how (in)capable is 1975 stock electrical

[nra424 10+ year member]

Hey ive got a recently restored, 1975 BMW 2002. After replacing the speakers and installing a new 4 channel amp, I'm looking to install this RE SE12 that's sitting in my room. What would I need to do to maintain healthy voltage? Im afraid the alternator is probably pretty lame...

Thanks

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[loopkiller 10+ year member]

Are you sure it even has an alternator? Some older cars used generators instead. If you gave us some specs, we could help more. If you need specs, check a BMW board.

 

[dman4486 5,000+ posts]

yes the 2002 came with an alt, but it was a 35 amp alt. there is a 45 you can buy, but that still may not be enough power:fyi:

 

[TurdFergueson2 5,000+ posts]

I just wouldn't do it. That amp you already have in there might give you problems with dimming.

 

[loopkiller 10+ year member]

You could always do a battery bank that is off circuit from the stock electrical and use a charger to keep them fully charged.

 

[nra424 10+ year member]

how about swapping in a h/o alt like this?

http://cgi.ebay.com/ebaymotors/BMW-Alternator-2002-1966-1976-95AMP_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem260359274182QQitemZ260359274182QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

 

[loopkiller 10+ year member]

how about swapping in a h/o alt like this?http://cgi.ebay.com/ebaymotors/BMW-Alternator-2002-1966-1976-95AMP_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem260359274182QQitemZ260359274182QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

That kind of made me laugh when it says HO alt and then says 95A in the same sentence. It would be an upgrade for sure, but not enough IMO.

Basically you are gaining 60A of current (max). That equates to about 850W RMS (before factoring in amp efficiencies). So you have about 900W~1000W max that I would try to run off that HO alt. If you think you can get by with the 1000W RMS maximum, then go for it. I still think you should think about a dual battery setup as well. Dual HC1400s would be plenty.

 

[dman4486 5,000+ posts]

how about swapping in a h/o alt like this?http://cgi.ebay.com/ebaymotors/BMW-Alternator-2002-1966-1976-95AMP_W0QQcmdZViewItemQQ_trkparmsZ72Q3a1205Q7c66Q3a2Q7c65Q3a12Q7c39Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZitem260359274182QQitemZ260359274182QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

That would be better of course. Add an additional battery to the rear and you will be fine.