Alternator Upgrade Question

Volvowith18psi · Post by **Volvowith18psi** » 05 Apr 2010, 08:56

Hello again all! Thanks a lot for the responses about Fitting an Optima battery in my 850!

On to a a few more questions if you guys would be so kind.

So, I finally broke down again and put a little bump in the trunk of my 96 850, but I'm worried my nightmares may come to life....

About 8 years ago, I put some bump in the trunk of my 85ish 240 600w rms, 2x MTX t5000 12's.... Well, all was well till I started to burn up alternators. I went through 5 brand new ones in about 2 weeks, so I had to sell my speakers.

Fast forward to now, I drive an 850, full power everything etc..., and I had 4x 5 1/4" installed, Kenwood deck, a Kenwood 9105D? amp and 1x Kicker L5 12 installed and I'm worried about my poor alternator....

Running 900w-ish rms @ 1ohm to the sub, and let me tell you, I never thought 1 speaker could be so loud! lol.... Anyhow... I have upgraded to a Optima Yellow Top battery, but I'm getting a very minimal, but noticeable amount of headlight dimming @ full volume while driving at night....

Is it time to shell out for a new HO alternator you guys think, or will my baby factory one be sufficient with a capacitor? Can my electrical system handle this? I figured it would be ok being its full power and has a factory amplifier already ( which has been bypassed and capped off so its not drawing any juice)

Price for a HO alt is around 525 non installed, bucks US from Ohio Generator. Guy said he will build a brand new one rated @ 180-200amp and bolt in as a factory replacement.... Orr Wire up a 250 dollar installed 5F capacitor in ?

The thing is, my car must start everyday lol....

Post by **jblackburn** » 05 Apr 2010, 09:02

What's your alternator putting out without anything on? Try holding the RPM's up around 1500 and testing the voltage across the battery terminals. If it's below 13.8 with no load, you may need to be looking at a new alternator anyway (or at least the voltage regulator/brush assembly).

I used to notice the same thing with the Sony stereo on my old Honda with the bass turned up, or an ex's Chevy Tracker. In that one, you could actually see the RPM needle twitch with loud music, just an awful car all-around.

Volvowith18psi · Post by **Volvowith18psi** » 05 Apr 2010, 13:07

Well, I found one from Powerbastards.com rated @ 110amps @ idle 220@1200 rpm... Just need to make a special bracket for it as its not a drop in replacement... Wonder if they are true to the numbers...

Post by **jblackburn** » 05 Apr 2010, 13:14

LOL that's like the alternators they put in big trucks and Jeeps. Probably not a bad idea, but getting the serpentine belt to fit it and around the rest of the pulleys might not be fun

Post by **vjaneczko** » 04 Jun 2010, 12:49

The dimming headlights are common when you’re sucking that kind of juice for a 900 watt amp (not sure what the factory amp is rated, but I’m going to guess no more than 150 watts). You don’t mention an amp for the 5 /14 speakers so I’m guessing their coming off the head unit? So the one amp, running at full power, is spec’d to pull 57 amps. Not sure what the alternator is rated for but I’d think it’s somewhere around 100 amps? You should be OK as long as you’re not cranking the tunes while you have the seat heaters cooking and the heat is on full blast.

Toss in a capacitor and it should smooth out the power draw for the amp and prevent the dimming lights. When the lights dim it indicates that the amp isn’t getting all of the power it needs, so it’s struggling to push the woofer and can increase distortion. Plus, adding a cap to your setup is cheaper than an alternator, so I’d go with the cheaper solution first. Even if you have to get a new alternator, the cap will help the amp – and don’t forget the Cool Factor of it!

Post by **cn90** » 04 Jun 2010, 13:04

Why don't you rebuild your alternator using quality parts? I wrote a DIY for my 1998 528i. The main difference between BMW and Volvo is the Front Bearing. Actually I will rebuild my Volvo alternator soon and will do a nice DIY later.

http://www.bimmerfest.com/forums/showth ... ?p=5209013

For the Volvo, this is what you need. Avoid using Chinese bearings!
1- Front bearing: SKF (or Koyo, NTN, F.A.G.) 6303-2RS....about $8-10 on ebay
2-- Rear bearing: SKF (or Koyo, NTN, F.A.G.) 6203-2RS...about $8-10 on ebay

3-Brush Holder about $40. Call Dave for quality HUCO brand Brush Holder:

Smith Co. Inc.
530 11th St.
Greeley, CO 80631
USA
Phone: (970) 353-3121
Ebay seller name "smithcoelectric".
http://www.stayingreen.com/5.html