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Results 1 to 22 of 22
  1. #1

    Default How to replace the original Prestolite alternator by a new 1 wire alternator

    Hello, first of all I would like to introduce myself.
    I am from Austria Europe and just bought a motor boat "Ilver Ecstasy 24" equipped with 2 OMC 165 HP engines from 1973.

    The situation I have here is that one engine is missing the alternator and on the other engine the alternator is down, it's totally blocked and the housing is broken.
    The type label on the original alternator mentions the part no. "Prestolite ALK 6210 3E" and it's a 12V, 34 AMP alternator. The OMC part no. of the alternator is 985964.
    I have 3 wires comming from the original alternator and on top of the engine there is a BOSCH voltage regulator mounted.

    On the internet I found an alternator which should replace the ALK 6210 or the OMC 985964 but the new alternator would be a 1 wire 10SI Replacement Alternator 1.

    So I really don't know if I can buy this part and use it as it has only 2 connections instead of 3.
    If I can buy it how will I have to connect it?

    Thank you in advance for all ideas and help!


    Attached I have added some picture showing the original alternator, the new replacement alternator and also the voltage regulator.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  2. #2
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    If the Delco 10si will mount correctly, you simply eliminate the field and excite circuits.... just install wire caps on each one.
    Connect the charge lead to the + terminal, and make sure that the chasis negative is connected to the engine block.

    The thing with the single charge lead 10si, is that it's self exciting.
    These need to see approx 1,200 + RPM before they self excite.
    Once excited, they remain excited at any RPM, until shut down again.

    Also, the 10si is available in what they call a "three wire" (actually four wire, if we include the chasis negative).

    The 10si can be made into either a single wire, or a three wire.


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

  3. #3

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Thank you! Now I hope I got you...
    You mean I do not need the 2 black wires anymore which are now connected to the old alternator.
    I only need to connect the brown wire to the +terminal of the new alternator and connect the chasis negative terminal to the engine ground?

    Would be great if that would be all. So I could go ahead and order the new alternators.

    Thanks again!

  4. #4
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Back to you................
    Quote Originally Posted by Marcel72s View Post
    You mean I do not need the 2 black wires anymore which are now connected to the old alternator.
    I doubt that black is original. Someone may have changed the colors.

    I only need to connect the brown wire to the +terminal of the new alternator and connect the chasis negative terminal to the engine ground?
    Again, I doublt that brown is original. Charge leads are typically red.
    Whatever color it is, yes.... connect the charge lead to the + terminal, and the chasis neg to the engine block.

    Would be great if that would be all. So I could go ahead and order the new alternators.
    Yes, but remember, the 10si is available in both the single wire and the three wire.
    Single wire is self exciting (needs to see 1,200 + RPM)...... three wire excites upon field/excite circuit power.

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

  5. #5

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Thank you again!
    The wire colors brown and black I used because these are the colors on the pictures I have attached to my question. The brown one is actually connected to "B+". One of the 2 black wires is connected to "61" and the other black one is connected to a terminal not showing any number or so.

    The 3 wire 10SI I found only with higher AMP. I think I need the original 34 AMP as I have ampmeters installed which have a scale with only +40 to -40 AMP.

    Will I still need the BOSCH voltage regulator after installing the new 1 wire 10SI alternator? Or can I remove this part?

    Thanks,
    Marcel

  6. #6
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    My only concern is it it a marine grade alternator. Alot of offroaders are converting to one wire alternators and just makes sense upgrading from a externally regulated system. If it bolts up and the belt lines up it sounds like a good deal. Put a heavy guage wire from alternator chassis ground directly to battery neg. That should give you alot more power for appliances. Do you have separate batteries for each engine you dont want two alteranators charging the same battery?

  7. #7

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Quote Originally Posted by kimcrwbr1 View Post
    My only concern is it it a marine grade alternator. Alot of offroaders are converting to one wire alternators and just makes sense upgrading from a externally regulated system. If it bolts up and the belt lines up it sounds like a good deal. Put a heavy guage wire from alternator chassis ground directly to battery neg. That should give you alot more power for appliances. Do you have separate batteries for each engine you dont want two alteranators charging the same battery?
    The new alternators would be marine grade alternators. The dimensions are the same like on the original alternators and so the belt will line up and the bolts will fit. The is already a heavy guage wire installed from the alternator holder on the motor block to the battery ned. I have separate batteries for each engine. And there are separate voltage regualtors installed.

  8. #8
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Quote Originally Posted by Marcel72s View Post
    The 3 wire 10SI I found only with higher AMP. I think I need the original 34 AMP as I have ampmeters installed which have a scale with only +40 to -40 AMP.

    Will I still need the BOSCH voltage regulator after installing the new 1 wire 10SI alternator? Or can I remove this part?
    Marcel, if you go with the single wire 10si, you can eliminate the Bosch regulator.

    IMO, there's no need to take the chasis neg directly to the battery bank. Your engine block is your "system negative common". Both battery banks will make their main negative connnection to the engine block.

    There is also no down side to both alternators charge being directed to a single battery bank.
    This is often done in a twin engine scenario whereby both engine alternators charge rate is directed to the HLBB (house load batt bank) via either an ACR or a VSR. Mine have been set up this way for years.
    The cranking bank is also charged while this occurs.

    If curious, take a look at the Blue Sea ACR products, or the BEP VSR's.
    ACR = automatic charge relay
    VSR = voltage sensing relay

    These take the place of the old school isolators.

    The 500 amp Blue Sea 7622 ML has a start isolation feature.

    BTW, the 10si that you show is screened, and will be approved for Marine use.





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

  9. #9
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    You can never have too many grounds. The alternator is already grounded to the engine by bolting it on, the wire from the alternator chassis to battery neg is a good upgrade especially in cold weather operation 10guage wire or larger.

  10. #10

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    I really hope I get you guys correct with my poore English .

    The part I am thinking to buy is on ebay http://www.ebay.com/itm/270803598365...ht_8793wt_1399

    There is says:
    OEM(s): Prestolite
    Voltage: 12 Volts
    Amps: 34 Amps
    Polarity: Negative
    Reg. Location: External
    Fan Location: External
    Approximate Weight: 9 lbs / 4.09 kg
    Please Note:
    This is a 10SI Replacement Alternator

    So I thought if it says "external regulator" I have to keep the BOSCH regulator to have only 12 Volts max. going to the system. Otherwise I would have about 14 Volts depending on the RPMs if I remove teh regulator!?!?
    Sorry I am bit confused now




  11. #11
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Quote Originally Posted by Marcel72s View Post
    There is says:
    OEM(s): Prestolite
    Voltage: 12 Volts
    Amps: 34 Amps
    Polarity: Negative
    Reg. Location: External
    Fan Location: External
    Approximate Weight: 9 lbs / 4.09 kg
    Please Note:
    This is a 10SI Replacement Alternator

    So I thought if it says "external regulator" I have to keep the BOSCH regulator to have only 12 Volts max. going to the system. Otherwise I would have about 14 Volts depending on the RPMs if I remove teh regulator!?!?
    Sorry I am bit confused now

    Your English is OK.

    Charge output voltage will be near 14.5 volts during start up charging. It will cut back shortly.
    Ambient 12 v battery voltage (when fully charged and after having been at rest for 8 hours), will be near 12.4 volts.


    There are several oddities with this seller's ad... so you may want to find another seller.
    Here's list of other sellers and prices.


    This alternator is screened. If it's screened at the rear, it's also going to be screened at the front side.
    This qualifies it for Marine use.
    The auto version of the 10si is not screened, nor will it have the rear tin cover.





    His ad says Polarity: Negative. I'm not following that one.
    By the time that GM came out with the Delco 10si, all American automotive electrical systems were Negative chasis systems.
    These are nothing more than the old GM Delco alternators that have been Marinized.

    He says Reg. Location: External, but clearly shows a single charge lead terminal.... or what they call a "single wire" 10si.
    There is no need for an external regulator with this model.

    He also says This is a 10SI Replacement Alternator.... Key word "Replacement".
    There are lots of Chinese knock-offs out there.





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

  12. #12

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Hi Rick, I need to buy you a beer if I am there in the states .
    I found some other alternators online. 1 and 3 wire alternators, but if they have the same design (3 fixing points to fix on the engine) they do have much more AMPs and all of them are 1 wire alternators. There are alternators available with 61 AMP, 75 AMP up to more than 100 AMP. At the moment a 34 AMP alternator is installed.
    All of them mention negative polarity -So this seems to be okay. Most of them mention internal regulator or "Regulator I/R"

    This one for exsample: http://www.ebay.com/itm/Arco-Marine-...#ht_1559wt_932

    Or this one: http://www.ebay.com/itm/ALTERNATOR-O...ht_1621wt_1170

    But like I said all alternators with the requested housing design are 1 wire alternators.

    What would I have to change to use an alternator with more AMPs? Remember I have 2 Ampmeters on my boat with a scale from -40 to +40 AMP.

    I went to the boat and checked the wiring between alternator, voltage regulator, coil and the black motor connector.
    Attached is a drawing showing the wiring - I used the original wire colors.

    On the coil is written "USE 12 VOLT ONLY!" and "DO NOT USE A RESISTOR!" So if I use the new alternator without the BOSCH regulator wont the coil get too much voltage in the time te alternator brings 14.5 volts?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Marcel72s; 05-21-2013 at 03:08 PM.

  13. #13
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    The one wire alternators are internally regulated and are self exciting meaning it will sense a load and adjust the output accordingly. Your better off using volt meters directly off the battery and ditch the amp guages. A fully charged battery is between 12.6 and 12.8 volts and you dont want to see more than 2.5 volts over battery voltage so 14.5 volts at high rpms is pretty normal when you start getting over 15 volts you need to figure out why usually a bad battery. The one wire alternator has one wire to battery posative and the ground. It sounds too simple to be true but just size the wires for max amp output but the alternator will only produce the current being used. Your ignition should be fused along with all other appliances.
    http://www.boatdesign.net/forums/att...anelwiring.jpg

  14. #14
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    .....................................


    Look closely at the mounting style of these two alternators.
    This is not the typical GM Delco 10si mounting.










    Now look at the GM Delco 10si Marine version.





    Your better off using volt meters directly off the battery and ditch the amp guages..
    I agree with Kim's second point.

    The ammeter circuit ends up being a long run for high amperage to go forward to the helm, and then back again to the battery banks.
    With the ammeters still active, a high output alternator may create an issue with this circuit.

    With a volt meter at the helm, the alternator charge path can now become much shorter.... (eliminating much of the resistance from the long charge circuit the helm and back).
    If you were to do this, installing a higher output alternator will not be quite the same issue.... as long as the circuit is capable of the alternator charge rate.

    As to Kim's first point, I see no real need to take the volt meter directly from a battery bank.
    If the helm's Pos/Neg circuits are good, the volt meter can receive it's power from this.
    These volt meters aren't extremely accurate to begin with.

    If you want accuracy, install a Xantrex LINK or Nasa BM system.
    With these systems, we start thinking in terms of Amp Hours IN/OUT, not simply voltage.


    BTW, an 80 or 100 amp Delco 10si does not function the same as a Balmar, or more expensive Marine alterntor.
    The Delco regulator will cut back the charge rate rather quickly. So don't expect a continuous 60 or 80 amp charge rate from these for any extended duration.

    This is not a deal breaker, per 'se........... just an FYI.





    .
    Last edited by RicardoMarine; 05-21-2013 at 11:12 PM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  15. #15
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Kim, just to clarify....... I don't disagree with you at all on principle. A direct battery voltage reading would definitely be more accurate.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  16. #16
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    That is why I gave the link for a common dash wiring diagram if you use key on hot you get a accurate voltage going to the ignition system while the engine is running. My question is what is the easy way to switch boat power between engines if necessary.

  17. #17

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Good Morning and Thank You very much guys!

    About the mounting style. I do need the mounting style which is not the typical GM Delco 10si mounting. Originally there was a Prestolite alternator installed on the engines. I can see that also in the original user manual and so I need the style with two claws bottom side and one claw top side.

    So I will go with a 61 AMP 1-wire marine alternator solution. I think it can't be bad to have 2 alternators with 61 APM instead of the original 34 AMP alternators?
    According to the user manual originally were 2 batteries with 60AH each used on this boat. The batteries I found now on the boat are 2 batteries with 115AH each.

    As much as I understand I will have to check the wire dimension and also the fuse dimension to change the 34 AMP alternator to a 61 AMP alternator.

    Attached find a drawing showing the new wiring by using the 1-wire alternator. Please have a quick look at it if thsi works.

    And I will remove the 2 ampmeters from the cockpit and install 2 new voltmeters which are directly connected to the batterie.

    Wow guys once again thank you very much!
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  18. #18
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Ah.... so you do need the double mounting arms. I wasn't sure about that.


    Your purple wire coming from the starter motor solenoid is for a "start-by-pass" circuit. This is the "I" or "R" terminal.
    If no external ignition coil resistor is use, this circuit is not necessary, as long as the engines fire up quickly.



    And I will remove the 2 ampmeters from the cockpit and install 2 new voltmeters which are directly connected to the batterie.
    Again, IMO, there is no need to pull a circuit from the batteries to your volt meters.
    Your helm circuits will provide power to the volt meters, and your MBSS will cut this power when turned to OFF.

    In order to use volt meters at your helm, you'll need to circumvent the ammeter wiring at the engine side.
    IOW, these no longer need to run forward to the ammeters and back again.
    (these could remain in the hull harnes, and possibly be used for something in the future)

    Instead, I would change the alternator charge leads so that they go directly to the starter motor "common" cable connections.
    This is schematically identical to a direct battery connection, but only when it passes through the MBSS (main batt selector switch).
    This will allow your MBSS to select the load and alternator charge destination...... unless you somehow do otherwise.

    Now you can use the higher output alternators without concern for over-loading these ammeter circuits.


    You could do something like this, with a single MBSS..... although two MBSS's can be used as well.
    You can manually switch to batt #1 or batt #2..... or use a Blue Sea 500 amp 7622 ML ACR to pull in the cranking battery bank during start up.
    This same ACR will appropriate shared alternator charging also.

    If you do not mind manually selecting your battery banks, then the Blue Sea 120 amp 7610 ACR could be used (it is less expensive).

    FYI... I drew this up for a larger boat with the need for a large HLBB (house load batt bank)..... this is why the four 6 volt Golf Cart batteries are shown.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by RicardoMarine; 05-22-2013 at 06:53 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  19. #19
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Quote Originally Posted by kimcrwbr1 View Post
    My question is what is the easy way to switch boat power between engines if necessary.
    Wow.... that's a tough one to answer because it can be done several different ways.

    Two MBSS's with a combining solenoid between the common terminals. (this is how mine was set up for years... and it worked well)
    Two BS's with a combining solenoid between the common terminals.
    Two MBSS's with a cable joining posts #2 on each. (switch to ALL/BOTH on each, and we have "combine" mode)
    Two MBSS's or BS's with a Blue Sea ACR 7622 ML between the common terminals using the start isolation feature.

    With today's ACR's and VSR's, we can do this so many ways.

    I often prefer the KIS idea...... Keep It Simple! Or maybe better said, keep it as simple as possible.


    The nice thing about the 7622 ML, is that it's automatic when that mode is invoked.



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

  20. #20

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Thanks again!
    I just ordered 2 new 61AMP 1-wire alternators.
    The voltmeters I will install the way you told me.

    There is no external ignition coil resistor used and so I wont need the purple and the purple-black wires I think.
    -The purple-black one comes from the starter motor solenoid
    -The purple one comes from the black motor connector and was used with the old BOSCH voltage regulator on terminal D+

  21. #21
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    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Back to you...............

    Quote Originally Posted by Marcel72s View Post
    The voltmeters I will install the way you told me.
    That's my suggestion only..... do as you wish!

    My thoughts are.... that if you power the volt meters directly from the batteries, you'll need a means to cut power to them when the boat is unattended.
    If you use helm power, your MBSS cuts this when you leave the boat.
    Yes... there will be some line losss.... but as said, these volt meters aren't very accurate anyway.


    There is no external ignition coil resistor used and so I wont need the purple and the purple-black wires I think.
    Yes, if they've been starting OK, I agree.

    This circuit was originally designed to provide full power to the ignition system during cranking when ambient voltage drops to approx 10 volts.
    The ignition generally required this in order to produce good spark.
    Are you able to draft up an existing schematic of your battery banks, MBSS's, engines, etc?
    That would help us see what you actually have going on.... and perhaps make a few suggestions or say "hey, everything looks good".

    Here are some schematic icons to use if you can. (some will not be needed)
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    Last edited by RicardoMarine; 05-22-2013 at 09:10 AM.
    Rick ... aka Ricardo
    Portland, Oregon
    28' SDN F/B w/ twin Volvo Penta 5.7L DP's

  22. #22

    Default Re: How to replace the original Prestolite alternator by a new 1 wire alternator

    Thank you guys!
    Parts are ordered and I will kepp you updated as soon as I have everything installed!

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