M25 Motorola 55 Amp Altenator question

[OS2Dude]

I am trying to update the wiring in my new (to us) 1985 Catalina 30. It has an M25 engine with a 55 amp Motorola alternator. The alternator output is currently hooked to the old wire harness. (Yes, I have that upgrade planned SOON) After reading all the posts, it seems that the prevailing wisdom is to hook the alternator output to the primary bank. Currently the output wire (Thick orange) along with the ground wire (Smaller Orange & Brown) disappear into the mass of black electrical tape that covers the harness. Am I correct in the output can be wired directly to the primary bank and the ground can be connected to the engine block? (The ignition wire stays as it is.)

Thanks

(Please be gentle, engine electronics are not my forte.)

 

[Stu Jackson]

Chris, yes.

Please remember, none of us was born an electrician (and this is electric, not electronics ).

You also have to be aware of the wire between the starter solenoid and the alternator output - see the box with "Bypass the orange red circuit" here:

http://www.pbase.com/mainecruising/catalina_36_alternator

The overall wiring improvements are covered in these:

OEM 1-2-B Switch Wiring History http://c34.org/bbs/index.php/topic,4949.msg30101.html#msg30101

Basic Battery Wiring Diagrams This is a very good basic primer for boat system wiring: http://c34.org/bbs/index.php/topic,6604.0.html

This is another very good basic primer for boat system wiring: The 1-2-B Switch by Maine Sail (brings together a lot of what this subject is all about)
http://forums.catalina.sailboatowners.com/showthread.php?t=137615

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A collection of boat electrical systems information is available here

Electrical Systems 101 http://c34.org/bbs/index.php/topic,5977.0.html

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There is a C34 Fleet on your lake with a bunch of skippers who have a lot of experience. Look up Dotty Toney.

Good luck.

PS DO YOUR HARNESS FIRST. Now. Immediately.

http://c34.org/bbs/index.php/topic,5078.msg35943.html#msg35943

PPS Are you aware of the upgraded alternator bracket issue? If not, read more in that last link. Most of it applies to your boat as well.

 

[OS2Dude]

Thanks for the reply and links. I had actually seen that page, but don't know what the DP and PDP notations mean, nor does it say where the ground from the ALT goes.

We just finished the engine upgrades. (Alt bracket, 3" Heat Exchanger, Oil Change, Impeller replacement) My brother is up from FL to help, so we're doing the things I need him to help with first.

 

[Stu Jackson]

Thanks for the reply and links. I had actually seen that page, but don't know what the DP and PDP notations mean, nor does it say where the ground from the ALT goes.

Chris,

DP = distribution panel (your main electrical panel)

PDP = Positive Distribution Post (where you collect your positive wires so only one wire has to run to the + battery post instead of loading up wires on the battery post; I used a Power Post Plus, others use bus bars)

The OEM Motorola is grounded to the engine by the case. You can also ground it to the engine separately. I never did that until I installed a higher output alternator, which had a (more) obvious ground post.