Help On 3G Page

[ArdWrknTrk]

My truck came with a voltmeter so I can't have an opinion on this.
But I will say that alternator output is critical to having balanced battery.

[Gary Lewis]

ArdWrknTrk wrote

My truck came with a voltmeter so I can't have an opinion on this.
But I will say that alternator output is critical to having balanced battery.

  Could you explain that, please?

I understand that your truck came with a voltmeter, but why can't you have an opinion?

And what's this about balancing a battery?

[ArdWrknTrk]

My truck doesn't show discharge v/ charge, it only shows what is available now.

If that's not enough to keep the battery charged, then it failed.

Q

[Gary Lewis]

Ah!  Ok.  Thanks for the explanation.

Still, I'm looking for any input I can get on what is out there.  Hello?  

[Machspeed]

I can't seem to get back in it, having skimmed it briefly before the game started.

[Gary Lewis]

I'm in: http://www.garysgaragemahal.com/3g-conversion---in-development.html

[85lebaront2]

Looks good so far sir.

Voltmeter vs Ammeter - Voltmeter displays the system voltage as available at the ignition switch, normal is 13.8-14.5 for a good alternator, battery voltage at key on should be a bit over 12 (keep in mind (a) these are approximate and (b) these gauges are not precision). Once the engine is started the voltage should come up to above 12, preferably around 13, depending on state of charge, amount of cranking and on a Diesel how long the glow plugs were/are on, the voltage will drop each time they cycle the voltage may not jump up at once. Some alternators have a "soft start" regulator to keep from slipping the belt due to a sudden load.

If the belt breaks, alternator stops charging or a fusible link or fuse protecting the alternator fails, the voltmeter will show a drop in the voltage (at night your lights will get dimmer).

Ammeter, in the real world an ammeter would show (and Chrysler's did) power into or out of the battery, however, high loads such as the heater/AC blower on high will show as an increased charge rate, but it isn't, it is showing how much of the alternator output is running the blower. On older vehicles with generators, you would see the meter go to discharge at stoplights, and if the voltage regulator stuck, it would go way into discharge.

Because alternators will charge fairly well at idle, automakers decided that a voltmeter is a better indicator of correct function than an ammeter, however for most uses, the simple "charge indicator" light is adequate, because if it stays on, you have a problem, but on some vehicles a burned out bulb can result in a "no charge" condition.

[JimsRebel]

I Think the Volt Meter should be a separate issue, and not tied to the ALT swap. It really a personal choice as to where you want to monitor the voltage, Battery or Fuse box, for example. It's really just 2 wires to connect, power and ground.

Also I really don't understand the reason for using ... Volt Meter Relay, energized by the stator output.
So if the ALT fails the voltmeter quits working? This is when you really need it to work, to figure out how much farther you can drive before the engine quits. You also can not check battery voltage before starting, or during cranking the engine over.

Regarding the AMP meter:
Even when it work like new, it was really useless. Do you really think you would notice a slow "needle deflection" to the left when on a long freeway drive, (daylight hours). After cruising on the freeway for 2 hours you make a "pit stop" to pee, only then do you realize you have a dead battery.
Also wiring mods, like headlight relays, mess with a correct AMP Meter reading. I sourced the power for my headlight relays of the battery side of the starter solenoid. Turning ON the headlights draw amps through the SHUNT (same as if you were charging the battery) causing the needle to move to the CHARGE direction.
So I turn ON the head lights, needle moves 5 amps in the charge direction. Then the ALT fails, I have a 5 amp load (IGN + misc stuff), needle then moves back to -5 amps, and doesn't include the headlight amp draw.
Point is, I really don't think I AMP meter is worth trying to save.


JIm #2

[Gary Lewis]

Thanks, Bill.

But on the voltage being measured, we are recommending that they measure battery voltage not ignition switch voltage.  If you look at the schematic the voltmeter has its positive leg tied to the fuse link that drops onto the starter relay's battery post.

Jim, Scott, and I had a discussion about it a few days ago.  Scott had a good idea that we could use the LG/R wire that is coming from the ignition switch to run the voltmeter, and while that will work Jim and I convinced him that it is better to know the voltage at the battery rather than in the cab since the latter will vary by what is turned on.

I've enjoyed watching the voltage on Big Blue now that I have the 3G.  There are times when I've had the lights on in the cab and the underhood light on for days working on it and the battery is down a bit.  When I start it the voltage goes to a bit over the top line on the Rocketman voltmeter, which is about 14.4v.  But as the day goes on I can see the regulator cut that back to just under 14v.  So I know the battery is fully charged.

And, I can see the same thing on the aux battery voltmeter, which has a 270 degree sweep and has numbers on the scale.  So I know that both batteries are getting fully charged and all is well with the charging system.

[Gary Lewis]

Jim - You have a very valid point about pulling the relay in with the stator!  I hadn't thought of that, but it is a bad idea.  Thanks!

And, I think I agree with you on the voltmeter wiring being a personal decision.  My problem is how to show that on the page that we have?  If I could figure that out I'd happily address it on the Voltmeter tab and give the people several options.  That way we won't have to address it in each of the scenarios.

As for the ammeter, I had roughly the same situation you described.  Drove Dad's truck from here up to see him about 100 miles and we went out to eat that evening before I was to head home.  That's when I realized that the lights were dim, and then the engine started to miss.  Yep, the alternator had died early in the trip but there wasn't enough pull through the ammeter to see it without anything on in the cab.

So while the ammeter idea is good, the fact that you can't see small discharges isn't workable.  If I'd had a voltmeter I'm sure I'd have seen it.

[JimsRebel]

How I did my 2G to 3G swap:

1: Buy a new Voltage Regulator plug, as you will need all 3 wires, not just 2 wires. Wire in the new plug, just match the colors, adding the stator wire.

2: I back fed the current power wire using a Large Fusible link. This was solder in at the junction point a few inches from the power plug, where 2 wires join into 1 black wire. The original 2G power plug was left so could keep my 2G as a ride along spare.
At this point you will have to decide if you think you truck will ever need more AMPs than the fusible link can provide.
Not sure??? Go to step 3

3: I add a large wire from the ALT output stud > to a 100 amp Circuit Breaker >  Battery side of the starter solenoid.

I have a photo of the 2G harness below. I have more photos if you want me to email them directly to you.
.


Jim #2

[85lebaront2]

Ok, here is what I did, I had bought a 1990 F250 as a donor vehicle for the EFI engine and E4OD. The engine to be rebuilt and using the F3TE heads, mild cam and a little more compression. I took the top of the 1990 engine and installed it on my 1986 short block. At the same time I had already decided to change the dash and wiring to a newer configuration. The first change was to mount the polygroove belt system and FS10 compressor along with the 1990 C2 pump with metric fittings. The alternator was still the 2G in 1990, so since I had a pair of them, and the 1990 had the plug changed to a permanent connection I used it initially. You will note that the alternator sense wire and charging output are all tied together at the fusible link rather than separated by the ammeter shunt.


I bought an uprated 3G, 160 amps from someone on FTE who needed the money, I installed it using the huge wire he had with it and used a 200 amp mega fuse in place of the fusible link, other than the M8X1.25 hole in the small lug it fit right in place. I did have a problem with it slipping the belt, but after looking at the 130 amp 3G on my 1994 Taurus, I found the pulley that came with it (which was the same as the 2G had) was quite small. I put an extra Taurus pulley on and never had any more problems. I did drill out the hole and tapped it for the 3/8-16 bolt the 2G used. It is essentially identical to the Taurus 3.8L 130 amp unit.


Since both the 1990 and the later 1996 wiring use a voltmeter rather than an ammeter and I had the 2G wiring, when my son's 1986 F150 ate the 2G alternator we installed the 1990 one, no charge still. Went into the 1986 wiring and found the portion where the alternator feeds in at the junction of the two fusible links that the BK/O wire from the alternator feeds into at splice S202 was burned, we were seeing 18 + volts at the alternator, but the regulator which is connected on the other end of the shunt, was only seeing the battery voltage, or about 12V. I am sure the intent of this wiring was to have the alternator keep the battery up to 13.8-14.2V, but any interruption of the charging output causes the alternator to overcharge. Since the feed into the main electrical system is the other end of the shunt, this can cause burned out lights among other things.

[Gary Lewis]

Jim - Thanks for your response and your offer of more pics.  I think I understand how you did your conversion, but while it obviously works for you I think we want an easier way to recommend to others.  And on the pics, let's see where this goes as right now I think I have what I need.  But thanks again.

Bill - The later schematic sure looks familiar as that's where I'm getting the 3G schematic I'm dropping into the 1 & 2G schematics.  But your experience with the burned junction explains why Jim/ArdWrknTrk recommends wrapping the sense wire right back to the output at the alternator.  (Which I've failed to do on the schematics so far, I'm now remembering.)

[85lebaront2]

The real issue with it, the 2G goes full output with no place to really load it down, if it doesn't fry every electronic piece on the vehicle, it can still set itself on fire like a Vietnam era Buddhist monk.

[ArdWrknTrk]

The 2G had the sense wire on the far side of the fusible link where the two 10Ga. output wires splice together.
If the fuselink burns the alternator has no sense, and just keeps ramping up, because it's output can't effect the running voltage of the system, and the regulator wants to see it's set point, not 12.6V or whatever the battery has left after the ignition coil and any accessories.

The other problem is when the charge plug corrodes.
It gets really hot and the brass springs lose their grip on the output pins.
If the plug gets hot enough it melts through and the brass terminals ground against the case.
Oh boy! Then it's off to the races.
The windings cook their insulation, the diode board can't handle the current charging into a dead short and it has a meltdown if it doesn't just catch on fire with the flames fanned by the very fan meant to cool it.

It's a lot better to have the y/w wire read the output stud.
There shouldn't be any appreciable drop in the big charge cable, and the voltmeter ( and idiot light in my case) will show the alternator is kaput.

[Gary Lewis]

Yep, I'm in full agreement.  So if I don't show the sense wire wrapped at the alternator in what I do remind me, please.  Albeit gently?  

There is sooooo much to do on this to get it "right" that it is taking a while.

[ArdWrknTrk]

Bill, is your schematic for a 1990 truck?
Because my '87 2G had the sense wire attached to the fender relay (on the other side of the fuselink)
I know it came that way, because I had never touched it.

[Machspeed]

Gary Lewis wrote

Bill - The later schematic sure looks familiar as that's where I'm getting the 3G schematic I'm dropping into the 1 & 2G schematics.  But your experience with the burned junction explains why Jim/ArdWrknTrk recommends wrapping the sense wire right back to the output at the alternator.  (Which I've failed to do on the schematics so far, I'm now remembering.)

Gary, does this mean you will be making some changes to your current wiring schematics?

[Gary Lewis]

Yes, sorta.  What I was talking about with the sense wire is very minor.  The diagram shows it connecting with the output at the megafuse.  Instead I'd shorten the sense wire and put it directly on the output stud.  

Electrically there's no difference, but if the connection between the sense wire and the output wire is done at the megafuse and then the output wire comes loose at the output stud the sense wire won't see what is happening.  But if you put the two together at the output stud there's a chance the sense wire will still be connected to the output.

And I'm making changes in the background on the Voltmeter tab.  I'm not done there, but I would appreciate all input, especially yours, on the 2G stuff.  After all, you are the test case.  So, does this make sense to you?

[Machspeed]

Sorta, I'm in and out on it, as I have other things going on. Tonight, I'm going to pull my 3G, as it is temp fitted, and begin the wiring process. May be lots of questions.