"Alternator" 115 Amp Bosch AL129X works in 123s! - Page 11 - PeachParts Mercedes-Benz Forum

whunter · #**151** 09-06-2007, 10:12 PM

Quote:

Originally Posted by renman

1984 300D turbo.
This is related so bear with me. I posted yesterday regarding a battery drain problem. After exhausting all the different tests suggested by forum members, I ordered the AL129x alternator today from California Alternator & Starter. Now here is the question. I scanned my wiring diagrams trying to determine where the (power) wiring ends when it leaves the alternator.According to the wiring diagram the alternator wires go to the starter. It doesn't. Deerefanatic had suggested they should terminate at the wiring terminal on the wheel well next to the battery. Not so on my car. The wiring travels up the passenger side wheel well, ducks under the battery box and I presume disappears inside the car under the dash. I can trace it, but I would rather not tear the car apart until I get the battery and have the new cable in hand. So how much cable do you guys think I need to get from the alternator to wherever it terminates? While I'm at it I will also redo the ground straps just for grins. I hope this alternator does the job.

With attached picture.
If it is a North America 300D chassis W123.133 = 1981 - 1984, the attached picture is what you have.

Please PM me your VIN# so I can check it for year and delivery nation.

renman · #**152** 09-06-2007, 11:09 PM

Roy I will Pm you in the morning with VIN# thanks:

vwnate1 · #**153** 09-07-2007, 12:07 AM

All you needs do is run a new wire from the output buss on the alternator to the positive terminal of the battery .

Your new alternator isn't going to be putting out 115 amps all the time unless you have rally nights and /or a 350 watt stereo .

An alternator only puts out what is demanded of it , not it's full rated capacity constantly
.

deerefanatic · #**154** 09-07-2007, 06:20 AM

Exactly. I suggest running a short run of heavy gauge cable from the output stud of the alternator to the hot stud of the starter. Lot's of heavy cable from there on up to the battery.

renman · #**155** 09-07-2007, 09:02 AM

Okay, but what do you guys suggest I do with the red power wires (2) presently going into the firewall area as previously described in the above post? I'm gonna have another look around for a wiring diagram for my car. Alternator won't be till Monday at the earliest anyway.

gsxr · #**156** 09-07-2007, 02:31 PM

It's perfectly fine to add an additional (heavy gauge) cable from the new alternator to the starter cable, and leave the existing cables where they are. If the existing cables are the blade-connector type, you can cut off the blades and crimp/solder on a ring terminal, and connect it to the B+ terminal also. There's no problem with two parallel outputs from B+ (one to the starter, which goes to the battery; and the second being the original pair of dinky wires to the junction block).

renman · #**157** 09-07-2007, 02:54 PM

Quote:

Originally Posted by gsxr

It's perfectly fine to add an additional (heavy gauge) cable from the new alternator to the starter cable, and leave the existing cables where they are. If the existing cables are the blade-connector type, you can cut off the blades and crimp/solder on a ring terminal, and connect it to the B+ terminal also. There's no problem with two parallel outputs from B+ (one to the starter, which goes to the battery; and the second being the original pair of dinky wires to the junction block).

This helps! The cable coming from the starter doe's terminate at the wiring junction just in front of the battery. So this means I could run the aforementioned new cable from the alternator to this junction box or to the starter; correct? You guys are suggesting 4/0 cable for this right? Thanks Dave this will probably save me a lot of time.

vwnate1 · #**158** 09-08-2007, 12:34 AM

What Dave said ~ .

No need for 4 gauge wire , that's sufficient to carry 500 ampers to crank over a V-ate engine ! WAYYYY overkill .

Hit Man X · #**159** 09-08-2007, 06:58 PM

Quote:

Originally Posted by vwnate1

What Dave said ~ .

No need for 4 gauge wire , that's sufficient to carry 500 ampers to crank over a V-ate engine ! WAYYYY overkill .

Go run 500A through a 4awg cable, then report back.

I have all my 130-150A units on 2awg.

renman · #**160** 09-08-2007, 07:51 PM

Quote:

Originally Posted by gsxr

It's perfectly fine to add an additional (heavy gauge) cable from the new alternator to the starter cable, and leave the existing cables where they are. If the existing cables are the blade-connector type, you can cut off the blades and crimp/solder on a ring terminal, and connect it to the B+ terminal also. There's no problem with two parallel outputs from B+ (one to the starter, which goes to the battery; and the second being the original pair of dinky wires to the junction block).

Hey Dave. I like the idea of leaving the wiring where it is and running an additional line up to the terminal box by the battery. I typed in 4/0 but having researched wire size, I'll probably use a 1/0 cable from the alternator.

I also got this e-mail from Roy yesterday afternoon regarding modifications necessary with the AL129X alternator after he had graciously offered to track down a wiring diagram for my diesel, when I couldn't locate one in any of my manuals. (Guess I don't have enough manuals)

Hello Cliff
Here is your answer.

1#. The existing harness is OK up to 150 AMP, unless it is seriously damaged.

#2. The critical point is matching terminal function.

#3. You need to know what pins/wires serve which function at the OEM alternator, then splice the new pigtail/connector in.

#4. Total R&R time should be roughly one hour.

#5. I would not run new wires unless there is a phyisical need = burnt/broken wires or installing a 300 AMP alternator.

Thank you
http://www.peachparts.com

Call Roy for tech support
So Roy is saying a rewire isn't absolutely necessary for this upgrade.

Cliff.

deerefanatic · #**161** 09-08-2007, 11:10 PM

Ok, No, not necessary. The original wires won't get so hot that they catch fire with this alt.

But that's not the issue. It's voltage drop. Smaller wire has more drop.

You can get by with a 1 inch exhaust pipe. do you want one?

1/0 gauge is definitely overkill... (That's ZERO gauge cable, 4/0 is QUADRUPLE ZERO cable...) I have plain old 4ga..... the stock starter cables are 6ga.... I upgraded them to 1/0........

I guess it comes down to this..... You paid $$ for a bigger alt so you can have more usable power... So what's a few extra dollars to get it's full potential? No, you won't burn the car down with the stock wires, but you WILL get an improvement from larger.... If nothing else, run one more stock (8ga) wire with the existing two...... It'd be close to 4ga equivalent and you've probably got something like that hanging around the garage.

This is posted from the guy who runs headlights, dual 55watt fogs, heater on high, stereo running, computer on inverter running, and keeps his voltage above 13v at stop lights doing all that!

renman · #**162** 09-09-2007, 01:44 AM

thanks Matt. I'm square on the wire size and directions.

vwnate1 · #**163** 09-09-2007, 01:05 PM

Every Caddillac with 500 C.I. engine ever made....

If you don't know that's O.K. but check a few Facts now & then , O.K. ? .

From the "Westinghouse Convenient Tables and Formulas" (no date, but it is so old that the address in the front doesn't have a zip code) use 10 gauge wire for up to 150 amperes .

BTW : the car's a Diesel so the battery cbales are not 6 gauge as mentioned , they're 2 gauge on all the Diesels .

-Nate

Quote:

Originally Posted by Hit Man X

Go run 500A through a 4awg cable, then report back.

I have all my 130-150A units on 2awg.

deerefanatic · #**164** 09-09-2007, 10:03 PM

Quote:

Originally Posted by vwnate1

BTW : the car's a Diesel so the battery cbales are not 6 gauge as mentioned , they're 2 gauge on all the Diesels .

-Nate

Thanks for the correction, I was mistaken on that.. Though mine are Zero ga now!

vwnate1 · #**165** 09-09-2007, 10:57 PM

..Is always a trade off between the engineers and the bean counters and with GM or Japanese cars , the bean counters always win

Mercedes has been very good about using good quality battery cables even though the charging system and perhaps the primary current wires are marginal when new .

On all my other vehicled I make up my own # 1 gauge battery cables in the shop using welding cable as it's finer stranded and this means greater ampere carrying capacity in the same gauge cable ~ replacing the stock 4 gauge cable on most cars with 0 or 1 gauge will instantly improve starting by delivering 100 % of the battery's available current to the starter . ALWAYS use soldered on clamps too ~ if any vehicle you own has those add-a-clamp repair things , get rid if them right now ! if you're too poor to afford a new 1 gauge $20.00 cable , go to the Pick-A-Part and find a good used original one from a junked Mercedes , they're cheap and you can clean off any corrosion with hot water and baking soda mixed .

In a Diesel or 6 volt application the differance can be startling .