Alternator help?

[mtx9500ridah]

I got 2 12'' type r's off a 2500d in my 1994 bmw 740il and am pretty sure i killed the alternator. the car ran good the first couple days the system was in then my stock battery died. i then had a yeloowtop installed but even with the yellow top my car woul idle really low then bog and die. i am pretty sure it is the alternator because i can get the car to run for a few minutes which, if the alternator was working correctly, would charge the battery. Now the battery cant even charge because it is completley dead, it just clicks. If this for sure sounds like my alterantor, will rewinding and building onto the stock 140 amp alternator support the 2500d, or am i not going to be able to run this amp in this car? thanks so much and i really need any help because i got the car sitting in the garage right now and is undriveable so i would like to know for sure before i tow it. thanks!

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[phyphoestilic 5,000+ posts]

Rewinding isnt a good idea, it makes it put out more power but it wont put out power at idle (3-700rpmish). see if u can find a local alternator store to build u a high output alternator or order one online.

 

[azimuth 5,000+ posts]

I got 2 12'' type r's off a 2500d in my 1994 bmw 740il and am pretty sure i killed the alternator. the car ran good the first couple days the system was in then my stock battery died. i then had a yeloowtop installed but even with the yellow top my car woul idle really low then bog and die. i am pretty sure it is the alternator because i can get the car to run for a few minutes which, if the alternator was working correctly, would charge the battery. Now the battery cant even charge because it is completley dead, it just clicks. If this for sure sounds like my alterantor, will rewinding and building onto the stock 140 amp alternator support the 2500d, or am i not going to be able to run this amp in this car? thanks so much and i really need any help because i got the car sitting in the garage right now and is undriveable so i would like to know for sure before i tow it. thanks!

alternator=engine running power. battery=engine off power. a higher output alternator will do the trick

 

[mtx9500ridah]

thanks guys ive just heard from my neighbor who has been a bmw mechanic for 50 years that i will not be able to put a different alternator than the stock one in the car, so i really do not know where i would go. so a new 140 amp wouldnt cut it then?

 

[azimuth 5,000+ posts]

thanks guys ive just heard from my neighbor who has been a bmw mechanic for 50 years that i will not be able to put a different alternator than the stock one in the car, so i really do not know where i would go. so a new 140 amp wouldnt cut it then?

i'm not big on german tech. why can't you put an alternator that puts out more amps in a beemer?

 

[phyphoestilic 5,000+ posts]

naw look around shop online, i know for a fact someone can build u a high output alternator that fits in the stock location. I had a local place build one for me my stock was 80amp I got 140amp built (this isn't a rewind). Rewounded alternators dont last very long.

 

[mtx9500ridah]

yeah well the stock alternator on mine is 140 but it was 13 years old, so would a brand new 140 amp supprt 2500 watts, or do i need a ho alt for that? Yea he said i couldnt fit anything else in the stock location, but maybe i could have one built, i dont really wanna buy something like an alternator which is so vital to your car from an online place, so i dont really know what to do. lol

 

[phyphoestilic 5,000+ posts]

140 amp seems fine for just running the 2500D as long as ur not playing it full tilt every second ur in the car. Wouldn't be a bad idea to get a 2nd battery neither have a little more reserve capacity.

 

[mtx9500ridah]

yeah, about the second battery, i heard that can cause more strain on the alt, because it has to charge both batts. is this not true then?