New Member seeking alternator input

[Patches]

Hello to all, and my apologies for the lengthy preamble to this request for input.

I recently became the owner of a 1990 Mark 1.25.  When purchased, it was in largely "stock," unmolested, condition including:

--M25XP
--two group 24 flooded lead-acid batteries
--original (and dangerous) engine harness with trailer connectors.
--original instrument panel in the cockpit
--Prestolite 51 amp alternator
--autohelm st4000 autopilot
--no refrigeration
--battery charging from the alternator via the 1-2-both switch on the panel.

My intent is to slowly upgrade the boat as the budget allows.  I live in the Pacific Northwest, and cruised this past summer for two weeks straight without any issues.  Longest time away from shore power was 4 nights.

Because of my lack of experience with inboards, electrical demands, and bigger boats, one of the first things I did (8 months ago) was purchase two new Group 24 batteries with 85 amp hours each.  (I know, I know, dumb)  This was a (more or less) direct replacement of what was there when I bought the boat, and it seemed to work fine for the sailing and cruising I did this past summer.

I also started to address some of the other priorities set forth by the surveyor.  I have purchased a new exhaust riser, exhaust flange, heat exchanger, engine soundproofing, engine panel and wiring harness, hoses, raw water strainer, and raw water pump.  To get the exhaust riser out, I had to cut it off near the flange on the exhaust manifold, take the manifold off, and then work for days to separate the flange from the manifold.  Eventually I succeeded.  Many thanks to the contributors on this forum to help me understand how to attack these things!

Which gets me to the present issue before I start putting everything back together:

I had to take the original alternator off to get to the rest of it.  When I did, it leaked oil.  I took it into an alternator shop which deals with Leece-Neville alternators, and the tech opined that it was not cost effective to rebuild.  It is also 28 years old.  Which raises the issue of the type of replacement.

After all the expenses recently made, the budget is not equipped to handle a serious upgrade to the battery bank, high output alternator, new pulleys and belts, external regulation, refrigeration, etc.. I would like to get a few more years out of the present configuration, which assumes the new alternator charging the "smallish" battery bank by installing a larger output wire (e.g. 8 awg-or larger) to the positive post of the starter as recommended by others.  And I would like to buy a replacement alternator to accomplish this goal until I'm ready to spend more money on a more comprehensive electrical upgrade.

My attempts at researching this suggest the following which, admittedly, may be ill-informed:

1. Sizing the new alternator depends on (1) the size of the existing battery bank and (2) the footprint of the old alternator.

2.  For lead-acid batteries, a rule of thumb is to size the alternator output at 25% of the battery capacity.  For me, this is only 170 amp hours.

3.  Prestolite/Leece Neville manufactured several internally regulated alternators which allegedly fit in the "footprint" of the original alternator.  These are a 51 amp model, a 72 amp model, and 90 amp model.  The 51 amp model I can't find anywhere.  The 72 amp (8MR2058PA) and 90 amp (8MR2069TA) models are still available.  These can be had for <$200 each.

My questions for those experienced in these things, and given my desire to tackle a more comprehensive battery/electrical upgrade later:

1.  Do I risk any harm to my electrical system or batteries by replacing my existing 51 amp alternator with another internally regulated 72 amp (or 90 amp) replacement from Prestolite?

2.  If so, what is the expected harm?

3.  Would a switch to either of these higher output alternators require upsizing wires?  I have the 4awg positive and ground wires from the panel to the starter motor and engine block, respectively.  How about the AO wire to the starter?

4.  Leece-Neville also makes other 51 amp and 65 amp (8MR) small frame alternators, although they have different dimensions (deeper and three mounting holes along the top).  Anyone have experience trying to fit these into the M25XP alternator bracket?

5.  Given your experience, what would you do in my situation?

Thanks in advance for your replies.  I really appreciate the depth of knowledge and willingness to share found here! 

[Jon W]

In response to your item 4- I have a 8MR2401UA 105a Leece Neville alternator on my M25XP with the upgraded bracket. The alternator has been modified to use a Balmar external regulator.

[Stu Jackson]

Whew.     It's late here in the WDT.  Lots to absorb to start to answer.  Good questions.  See you tomorrow.

[KWKloeber]

Patches

Oil leaking?  hmmm...   Splain?

It sounds as if you want to get away as least expensive NOW until you have the ability to do a wholesale upgrade LATER?   You can't really do a mini wholesale (halfway -- like slap in a 100a alt and do nothing else.) 

<<<5.  Given your experience, what would you do in my situation?>>>

IIWMB I'd either replace what worked before (Motorola 2049K ) or at most the 75 amp option that was used on some M-25/XPs.  More than that you'll run into problems w/ belts and pulleys, etc. driving a larger alt.

I have sold a few of the 72a / 75a, remanufactured.   I like WILSON, a great company (IMO) that does TOTAL remans.  They do both the 2049K and higher amps. Have used the one (72a? 75a?) with the multi holes -- it fit just dandy on the XP bracket.  One plus with that model is that it has an external sense wire.  If you decide on one of those, let me know and I'll chk some sources to see where you can get it for least $ (several sell the Wilsons, like NAPA etc.)  In the past, I have contacted the Wilson techs to have em ship the unit on the shelf that tests out w/ the highest V setpoint on the regulator (since it's not adjustable.)

To do a wholesale you have to design the system/alt/regulation/cables/etc etc (as you allude to) but you're not doing that now.  So to an extent you're bewteen a rock and.... until you have funds/ready to do the wholesale.

What harness did you get? If Catalina Direct make sure you add overcurrent protection to meet ABYC (they trick customers into installing a non-compliant harness.)

You need to upsize the AO cable (AND add an alt negative cable) regardless - minimize the V loss.  There's a lot you can do to optimize charging if not doing a wholesale re-do.  Doing so becomes more important to optimize if you are NOT doing the wholesale. I worked w/ an owner on a hook that was losing V every time he ran the engine (short times, to/from the hook.)  He went from losing V each time, to better charging, gaining V, and getting it back to batt capacity by doing some simple, inexpensive upgrades (no change in his motoring use.)

JTSO,
-ken

[Patches]

Ken:

You have properly grasped my situation!  As mentioned, my upgrading budget is much smaller now that I have begun some of the critical fixes.  The major electrical upgrades are a few years off.  The good news is I've been able to knock off a bunch of the other upgrades to the motor in this first year.  My thinking is also informed (in part) by the fact that the boat operated in its original "relatively low electrical demand" condition for 28 years for two prior owners.

One of the things you mentioned was an "external sense wire", and this seems to be important for the replacement alternator.  Conceptually, and after doing a little research, I think this means the alternator--being dumb--needs a wire to the battery "+" to figure out the state of charge (SOC) in order to know how much power to direct back to the battery.  Is this right?

As I looked back at my replacement choices set forth my original post,  the 72amp (8MR2058PA) does NOT have a remote sense wire.  Nor do the 51 amp or the 65 amp models that the local alternator shop was able to sell me off the shelf.  The 51 amp direct replacement version (8MR2091KSS)-- which I can't find anywhere--does.  So it sounds like your idea of a remanufactured Motorola is a good one.

And as originally designed, it sounds like the sense wire assessed the battery SOC through the starter "+" post where the 4 awg positive wires came in from the selector/switch, and prior to that the batteries?  So it assesses SOC there--a long (and winding) way from the batteries.  I think I get why a comprehensive upgrade, including wiring the AO directly to the batteries is in my future.

The other wiring things I'm tackling near the engine include:

(1) moving the 4 awg negative off the bell housing to the starter "-" where the other 4 awg negative is attached.  From there I'm planning to run a negative 6 awg to a negative bus bar mounted on the port side to pick up the other grounds.

(2) increasing the AO positive to the starter "+" (8 awg), as well as a 8 awg "-" to the new negative bus bar.

(3)  Yeah, I bought the Catalina harness because I bought a new instrument panel as well.  The old one was pretty bad.  So I intend to inline fuse the "+" panel feed (red #10 wire) within 7" of the starter "+" as recommended here, and run the new #10 yellow/red start wire (unfused) to the solenoid.

(4)  I tossed the euro strip which came with the new CD instrument panel.  My boat does not have the glovebox-type pocket in the access panel for the euro strip to sit in, so i used heat-shrink butt connectors to connect the new harness wires to the new panel wires, and will be securing the harness run every 18" to the engine compartment. 

(5) On the engine side of the new harness, I'm thinking of running the wires to a terminal strip on the port side of the engine compartment, aft, up high, to be accessible for future work.

Any thoughts on these ideas?

I SO appreciate the input, because there is so much to learn. 

[mainesail]

Keep in mind that with only two batteries on-board, one is acting as house and one is reserve/start. An 85Ah battery is a very small capacity for a 34' boat, especially if it is cruised. The math on batteries looks like this:

Max Recomended Depth of Discharge = 50% SOC

85Ah @ 50% SOC = 42.5Ah usable from a 100% SOC charge

When out cruising your alt will usually only get you back to about 80-85% SOC due to the duration the engine is run. So the real math when out cruising looks closer to this.

50% SOC to 85% SOC = 29.75Ah of approximate usable capacity and this is only true if your batteries actually can produce their rated capacity.

In reality your daily Ah use dictates what you will be best served with.

By using an external regulator, such as a Balmar ARS-5 or MC-614, and a larger alternator such as a 90A - 105A, you can program the reulator to not exceed belt load. The benefit if this is that the alternator will live a very easy life working less hard. The problem here is the alternator set up is about double the same alternator with a dumb regulator. Dumb regulators can work, if used appropriately, and they fit within your ideal usage pattern.

Be careful with the 8MR Leece-Neville alternators as most of them use a 5/8" shaft and only one or two use a 17mm shaft. These alts ship minus pulley, some minus fan, and 1" foot versions ship without a "fit-kit" to make it a 2" foot. The pulleys you'll normally find are also cheap stamped steel. Also, the 8MR frame alts do not have a pulley offset, like a Delco does, so even if you buy a 17mm shaft version, such as the 8MR2069, a 17mm Delco pulley will need custom machining in order to fit corectly. The correct pulley to fit the most common 8MR's, a 5/8" shaft are very, very diffuclt to find in machined steel. We have the 5/8" shaft pulleys specifically machined for us out of billet steel.

If sticking with an internal regulator the maximum amperage I would recomend would be a 90A. With very little price differnce between a 65a and a 90A it makes little sense to go with a 65A. I would also strongly suggest, if going with the internal regulator, to find one that uses the LN 105-280 adjustable internal regulator. The positive & negative wires on this regulator can be used for voltage sensing and the regulator is adjustable for absorption voltage. It is still only a bulk > absorb two stage regualtor but it can be adjusted.

If you suspect you may cruise more, and want to go to external regulation in the future, be sure you are getting a genuine Leece-Neville product as the LN external regulation kits do not fit many of the knock-off 8MR's.

The articles at the link below will get you up to speed pretty quickly on marine alternators.

https://marinehowto.com/category/alternators/


.

[Stu Jackson]

>>>>>>>>>>>>>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>>>>>>>>>>>>>
My questions for those experienced in these things, and given my desire to tackle a more comprehensive battery/electrical upgrade later:

1.  Do I risk any harm to my electrical system or batteries by replacing my existing 51 amp alternator with another internally regulated 72 amp (or 90 amp) replacement from Prestolite?

2.  If so, what is the expected harm?

3.  Would a switch to either of these higher output alternators require upsizing wires?  I have the 4awg positive and ground wires from the panel to the starter motor and engine block, respectively.  How about the AO wire to the starter?

4.  Leece-Neville also makes other 51 amp and 65 amp (8MR) small frame alternators, although they have different dimensions (deeper and three mounting holes along the top).  Anyone have experience trying to fit these into the M25XP alternator bracket?

5.  Given your experience, what would you do in my situation?

Thanks in advance for your replies.  I really appreciate the depth of knowledge and willingness to share found here!

Welcome, Patches.

Your situation appears to be less one of knowledge than one of budget, cash flow and priorities.

Your repairs discussed in your followup post cover the important basics "while you're in there."

Given that you've determined your existing alternator isn't worth a rebuild, then the choices become somewhat clearer:  small internally regulated -essentially replace OEM; OR  get a larger nominal 100A alternator - the future final fix - and an external regulator, which you can run in Small Engine Mode and/or de-rate the output.  This makes the battery bank size meaningless in your situation.

Since you're new here, I don't know if you've had a chance to read through Electrical Systems 101   http://c34.org/bbs/index.php/topic,5977.0.html  These issues and the hardware are discussed there.

I kept my OEM alternator for a few years until I got up enough boat bucks to make the upgrade.

Much of your choice has to do with how you intend to use your boat.  If you are marina hopping compared to staying out in remote anchorages will help guide your decision.  If you can't afford an up-sized alternator now, you should be able to find a smaller less expensive one to carry you along for a year or two.  These folks could help you:  http://www.ase-supply.com/Leece_Neville_110_603_12V_90_amp_ALTERNATOR_p/mo-110-603.htm   The alternator that pops up is an example, NOT anything specific but rather to link to ASE as a source.  They are very helpful on the phone.

Of course, buying two alternators is more expensive, but cash flow...

Good luck.

[Patches]

Thanks Stu and others.  I contacted ASE and received helpful input from Bob.  I measured my OEM shaft at 5/8" and the pulley at a 2 5/8" diameter.  After researching a few options, the choices appeared to boil down to the following internally regulated options:

1. A remanufactured Motorola 2049K in 55 amp or 72 amps.  This was mentioned by Ken and I was unable to learn much more about whether these are a direct replacement for my M25XP which has the alternator bracket upgrade.  However, they have the ability to run a voltage sense wire to the starter post to aid the internal regulation.

2. A new Arco 60050 55amp alternator.  This was recommended by ASE, and Bob mentioned that this is actually a "Mando."  He said it should be a close replacement, with the exception of the pulley which is 2 3/4" vs. the 2 5/8" pulley on my OEM alternator. 

3.  A new Prestolite 110-656 51 amp alternator with external sense wire.  It is slightly deeper in profile than my OEM, and comes without a pulley.  However, a Motorola "162" 2 5/8" pulley is available for the 5/8' shaft, and ASE with install it for me.  The mounting ear size is only 1", and the mounting bolt size is 1/2" vs 3/8" OEM.  But it looks like the the spacer kit resolves these small differences when mounted.

Any preferences/experience with any of these alternators?  Anything I haven't really considered?

Thanks in advance for your feedback.   

[Steve McGill]

Patches,

If you haven't already,

Go back up to post #5, Mainsail's post. Go to his link at the bottom and click on his store. Many options for you needs.
Just my thought,

Steve

[KWKloeber]

[EDIT]

2049K in 55 amp or 72 amps.  This was mentioned by Ken and I was unable to learn much more about whether these are a direct replacement for my M25XP which has the alternator bracket upgrade.  However, they have the ability to run a voltage sense wire to the starter post to aid the internal regulation.

The 2049K (internal sense) IS THE direct replacement for the M-25 and XPs.  Universal used the 2049K on (most?) those engines.
The 72-amp (external sensed) was an option.  (Universal p/n 300746 -- I don't know what Motorola model it was.)
Both are irrelevant as to the bracket - they were used on both the OEM bracket and the upgraded bracket.

Ken:

One of the things you mentioned was an "external sense wire"

a wire to the battery "+" to figure out the state of charge (SOC) in order to know how much power to direct back to the battery.  Is this right?

It's not actually SOC but I get what you mean.  It's sensing the V at the batt, feeding that back to the regulator, vs. an INTERNALLY-sensed regulator (eg, the 2049K.)  A dumb regulator basically turns ON or turns OFF, depending on the sensed V.
Use RC's site, it's a go-to reference on alternators and the crazy electrical world!

The 51 amp direct replacement version (8MR2091KSS)-- which I can't find anywhere--does.

The 2091KSS is around, both new and remans.

Data:
http://www.prestolite.com/pgs_products/specs.php?item_detail_id=890&item=8MR2091KSS#

The 2049K is around in the Wilson remans.

Again, the nice thing w/ a Wilson shipped is that there's a chance for getting one that has a higher setpoint, instead of the usual auto battery setpoint.

Data:
http://www.prestolite.com/pgs_products/specs.php?pf=true&item_detail_id=16374&item=8MR2049K

It seems to be (boiled down to) do I:

Bite the boat bucks bullet - buy a high capacity alt and ext reg now as RC and Stu explain (ramp it down for now, nothing to throw away later.)

OR

Get the least expensive now (51/55 amp-ish) and throw it away (eBay it) later.

OR

Buy the next better (72 amp-ish) and throw it away later.  I guess you could possibly turn it into an externally regulated to use (if 72a will meet your ultimate needs) -- but it will be "giving her all she's got, Scotty!" instead of a hi amp that works much less (and will last much longer.)

It may be too early to answer those Q?s, unless you can predict your energy needs (see the 101, do an energy budget, etc.) 
All depends on how you will use the boat later on?  Day, weekends, on hooks, months cruising, etc etc.?

All things YOU need to decide!

The boat and usage profiles drive your battery needs (amp-hrs used from full charge 'til full recharge.) 
Then your recharge profile (tied to a charger every night? Solar? engine only?) determines your alt needs (AHs to replace before the next discharge.)

-k

[KWKloeber]

Any thoughts on these ideas?

Patches, here's what I had him do to up his efficiency -- he went from losing V each time off the hook, to gaining V each time, and back to full charge.  Not the ultimate solution for cruising needs but was his 1st step.  It's on a 30, so not as much demand as your 34. but still, a benefit until you do the major upgrade.

Install a power post on the engine stringer.
Move the batt NEG cable to the starter bolt.
Run a heavy NEG cable from the starter bolt to the power post.
Run a heavy AO cable to the solenoid "B+".
Run the same size Alt NEG to the power post.
Run the harness NEG and all other local NEGs to the #8 terminals on the power post.  (Or you can use a bus bar.)
Clean ALL connections/terminals well and use a dielectric to prevent corrosion.
Replace the engine ends of all harness wires (oftentimes the harness itself is in OK shape, the problem is at the engine ends and the panel ends.
Install a fuse on the panel power wire from the solenoid "B+".
Eliminate the quick-disconnect (I call it, quick loosen, corrode, fall-off) terminal on the solenoid "S" wire.

I'll do a new harness for him (eventually.)

I say "heavy" because the size will depend on the alt you install and major upgrade later.

I use LUGs for anything terminated where there can be (i.e., WILL BE) movement (Alt Pos, Alt Neg, Solenoid B+, etc.) ring terminals are too light and flexible and fail.

For the fused harness power wire, I do this:

Get a:
Weathertight AGC fuse holder w/ #10 awg tinned wire (difficult to source).
FTZ #8 x M8 tinned starter lug
#10 butt connector.
Clip the wire loop on the fuse holder 2" from the fuse, and crimp the butt connector to the 2" stub.
On the long end, strip insulation double long, fold back/double up, and crimp on the #8 lug (need a tool to do #8 lugs.)
Crimp the butt connector to your red cable.
Heat-shrink both connections with mil spec AHS for strain relief.
Voila' your harness is now ABYC compliant.

-k

[mainesail]

We can always build a 72A (CMI-72-IR), and we've done a few, but I my opinion it does not represent a great "value" because the fame is less "universal" and the components are only avaialble in non isolated ground. The way we build these is with the standard 2" foot and single mounting ear (this frame is dictated by the stator/rotor combo), 72A stator/rotor, oversized fan, epoxy-coat frame, high copper content brushes, billet machined pulley, and the fully adjustable self excite & external sense capable Leece-Neville 105-280 regulator. This is not a unit you will find retail because we custom buld them per order.

The problem with these is, as a finished unit, they run darn close to the same money as the 90A or 105A externally regulated unit does. LN has dropped a lot of the 8MR alternators they used to offer, so for us it is more cost effective to stock components and build them vs. buying complete units then throwing away components we are not happy with or don't use. We don't show the CMI-72, 90 or 105-IR units in the MarineHowTo.com Web Store but we can always quote them. Unlike other sources the CMI alternators come ready to install with a custom machined billet steel pulley.

We can also build 8MR fit units on a Delco platform, for a bit less money, but no "adjustable" internal regulator option..

[Patches]

Thanks Ken and Mainesail.

Let me say initially I appreciate your desire to steer me the right way the first time around, as well as the obvious depth of knowledge you bring to the discussion.  I also want to say that --at every future opportunity --I intend to support the good work of Mainsail when I upgrade my electrical and fully sort out my electrical needs.  I just don't know what that will look like exactly, and how solar or refrigeration or an inverter will fit in.  I just hope he is still in business when I pull the trigger--likely in a couple of years--because (1) I believe in rewarding good work and (from what my inexperienced electrical mind can tell) (2) he pretty much makes the best stuff for the job.

By your previous responses, it occurs to me that I haven't explained my use/intended use well.   Right now my boat is hooked up to shore power every day, and is used sparingly November-March and will be used often (up to 4-5 days a week) for daysails from April to October.  I work as a charter captain, and starting this year I will be using my boat as part of the business.  I will also have the yearly 2 week cruise in September with my wife.

I am currently making all of the wiring upgrades that Ken has mentioned that he made on a friend's Catalina 30.  I'll have all new engine and panel wiring, and a new instrument panel and gauges.  Which leaves the choice of alternator.  For the sake of simplicity, and until I can return to Compass Marine with a clearer long-term design in mind for my electrical system, I'm looking to (1) get the engine to start (2) to get me out sailing for a few hours at a time, and (3) without using much in the way of electricity while I'm out sailing.  The vast majority of the time I won't even be using running lights or a depth sounder.

Hence my decision to stay simple for now when replacing the alternator.

Ken:  I've not been able to find the 8MR2091KSS anywhere.  It was listed as the direct replacement, so naturally I thought of that first.  ASE doesn't have them, my local alternator shop doesn't have them, and after I ordered one online from a place that said they were "in stock", I was told they don't have them either and couldn't source them from a competitor.  So if you know where to get one, please let me know!

As for the re-manned Motorola 2049K's with the external sense wires, if these are preferred to the other 2 options I arrived at please let me know where to go for those.

Otherwise, I will work with ASE to get the "next best" option given what I've learned here.

Thanks again for your input!

[KWKloeber]

Patches

I'll throw out a couple emails to verify availability and PM you.

Also, just on Rods comment -- please don't misunderstand, I didn't mean to imply that a 70-ish amp would be a good choice if it were a custom marine alt job (it's NOT cost effective) -- only a "cheap" way to get back in the saddle right now.

-k

[Stu Jackson]

Patches,

Given your reply with your more detailed plans for the next few years, here's what I recommend:

1.  Get the least expensive, slap-in, internally regulated (w/correct V out) alternator you can find.  There is a link on the Elec 101 from Maine Sail about the differences: 
How Alternators & Regulators Work PLUS External vs. Internal Regulators (by Maine Sail):  http://forums.sbo.sailboatowners.com/showthread.php?t=125392

2.  Add a battery or two to your house bank.  Marina hopping or staying plugged in you're fine, but a night on the hook would be iffy, specially if you have a fridge.  Counting electrons because you didn't buy a $100 battery is wasteful, stressful and not good seamanship.

3.  Those two relatively inexpensive things will get and keep you going until you've had time to get your head around what you want.  Keep the first alternator as a spare in the future.

4.  Spend the next year reading all the stuff you can, and coming back here.  By that time you will have learned a lot more, refined your plans on boat use, and better know the differences between wants and needs.

PS - I added this to the Elec 101 recently, don't know if you've seen it, but it's the other end of the spectrum compared to your current situation: 
Alternator Upgrade - a 2018 thread with input from Maine Sail
http://c34.org/bbs/index.php/topic,9773.0.html
There's lots of electrical upgrades on the tech wiki, too.

Just so you know, what I have is a 100A Blue Circle alternator , Balmar MC-612 external regulator, AO to house bank, Yandina combiner, Freedom 15 I/C.  I started out with a stock alternator with an AutoMac.