"Alternator" 115 Amp Bosch AL129X works in 123s! - Page 3 - PeachParts Mercedes-Benz Forum

rg2098 · #1 12-10-2004, 10:31 PM

Quote:

Originally Posted by pawoSD

How much juice can the 65amp alternators actually maintain......say if I wanted to use a 1000 or 1500 watt power invertor clamped to my battery terminals/cables with the engine idling and all car electronics/fans and lights turned off? Would that apply too much to a 65 amp alternator? I have run a 400 watt one off it with a few hundred watts load with no issues......So I am wondering what the capacity would be for running invertors......the more I can run off it the more portable power/less I have to turn off in a power outage.

I have the very same question.

gsxr · #2 12-10-2004, 10:54 PM

A 65A alternator will put out about 65A of juice above idle. At idle, a bit more than half that - maybe 35A, and if demand exceeds supply the voltage will drop down. The 115A unit can probably put out 50-60A at idle. If you need the power, upgrade the alternator - it makes a big difference. Much easier on the later engines with serpentine belts...

81Wagon · #3 12-10-2004, 11:45 PM

Quote:

Originally Posted by rwthomas1

81Wagon,
What exactly are the modifications to the wiring? I can do darned near anything mechanical but when I work on electrical stuff I let the "magic smoke" out of the wires.... Step be step details would be great. RT

Basically, you're going to have to completely replace the wiring from the alternator to the battery (or rather, the little junction box near the battery). Lots of auto parts stores will carry something like an alternator wiring kit (basically just a couple very heavy-gauge (8 gauge should do it) wires and appropriate connectors).

The stock Bosch alternator has a three-prong connector and your car has a plastic plug with three wires that connect to it. The two big wires are positive (+) output from the alternator, and connect to the little black junction box between the battery and the coolant resivoir. The little wire, which should be blue, eventually connects to the battery light on the dash, performing whatever magic is necessary to make sure the light doesn't light up when it should (leaving you unexpectedly stranded with a dead battery and crapped out voltage regulator

). The stock connector will not work with your new alternator, but that isn't much of a problem since you'll have to rewire the alternator anyway.

Once your old alternator is out, you can cut the blue wire about an inch back from the plastic connector end. Attach another few feet of the same gauge wire to it (blue wire if you want to keep with the color scheme). You will need this wire later to connect to your new alternator.

Leave the other wires alone, and protect the stock plastic connector from shorting out by wrapping it with lots of electrical tape (or something, be creative

). Then use a tie-strap to secure it to something. You will always be ready to go back to a stock alternator if need be!

Install the new alternator (it will be a tight fit and the belts will be hard to get back on). As described earlier in this thread, you can take out the four screws in the alternator body and rotate the back half to a point where the alternator's electrical connections and voltage regulator aren't blocked by your car's AC hoses.

Once the new alternator is in, get out the alternator wiring "kit" described earlier. Crimp and/or solder ring connectors onto one end of each of the wires, and attach one each to the two larger junctions in the junction box near the battery (flip the top of the little black box open, there should be two big screws and one little one holding down the wires. Unscrew the two big screws, add in your new wires, screw them back in, and close the top of the box).

Now, route the cables down toward the alternator using the best (shortest) path you can find, securing the wires with tie-straps every foot or so. You also want to route the blue wire from earlier over to the alternator.

The alternator has three connectors: two big, obvious ones (one is just a bolt and the other is a slightly smaller bolt with a flat connector on it too) and one sort of on the opposite side that is a smaller flat connector (recessed in the body of the alternator, not sticking out). Cut the blue wire to the necessary length and attach an appropriately-sized female connector to it, and plug it into the smaller, recessed connector.

The two heavy-gauge power wires each get cut to length and connected to one of the remaining two larger connections using appropriate connectors (ring connectors or a ring and a flat connector).

So in a nutshell, what you want to do is this:
* Connect your old blue wire to the new alternator at the small, recessed connector, and get the old power wires safely out of the way.
* Connect two new heavy-gauge (8 gauge should do it) from the car's power junction box to the power connectors on the new alternator.

You're done! Enjoy your new alternator!

Quote:

Originally Posted by pawoSD

81Wagon,
How much juice can the 65amp alternators actually maintain......say if I wanted to use a 1000 or 1500 watt power invertor clamped to my battery terminals/cables with the engine idling and all car electronics/fans and lights turned off? Would that apply too much to a 65 amp alternator? I have run a 400 watt one off it with a few hundred watts load with no issues......So I am wondering what the capacity would be for running invertors......the more I can run off it the more portable power/less I have to turn off in a power outage.

Watts divided by voltage equals amps. So 1500w/13v = 115A, and 1000w/13v = 77A. Using the same equation (and unrealistically assuming everything is running perfectly) you can find that 65A alternator can put out about 845 watts maximum. But I don't think the alternator can put out the max amps at idle speed...

jayb79 · #4 12-11-2004, 10:50 AM

DON'T FORGET TO DISCONECT THE BATTERY BEFORE YOU START!!!

That will lesson the chance of letting the smoke out.

81Wagon · #5 12-11-2004, 11:41 AM

Quote:

Originally Posted by jayb79

DON'T FORGET TO DISCONECT THE BATTERY BEFORE YOU START!!!
That will lesson the chance of letting the smoke out.

This is good advice. I didn't mention that because I figured it was a necessary step as part of taking the old alternator out, but I suppose one can never be too careful.

pdxwaker · #6 01-10-2005, 01:22 PM

Quote:

Originally Posted by 81Wagon

The stock Bosch alternator has a three-prong connector and your car has a plastic plug with three wires that connect to it. The two big wires are positive (+) output from the alternator, and connect to the little black junction box between the battery and the coolant resivoir.

Why do alternators always have two positive outputs like this? Before I read this I assumed that one was positive, the other was ground...

I'm getting ready to perform this alternator upgrade on my '83 300DT so I would like to understand this a bit more before I move ahead...

-John

gsxr · #7 01-10-2005, 01:46 PM

That was to allow good enough connection using blade connectors and small wire. Later, higher-output models use a threaded post and a single large wire to the battery instead of two small ones.

#8 07-25-2006, 11:57 PM

I just did the alternator conversion decribed but when I turn of the car the battery light on the dash stays on? I'm concerned this will kill the battery.

Also when the blue wire is hooked to + power the glow plug light won't go on & the battery lights come on when attempting to start. Do I need the blue wire hooked up? Any advice would be great! -85' 300DT

Quote:

Originally Posted by 81Wagon

Basically, you're going to have to completely replace the wiring from the alternator to the battery (or rather, the little junction box near the battery). Lots of auto parts stores will carry something like an alternator wiring kit (basically just a couple very heavy-gauge (8 gauge should do it) wires and appropriate connectors).

The stock Bosch alternator has a three-prong connector and your car has a plastic plug with three wires that connect to it. The two big wires are positive (+) output from the alternator, and connect to the little black junction box between the battery and the coolant resivoir. The little wire, which should be blue, eventually connects to the battery light on the dash, performing whatever magic is necessary to make sure the light doesn't light up when it should (leaving you unexpectedly stranded with a dead battery and crapped out voltage regulator

). The stock connector will not work with your new alternator, but that isn't much of a problem since you'll have to rewire the alternator anyway.

Once your old alternator is out, you can cut the blue wire about an inch back from the plastic connector end. Attach another few feet of the same gauge wire to it (blue wire if you want to keep with the color scheme). You will need this wire later to connect to your new alternator.

Leave the other wires alone, and protect the stock plastic connector from shorting out by wrapping it with lots of electrical tape (or something, be creative

). Then use a tie-strap to secure it to something. You will always be ready to go back to a stock alternator if need be!

Install the new alternator (it will be a tight fit and the belts will be hard to get back on). As described earlier in this thread, you can take out the four screws in the alternator body and rotate the back half to a point where the alternator's electrical connections and voltage regulator aren't blocked by your car's AC hoses.

Once the new alternator is in, get out the alternator wiring "kit" described earlier. Crimp and/or solder ring connectors onto one end of each of the wires, and attach one each to the two larger junctions in the junction box near the battery (flip the top of the little black box open, there should be two big screws and one little one holding down the wires. Unscrew the two big screws, add in your new wires, screw them back in, and close the top of the box).

Now, route the cables down toward the alternator using the best (shortest) path you can find, securing the wires with tie-straps every foot or so. You also want to route the blue wire from earlier over to the alternator.

The alternator has three connectors: two big, obvious ones (one is just a bolt and the other is a slightly smaller bolt with a flat connector on it too) and one sort of on the opposite side that is a smaller flat connector (recessed in the body of the alternator, not sticking out). Cut the blue wire to the necessary length and attach an appropriately-sized female connector to it, and plug it into the smaller, recessed connector.

The two heavy-gauge power wires each get cut to length and connected to one of the remaining two larger connections using appropriate connectors (ring connectors or a ring and a flat connector).

So in a nutshell, what you want to do is this:
* Connect your old blue wire to the new alternator at the small, recessed connector, and get the old power wires safely out of the way.
* Connect two new heavy-gauge (8 gauge should do it) from the car's power junction box to the power connectors on the new alternator.

You're done! Enjoy your new alternator!

Watts divided by voltage equals amps. So 1500w/13v = 115A, and 1000w/13v = 77A. Using the same equation (and unrealistically assuming everything is running perfectly) you can find that 65A alternator can put out about 845 watts maximum. But I don't think the alternator can put out the max amps at idle speed...

woodall33 · #9 08-11-2006, 11:54 AM

Ok, I read through all of this, but have yet jumped into any install/uninstall work. Basically it boils down to not having time lately.

I have a couple of quick questions, that maybe were absolute solutions stated, but I may have misread them. Just looking for a little verification here.

I have an 82 300SD, 126 body. I'm looking to upgrade the alt, basically to as big as possible. One post on this thread started by mentioning the AL129X (115A) from a Saab 9000. Then later on, someone mentioned a 150A option, but I was unsure if they were talking with regards to a 300SD, or a different model. 115A would probably get me by just fine, but if I have the option of something a little bigger, I'm probably inclined to go ahead and give it a shot.

So, fast forward from the earlier mentioned discussions in this thread. I have talked with a tech from a alt company who claims his GM style small chassis alternators will fit, but he was not 100% if the bolt holes are the same. Can anybody tell me what the hole-to-hole distance for the mounting holes is for this car's alternator? He says his replacement is 5 7/16 inches, and "should" be the same. The "should" scares me, as he won't cover return shipping should it not fit. His price is right, which is why I'm as interested as I am. This is what he has: http://www.alternatorparts.com/cs130d_cs144_trk_suv_upgrade.htm

Any input is greatly appreciated.

HughO · #10 04-21-2021, 12:18 PM

Quote:

Originally Posted by 81Wagon

Basically, you're going to have to completely replace the wiring from the alternator to the battery (or rather, the little junction box near the battery). Lots of auto parts stores will carry something like an alternator wiring kit (basically just a couple very heavy-gauge (8 gauge should do it) wires and appropriate connectors).

The stock Bosch alternator has a three-prong connector and your car has a plastic plug with three wires that connect to it. The two big wires are positive (+) output from the alternator, and connect to the little black junction box between the battery and the coolant resivoir. The little wire, which should be blue, eventually connects to the battery light on the dash, performing whatever magic is necessary to make sure the light doesn't light up when it should (leaving you unexpectedly stranded with a dead battery and crapped out voltage regulator

). The stock connector will not work with your new alternator, but that isn't much of a problem since you'll have to rewire the alternator anyway.

Once your old alternator is out, you can cut the blue wire about an inch back from the plastic connector end. Attach another few feet of the same gauge wire to it (blue wire if you want to keep with the color scheme). You will need this wire later to connect to your new alternator.

Leave the other wires alone, and protect the stock plastic connector from shorting out by wrapping it with lots of electrical tape (or something, be creative

). Then use a tie-strap to secure it to something. You will always be ready to go back to a stock alternator if need be!

Install the new alternator (it will be a tight fit and the belts will be hard to get back on). As described earlier in this thread, you can take out the four screws in the alternator body and rotate the back half to a point where the alternator's electrical connections and voltage regulator aren't blocked by your car's AC hoses.

Once the new alternator is in, get out the alternator wiring "kit" described earlier. Crimp and/or solder ring connectors onto one end of each of the wires, and attach one each to the two larger junctions in the junction box near the battery (flip the top of the little black box open, there should be two big screws and one little one holding down the wires. Unscrew the two big screws, add in your new wires, screw them back in, and close the top of the box).

Now, route the cables down toward the alternator using the best (shortest) path you can find, securing the wires with tie-straps every foot or so. You also want to route the blue wire from earlier over to the alternator.

The alternator has three connectors: two big, obvious ones (one is just a bolt and the other is a slightly smaller bolt with a flat connector on it too) and one sort of on the opposite side that is a smaller flat connector (recessed in the body of the alternator, not sticking out). Cut the blue wire to the necessary length and attach an appropriately-sized female connector to it, and plug it into the smaller, recessed connector.

The two heavy-gauge power wires each get cut to length and connected to one of the remaining two larger connections using appropriate connectors (ring connectors or a ring and a flat connector).

So in a nutshell, what you want to do is this:
* Connect your old blue wire to the new alternator at the small, recessed connector, and get the old power wires safely out of the way.
* Connect two new heavy-gauge (8 gauge should do it) from the car's power junction box to the power connectors on the new alternator.

You're done! Enjoy your new alternator!

Watts divided by voltage equals amps. So 1500w/13v = 115A, and 1000w/13v = 77A. Using the same equation (and unrealistically assuming everything is running perfectly) you can find that 65A alternator can put out about 845 watts maximum. But I don't think the alternator can put out the max amps at idle speed...

excellent writeup geared to newbies but useful to all

MTUpower · #11 12-12-2004, 07:34 PM

I was pulling one of these out of a SAAB today- what a nightmare! Now I gotta go back to finish the job this week.

#12 12-14-2004, 09:38 AM

I am hitting up the Foriegn Auto U-Pull It tomorrow.
If I can find more than one...would some forum members be interested in one? I used to rebuild these babys every day at work and, if people want more than just a core to work with, I could perhaps throw some new internals in (regulator, brushes, give it a little polish)

Yes/no?

Hopefully I will find one...if I find a few...I will see how much for them and if cheap enough...hook you guys up

If anyone FOR SURE wants one if I find some I will get you one
Cost= Alternator from Yard + Shipping + Few Fuel Dollars (its a ways away)
if you wanted it tested I coudl do this too at old work...but we will see how it goes

Email me, or you can call me

Brandon
brandon314@gmail.com
Cell: 503-476-5610 (don't call before 11am-12pm...I sleep late :-D)

I am going to bed (6am here) so don't expect replies for about another 5 hours or so

boneheaddoctor · #13 12-14-2004, 09:50 AM

Quote:

Originally Posted by Brandon314159

I am hitting up the Foriegn Auto U-Pull It tomorrow.
If I can find more than one...would some forum members be interested in one? I used to rebuild these babys every day at work and, if people want more than just a core to work with, I could perhaps throw some new internals in (regulator, brushes, give it a little polish)

Yes/no?

Hopefully I will find one...if I find a few...I will see how much for them and if cheap enough...hook you guys up

If anyone FOR SURE wants one if I find it (and are willing to pay shipping plus a few bucks for my pulling time plus the cost of the alternator from the yard) I will get you one.
Email me, or you can call me

Brandon
brandon314@gmail.com
Cell: 503-476-5610 (don't call before 11am-12pm...I sleep late :-D)

You have email........

#14 12-14-2004, 09:12 PM

Ok...this wrecking yard let me down this time
No alternators (maybe they pull them?) and they overcharged me on everything I got

Chodes..

Anywho...I will keep my eyes out for alternators. If anyone has a hook up please let me and the forum people know.
I was offering to do rebuilds (brushes, regulators unless new looking ones, and tests) for 20 bucks plus parts if members payed to ship to and fro my house. (so like 30 bucks plus parts?)

I would like to find one of these for my car also so maybe someone here has one.
Thanks a bunch!

(visiting another wrecking yard later this week)

Brandon

rwthomas1 · #15 12-14-2004, 11:20 PM

These AL129X's are not that common. According to the wrecking yard they were optional. There was also an 80amp unit installed in the same cars, same years. I looked at a Saab motor today but I couldn't tell by the alt, all the markings were gone, which one it was. They also had an 89 Saab 9000 which according to the yard also MAY have the 115, but it MAY have the 80 too. After looking at what it would take to remove it (Saab "engineers") and the outside temps I chose to not attempt to remove it. Hmmmm, gotta try some other yards. RT