MarineEngine.com - Your online store for all types of marine engines and boat parts.
PHONE ORDERS
Monday - Friday
9:00 AM - 5:00 PM EST
Click for TOLL-FREE Number
Online Checkout
Special $9.95 Flat Rate Shipping
(800) 209-9624 | Home | Contact | Shipping | Returns | Cart View your shopping cart.
Part Number Search
Shop by engine/drive part number.
Original & matching parts for sale.
Manuals & Accessories
Shop by description, item number
or manufacturer's model number.
Boat Repair Forum Boat Repair Forum   Boat Video Gallery Video Gallery
   
Click for Crusader parts and manuals!
Results 1 to 20 of 20
  1. #1
    Join Date
    Aug 2008
    Location
    Holden Beach, NC, USA
    Posts
    61

    Default 3 wire vs 1 wire alternator

    Hello everyone! Haven't had to post in a while (good thing right?) but got another issue I would like to get a little input on. Currently have a 1988 Crusader270 (350cu) with a bad alternator. Of course some ding bat had put an automotive type on it. Went to get a marine alternator to replace it but ran into a question. The original sevice manual lists Prestolite or Motorola 2 wire alternators. The automotive one on there now is a 3 wire. The guy at the boat shop said use a one wire. After a little research found that the one wire is always on, with the battery on that is, and after a period of time would run down the battery. The three wire uses a battery sensor lead that tells the alternator how much to charge. This should come from near where most of the accesories pull from (ignition) and not at the battery so you allow for voltage drop and only turn on the alternator when the switch is on. Am I barking up the right tree? Looking to go with a Delco marine 105 amp 3 wire. its not the 3 ear mount like OEM but will fit the current set up. Whatcha think??? Capt Al

  2. #2
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    6,579

    Default Re: 3 wire vs 1 wire alternator

    If he's talking about the Delco 10si Marine version....., he is incorrect.

    He is also incorrect with this comment.... or he's not understanding it himself
    The three wire uses a battery sensor lead that tells the alternator how much to charge. This should come from near where most of the accesories pull from (ignition) and not at the battery so you allow for voltage drop and only turn on the alternator when the switch is on.
    The difference is minimal. Either will sense voltage, and will predicate charge rate accordingly.

    I'm running a pair of them on my current boat....., and have run them on many boats, and for years.
    Never heard of such an issue before.

    The 10si is available in the single wire, or the three wire (not to confuse the Negative that must also be connected to the engine block)
    The three wire excites upon start up.
    The single wire units require a bit of an RPM "Bump" to excite them. Once excited, they remain excited.
    Other than that, they work very well.

    You can find the 10si being offered on e-Bay for as little as $60 for a 42 amp....... $76 for a 63 amp.... there is also a 90 amp.
    Do NOTE that alternators cut back charge rate rather quickly.
    It can be somewhat of a misnomer to think that most will produce the Amp Rating for durations..... when in fact, they usually will NOT...... Not until you get into the very expensive Marine Alternators. Then the Power out and Neg wiring changes also.
    Probably nothing that you need to worry about, unless your damands are greater than what you're letting on here.


    These are inexpensive enough to make carrying a spare on board very affordable.




    I'm not sure that I am following some of your Motorola 3 ear mount question.
    Scroll down on this e-Bay page and look at the 10si conversion alternator.

    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  3. #3
    Join Date
    May 2010
    Location
    DC Burbs/Maryland Eastern Shore
    Posts
    759

    Default Re: 3 wire vs 1 wire alternator

    Everything Rick wrote.
    The SI ( for System Integrated, which basically means internally regulated, a big deal when these first came out ) series for boats is virtually identical to the automotive one save for the spark screen over the rear where the slip rings are. They're very robust and easy to care for. You can field repair these with a few tools and a toothpick. Keep a spares kit on board and you can rebuild one in about a half hour. Or a whole one as he says.
    As Rick mentioned, an alternator's amp rating is nothing near what the real world output will be. Divide it by two and that's probably a more realistic number under normal operation.
    I gotta ask what your charging needs are that you think you need a bigger alternator. Are you away from the dock for over night or a few days where you cannot plug in to shore power to recharge? If yes, and you need reliable fast recharging, then consider upgrading to Balmar alternators and regulators. About a grand to do but will keep you humming with no worries.
    Practicing the ancient art of ren-ching

  4. #4
    Join Date
    Aug 2008
    Location
    Holden Beach, NC, USA
    Posts
    61

    Default Re: 3 wire vs 1 wire alternator

    Thanks for the feedback Rick. The automotive alternator that is on there now is the same as the 10si, just the 3 wire version Not sure of the model number. I had read on a hot rod post about the 1 wire vs 3 wire. They were saying that if you have a long cable run that the voltage drop for running several accessories would put a lower voltage at that end. The advantage of the 3 wire is that the exciter voltage would come from that area instead of the 1 wire system that would measure the voltage at the battery. Doesn't the input voltage whether at the single wire or exciter lead determine the voltage output? Not sure if the voltage drop would even be enough to make a difference. That's why I wanted a little input. I agree about the marine models on ebay. Found several there at a good price. Also seen those three hole adapters. Apparently it was used for the Motorola and Mando style alternators that originally came on the engines so you could adapt the 10si style. The 10si fits just fine in my application. Thanks again!!! Capt Al

  5. #5
    Join Date
    Aug 2008
    Location
    Holden Beach, NC, USA
    Posts
    61

    Default Re: 3 wire vs 1 wire alternator

    o2batsea I do stay out overnite a lot. Main reson for getting the 105 amp vs the 42 amp was $3 difference. Figured it wouldn't hurt. Right on the rebuild also. I've fixed many of the si in the field with a McGyver knife and a stick!!

  6. #6
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    6,579

    Default Re: 3 wire vs 1 wire alternator

    Quote Originally Posted by captal View Post
    Thanks for the feedback Rick. The automotive alternator that is on there now is the same as the 10si, just the 3 wire version Not sure of the model number.

    I had read on a hot rod post about the 1 wire vs 3 wire. They were saying that if you have a long cable run that the voltage drop for running several accessories would put a lower voltage at that end.

    The advantage of the 3 wire is that the exciter voltage would come from that area instead of the 1 wire system that would measure the voltage at the battery. Doesn't the input voltage whether at the single wire or exciter lead determine the voltage output? Not sure if the voltage drop would even be enough to make a difference.

    Thanks again!!! Capt Al
    Capt Al, I'd suggest that you quit reading Automotive information for any cross-over into Marine. It will do nothing but get you into trouble.
    You must know precisely what will cross-over, and what will NOT.

    Secondly, when your alternator is connected to your engine, and if the Engine Harness is still OEM configured, it will be using a portion of the Harness for the charge circuit.
    Again, if OEM configured, this same charge circuit makes it's way back to the battery bank, via the "common" starter motor cable that will connect to your MBSS (main battery selector switch).
    Therefor, I'm not sure how the above applies to that theory of a voltage drop! (unless this boat is not cabled as such!)
    Again, if this is coming from a Hot Rod article, I'd pay little to no attention to it.... who knows what they're actually doing -vs- that of Marine????


    Lastly, and not in order here.... but you can convert your auto 10si to Marine with this for about $25 delivered.
    This kit does not show any slip ring replacements.... not sure if required, but O2Batsea did mention this.



    However, at the low cost of a 10si ready to go, it's hardly worth it.


    .
    Last edited by RicardoMarine; 04-02-2011 at 07:43 PM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  7. #7
    Join Date
    May 2010
    Location
    DC Burbs/Maryland Eastern Shore
    Posts
    759

    Default Re: 3 wire vs 1 wire alternator

    Well if you can score a 105 amp marine Delco 10si one wire alternator for three clams more than a low amp one then there is no question you should get the bigger one.
    The advantage is that it will recharge faster. What do you have for batteries and have you upgraded to LED lighting? When I put in all LEDs, my amp draw for lighting went from 12 to less than one.
    Practicing the ancient art of ren-ching

  8. #8
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    6,579

    Default Re: 3 wire vs 1 wire alternator

    One issue with going to a 100 or 105 amp unit may be the OEM engine harness itself.
    If the harness is not designed for this amp rating, we're going to have some heat resistance in this charge circuit.
    We can re-wire this and/or incorporate an ACR as well.

    BTW, off topic a bit..... the Xantrex LINK system is a great battery monitoring system, in that it actually measures AMP HOURS.... of which is a much more meaningful number to monitor.
    Once Zero'd in..... it will track amp hours consumed.... and amp hours replenished into the battery bank.... all via a shunt resistor and circuitry algorithm.
    Much more meaningful over that of a voltage reading alone.
    Somewhat expensive???.... yes!
    Worth it????.... if you care about battery longevity...... yes!

    There are several models of the LINK system.



    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  9. #9
    Join Date
    Jul 2010
    Location
    Canada
    Posts
    630

    Default Re: 3 wire vs 1 wire alternator

    You nailed it Rick, my thoughts exactly. I've found once someone has made up thier mind to increase output it's difficult to convince them otherwise.....and that's OK, not saying to forget about the HO alternator, but you must consider added stress on the current wiring. It was designed to handle half the load you're thinking of changing to. The few dollars extra for the additional amperage is great. Your savings will go out the window when you need to replace a harness (or boat) because of a wiring oversight. Seen it happen, and it can be pretty messy.

  10. #10
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    6,579

    Default Re: 3 wire vs 1 wire alternator

    Yep, and the truth is, Woodie, if you really want high alternator charge output, you need to do as o2batsea suggests, and go with the Balmar alternator and regulator, and increase the Pos/Neg portion of the charge circuit.

    The other actual truth is, for those more serious people out on the hook, they really need a good O/B Smart Charger (of substantial Amp Output), and a Generator..... whether O/B, or one of the little portable Honda EU's.
    My Xantex Chrg/Inv 1000 (while using my Kohler Gen), will kick butt over my previous 100 amp alternator.... of which I eventually removed, and went back to a 63 amp. The Charger output is only 50 amps, but like said, it kicks butt, and does not cut back at the same rate.

    Long as I'm on my soap box here; battery management is key!
    If left in a SOD (state of discharge) below a safe level, and for any duration, we begin to kill our batteries!
    Usage cycles is one thing.... but cycles of being left in a state of discharged will kill them prematurely.
    These are not air tanks whereby we can simply pump them back up, and expect all to be good!

    For any of us who spend a considerable amount of time on the hook, I'll suggest again that the Xantrex LINK System can't be beat!
    I believe that there is one more monitoring system that uses Shunt Resistor data.... but can't think of the brand right now!

    BTW, the LINK that I have also acts as a function control for my Chrg/Inv!
    The little round LINK units are stand-a-lone only, I believe!

    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  11. #11
    Join Date
    May 2010
    Location
    DC Burbs/Maryland Eastern Shore
    Posts
    759

    Default Re: 3 wire vs 1 wire alternator

    Meh, if it's the standard issue 10g wire from the alternator it should be just fine. A 105 A alternator at full cry is only gonna do about 80 amps, well within a 10g wire's ability. Really worried? Get 4 feet of 8g wire.
    Do check to be sure that the connections are clean and tight tho.

    Not saying I have the perfect set up, but I run a Mando 65A and a Balmar MaxCharge regulator. I split the charge to start and house with a Yandina 150 combiner. I have the remote emergency parallel switch on the dash. Start bank is an AGM group 27, House is two AGM group 31. This way I have no battery selector switch.

    I like that Link thing. I might have to get that instead of the analog meters I have now.
    Practicing the ancient art of ren-ching

  12. #12
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    6,579

    Default Re: 3 wire vs 1 wire alternator

    You'd like the LINK. Some call it a "fuel gauge" for batteries!
    The Shunt installs in the Negative return path for the bank being monitored.
    Even if combining for a short or long duration (draw or charge), it tracks only those amp hours pertaining to that particular battery bank.
    (if the Shunt is installed correctly, that is!)
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  13. #13
    Join Date
    Jul 2010
    Location
    Canada
    Posts
    630

    Default Re: 3 wire vs 1 wire alternator

    IMO, to be safe, one can't assume the alternator won't put out full charge when determining wire size, regulators can fail. The OEM wire is seemingly bigger than needed for a reason. A certain AWG wire on it's own may handle the max load it's designed to, however, when bundled for example, one must reduce the rating by 30%, not to mention it is operating around a hot engine which drastically reduces capacity even further. The current wiring may handle the extra load for a long time, but if the chance is there for things to go wrong due to inadequate wiring, Murphy will rear his ugly head, it's just a matter of time, especially on a boat!
    Last edited by WoodieMan; 04-03-2011 at 09:08 PM.

  14. #14
    Join Date
    Sep 2003
    Location
    New Tripoli, PA, USA!
    Posts
    12,061

    Default Re: 3 wire vs 1 wire alternator

    The Vee belts need to be a double setup for that much power so they won't slip.

    Jeff

  15. #15
    Join Date
    May 2010
    Location
    DC Burbs/Maryland Eastern Shore
    Posts
    759

    Default Re: 3 wire vs 1 wire alternator

    They don't seem to have the Link any more. They now have LinkPro and LinkLite which fit in a 2" gauge hole. Awfully cool.
    Practicing the ancient art of ren-ching

  16. #16
    Join Date
    Mar 2009
    Location
    Portland, Oregon,
    Posts
    6,579

    Default Re: 3 wire vs 1 wire alternator

    I believe that both the LINK 1000 and LINK 2000 will be available for some time yet to come.

    I'm using the LINK 1000, as it also controls my Chrg/Inv.

    .
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  17. #17
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,477

    Default Re: 3 wire vs 1 wire alternator

    CAPTAL:

    You'll find the physical mounting is different between your stock Alternator and a Delco. You can accomodate this a few differenet ways; whichever choice you pick just keep in mind the replacement/service requirements. We did it by custom milling the brackets and the cases which is far from ideal - maintenance-wise - over the long haul.

    I'd suggest the 3-wire version, having had the one wire versions. The behavior of the 3-wire setup is much better than the 1-wire rig and doesn't take much longer to get the wiring harness to accomodate it. Assuming your harnesses are close to OEM, you'll likely appreciate the 3-wire configuration, especially if you move the sense wire from the starter lug to the battery.

    You also need to consider your current battery 'chemistry'. We have Gel-Cells and the 'standard' 10si regulator will destroy them in short order. Good news is that regulators with alternative set points are easy to obtain.

    Having rebuilt a few, as noted in the pic Rick posted, there are two spark suppression screens required to marinizer a 10SI case.

  18. #18
    Join Date
    May 2010
    Location
    DC Burbs/Maryland Eastern Shore
    Posts
    759

    Default Re: 3 wire vs 1 wire alternator

    OOOoowee. almost 600 clams for the link 2K. I'll suffer with the needle meters for a while more. I have a Charles charger and no inverter.
    Practicing the ancient art of ren-ching

  19. #19
    Join Date
    Aug 2008
    Location
    Holden Beach, NC, USA
    Posts
    61

    Default Re: 3 wire vs 1 wire alternator

    Hey Mark! Thanks for the input. Got the new marine 10si alternator on and it works fine. I did go with the 3 wire. MUCH better set up. I do have a heavy charging lead so the higher amp was no problem. I did encounter the mounting problem. That was the old 3 ear adapter I referred to earlier. The 10si has the 2" mount where as the Crusader bracket was set up for a 1" mount. A little hacksaw work did the trick. I have the AGM deep cycle batteries. Does the Delco work OK with them or do I need a different regulator?

  20. #20
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    5,477

    Default Re: 3 wire vs 1 wire alternator

    I think the AGMs tolerate the "normal" (~14.6 VDC setpoint) regulators - best to check with the maker of your batteries. I know my GELCELLS won't tolerate any charge over 14.1 VDC without shortening their lives.

Similar Threads

  1. Alternator Excitor wire
    By jcampbell in forum Volvo Penta Gas Engine Forum
    Replies: 9
    Last Post: 06-13-2010, 01:14 PM
  2. One wire Alternator
    By agitator in forum Chrysler Inboard and Sterndrive Forum
    Replies: 14
    Last Post: 05-26-2009, 10:35 AM
  3. Alternator purple field excitation wire
    By tonycma in forum Volvo Penta Gas Archive
    Replies: 3
    Last Post: 08-07-2008, 02:51 PM
  4. Replies: 2
    Last Post: 05-19-2008, 09:10 PM
  5. Alternator wire size
    By rich_b in forum Mercruiser Sterndrive Archive
    Replies: 6
    Last Post: 02-14-2008, 08:02 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •