SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: marceldawson70 on August 18, 2008, 10:01:42 PM

Title: is a motorola 12v 55amp alt ok?
Post by: marceldawson70 on August 18, 2008, 10:01:42 PM
my spare alt is a motorola 12v 55amp alt, is this OK?   will this peg my 50amp gauge or is it only 55amp when a major charge or load is required? I know new boats require a greater amperage due to the greater draws(ecu,injection,and other stuff) all I have is stereo ,blower,amps, 2 bildge pumps, and lights.
Title: Re: is a motorola 12v 55amp alt ok?
Post by: GT Jets on August 18, 2008, 10:29:21 PM
IMO your amp guage should never peg unless there is a problem with the battery or the regulator, the motorola alt. is a nice piece, Mercruiser, Hardin Marine and Indmar all used them, I think even some of the Berkeley Pakajets had them on most models, if your using more then 55 amps, something is FUBAR, your gauge should read about 10-15 amps or so cruising (3500 RPM).

GT
Title: Re: is a motorola 12v 55amp alt ok?
Post by: speedymopars on August 18, 2008, 10:41:25 PM
Run your ignition and the engine stuff off the alternator, and let the gauge only do the work when it is charging the battery.

55A is OK, an ignition only pulls 5A -15A, lights 10A, pumps 10A, and the stereo can be a little to alot....

Title: Re: is a motorola 12v 55amp alt ok?
Post by: marceldawson70 on August 19, 2008, 07:22:59 AM
came in to work early pulled the motorcraft alt and it says 60amp that should be ok! maybe its my connections? orange to bat and purple to fld right?
Title: Re: is a motorola 12v 55amp alt ok?
Post by: marceldawson70 on August 19, 2008, 07:52:27 AM
after looking this thing (motorcraft- duralast tag on it) it is externaly regulater like old fords. do I add the box? or try to make the motorola fit? motorola has a smaller bolt thru it- changing belts and mounting area! Head ache!
Title: Re: is a motorola 12v 55amp alt ok?
Post by: GT Jets on August 19, 2008, 07:56:11 AM
marceldawson, My have misled you do to verbal diarreah :P

The Ignition switch battery lead comes from the ammeter so it will reflect the negative amp draw when the ignition is turned on, in other words , like speedy mopars is talking about, the amperage you will see at the meter will be battery amps, instead of alt amps... here's a new/improved diagram (hey we may finish it someday to have a complete diagram :sly:)

The Motorola alternator has a rear mounted regulator I believe with two leads coming out the side (red/blue and purple) and you are correct, I believe the purple is the "exiter wire" I need to look that up for sure......

BTW the second Purple wire is only if you have an external ballast ign. coil...

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Title: Re: is a motorola 12v 55amp alt ok?
Post by: GT Jets on August 19, 2008, 07:56:53 AM
after looking this thing (motorcraft- duralast tag on it) it is externaly regulater like old fords. do I add the box? or try to make the motorola fit? motorola has a smaller bolt thru it- changing belts and mounting area! Head ache!

What are you changing it from? a Delco?
Title: Re: is a motorola 12v 55amp alt ok?
Post by: jet boat performance on August 19, 2008, 11:04:30 AM
after looking this thing (motorcraft- duralast tag on it) it is externaly regulater like old fords. do I add the box? or try to make the motorola fit? motorola has a smaller bolt thru it- changing belts and mounting area! Head ache!

It uses an externall regulator ?? Use the motorola ,just pass a 7/16 drill thru the mount boss & bolt it up and go or switch to a 60 amp Delco marine "one wire" 99 bucks and be done, Call if you need help
Title: Re: is a motorola 12v 55amp alt ok?
Post by: marceldawson70 on August 19, 2008, 12:42:55 PM
drilled hole on motorola! now it doesnt have leads hanging out but does have posts! my coil is external ballast. so I guess I still need the purple lead. do I still need to use the sense B+?    If so where do i connect it?
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