Upgrading the alternator - PeachParts Mercedes-Benz Forum

190D22 · #1 07-06-2002, 02:03 PM

Once I get my exhaust replaced and a motor mount (had it checked the passenger side is the only one needed) repalced I am thinking of doing some stereo upgrading to it. But seeing how the car only has a 55 amp alternator, 2 12"s with at least 200 watts driving them will make my headlights dim. I see parts stores sell a 55 A direct replacement and then they sell a 70A replacement. But I'm not sure if 15 amps will give me that much more headroom to clear up power drains from subs. I would of course put at least a 1 farad capacitor on the amp to help. Any thoughts on this?

Also, would I need to get a voltage regulator with it, or does it come with the alternator. How hard is that thing to replace? If it's that much of a pain I'll say screw it and just get really really nice rear speakers and put a crossover on the front ones. Any help is greatly appreciated! Thanks.

#2 07-06-2002, 09:23 PM

A 200 Watt audio amplifier is RARELY actually drawing 200Watts. Even if it were CONSTANTLY drawing 200 Watts, that's only about 16 Amps or so. You should not have to use a heavier alternator.

Have a great day,

MVK · #3 07-06-2002, 09:32 PM

************************ has a relay that is esp meant for high intensity halogen lamps. It has all the details there. I think something like this will help. I say a similar relay at Radioshack for about 8 bucks. I dont know anyone who has used this personally. But its worth looking into.

Also I dont know if putting a high amp alternator will help you. I had replaced my 65 amp Oldsmobile(V6) alternator with a 105 amp one and it still would slow things down when I would put my xtra vision lights on. So check with an auto electrical specialist before you really go ahead and spend those xtra bucks.

MVK

190D22 · #4 07-07-2002, 12:26 AM

Yeah. I just notice that even rolling the windows up or down dims the headlights. Hell even when the bass 'hits' with what I have right now the deck (cd player) back light dims. Maybe that's just a function of the deck though. I figure that if I put a bigger alternator in it won't allow the other systems to have such a drain. Especially with a capacitor or two on the amp. With both of those things it would allow me to crank more.

What would a relay do for me? All a relay is is an electromagnetically controlled switch. Low voltage on the switch side and high voltage on the relay controlled side. Cars use relays so you can run small wires and low current into the passenger compartment to switch on and off high current equipment. That doesn't solve my 'current' (heh) problems. That just allows me to turn the amp on and off...

And since the alternator is 18 years old, the brushes in it would be getting old. You'd also think that with age it might loose capacity, but maybe not. Thoughts?

Thanks for the help so far!

RG5384 · #5 07-07-2002, 12:53 AM

on my SD i have two 12's running 300 watts, no caps etc, and i have a factory spec alternator. No problems with lights etc really, and yes, my backlight dims as well, always has, subs or not. The differance between a gas and a diesel as far as amps of the alternator go is that a diesel really doesn't need an alternator to run, it only needs it to power the accesories. In other words, all the amps that it puts out go to the power functions of the car, not to run the engine as well.
hope this helps
Ryan

#6 07-07-2002, 05:20 PM

With the symptoms you describe, something is wrong that I feel quite sure a larger alternator would not fix.

I would start by checking your battery terminals and then move to your audio system connections. Also, have you paralleled any loads on the audio system? You should not have less than a four ohm load. Two four ohm speakers in parallel will apply a 2 Ohm load to the amp, which will theoretically double the current draw.

Good luck,