upsizing alternator & Universal Motor Drive pulleys

[svAlainn]

I have a 36' MKll 1999, I am interested in upsizing my alternator, what size can I achieve as we have extended days without solar, Can this be upsized within the box enclosure without alterations and can a new alternator adapt to the existing framing?
Also having just purchased the boat recently I have discovered that the pulleys on my Universal diesel 35 horse (M35B)which includes on the alternator they were made in China and rusting causing the pulleys to chew at the drive belt leaving a black dust in my engine compartment leaving a oil like residue and dust, is their a better pulley manufacturer out there.
Much appreciate any help on these issues.

Stan

 

[jssailem]

Query 1.
Yes, you can install a larger alternator. Be sure to choose one that matches the foot design of your motor. I know a 105amp can work and fit, as I helped my buddy install one on his 36 Mk1.

Query 2.
I am using NAPA Gold Stripe Belt Alternator belts. Gates makes them, and they have proven excellent on my boat.

 

[svAlainn]

Thank you both for your quick reply.
Does your buddy have the same enclosure over the motor on his MKl as the MKll
If I can not find a non Chinese product which has failed, I may have to remove all 3 pulleys and have them sand blasted and powder coated.
What brand and model did your buddy use on the upgrade of his alternator ?
Gates belts are good but they have a shorter life with inferior pulleys.

Thanks

 

[Stu Jackson]

In addition to the pulleys you must look carefully at the alignment of the pulleys.

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment 101 IMPORTANT

Universal M-25 & M25XP Alternator Bracket Upgrade & Alignment
and
Careful Engine Inspection & M25 Alternator Pivot Bolts Careful Engine Inspection & M25 Alternator Pivot Bolts & Tension Nuts

******************

I have a 100A alternator with EXTERNAL Balmar MC-612 regulator and a Small Engine Mode switch on my M25 engine with a 3/8" belt. Works just fine when properly aligned per Maine Sail's advice.

 

[Ralph Johnstone]

Hi @svAlainn and welcome to the site where you'll find out about every thing you want to know and a whole bunch you really didn't want to know.

Works just fine when properly aligned per Maine Sail's advice.

I would say that misalignment and water leaks (especially salt ones) from the engine are the biggest enemies of engine pulleys.

I agree with installing new smooth ones to reduce belt wear, but NOT until you find out what is destroying your current pulleys.

This is one 27 YO pulley on the engine crank of my Yanmar :

The water pump and alt. pulleys are the same. No belt dust and the belts don't show wear.

I have discovered that the pulleys on my Universal diesel 35 horse (M35B)which includes on the alternator they were made in China and rusting causing the pulleys to chew at the drive belt

Chinese steel (even if crappy) does not promote corrosion, just reduced mechanical strength. You are looking at an engine mfg, an alt. mfg, and a water pump mfg, and who knows where they sourced their pulleys.

If I can not find a non Chinese product which has failed, I may have to remove all 3 pulleys and have them sand blasted and powder coated.

At three times the cost of new pulleys. Not sure about powder coating but it may make the pulley interiors slippery. Remove your pulleys and take them to Motion Canada. Used to be BC Bearings who were above and beyond excellent about 10 years ago so phone first.

Talk to the pros first and see what they suggest. But even before that, check out your leakage and/or misalignment problems or pulley replacement could become an annual procedure .

BTW Do you have a photo of your pulleys just to see what you are dealing with ?

 

[Ralph Johnstone]

I have a 36' MKll 1999, I am interested in upsizing my alternator, what size can I achieve

What problems are you seeing with your present alt. ?

 

[JoeWhite]

Stan, I have the identical boat and engine. Mine also had black dust when I first bought it. The belt dust was because the alternator sits too far back and the belt rubs against the engine only while idling. To fix the problem I added 2 washers beneath each mounting bolt for the alternator moving it forward. No more dust.
Also check for cracked alternator bracket that mounts to the engine block.

 

[Hayden Watson]

With a single 3/8" v-belt, you can only get about 70A before you start dusting the belts. With a single 1/2" v-belt you can get about 100A. With double pulleys you can get about about 1.8x of those values. If you go to m multi-v rib belt you can go much higher.

On my C30, I have a 23-hp Universal M25XP engine and added a J10 [ten-groove multi-v belt] and it runs my 250A large frame alternator without problems.

 

[dlochner]

The alternator is just one part of the overall electrical system, an important part to be sure, however just popping in a larger alternator may not achieve the goal you are trying to achieve.

Start with determining the loads on your system. How much electricity do you use when sailing, when anchored, when motoring and when on the dock with shore power. Without this information you're just guessing at the size of the alternator. Stock, internally regulated alternators are designed to charge the start battery and their out put drops quickly and well below their rated capacity. To be most efficient at house battery charging an externally regulated alternator is best.

The type of battery also makes a difference. What is the maximum charge the battery can accept? If the maximum charge the battery can accept is 20 amps, then any charge source larger than that doesn't offer much advantage. Also consider the charge acceptance rate. The charge acceptance for lead acid (LA) batteries decreases as the battery approaches a 100% State of Charge on the other hand, LiFePO4 batteries have a flat charge acceptance, these batteries will accept acceptance as much current as you can throw at them (within a few limits).

My suggestion is to clean up the rusted pulleys, make sure everything is aligned and tensioned correctly, and make a long term plan for upgrades to the electrical system. And don't powder coat them. Between engine heat and friction the pulleys can get quite warm, I'd be concerned that the powder coating would soften when heated for long periods of time and make quite a mess.

Spend some time on www.MarineHowTo.com and learn about batteries, charging, and alternators among many other topics. Also join the Attainable Adventure Cruising site. There you find a treasure trove of some best advice from John Harries and other experienced and knowledgeable sailors. This week, there was an excellent article on fine tuning a regulator to improve alternator efficiency. The site is worth every penny spent on it.

Good Luck.

 

[Hayden Watson]

With a single 3/8" v-belt, you can only get about 70A before you start dusting the belts. With a single 1/2" v-belt you can get about 100A. With double pulleys you can get about about 1.8x of those values. If you go to m multi-v rib belt you can go much higher.

On my C30, I have a 23-hp Universal M25XP engine and added a J10 [ten-groove multi-v belt] and it runs my 250A large frame alternator without problems.

I agree with Dave that you need to know what you need to figure out how much and from which sourses you will make power.
FWIW, my system is as follows

• I have no solar because I cannot figure out where to put it that would look good.
• Most of my sailing is cruising of a week or more and I almost never go into a marina.
• Most of the time is at anchor.
• Over the past 4-years, I average 100A per day of total power consumption.
• I have 560Ah of LFP batteries for the house and a 15-year-old group 31 AGM for the start.
• The alternator is the only charge source for the start battery and also provides all power to the house bank when cruising.
• The alternator sends power to both the start and house bank through an ArgoFET battery isolator and all loads from the two banks are completely isolated from the other.
• I control the 250A alternator with a Zeus regulator which is set to limit the max alternator output to 205A and the max charge to the LFP at 190A. It is also set to limit the alternator temperature to 205º as recommended by the manufacturer.
• In order to get the max power out of my 250A alternator, I needed to upgrade the belt and pulleys to a J10 multi-v rib belt from the factory 3/8" single V belt.
• I also make use of the Zeus' output limitations based on engine rpm so that the alternator make very little power at idle and WOT and ramps up to the max output at 1800rpm and then starts to go back down at 1900rpm. This keeps the little 23-hp engine happy while providing boat loads of power to the batteries.
• I have also made a forced air ducting system that brings cool air to the intake vents of the alternator and pulls the hot air from the exhaust ports to discharge out the transom.