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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through January 14, 2005 » Alternator upgrade question « Previous Next »
By Brad Birlew (bradb) on Wednesday, November 03, 2004 - 11:11 am:    Edit Post Delete Post
I've just upgraded my stock alternator in my '94 ski nautique (51amps) with a 90 amp model.
I have 2 questions:
1) should I upgrade the 10 guage wiring from my alternator to the 50amp breaker?
2) should I upgrade the 50 amp breaker that seems to be between the alternator and the battery? From what I can tell, the power for the accessories to the dash comes from the alternator side of the breaker. Does this wiring setup make sense?
I'm a little confused and would apreciate any help. Thanks,

(Message edited by bradb on November 03, 2004)

By Harold (wikd281) on Wednesday, November 03, 2004 - 11:27 am:    Edit Post Delete Post
I think that if you would like to use the factory wiring you can....but> I would definately change the breaker. What you can do is run a charge line off the alternator directly to your batteries. I had a 93 ski nautique and I went from the factory 50amp alternator to a 130amp ho alt. It would run for about 10 minutes then the whole boat would shut off because of that red 50amp breaker shutting off. I would have to sit there dead in the water for about 15 minutes for it to re-set. I would push the button for it to re-set and it would not work. I think it needed time to cool off. It would happen repeatedly. You should have three wires to the alternator. One is the charge line. The next is a ground. And the last is a remote wire or ignition on. Depending on the regulator you are running- if its a self exciting regulator, you can run just a charge line from the alternator to the batteries. If its a non-self exciting reg. than you will have to run the ignition on and the charge line to the batteries.
Hope this helps!

By Harold (wikd281) on Wednesday, November 03, 2004 - 11:30 am:    Edit Post Delete Post
Here is a link to Grant's site....these pics can probably help you with the wiring.


By Harold (wikd281) on Wednesday, November 03, 2004 - 11:33 am:    Edit Post Delete Post
Grants alternator
By Brad Birlew (bradb) on Wednesday, November 03, 2004 - 12:14 pm:    Edit Post Delete Post
Thanks for the quick reply. I've checked out grants site in detail. You guys do fantastic work.
The alternator I bought wires in exactly the same as the last one came out... 3 wires: 1 pos, 1 ground, 1 exciter.
You can see from the pic I posted that the exciter wire (31) is wired from the 12.5 amp breaker at the back ((41)on the pic I think). This is where I get confused as well...
You are suggesting that I wire the same exciter wire up as before, but run a new pos off the alternator directly to the battery? Should I put a breaker on it? Then I should disconnect wire 23 from the 50 amp breaker, but leave the rest of the stuff connected to it? (ie. This would leave wire 22 connected from the battery through the 50 amp breaker to the wiring harness. It would also leave my accessories wiring protected through the 50 amp breaker - I mentioned a third wire comming into the left side of the 50 amp breaker that I believe goes to the dash accessories)
Hope that makes sense, and thanks again for the help. I just want to get this right, and not wreck anything!

By Harold (wikd281) on Wednesday, November 03, 2004 - 1:07 pm:    Edit Post Delete Post
Thanks man. Grant does do AWESOME work. Thats why I was stoked to have him work on my boat.
If you can upgrade the wiring to a little larger gauge. If you do a search online there is a simple chart that will suggest a wire size per how long it will be and how many amps you are running. What you want to do is bypass the factory circuit breaker-so> the charge wire off the alternator (the largest wire) you do not run that to the factory breaker- run a breaker just like Grants (pictured) and then run the wire directly to the battery. This way the alternator charging output will not go thru the factory wiring- it will go direcectly to the batt. If you have a grounding wire to the regulator you can still use it- but most of these alternators ground from the mounting feet. I know that I did not have to ground my alternator on my 02 SANTE because it was grounded thru the feet. If you have a 90amp alternator you could probably run a 100 amp magnetic circuit breaker and be fine. One thing to note- never run your alternator with the magnetic circuit breaker OPEN- You will fry your regulator.
Anything else just let me know!
Hope this helps.

By Brad Birlew (bradb) on Wednesday, November 03, 2004 - 5:10 pm:    Edit Post Delete Post
Thanks again. I guess the thing that bugs me is that my dealer keeps telling me to just swap the alternators, and everything will work ok (same breaker and same wiring). He sais that the new nautiques come with a 90 amp alternator still have the 60 amp breaker (It's actually a 60amp breaker in my boat too... I just keep calling it a 50amp one because that is what it was in the user manual pic I scanned) as it is setup in my boat already. It would surely be easier that way (just undo the three wires on the back of the alternator, and re-attach the new alt.) but I would rather do it right than quick! Could I wreck anything by doing it the way that the dealer suggested, and then if I find that the breaker flips on me I can change it later?
I will be wiring 2 amplifiers (just small ones - nothing exciting - 100watts each) and one or two heaters off the battery.
My dealer has always been right before (and super helpfull in troubleshooting all my other probs) but somthing just seems wrong about this one... I don't know...
Sorry about the rambling, and thanks for the help.

(Message edited by bradb on November 03, 2004)

By Harold (wikd281) on Wednesday, November 03, 2004 - 5:55 pm:    Edit Post Delete Post
I have been STUCK out on the water before...if its one thing that I learned from if I do something like this- dont half ass it or guess if it will work- make sure it will work! You could Mount a new circuit breaker right on the same plate that your factory one is on and just take the wires off the back of the factory breaker- then just run the wires to the new breaker. I am speaking from experience....youre loading up your boat with a bunch of friends> going to have a great day on the water> you launch the boat everythings going fine- then as youre going past all the larger boats that throw wakes that are the same SIZE as your boat...... all the sudden- Your boat dies! All power is off. What do you do? Try to reset the breaker and have to wait for it to cool down- most likely around 20 minutes. Doesnt sound like fun to me! This happened to me with my first boat- It REALLY sucked! I would not like to see this happen to you! If the new boats run ok than I guess you will be fine...but I dont feel comfortable with trying to squeeze 90 amps of current thru a 60 amp breaker. Especially when you are playing youre stereo and running the heater and maybe some docking lights. That can pull some big power.
Good luck in youre decisions.
If I can help in any other way just let me know.
If you have seen the latest movie of Startsky and hutch ( Do it- Do it- Just Do it!)

By Mike (mikeski) on Wednesday, November 03, 2004 - 6:47 pm:    Edit Post Delete Post
The 60amp breaker should not pass more than 60 amps for longer than it's transient rating (probably a second or so) unless it is faulty. The powerline from the alternator splits before the breaker between the to the 8 pin wiring harness plug and again at the breaker, it's unlikely those loads will bleed enough current to keep the alternator from tripping the breaker. If it were my boat I would leave the existing wiring as is and add a number 8 wire through another 50 amp circuit breaker following the same electrical path to the starting relay where the heavy battery cable attaches. Alternatively you could run the second charging wire to a second battery (stereo dedicated) if you have two. Maybe add an isolator at the alternator if this is the case.

If you have the time you should put a dead battery in and see how it reacts, at a dock in a controlled situation. Watch for hot wires, smoke/smell. Make sure the battery is covered in case it bubbles over (or worse, explodes). This will be the case if you run your battery dead at the lake.

I think you should definately check with a few others, if that alternator delivers anything close to 140 amps you will turn that number 10 wire into a heating element.

By Brad Birlew (bradb) on Thursday, November 04, 2004 - 9:45 am:    Edit Post Delete Post
Hey Guys,
I appreciate all the advice and help. I was still worried about what my dealer told me (just wire the alternator up and leave the wires and breaker as is), so I called correct craft in orlando. I explained everything I was going to do, and he told me the exact same thing... Just wire it up as is, with the 60 amp breaker and same wire as before. He also confirmed that the new boats have a 100 amp alternator with the same wiring and breaker as my boat. Now I'm just as confused as ever!
Anyways, Thanks for all your advise guys. I'm taking it all into consideration.

By Harold (wikd281) on Thursday, November 04, 2004 - 10:06 am:    Edit Post Delete Post
You could just take it to a stereo shop or even better a boat shop and have them do it? It sounds like you dont want to run into problems.....but if you have someone else do it for you there should be a warranty and they have experience with doing the same thing over and over again. If its your first time with wiring...dont sweat it! I have always been one that will over build something- because I dont like to break down or have a weak link in a system.

By Mike (mikeski) on Thursday, November 04, 2004 - 9:17 pm:    Edit Post Delete Post
Just in case anybody else reads through this I thought Brad had posted the picture of the 130 amp alternator so my earlier post might be a bit overkill. Still, the true test may come at a very inopportune moment. I would hate to find out that my alternator is tripping the charging circuit breaker or worse melting the wiring harness out at the lake...

About 20 years ago I had a VW Rabbit GTi running about 1500 watts of stereo, high power headlights, fog lights, defrosters on high, and wipers running melt the insulation right off the charging wires one rainy night. It was not a fun experience and the car was never the same. It would probably be worse in a boat.

By Rod McInnis (rodmcinnis) on Thursday, November 04, 2004 - 9:47 pm:    Edit Post Delete Post

I would recommend establishing for sure where the Positive wire of the alternator connects. Don't worry about the "exciter" wire, it would be a low current wire. Ground is,well, ground. I would expect that most of the ground current actually goes out the case to the engine frame.

It is the Positive wire you need to worry about. This should be a fairly big wire and thus easier to trace. I would expect it to connect on the battery side of any breaker. To connect an alternator to the load side of the breaker defeats the purpose of the breaker.

If the positive side of the alternator connects to the battery side of the breaker then you don't need to (and shouldn't) change the breaker. It is possible that the wire from the alternator is too small to carry the load, however, in which case you may need to replace the wire.

If the alternator does connect to the dash side of the breaker then you actually have a real mess that isn't easily solved, other than rewiring the alternator to connect it to the battery side.

If the alternator current has to pass through the breaker to get to the battery and you don't increase it to match the alternator output then the breaker can trip when the alternator is charging a heavily discharged battery. Since I assume this is what you bought the alternator for it would not be an unexpected event. If the breaker opened while the alternator was under heavy load it could easily destroy the alternator and perhaps take out electronics in the boat.

If you simply increase the size of the breaker then you lose the protection that the breaker was put there for in the first place.

I can't quite make out that wiring diagram that you posted so I can't trace the wiring based on that. It shouldn't be hard to trace in the boat though.

By Brad Birlew (bradb) on Friday, November 05, 2004 - 10:44 am:    Edit Post Delete Post
Thanks for your input.
Wire 23 on the diagram from the alternator is positive, and connects to the left side of the breaker. Current continues through the breaker on the wire now labeled 22 from the right side of the breaker. It makes a quick stop at the starter relay and continues on to the battery positive terminal. The diagram is exactly how the boat is wired... I've followed it.
(If you save the pic to your computer, you can zoom up on it.)
I'm just perplexed that the correct craft tech guy and my dealer both told me to wire it up the same. I told them exactly what I was going to do (add amplifiers and heater).
Rod, I agree that if the pos from the alternator came in on the battery side of the breaker, there wouldn't be an issue. The alternator current would charge the battery (and power the amps and the heater), and the 50 amp breaker would protect my dash accessories and the current going into the wiring harness.
I'm still reluctant to change the factory wiring, and go against the wiring diagram and the advice of the nautique factory/dealer... I'll have to look at it again this weekend. Thanks guys.

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