my old e99, both batts grounded to the same location on the lower block. On my current 02, I cannot recall if both batts terminated there (even though I did the alt upgrade thing back in December). In both trucks, there was enough stud length to add another ground wire (either from a negative batt terminal or the alt case).
And just to add to the discussion about extra grounds: awhile back I worked in a huge sawmill. The main piece of equipment was a 3-axis saw that relied heavily on sophiscated controls. After I started, I learned that the saw would have a "mind of its own" on random ocassions. Since it was my job to keep the plant running, I needed to figure out what the deal was, because it was getting worse. The mill was constructed in 1974 (I started in 2005), and like most heavy industrial facilities, a ground grid was put in before the slab(s) were poured. On a hunch we checked for stray voltage on the ground system. Sure enough, it was a mess (underground corrosion was getting the upper hand as it turned out). We cut a hole in the floor next to the big saw and drove a giant rod into the earth (amongst other remedial efforts). Problem solved. The take-away? Stray voltage (which is a form of bad ground) raises holy-old-heck on sensitive electronic control equipment - which normally runs at sub 50v DC by the way - just like the PCMs.
In regards to our 20+ year old rigs, connections will be compromised - even in the most arid conditions (my 02 was from AZ and one of the first things I did was clean all the ground points I could, and it needed it). Anything that can be done to keep electric current in its place will be in the best interest of minimizing/eliminating nuisance or intermittent problems. Or leading one down a false path of troubleshooting. Especially in these floating ground systems that are not truly grounded - to earth. Having done an alt upgrade on two of these things, including upgrading cable size and adding an extra block ground connection at the alt, my seat of the pants take is that starting is more spirited and my batteries got a season longer out of them than before the upgrade (on my 99, i havent had the 02 long enough to tell). And it may sound weird, but my lights seemed brighter. Is this all due to an extra ground? prob not entirely. But if one is going to up-size the alternator and red lines, doing the same (and more) on the black lines will ensure you dont introduce some wildcard problem that keeps your truck in the driveway instead of on the road.
I'll add to this that since I've installed the aux power and ground cables to my alternator assembly, the volt meter on the dash reads consitantly higher than it did before.
That's one reason I don't quite understand this mod. lol
Good electrical practice is to have both positive and negative cabling the same size. If one goes with a larger alternator, larger positive leads should follow*. Therefore the need for "larger" negative leads. The options there would be to upsize the existing battery to ground cabling in proportion to the upgraded positive cabling, or; add another intimately connected ground to the system (in this case alternator to block) and keep the stock battery to ground cabling.
*Soon after getting my '02, I decided to slam in my IdlePro from my "retired" e99 since I was changing the belt. I put it in without changing the cabling (that I also kept). After a quick spin, not only was the alternator screaming hot**, but the stock wiring was quite hot too.
**I have been noticing an occasional nearly too hot to touch alternator (IdlePro with upsized cabling all around + additional alt to block cable). I am coming around to the fact that it is because of the state of charge of the batts going into a cold weather start (less than 0F), where I forgot to plug in trickle charger, and after a short drive type scenario. However warm the alternator case may be, the wiring is never warmer than the general engine compartment temperature.
Goes from the negative battery straight to the engine block on both side batteries. That's one reason I don't quite understand this mod. lol
That is OK, we all do things we don't fully understand at times. Sometimes it works out and sometimes it doesn't.
The way I see it is that people a lot smarter than me have completed one form or another of the grounding "mod" and the electrical system in my truck has been running at top notch capability even after 24 years of service.
To each their own, but I saw no issues with the few dollars it cost me for ground cable and lugs since I was in there installing multiple parts at the time.
Originally Posted by pvdiag
On my old e99, both batts grounded to the same location on the lower block. On my current 02, I cannot recall if both batts terminated there (even though I did the alt upgrade thing back in December). In both trucks, there was enough stud length to add another ground wire (either from a negative batt terminal or the alt case).
And just to add to the discussion about extra grounds: awhile back I worked in a huge sawmill. The main piece of equipment was a 3-axis saw that relied heavily on sophiscated controls. After I started, I learned that the saw would have a "mind of its own" on random ocassions. Since it was my job to keep the plant running, I needed to figure out what the deal was, because it was getting worse. The mill was constructed in 1974 (I started in 2005), and like most heavy industrial facilities, a ground grid was put in before the slab(s) were poured. On a hunch we checked for stray voltage on the ground system. Sure enough, it was a mess (underground corrosion was getting the upper hand as it turned out). We cut a hole in the floor next to the big saw and drove a giant rod into the earth (amongst other remedial efforts). Problem solved. The take-away? Stray voltage (which is a form of bad ground) raises holy-old-heck on sensitive electronic control equipment - which normally runs at sub 50v DC by the way - just like the PCMs.
In regards to our 20+ year old rigs, connections will be compromised - even in the most arid conditions (my 02 was from AZ and one of the first things I did was clean all the ground points I could, and it needed it). Anything that can be done to keep electric current in its place will be in the best interest of minimizing/eliminating nuisance or intermittent problems. Or leading one down a false path of troubleshooting. Especially in these floating ground systems that are not truly grounded - to earth. Having done an alt upgrade on two of these things, including upgrading cable size and adding an extra block ground connection at the alt, my seat of the pants take is that starting is more spirited and my batteries got a season longer out of them than before the upgrade (on my 99, i havent had the 02 long enough to tell). And it may sound weird, but my lights seemed brighter. Is this all due to an extra ground? prob not entirely. But if one is going to up-size the alternator and red lines, doing the same (and more) on the black lines will ensure you dont introduce some wildcard problem that keeps your truck in the driveway instead of on the road.
Well said sir.
Originally Posted by John in OkieLand
I have never been underneath my '02 Excursion, so don't know where the grounds go...
I need to find them and clean them up...
Bottom side and just behind the fan toward the front (radiator) of the engine. Very easy to get to once you know where they are at.
Good electrical practice is to have both positive and negative cabling the same size. If one goes with a larger alternator, larger positive leads should follow*. Therefore the need for "larger" negative leads. The options there would be to upsize the existing battery to ground cabling in proportion to the upgraded positive cabling, or; add another intimately connected ground to the system (in this case alternator to block) and keep the stock battery to ground cabling.
I understand what your saying and why people think it's a good idea just seems redundant to me when there are already 2 of that are the same size or bigger then then alternator cable people use. Wouldn't that make it sufficient? 2 of the sameish size is larger then one.
Seems about like the same logic as wearing 2 pair of underwear to me. I guess accidents do happen though. 😂
This picture is a good illustration on why I started installing parallel charge circuits years ago. The fuse panel in the picture is typical of what you would find on a MK4 VW Jetta with a lot of accessories. (Heated seats, etc.) The electrical load is simply too much for the steel stud to carry without getting so hot it would melt the plastic housing that the fuze box was made out of. Fuse never blow out, but the circuit had a high impedence because that steel stud was so hot. Installing a new fuse box assembly was a guarantee that the fix would only be temporary and they would be back and this time the fix would be on my dime and time. So what I did instead was install a 4g cable routing the circuit around that weak point from the output of the alternator directly to the positive post of the battery along with a new fuse box assembly.
Not every vehicle has this issue. My Ford does in the fact that the charge voltage at the battery is lower than at the alternator post, so that's why I installed the Pos and Neg cables. Every MK4 VW does, so they would get at least the Pos cable and make sure the ground cable was clean, down to bright shiny metal at every connection. The body ground was under the battery tray but removing that was four bolts and it's out. My 2002 Silverado does not. I can turn everything on with that truck and the voltage stays at 14.25, even at idle.
I 100% understand why it's done and upgrading the positive cable on the alternator for a bigger alternator. This thread is about running a ground wire to the alternator on a 7.3 though. Which again seems redundant and not needed to me when there are already 2 ground cables that are roughly twice the size of the stock alternator cable already. Which work fine for the starter motor which I'm fairly ok with saying is going to draw more amps then your upgraded alternator will ever pull.
Alternators these days are internally regulated. "Technically" it shouldn't make a difference on how well the charging system maintains correct battery voltage, but I'm always on the side of "too much is better than not enough", so I always run the extra ground cable to the alternatory so I have no doubts in my mind about the accuracy of what the alternator needs in order to get it's job done.
The frame and body panels conduct much better than any size cable. Of course a rusty mess will have problems and the hidden ground straps may get overlooked.
But our older vehicles may not be as sensitive to ground loops or elevated voltage on a ground plane and we can get away with less than optimal practices.
Seems about like the same logic as wearing 2 pair of underwear to me. I guess accidents do happen though. 😂
More like wearing two condoms after a night of heavy drinking and going home with a sketchy date. We all know these trucks can be a hot mess at times and electrical gremlins are even worse.
I want to clarify. I’m not arguing the fact that some extra block grounding may be better, especially with the aging of our trucks wiring. I just don’t like the thought of grounding it near or possibly through the alternator. If there’s a chance the other ground is compromised then the starting current could be directed through the alternator.
The link that was posted kind of describes my concern. Just replace alternator where they say ECU.
Same goes when jump starting a modern vehicle. Make sure it’s not grounded near the ECU.
Although I added the additional alt case to engine block grounding on my truck, I can understand the argument that it isn't really needed. However, I will point out that at least the IdlePro (which I have) goes out of its way to include additional case grounding protection to the design. I suspect the reason for this is that the higher outputs (current) are susceptible to "bleeding" into the case, which is kept to the absolute smallest it can be to retain fitment and keep costs down. When I first looked into this upgrade, my first thought was I had better plan for an added ground cable to account for the higher output and never thought more of it. Namely because I have had very good experience in setting a common ground point in my boat and to make sure everything connects to it.
Although I added the additional alt case to engine block grounding on my truck,
This is different than what I was making my argument against. There shouldn’t be a possibility of starter pulling through this setup and I can’t imagine any potential negative aspects grounding like this. But you’re the electrical expert and know much more than me regarding this stuff.
When talking about electrical upgrades, a few posts talk about a direct grounding wire from the alternator case to the negative battery post.
What is the value added for this? The alternator is grounded to the engine block, the engine block is attached to the negative battery post by a cable.
Trying to learn
Originally Posted by MDHunter
I upgraded my battery cables to 3/0 welding cable about 2 years ago, keep coming across "you need to ground your alternator" posts... was wondering if I was missing something.
As pvdiag mentioned, following the instructions of the alternator manufacturer in his (and my) case, as well as the suggestions of Ford and International, is not a bad idea.
The particular upgraded alternator I am talking about, and more importantly to this tangent of topic.. the upgraded wiring kit, which included a negative cable, was also sold by Ford for the Ford Low Cab Forward (no longer available), and is still sold by International for the discontinued City Star... which is the same vehicle as the Ford Low Cab Forward, built by the now defunct Blue Diamond partnership that fizzled between Ford and International.
Despite that partnership losing its "ground", the manufacturers involved (Prestolite Leece Neville, Ford, and International) made sure that the upgraded alternator wouldn't lose its ground, as snippets of an installation TSB shown below demonstrate:
While the International Part # for their cable upgrade kit was designed to fit the LCF cab over with the 4.5L V6 diesel, which was the ill fated short lived baby brother to the 6.0L PSD, the operating principle still applies to the 7.3L, which also have rather small wiring to match small 110 amp alternator that was original equipment.
It is useful to consider the patterns and choices of OEM manufacturers, who have the resources to validate what value is added by any given component, and who also have an incentive (cost reduction) to not include or add any additional component without a well justified reason, usually vetted by engineers, accountants, lawyers, and management.
It is doubtful that any harm could be done by following the pattern and instruction prescribed by the OEMs.
