Alternator Upgrade

[Rocinante33]

As noted in other threads, I recently upgraded my M25 to a 90 amp marine alternator made by Prestolite, Leece-Neville division. Prestolite is an old, respected name in automotive applications and their Leece-Neville division makes alternators for emergency vehicles, farm & construction equipment and fire trucks, as well as this marine alt. The alt cost me $169 as compared with over $500 for a Balmar plus $100 to $200 for an external regulator. Quite a bit of $avings, IMHO. Please see these URLs for important info on the Prestolite alt;
http://www.prestolite.com/pgs_produ..._id=896&item_series_id=105&refresh=1185927037
http://www.prestolite.com/literature/alts/PP1128_marine.pdf
http://www.prestolite.com/literature/alts/PP1113_AG_Const.pdf

To buy one in your state;
http://www.prestolite.com/pgs_buy/d...ountry_id=2&country_name=USA&province_code=CA
When you buy the alt, don’t forget to get a new pulley. The old alt shaft is a smaller diameter, so is not compatible. The new shaft is 17 mm, which is an unusual size. I got a Delco Remy, part # 10495191, for about $5.

I did the alt bracket upgrade at the same time. It requires draining the coolant from the engine. That bracket upgrade kit now costs $157 from Marine Diesel Direct (up from $98 in '03!). Part# 256891. See
http://shop.torresen.com/ships_store/index.php?mfc=Universal&pn=256891&p=numberresults&storetype=mdd
You might try another source for this; perhaps Engine 1, or Foley’s.

If you do these projects, required readings are the fine thread from Geoff Johnson in '03
http://www.ericsonyachts.org/mainframe.htm
and the link to the Cat*lina owners installation, below. This is a very good description, though I think some of his wiring labels are incorrect.
http://www.pbase.com/mainecruising/catalina_36_alternator

OK. To start the project shut off the batteries, then;
1. I suggest labeling the wires that attach to the back of your existing alt. Most important is to identify the field. It is usually a purple wire. The tach is usually gray. As additional security, a digital picture of your alt may be a good idea for future reference, though not completely necessary.
2. Drain the coolant.
3. Remove the wires and unbolt and remove the alt.
4. The bolt that holds the old bracket in place is probably frozen. It is iron threaded into aluminum. I was unable to get it to release, even with WD40 & an impact driver. Drill the head off of it. Then remove the bracket. Hacksaw the bolt off as close to the engine as possible. The stub of the bolt won't interfere.
5. Review the instruction sheet for the new bracket. Remove the appropriate nuts & studs from the manifold. Coolant will run out if you did not do step 2. I had to use vise grip pliers to remove these studs. Be careful as there is not much thread & the old studs have to come out!
6. Install the new hoses that came with the kit. I had to trim some of them.
7. Install the new studs & bracket loosely. You will need to put ground attachments under a couple of the nuts holding the bracket to the manifold.
8. Try putting the new alt in place. Looks gooooood, huh?
9. My old Motorola alt had two yellow wires attached to a resistor or a diode that was screwed to the bulkhead. It was about 1 1/4" square. Remove it & discard it.
10. Connect the wires. Main output should be at least a 10 ga. wire (red to the starter solenoid ala Tom Meztger's owner’s project). Add a similar sized black wire from the alt ground to the nut on the manifold.
11. The new alt has 2 terminals, each labeled "AC." Connect your field (purple) wire to one and your gray tach wire to the other. Crimp new terminals for each of these wires before connecting.
12. Install the belt. My kit included 2 different sized belts. The smaller barely fit with great effort. The larger was too loose. Snug the belt on the pulley and tighten the pulley retaining nut. The armature can be held with an allen wrench while tightening this nut.
13. Tighten everything up.
14. Add new coolant 50/50 with DI H2O.
15. Double check wiring. No hot wires touching ground!
16. Start her up! Check for leaks. Check for tach function. Check alt output with a digital voltmeter. I see 13.6v at idle, increasing to 14.5v with more RPM.

OK. I will supply pictures in a separate post.

 

[Rocinante33]

Alternator upgrade pics

Here are shots of the project. 1st is the new bracket installed. 2nd the rear of the new alt. 3rd is the new alt installed & project complete!

 

[Glyn Judson]

Upgrading your alternator.

Loren, Rob, Keith & Ron, I'm sure that those of you plannng this upgrade have thought it through already but for those anticipating fitting a larger alternator to your engines, just remember that the bigger they are, the more power they'll take from the engine. As an example, my 22 1/2 hp Yanmar3GMF has the original 30(?) amp alternator fitted to it. The buying public clammored for more output and the 27 hp Yanmar was born, fitted with a 55 or 60(?) amp alternator. My point here is that to presumably deliver the approximate same amount of power to the prop and to provide more alternator output, the engine had to be upped by about 5 hp. Whenever I read about folks going to larger alternators regardless of the jump up in size, I'm reminded that at some time on down the road in less than ideal sea conditions, one might wish he had that more power to punch on through. Yes, I imagine one could rig a switch to defeat the charging ability of the alternator but I'm just talking about a simple swap to a larger one. There's also increased heat in the engine room to think about too but less so of a concern to me than the loss of power. All that said, I remember reading in an old, old, old issue of Practical Sailor about a chap rather economically fitting a much larger, (read really large) alternator to his big Perkins or some such engine. He simply installed a rebuilt GM bus alternator on the order of 170-190 amps or the like. So if anyone reading this wants to go that big and has the engine to deliver, that might be a good alternative to the expensive Balmar type units that are in the many hundreds of dollars. 'nuf said, I hungry and it's almost dinner time, Glyn Judson, E31 hull #55, Marina del Rey, CA

 

[rwthomas1]

IIRC, every 25 amps consumes 1hp from the engine. The loss of power can be handled in several ways. With a "smart" external regulator the bulk phase of charging is when it will demand the most from the alternator. Once past the bulk phase the batteries accept a diminishing amount of amps the charge level increases so the load is also greatly reduced. The benefit here is the smart regulator will recharge the batteries faster so the amount of time the sailboat spends with reduced power will be shortened as well. An internal single stage regulator will spend longer periods charging drawing less power from the engine but still a significant amount. Switching the alternator off is a simple thing to do. On my Ample unit I could simply install a switch in the power supply to shut it down when needed. The other option that most smart regulators can be current limited. This is to allow a higher output alternator to be driven by a single thin belt or to not overload the engine. Obviously this option would depend on how easy it is to enable the limiting function. Knowing the charging protocol would be the key to avoiding needing ALL the power when in the bulk charging phase. Knowledge of this is key. FWIW, the Leese-Neville is just about the only off the shelf alternator that will survive the abuse of a 3 stage smart regulator. Almost all others will just burn up. I did plenty of research before settling on the Ample Power product. I very seriously considered modifying a Leese-Neville for external regulation. In the end I went with the convenient solution. My only "problem" is that I don't have a double belt setup. With a 105amp hot rated alternator I am over the limit for the single 3/8" belt. If I can find a source for double groove crank and waterpump sheaves then I will upgrade. Until then if I have a problem I can reduce the output of the alternator. RT

 

[JohnK]

My only "problem" is that I don't have a double belt setup. With a 105amp hot rated alternator I am over the limit for the single 3/8" belt.

Why not put on a 1/2" belt a la Tom Metzger? This has been discussed and proven by many - see this thread. I have a 125amp Powerline alternator with a 2.2in. 1/2" pulley driven by a green NAPA 4L440 belt and it works like a charm :nerd:

 

[Mike.Gritten]

I agree. Install a 1/2" belt. It may work for a while with the 3/8" belt but it WILL fail at some point - probably when you need it most. I am fairly sure that the stock pulleys will accept the 1/2" belt with no modification at all. We upgraded out alternator/regulator combo last year and have had no problems at all with the 1/2" belts. Just keep them adjusted correctly. If you go to something in area of 110 amps plus, then you WILL need to find the double pulleys. At least that's the scuttlebut that I've read, and I have no reason to doubt Nigel Calder!

 

[Rocinante33]

Well, it remains to be seen if my bigger alt will be a huge power draw from my 21 HP M-25. So far, there seems to be a slight draw down in RPM when the alt kicks in, With partially depleted batteries, it may pull more pwer away, Glyn. As I said though, time will tell.

As far as the belt size, I have read that this 90 amp is about as large as you can go with a single belt. I have no slipage so far.

 

[rwthomas1]

Mike & John,
Yes you are correct and thanks for the reminder! I will be hitting the local Napa for a 1/2" belt. That part number helps too! While I understand that a 1/2" belt will survive the alternator load I still would like to do the double belt setup if I can. I used to know of a custom sheave source but I can't seem to find the info. I have also considered getting custom sheaves built for flat/serpentine/microgroove type belts. I used to build hovercraft and hotrods and there are shops that make this stuff and its not as spendy as you might think. This is a winter project for sure. Thanks, RT

 

[Rocinante33]

Addenda

Related to my first post on this thread;

Geoff Johnson's original thread was titled, "M25 alternator mount cracks gear case cover."

The part #s for the alternator are;
8MR2069TA, order # 110-602

After installation, or any alternator change (bracket, eg), be sure to check the belt alignment with a straightedge. If necessary, shim the alt with washers to improve belt alignment (though I did not have to for my project).

 

[Mike.Gritten]

All the pulleys should be available at most good chandlers that carry alternator upgrades (we have 2 here in Vancouver). I was in River Marine last week and they even have the ones for the cogged serpentine belts on the shelf.

 

[Mike.Gritten]

Just one more note on alternator upgrades. When I replaced mine last year, we made 2 non-standard changes that might be of interest. We installed an item called "Zap Stop" on the back of the balmar. It looks to me to be a fuse, but it is supposed to stop the diodes from frying if you turn off the key with the motor still running (I've never done this, but an ounce of prevention....)
The other mod was to install a small switch (on-off) to allow us to switch the alternator off we needed. IIRC it is an option with the Xantrex regulator we installed. The only note I would make of this is that when the switch is "off" I get no reading from the tach. Not really a problem (I can tell that the engine is actually running!) but an observation.

 

[JohnK]

I have also considered getting custom sheaves built for flat/serpentine/microgroove type belts.

Maybe check Beta Marine before you have some custom-built. They sell their diesels with the multi-groove serpentine pulleys as an option. Maybe you can get some from them since they're built on Kubota blocks too? Or maybe Kubota themselves have them.