New Stereo/old Alternator - BMW Forum -

Audio and Electronics The place to go to discuss sound systems and show off your I.C.E. along with security systems and radar detectors too!

LinkBack Thread Tools Display Modes
post #1 of 2 (permalink) Old 12-07-2004, 12:18 AM Thread Starter
plusnone's Avatar
Join Date: Dec 2004
Location: Santa Barbara, CA
Posts: 28
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
plusnone is an unknown quantity at this point
Send a message via AIM to plusnone
(Thread Starter)
I'm working on upgrading the stereo in my 1987 325, and want to know whether I'm going to overload the alternator. If all goes well, I plan to be running:

-1x Audiobahn 600W RMS Amp powering two Alpine 10" subs
-1x Audiobahn 400W RMS Amp powering two Alpine 6"x9" rear speakers
-1x Pioneer head unit, rated to ouput 22W x 4 RMS

I don't fully understand Ohms (and Ohm's law), but from what I've been reading, I should set up the 6x9s to draw 100W each at 4ohms. Does this still mean that the amp will be drawing 400W?

From the manual, my alternator ouputs 80 Amperes at 14 Volts, for a total of 1120 Watts. My air conditioner does not work, and my headlights are original (although I don't know how much current they draw). Am I correct in thinking that if my system isn't running at full volume all of the time, I should be safe with my current alternator? If it matters, my starter is brand new, but I don't know how much power it draws.

Thanks for any advice,

My 1987 325 is no longer. Rain and an relatively inexperienced driver are not a good combination, to say the least. Luckily no one was seriously injured.
plusnone is offline  
Sponsored Links
post #2 of 2 (permalink) Old 12-07-2004, 05:47 AM
1st Gear Member
PMB's Avatar
Join Date: Jul 2004
Location: Isle of Man
Posts: 200
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
PMB is an unknown quantity at this point
Unless you are planning on going into competition you will be fine. The stock alternator is more than adequate. However, you should consider installing a 0.5-1.0 farad capacitor. This acts as a buffer by storing the power that is required for sudden hard dynamics, thus helping to protect the battery by smoothing it's power delivery requirements.
PMB is offline  
Sponsored Links

  BMW Forum - > General Category > Audio and Electronics

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
e39 540i alternator and battery question HardStep 5-Series (E12,E28, E34, E39, E60) 5 10-11-2005 12:18 PM
Alternator Removal. simbotto 3-Series (E21, E30) 1 02-19-2005 04:49 PM
Unloader Relay - Alternator - Where To Buy donberry 5-Series (E12,E28, E34, E39, E60) 0 12-22-2004 06:25 PM
Completed my Valeo to Bosch alternator conversion MOTRSPRT 3-Series (E36) 5 01-26-2004 06:16 PM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome