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View Full Version : Re-wiring (& circuit breaker) for higher amp alternator ?


davekro
07-14-2007, 04:12 PM
I am just upgrading from 51A to 100 amp alternator. I am reading that I need to increase my OEM wire size from the alternator to the battery from current 10 or 12 awg to 4 awg!

To add confusion to my situation ('91 MC Prostar 190), the 12 awg (I think, may be 10awg) wire from alternator goes to the terminal block (at rear of engine), jumpers to a 32 volt breaker, then to the 'battery' side of the starter solonoid (where the red 2 awg cable attaches from the battery).

First, not being an electrician, I don't understand how anywhere near the factory 50 amp charge rate can get to the battery thru this 32 amp breaker (mounted underneath the terminal block) without tripping??

Assuming there is some reason my OEM system CAN actually charge 50 amps, do I need to:
1) replace the 32 amp breaker with some higher amperage (or would that leave the rest of the electrical system open to 'frying' if an electrical problem occurred)
2) Leave the 32 amp breaker in place and add a second higher amp breaker just for the larger awg wire from between the new alternator to the solonoid? (would I need to leave the original OEM wire from the alternator to the terminal block for any reason?)

Any insights would be very helpful.

Thanks, Dave

snivesatgt
07-16-2007, 07:35 AM
Unfortunately I'm not sure the answer to your question, but sparked another question from it. I hope I don't perform a thread-hijacking...but:

Your alternator goes through a 32 amp breaker between your alternator and battery?

From the sounds of it. It sounds like it just uses the battery side of the starter solenoid so that it doesn't need to have another cable run all the way to the battery itself. Much like when you ground things to the chassis rather than the negative of the battery.

Why it needs to breaker between the alternator and the battery confuses me slightly. If the breaker flips while the engine is running - will the alternator not have a connection anymore and get fried?

Much like if you have a perko switch and switch it off while the boat is running...

so my main question (related to Dave's) What function does that breaker have for the altenator-battery connection?

ksmaristar91
07-16-2007, 08:33 AM
I have been pondering the same questions, I want to upgrade alternator, and charging leads, and have the same breaker inline. Any help would go miles, thanks...

davekro
07-16-2007, 11:11 AM
If my boat was on a trailer, I'd take it to an auto electrical shop for specifics on how to upgrade wiring for my new alternator with this circuit breaker issue. I have to believe someone else with a circuit breaker set up like ours has upgraded from a 50 amp alternator. I hope we hear from them. :o)
Dave

Engine Nut
07-16-2007, 08:25 PM
[QUOTE=davekro]If my boat was on a trailer, I'd take it to an auto electrical shop for specifics on how to upgrade wiring for my new alternator with this circuit breaker issue. I have to believe someone else with a circuit breaker set up like ours has upgraded from a 50 amp alternator. I hope we hear from them. :o)
Dave[/QUOTe

The wire from the alternator to the 12V stud on the starter solenoid does not go through the breaker. All you need to do is to run a new wire from the alternator directly to the starter solenoid. Also if your current altarnator is grounded theough a separate wire instaed of through the alternator case, you will have to increase the size of the ground wire as well.

Engine Nut

davekro
07-17-2007, 09:11 PM
The wire from the alternator to the 12V stud on the starter solenoid does not go through the breaker. Engine Nut

Engine Nut, what year/model is your boat? On my '91 PS 190 the (orininal) orange wire (I changed it to black 10awg recently w/red pipe cleaner wrapped around it in picture) from alternator DOES NOT go directly to the starter soloniod. It goes to the third lug (from port) on the terminal block. There is a jumper wire from this location to the second lug, which in turn, has a wire down to the 32 amp breaker mounted in the terminal block assembly. A wire then goes from the 'other' side of the breaker directly to the starter solonoid on the battery side (along with the 2 awg cable from battery). It is dead obvious in person.

I have owned this boat since new, so I know it to be OEM wiring (except my recent change to black 10awg wire). But since a few people have said this wire should go directly to the solonoid, I am uncertain if I should:
1) run my 'new' 6 awg wire from Alt. directly to solonoid and remove OEM orange wire from Alt. to terminal block. (having only the 6 ga. wire from Alt.)

0r
2) run my 'new' 6 awg wire from Alt. directly to solonoid and LEAVE the OEM orange wire from Alt. to the terminal block (having two wires from Alt).

Deviating from OEM to do #1 makes me wonder if I mess something electrically up??
Doing #2 would seem to (my non-electrician mind) to leave the OEM circuit in tact, while allowing the bulk of the increased charging amperage/voltage to go directly to the battery. Anyone see a down side to this #2 option?

Thanks, Dave

Engine Nut
07-17-2007, 09:39 PM
Engine Nut, what year/model is your boat? On my '91 PS 190 the (orininal) orange wire (I changed it to black 10awg recently w/red pipe cleaner wrapped around it in picture) from alternator DOES NOT go directly to the starter soloniod. It goes to the third lug (from port) on the terminal block. There is a jumper wire from this location to the second lug, which in turn, has a wire down to the 32 amp breaker mounted in the terminal block assembly. A wire then goes from the 'other' side of the breaker directly to the starter solonoid on the battery side (along with the 2 awg cable from battery). It is dead obvious in person.

I have owned this boat since new, so I know it to be OEM wiring (except my recent change to black 10awg wire). But since a few people have said this wire should go directly to the solonoid, I am uncertain if I should:
1) run my 'new' 6 awg wire from Alt. directly to solonoid and remove OEM orange wire from Alt. to terminal block. (having only the 6 ga. wire from Alt.)

0r
2) run my 'new' 6 awg wire from Alt. directly to solonoid and LEAVE the OEM orange wire from Alt. to the terminal block (having two wires from Alt).

Deviating from OEM to do #1 makes me wonder if I mess something electrically up??
Doing #2 would seem to (my non-electrician mind) to leave the OEM circuit in tact, while allowing the bulk of the increased charging amperage/voltage to go directly to the battery. Anyone see a down side to this #2 option?

Thanks, Dave

I was referenging a newer engine that doesn't have a terminal strip like yours. I would use your option 2. Run an additionalwire from the alternator to the solenoid and leave the existing wires in place.

Engine Nut

davekro
08-31-2007, 09:01 PM
Engine Nut,

I did do option #2 and just added a second wire (6 awg) from the new 100 amp alternator to the battery side of the solonoid. It has been working great since I did this install about 6 weeks ago. Thanks for the concurring on this option. :o)

Dave

drbesvold1
08-31-2007, 09:15 PM
i have a 88 m/c and was wondering if a person could change that circiut breaker into something diffrent , this is pics of what mine looks like and would like to change it around if possible

davekro
09-01-2007, 01:12 PM
What would you like to change exactly?
Thanks for the pics. I'll forward the one showing your PCV line going directly to your intake manifold. (relating to a different discussion)

drbesvold1
09-01-2007, 06:00 PM
to change that whole circut breaker to a new style or something else if possible might even upgrade to the 50 amp cause right now im at a 35 amp

Engine Nut
09-01-2007, 06:08 PM
That breaker is sized at 35 amps for a reason. Do not change it to a 50 amp breaker.You might be compromising the integrity of the engine wiring harness and you do not want to risk that. Also, I know for a fact that Indmar does not have any replacement wiring harnesses for those engines.

drbesvold1
09-01-2007, 06:46 PM
ok now can u get that 35 amp at any auto part store or is that a special marine amp breaker?

TMCNo1
09-01-2007, 08:25 PM
drbesvold1, just so you will know, Engine Nut is a Indmar employee and anything he says is gospel. Meaning, if he says it, believe it!

drbesvold1
09-01-2007, 08:48 PM
copy that thanks i didnt know that but now i have a contact at indmar

davekro
09-02-2007, 07:27 AM
drb,
So, do you want to replace the breaker because you suspect that your OEM circuit breaker is faulty? The circuit breaker is only a small component that happens to be mounted under the long terminal block in your picture. The inscription: 'circuit breaker', is just to show where the manual reset button is on the back (center) of the black plastic cover.

Do you have corrosion or some other reason you want to "to change that whole circuit breaker to a new style or something else if possible"?

Why the desire to change the assembly?

KHall
09-02-2007, 06:39 PM
Yeah, Do NOT upsize breaker. Asking for trouble if you do. If you need more power somewhere run another circuit. If the 35 is poping then find the short circuit or replace breaker w same size.

mjw101081
09-04-2007, 04:48 PM
davekro
did you change your alternator to add a battery for, let's say, a stereo? I want to add an amp for a stereo upgrade but am afraid i may have to add a battery(i may be completely off base). Have you or anyone else done this, heard of this, or have another suggestion? I have a '90 TS ford 351.
thanks

davekro
09-04-2007, 08:42 PM
mjw,

Many (most?) recommend and do add second batteries when using very large (and multiple) amps. I want to keep weight (and expense) down, so I still have just one battery. MY two amps are not that big, so I can get by. But my problem was my stock 51 amp alternator was not keeping the battery charged with all the frequent re-starts when skiers fall and the stereo on top of that.

Certainly if you have a location and WANT more weight for boarding, then a second battery is only a plus.