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Thread: BT7 conversion to alternator

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    BT7 conversion to alternator

    i have been reading posts and articles on the conversion. i want to use my voltage regulator so i wired today as i have seen in these articles. just wanted to make sure this looked right to you all. basically A1 terminal has the blue/brown wire; A terminal has the yellow wire from the alt and the two brown wires; the F terminal has no wires; the D terminal has the yellow green wire from the alt and the smaller yellow wire from the dash light; the E terminal has the black ground wire.

    see picIMG_0275.jpg

    few questions:
    do i need to run any other wires for the conversion? obviously i need to connect the ones to the alternator when i finally get one. i thought i read somewhere about getting a three wire alternator so wondered where the other wire went. not sure i saw anything about that.

    this is a new wiring harness. are the wires in the harness heavy enough?

    last, i read a lot about the wiring but not really how to place the pieces in the contacts so they can not connect. i used wire shrink to isolate the connections. i slipped one over the verticle bar on the right, isolating the front and the back of it. then i slipped another piece behind the contacts next to the coils. is this enough? anything else i need to do?

    No engine in yet so i can do most anything necc without much fanfare.

    Thanks

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    Re: BT7 conversion to alternator

    Oh one good thing learned today... My steering wheel button and my voltage regulator cover were quite dull. after cleaning and trying a few different ways to polish, i still was not happy with them. So i tried some S100. it did a great job on both. going to hit the gearshift knob tomorrow.

    IMG_0277.jpgIMG_0278.jpg

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    Re: BT7 conversion to alternator

    I used to be in favor of the 3-wire alternator, but now I favor the 1-wire version in combo with a voltmeter. The no-charge light is too small to see anyway.

    The big wire from the generator seems to be a 12 ga. Maybe not good enough at high speed. I ran a separate 10 ga from the alt to the battery cable mount on the solenoid. The big yellow if used, connects to the big brown wire from the solenoid. There are multiple threads here on how to connect these. Your pic may not be quite right.
    Also see http://www.healey6.com
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    Re: BT7 conversion to alternator

    The terminal strip in my drawing is the layout of the screw terminals on the voltage regulator. Your wires should be connected exactly as are shown on my terminal strip. They are from the left, the Brown/Blue wire, the next terminal would have a large Brown with a large yellow wire, the 3rd screw from the left would have nothing on it, the fourth screw from the left would have the smaller yellow/ green wire (may drawing accidently shows it as a small yellow/brown) this fourth screw also has the small yellow wire from the ignition warning light on it. The last terminal on the right is just for a black ground wire.
    Now you have to realize that on the left the Brown/Blue, the Brown and the larger yellow all have to be tied together, that is why i show a jumper on the two left most terminals on my drawing. I do not remember how the voltage regulator in internally connected so it is my opinion that all the internal connections to these voltage regulator screws must be cut away from the terminal screws. The only wires that are to be touching each other are the ones on my drawing. In your picture it appears that at the minimum you do not have the two left terminals tied together which would connect the Brown/Blue, the Brown and the Heavy Yellow.
    Also, the wires in the original harness are not large enough for an alternator. It will electrically work but it is a hazard. I believe the largest wires in the original harness are #14. They may be #12 but even #12 is not large enough. This is why my preference is for a 3 wire alternator. Because the 3 wire alternator has a stand alone "BAT" terminal. this is the output to the battery. I run a #10 wire from the alternator "BAT" terminal to the "BAT" terminal at the solenoid. This then is the direct connection between the alternator and the Battery. Even a #10 could theoretically be too small but it is a good compromise in the it will carry between 30 and 40 amps. (yes I know it is not rated for 40 amps but it will carry it. and it will carry even more for short periods of time.) The original wire in the harness is rated for 20 amps max. Most Alternators are capable of putting out at a minimum of 60 or 65 amps. Some older ones may be only 45 amps. Anyway, this is not to be looked upon as that your car's equipment will never pull the rated amps of the alternator. The fact is that if your battery is in a low state of charge, or as such, is old, or just out of storage, etc, the alternator will put out up to its max rating to try to keep the battery up. This will easily overload the original wire in the harness. So put at least a # 10 wire from the alternator "Bat" terminal and the solenoid "BAT" terminal.
    Edited, last terminal on right is ground wire.
    Attached Images Attached Images
    About TV Shows-
    "...you really can't restore a car in 10 days. I don't want to watch a race where people have to restore it in a week. It's not going to drive, and those cars never work. In real life, it takes years to get it right. " Jay Leno.

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    Re: BT7 conversion to alternator

    vette
    it seems the only thing i am missing is the jumper wire between the A1 and the A terminal. i would assume a 16 gauge wire is fine for that.

    i also have the brown wire that goes to the horns on the A termninal as is on the original diagram.

    Now i thought that in multi-strand wire that the rating for wiring is like this: 16 ga / 20 amp; 14 gauge / 40 amp; and 12 gauge is 60 / 60 amp. (depending on length of run) i know in house wiring which is single strand that 12 guage is rated at 20 amps but i thought multistrand was different. guess i need to look that up again.

    either way i may as well run the extra 10 gauge wire to the solenoid. simple enough.

    as always, thanks for the help

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    Re: BT7 conversion to alternator

    steve
    you say "the big yellow if used"... does this mean if i run the 10 ga back to the solenoid, i do not need the big yellow? in vette's pic it appears he uses both.

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    Re: BT7 conversion to alternator

    Quote Originally Posted by Drone Dog View Post
    steve
    you say "the big yellow if used"... does this mean if i run the 10 ga back to the solenoid, i do not need the big yellow? in vette's pic it appears he uses both.
    If you use a separated 10 ga, isolate the big yellow.
    AlternatorVoRegConnects.jpgAlternator3wireConnects.jpg
    Steve Gerow
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    Re: BT7 conversion to alternator

    Steve
    so you put the brown/blue right on the same terminal as the brown to save the jumper.
    no ground needed I assume since it is just a junction.

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    Re: BT7 conversion to alternator

    And I would guess only the right side of the voltage regulator needs to be isolated?

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    Re: BT7 conversion to alternator

    Quote Originally Posted by Drone Dog View Post
    And I would guess only the right side of the voltage regulator needs to be isolated?
    Say Drone Dog, You don't want to do any guessing here. I want to caution you to not mix and match different concepts here from other posters. I'm not faulting anyone, I just don't know what other types of alternators that others might have used. If you hook it up the way I showed it with the type of alternator I used I know it will work fine. as far as eliminating certain wires then make sure you do it with the same equipment that is used in that scheme. I also want to restate that internal connections in the original voltage regulator would change everything that I have on my drawing so if you do it as my drawing shows you must make sure that nothing else is connected to those wires except what I have shown.
    Also, a #16 wire is not large enough for the jumper that I have shown. The Brown/Blue wire and the Brown wire have the heavest load of the whole harness on them. Make this wire at least a #14 and a #12 if possible.
    About TV Shows-
    "...you really can't restore a car in 10 days. I don't want to watch a race where people have to restore it in a week. It's not going to drive, and those cars never work. In real life, it takes years to get it right. " Jay Leno.

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    Re: BT7 conversion to alternator

    Makes sense. So get my equipment and then set up my wiring accordingly.

    you have a three terminal. Is that a Delco unit?

    i am am thinking a Hendrix mount and then buying an alternator to fit. Current plans anyway.
    Last edited by Drone Dog; 11-16-2017 at 11:05 PM.

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    Re: BT7 conversion to alternator

    DD,
    For the purpose of figuring this out, suggest buying a terminal block at the electrical/home store. Use that instead of the regulator. That way you're not destroying the reg.
    TerminalBlock.jpg
    The pictures I've posted above directly reflect the Hendrix kit instructions. IMO these are the simplest way to hook up the alternator.

    The 10ga wire direct to the solenoid is most effective because going to the connection block then jumping to the brown wires puts all the current at high speed through the brown wire from the block to the solenoid connection.

    PS - those instructions also state you can use wire nuts to join the wires. This would suffice as a very temporary solution while you figured things out.

    I'd advocate use of a voltmeter over an ammeter as it is installed in parallel on your switched ignition circuit, rather than in series as the ammeter, which requires heavy wires with full current. Flame away.
    Steve Gerow
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    Re: BT7 conversion to alternator

    sent an email to Hendrix today to get info.

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    Re: BT7 conversion to alternator

    Drone Dog, just to answer your questions to me, I am using a AC Delco alternator of approximately 1994 vintage. My alternator mounting is from Hendrix. I also recommend to NOT use an Amp meter. Even thou it can be installed in a safe manner (many vintage cars had them, including my 1970 Corvette which has not had the meter or the connections changed for over 30 years), the Amp meter is not as helpful as a voltmeter.
    About TV Shows-
    "...you really can't restore a car in 10 days. I don't want to watch a race where people have to restore it in a week. It's not going to drive, and those cars never work. In real life, it takes years to get it right. " Jay Leno.

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    Re: BT7 conversion to alternator

    Thanks for the info. I did some reading last night on alternators and have a much better understanding of why yours, and steve’s System works. Should probably have started there first before worrying about the voltage regulator. I do like the look of it being there so I will work it out.
    Thanks again.

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