Installed a 143A alternator in my W124 (86-95E-class) - with photos - Page 2 - PeachParts Mercedes-Benz Forum

85drtysthbenz · #16 11-19-2003, 12:21 AM

im sure this is a pretty stupid question,but im going to ask anyway....could you possibly convert all the existing pulleys to accept a serpentine belt,and just convert the whole pulley system?

gsxr · #17 11-19-2003, 12:29 AM

That would be the best solution, of course! But so far, nobody has figured out how to swap OE parts to the older engine to make everything serpentine with an automatic tensioner, or created an aftermarket kit either. It would be easier (most likely) to have a custom pulley made for the big alternator, assuming you could find a way to mount the blasted thing - it's a LOT larger (I think) and the mounting points are very different. And, the V-belt setup requires the alternator to move for adjustment. AND, someone else pointed out that V-belts might slip, and not have enough friction to drive the higher load of the high-ouput alternator. Lots of "gotchas" with the whole concept...

#18 11-30-2003, 06:56 PM

hi,

I like knowing first; what the stock alternator output is in my 500E and if its a good idea upgrading to a higher output alternator. thanks

gsxr · #19 11-30-2003, 08:44 PM

Hashem,

Your 500E probably has a 110 or 120A alternator. You don't need to upgrade unless you have rather large auxiliary electrical loads, such as a killer stereo system, or megawatt headlight bulbs (100-130W in all 4 spots). Besides, I'm not sure how easy it would be for you to source a cheap 143-150A unit outside the USA... and the cost new is insane.

Strider · #20 12-07-2003, 04:30 AM

Quote:

Originally posted by gsxr
Hi all,

...

The 143A unit could put out roughly 100 amps at my ~600rpm idle speed, and appeared able to put out max current at barely above idle, not even 1000rpm! The highest load I could generate, including some current to charge the battery, was 125-130 amps. At 1000rpm, it put out the 130 amps and did so at 14.1 volts! And at idle, same thing, 14.1 volts (with a smaller load, under 100 amps.) The only time voltage dropped was with VERY high load at idle and I don't think I ever saw it go under 13 volts, and that was with an "artificial" load that is unlikely to occur in normal use.

My "normal" load is low beams (90Wx2) and ACC fan, plus whatever the chassis electrical stuff pulls (EDS, gauges, etc.) This appears to be roughly 40 amps, plus some current to charge the battery. The good news is, with my "normal" load I get a solid 14.1-14.2 volts, even at idle! VERY nice. I'd like the voltage a bit higher (14.4-14.6) but there is not an adjustable regulator available for the 143A unit (AFAIK). No big deal, I'm happy with the setup as-is. The stock unit badly needs an adjustable regulator, and I'd highly recommend one for those of you not interested in the full big-alt swap. Set it when stone cold to 14.6v or so, it will drop a bit as it gets hot, and you want to set the HIGHEST point.

The only down sides are extra weight and horsepower loss. The 70A unit weighs about 11.5 pounds, the 143A unit is 16.8 pounds. Not a big deal. But when you spin the shaft of the 70A unit, it feels light and spins easily. The 143A is MUCH heavier (massive) and definitely takes some extra crankshaft power to spin, even with no electrical load. I'd guess it could easily sap 3-5 HP more compared to the original. Still worth it, IMO.

Regards,

Excellent Mod, thanks for the info. I once did something very similar to my old RX-7.

BTW, Don't worry about the voltage at 14.1. That is exactly where you want it and the voltage regulator seems to be working perfectly. Any higher and you'll generate excess hydrogen gas and sulfate up your lead plates in your battery. 14.1 V is exactly the right voltage for charging batteries for best life, especially since you'll have very little voltage drop between your alternator and the battery with your new cables.

Also, to figure out how many ponies are robbed, lets do some math: Since Power = Volts * Amps, Power = 14.1V * 130 Amps = 1833 Watts. 1833 Watts = about 2.5 hp. Assuming about 80% effeciency for converting mechanical energy to electric energy (fairly conservative estimate), and that's 2.95 hp.

Hmmm, I'm a mechanical engineer, not electrical...how do I remember this crap?

odelag · #21 11-09-2004, 12:00 AM

Does anyone know if the 143 amp alternator will bolt on in a 1985 190e 2.3 without mod (other than replacing the pulley and rotating the rear housing)?

gsxr · #22 11-09-2004, 12:05 AM

It should, assuming your 190E has a serpentine belt. You'll need to do electrical mods since the stock wire harness has blade connectors and the 143/150 units have post connectors. But, you'd want to increase the wire size anyway so I'm assuming you planned for that. I'd recommend 4ga cable from the alternator to the battery.

odelag · #23 11-09-2004, 12:18 AM

It does have a serpentine belt, so I am going to give this solution a try.

This is actually the second alternator swap I'm doing on this car. I swapped out the original 65 amp alternator for a 120 amp Volvo alternator when the stock amp couldn't handle my stereo amplifiers. This required the shop (the car is in Peru) to modify the mouting bracket and install a slightly longer belt. I've never been happy with the modification, as the pulley is not perfectly true and in line with the rest of the pulleys and wheels that the belt winds around. This causes a lot of stress on the belt tensioner -- which I have had to replace twice after it snapped off the mounting bracket.

I'm going to ditch the Volvo amp, replace the modified alternator bracket with a new stock bracket, and install the 143 amp alternator.

gsxr · #24 11-09-2004, 09:29 AM

Awesome! Let us know how it works out.

wbain5280 · #25 05-27-2005, 04:51 AM

Quote:

Originally Posted by Strider

Also, to figure out how many ponies are robbed, lets do some math: Since Power = Volts * Amps, Power = 14.1V * 130 Amps = 1833 Watts. 1833 Watts = about 2.5 hp. Assuming about 80% effeciency for converting mechanical energy to electric energy (fairly conservative estimate), and that's 2.95 hp.

Hmmm, I'm a mechanical engineer, not electrical...how do I remember this crap?

You're an engineer, certain numbers are memorized during school, 746 w/hp, Pi, C, 3-4-5 triangle, etc.

amosfella · #26 10-11-2006, 01:41 AM

Can you tell me more about the distriibution block?? Can the old one be rebuilt to work with the bigger alternator?? Or will I have to find one off another car??

gsxr · #27 10-11-2006, 10:56 AM

Quote:

Originally Posted by amosfella

Can you tell me more about the distriibution block?? Can the old one be rebuilt to work with the bigger alternator?? Or will I have to find one off another car??

You could use the stock distribution block but that will limit the size of the wire you can run from the alternator, limiting the effectiveness of the upgrade. If you read my post carefully, you'll see that I added an aftermarket distribution block in addition to the stock on, I didn't replace it.

lee polowczuk · #28 10-11-2006, 01:42 PM

how difficult is it to change pulleys?

gsxr · #29 10-12-2006, 02:35 PM

Pulley changes are usually easy if you have an impact wrench, although I was not able to remove my old pulley despite extreme efforts. I bought a new pulley (~$25) for my two diesel upgrades, and I have never had trouble removing the pulleys from the 143/150A units with an impact wrench.

gsxr · #30 01-02-2009, 12:58 PM

I just did another upgrade, this time I installed a 150A alternator into my 1993 300D (this was LONG overdue... wish I had done it sooner). For this installation, I kept the stock battery cables, battery terminals, and factory power distribution block all intact. I hadn't done this before - my previous installs used aftermarket items instead.

This method makes for an easier install (and cheaper, too). I used two 4-guage cables to simplify connection at the stock distribution block. It works perfectly. If you don't need to attach large cables to feed aftermarket stereo amplifiers, etc... I'd recommend duplicating this setup. I took extensive photos this time, and documented the creation of the custom cable. A few sample photos are shown below... the full batch of pictures are available at this URL:

http://www.w124performance.com/images/W124_stereo/alternator/