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Thread: New Alternator Rectifier for Bosch 489 Series Alternator

  1. #1
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool New Alternator Rectifier for Bosch 489 Series Alternator

    I picked up the Alternator rectifier plate from eBay($22 euros shipped had coupon for $5 euros or so) This rectifier use 50 Amp avalanche diodes whereas standard Bosch diodes on 65 Amp alternators use 35 to 40 Amps, the benefit of higher amperage diodes is the higher overhead when in use, uses less capacity when charging the battery when many items are on--lasts longer basically. Made in Poland by As-PL and was shipped by trading partner out of Riga, Latvia.

    IMG_20220725_071330_562.jpgIMG_20220725_071226_665.jpgIMG_20220725_071250_160.jpg, The threaded post is B plus, connect to the battery positive post thru wiring,, The shielded male spade terminal( with the black plastic piece) is the D plus which goes to the instrument alternator light, the unshielded male spade terminal is an auxillary terminal and connects to a capacitor to stop radio interference.

    The rectifier passed all 4 bench tests testing forward voltage in the the positive and negative diodes, 2 tests from B plus post and 2 tests from the ground or negative side of the alternator rectifier plate. All diodes showed .517V forward and OL in reverse direction. All good,, I'll use this to rebuild my Bosch 489 series 100 Amp alternator that has extra stator winding (4 loops instead of 3-connected to 3 output stator wires) for higher amperage, yet fits the standard Bosch 489 Series 65 Amp Alternator Cases--BMW 1980-83 320i's E21 Body.

    Randy
    Last edited by 320iAman; 07-25-2022 at 11:10 AM.

  2. #2
    Join Date
    Dec 2016
    Location
    Atlanta Ga
    Posts
    127
    My Cars
    98 M3 Sedan, 82 320i
    I have been wanting to rebuild my stock 82 alternator. What are the parts needed, 2 bearings and this Rectifier Plate, is their a kit ? I put in the outer mounting bushings and a new regulator, which helped out greatly but I feel the need to go for a full refresh.

  3. #3
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    This threads:

    Bearing Refresh:

    https://www.bimmerforums.com/forum/s...earing-Refresh

    Bosch 65 Amp Alternator Rebuild:

    https://www.bimmerforums.com/forum/s...rnator-Rebuild

    Randy

  4. #4
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    Done, Soldered in the AS- 50 Amp Rectifier on to stator with 4 loops and put together in Standard Bosch 489 Series alternator case with poly bushes-bearings and slip rings were like new, with rectifiers one needs to get one the same size with the same number of solder points on the positive diode side-same no. of diodes if using a Bosch 489 series alternator case,, I have 4 of them now, one on the car and 3 good rebuild ones in the box..

    Randy
    Last edited by 320iAman; 07-28-2022 at 03:57 PM.

  5. #5
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    Added the final item Voltage regulator from Hella.

    Stator Specs

    Voltage: 12
    Low Output Amps: 55
    High Output Amps: 65
    Lam Stack ID: 3.52in / 89.4mm
    Lam Stack OD: 4.921in / 125mm
    Lam Stack Thickness: 1.004in / 25.5mm
    Number of Leads: 3
    Application: Bosch 489 Series I/R Alternators

    For Stock Stator,,

    Stator installed has higher amp output more likely 80-100 Amp and same size as stock stator.DSCI0381.JPG 4 loops of copper wire instead of 3 in stock 489 series stator.,, 50 amp rectifier-IMG_20220725_071250_160.jpg, stock 35-40 amp.

    IMG_20220810_134430_879.jpg IMG_20220810_134518_422.jpg, New poly bushings...... I have two alternators I rebuilt myself and one rebuilt by a shop- all good and a new Bosch installed in the car.

    Randy
    Last edited by 320iAman; 08-10-2022 at 05:06 PM.

  6. #6
    Join Date
    Apr 2014
    Location
    DFW TX USA
    Posts
    1,447
    My Cars
    1983 320I, 1986 325E
    A GM CS-130 alternator will bolt up and fit. I have a 220 amp alternator in my 320i. It's nice seeing a consistent 14.4 volts. Just make sure you get an alternator that has the output post on the side or you will have clearance issues with the oil filter / oil filter housing.

    Sent from my ONEPLUS A6013 using Tapatalk

  7. #7
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    I'm more into remanufacturing stock 489 alternators so fitment is never a issue, as too voltage output that's dependent on set point of the voltage regulator and sensing the battery, on startup the voltage will rise to set point and and as the battery gets charged to replace the amps used by the starter the voltage will come down typically to 13.8 Volts as higher voltage is no longer needed,, here is an a voltage regulator with set point 14.8 Voltage that works with stock 489 alternators. The set point on the Hella above is 14.1V. If your running a high output stereo system with air conditioning ect a much higher amp output alternator would be necessary, me , I don't. ac also saps power form these 1.8L builds, I carry ice water instead. being cool for a few months in the car I dont find necessary.

    https://www.ebay.com/itm/363802613594

    Randy
    Last edited by 320iAman; 08-11-2022 at 10:57 AM.

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