Alternators

from the

Sailnet Tayana List

My surveyor had a hand held rpm meter and took the reading off the crankshaft.

The previous owner had upgraded the alternator, Balmar 100amp, with a different pulley size. This probably affected the Tach. Although it may not have been right to begin with, who knows. I will need to get a better look at things to see if the wire from the tach goes to the alternator. Maybe I can move the wire to a different tap on the alternator.

Ray Slaninka The S/V Lorna Doone April 1999

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Question: Can you operate 150-amp alternator off a single engine pulley?

I would put a double on it. I run a single with a 120-amp alternator but rarely ask for more than 95 amps. That seems about it to keep the belt from slipping long term. Plus the 120 amp soon ends up at 100 anyway when the alternator heats up. A new fresh water pump with bearing is only around $98. Rebuilt ones go for $57. The double pulley probably costs more than that.

Wayne Strausbaugh V-42 C/C RESTLESS March 2000

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Usually the Perkins electrical tach only works when the alternator field is energized. No tach can mean:

1 - a broken tach or wire

2 - no alternator output. When diodes fail, electrical output diminishes based on how many diodes have blown but the tach still works. If a ground wire (to the alternator) is loose, then the tach will fail as well as the charging circuit.

I replaced my Perkins tach with a VDO. The advantage is that you can adjust the tach to compensate for any size alternator pulley so the tach reads the correct RPM. As I recall, an extra bezel (a VDO item) was required to get the tach to fit the Perkins engine control panel. Good luck with your troubleshooting...

Wayne Strausbaugh V-42 C/C RESTLESS June 2000

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I've had a 65-amp Motorola propshaft alternator mounted on my Hurth 150 transmission since 1984. I don't use it anymore since it doesn't work with an Autoprop but it used to really put out the amps with a fixed three-blade propeller. It took about 5 ˝ knots to get about an amp but the faster you go - the more amps. I remember seeing 30 amps once when I was doing 8 1/2 knots! It supplied all the power I needed on a 5-day trip from the Bahamas to the Virgin Islands. In fact, without a regulator, it would have fried the batteries.

Wayne Strausbaugh V-42 C/C RESTLESS August 2001

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My propshaft alternator sits on top of my Hurth on a large aluminum bracket that mounts on the left side of the transmission. It just bolts onto 4 existing, threaded holes (5-minute job). A small bracket on the other side adjusts tension on the belt. It just mounts on an existing bolt on the aft or right side of the transmission. A large plastic/phenolic (?) flywheel bolts onto the transmission output and replaces the ceramic drivesaver usually used there between the transmission and shaft. Drive is by belt with at least a 10:1 ratio. A wiring harness goes to a special electrical panel that came with the kit. It has an off/on switch to control the alternator (energizes the field) plus an amp gauge to monitor output. If the engine driven alternator has got the voltage up above 13.2 volts or so, the field won't energize and the alternator turns but doesn't put out any juice. I got the kit from Mastry Engineering in Tampa, FL, back in 1984.

Output is strictly a function of prop size and speed. It worked well with my old 18 X 10 prop and a little less so when I cut it down to 16 X 13. I could keep up with the boat's power draw when at or above 6 1/2 Kts. Over 7 knots and it really puts out the power. My boat and yours are pretty much the minimum size boats to use something like this. With their bigger prop and higher speeds, the larger Tayana’s (47 feet and up) could really make the amps.

The only problem I ever had was starting the engine and engaging the shaft with the shaft alternator in the "on" position. I found it hard to achieve enough belt tension to keep the belt from slipping and making a loud squeal. I didn't like to keep it real tight all the time. I also had to add power rather slowly to keep from getting slippage. But in normal operation, I only turned it on under sail. I wanted the shaft to be rotating first before I put a load on it. Otherwise, I would have to go over 6 Kts to overcome the alternator load and get the shaft spinning.

A shaft alternator is not a bad idea but not many of these were sold. Maintenance, however, has been zilch and a long distance sailor might find this rig useful - if you can sail at 6 to 6 1/2 Kts consistently...

Wayne Strausbaugh V-42 C/C RESTLESS August 2001

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I have a T-47 that I just repowered. She had a Yanmar 55hp with 5500 hours. It was not in good condition, and a complete re-build was in order. I decided to replace it with a 100 hp Yanmar. My rational was as follows. I am preparing for an open-ended cruise, and so a new engine I hope will offer me more reliability, at least for the initial part of the cruise. The 55 was underpowered for the boat. The cost differential was about 2 times more expensive in the end, but when I thought about the overall cost amortized over the life of my cruise, it seemed like the better choice.

There were a couple of unanticipated problems. The 55 hp engine had a duel belt pulley that ran a 125-amp alternator and the compressor for the refrigeration. The new 100 could not accommodate a 2 belt pulley. The new engine came with a 55-amp alternator, not sufficient capacity for my needs. So I had to replace it. The largest single belt alternator was a 100 amp Balmar. I had to buy a new bracket for the refrigeration compressor, and am not especially pleased with the long belt I need to use in order to use it. The new engine is equipped with an intercooler. In order to access the starter motor or the raw water impeller, the intercooler has to be removed. I'm not particularly pleased with this additional work either.

As is often the case with upgrading, with all that new horsepower, I decided to upgrade my prop. I went from an 18 in. fixed 3 blade, to a 21in. feathering Max-Prop. In order to install it, I needed a custom-made end nut and had to shave about a 1/16th of an inch off the end of my shaft. (of course, you don't realize this when you’re ordering, only when you’re installing).

Notwithstanding the certain degree of frustration, I am pleased with my decision. The boat really moves along much better with the extra power. The Max-Prop is amazing. I am getting almost an extra knot of speed sailing. And while I am still getting use to backing down with it, there is almost no prop wash. The boat actually backs straight. I still have a tendency to approach a dock at a more severe angle than is now necessary. After years of mastering swinging my port side to the dock in reverse, I now don't have that action. Good luck with your decision.

Phillip Yaffa S/V Peregrina October 2001

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With regard to the Balmar...... My 100 amp alternator uses a single belt with absolutely no problem.... The reason is that Balmar also sells SMART regulators that allow the alternator to **slowly** come on-line and therefore does not overload the single belt with "starting torque" problems. This allows the single belt system to work efficiently and without shocking the single belt system with mechanical overload during high alternator starting load requirements that would otherwise require a two-belt system. Additionally, these smart regulators can also be manually switched so that you can entirely turn off the alternator in 'emergencies' thus gaining maximum output of the engine hp to deliver ALL it has to the prop. Without this function you will naturally simultaneously run the alternator (requires hp) thus not getting full hp to the prop. I run all gel batteries, so proper charging cycle is important to attain maximum useful battery life. These smart regulators are programmable so that you can change the charging cycle program to exactly meet your needs. They also have a data readout so that you can see the actual battery charging voltages and the 'target' voltages during the charge cycle.

Rich Hampel October 2001

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In regards to alternators....

Having just completed the rebuild of my Perkins 4-108, I am now looking at upgrading the old 55-amp alternator. Initially, I took it for granted I would be installing a Balmar marine alternator. After talking to a marine alternator shop here in FT Lauderdale, I was recommended an alternator by Leece Neville, the AV1128 as a half-the-cost alternative to the Balmar.

As I don't want to modify everything to run double pulleys, I am in the 100-115 amp range. Is anyone using one of these alternators? - this model is supposed to be pretty new. If so, how do they perform in comparison to the Balmar alternators? Any info would as usual be greatly appreciated.

Phill T37 #101 October 2001

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Phill,

I put in a Leece Neville about a year ago. It is now a subdivision of Motorola Corporation. It is not a "new" model, and in fact, the SSCA (Seven Seas Cruising Association) rated it as one of the best of the alternators used by their membership as far back as 1988. They do an equipment survey that is even better that the evaluations of Practical Sailor, based on the experience of their members having used much of the equipment for tens of thousands of miles of ocean work.

I can't recall the exact model number that I bought, but I wrote myself a bunch of notes about it at the time (see below). The only problem that I had with it is that the actual RPM of the engine was now higher than the value shown on the panel tach- meter.

We bought it new - I don't advise buying used alternators, as many of them are very improperly reconstructed, unless they are done by the factory itself. The total cost was only $210.00 at PG Auto Parts in San Diego. They were having a factory-sponsored special at the time, so you may pay a bit more for it. If you are based in the San Diego area, I highly recommend the people at PG Auto.

Here are my notes that I wrote at the time of purchase and installation.

" ...the Leece-Neville/Motorola 90-amp output unit. It has tach outputs, is marinized for spark prevention, corrosion resistant treatment, better output curves for the lower RPM of a marine diesel, and has adjustable output voltage. (Factory default is 14.2 volts). With the spindle installed by P-G, according to the graph provided by the factory, it should hit 45 amps with 1,000 RPM, 90 amps with engine RPM of about 2,000. They estimate that the Tach should be fairly accurate [It finally turned out that the Tach reading is erroneous]. This unit does not require an external Field wire. Installed it immediately, with new belt, in about 15 minutes. I left the Field wire connector in place, though taped over, in case I have to go back to a more traditional auto alternator. The connector for the Tach output is slightly different, so I crimped on a suitable connector to the original unit, so that I still could use the original wiring if I have to go back to an auto type alternator.

Results were very satisfying and notable. Physically fit in the same location without any problem. Voltage sits at 14.2 volts regardless of engine RPM. Tach and Ammeter work at all engine speeds. Most notable of all was that the engine seems to run smoother and at lower RPM once the engine is at operating temp of about 160 degrees F. Easily run as slow as 500 RPM, and tested it only as fast as 2,000 RPM - all done only at the dock. Still have to test it in the bay or ocean. Seems to recharge battery much faster than previous alternator. It does have a slight roughness when running at ca. 650 RPM, but that disappears at both 500 RPM, and also when raised to 800 RPM. Once battery if fully charged, voltage settles at ca. 13.2 volts.

All told, a very satisfactory improvement.

Conclusion is that Voltage outputs are correctly set and do not require modification.

P.S. SSCA rated the Leece-Neville Alternator as one of the two best units in their 1988 survey."

I subsequently had new engine mounts installed, and the engine very carefully aligned. In conjunction with a flexible coupling (by PYI), the engine ran much smoother. But I was puzzled about our seeming dramatic increase in speed at the same nominal RPM. I finally borrowed a direct reading Tachometer, and compared the results on the panel tachometer with the more accurate external Tach. The readings were off by about 25% at all RPM values. The Panel Tachometer was always far below the true engine RPM, accounting for my higher speed at seemingly lower RPM. Thus, when the panel tach read 1000, it was actually 1250. 1,700 RPM on the panel was actually a bit over 2,000. 3,000 on the panel was actually close to 3,600 RPM.

I suspect that there is just enough of a difference in the diameter of the pulley on the Leece-Neville, compared to the old Delco unit, to account for this.

Other than this very minor problem (which I understand can be corrected with a trim pot on the panel tachometer itself), I am quite happy with this unit. Our batteries stay a lot healthier, and it's very comforting to see that the voltage output of the alternator is steady as a rock.

I do have one continuing concern, but it is not a fault of the Leece Neville unit. The current output wire from the alternator that the original 4-108 provided is probably too small for the length of the run and the higher current output of this new unit. This is of minor consequences if the batteries are generally in top condition and nearly fully charged. However, we are in the process of installing an electric windlass. This can draw nearly a full 100 AMPS if your anchor is deeply wedged. Under those circumstances, the alternator is likely to be called upon to put out a full capacity output of 90 AMPS. The present unit has only AWG 8 or AWG 4 wire. It should be at least AWG 1/0 from the alternator, through the panel meter and then to the battery switch (assuming a total run from alternator to panel meter to batteries of less than 15 feet. The correct wire size should be based on the total two-way length of wire, both the red and the black, relative to the current to be carried. See table in Nigel Calder for further detail).

We considered that Balmar, and found it of very high quality, but no better than the Leece Neville, and more than twice the price.

Do not use any alternator over about 100 AMPS. That would require a double pulley. The double pulley configuration would unduly stress the main drive of the Perkins 4-108, unless the whole system is modified. The 90 AMP Leece Neville should prove more than adequate for the majority of sailboats in our size range. Hope this helps.

regards, Harvey October 2001

(The Perkins 4-108 offered the following as optional equipment. This illustrates the limits when adding additional equipment. As a reference, max engine torque at 2300 RPM is 78 lbs.ft.:

Front Power Takeoff - 1.5” diameter by 1.875" extension shaft bolts to crankshaft pulley, allowing accessory drives to 20 lbs. ft. torque axially. Wayne Strausbaugh – 2005)

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Bravo, just the kind of feedback I needed to hear. Thank you for your comprehensive reply. I contacted a company in Miami today who said they can order from the factory a 110-amp alternator for me.

When I asked the question is it marinized, no one could answer my question. The one I saw at the local dealer was white and blue similar to the Balmar. When I went to the Leece Neville website, the pic was of a gray aluminum casing. What does your Leece Neville alternator looks like? Is there more to marinizing than a paint job? This company I spoke to today wanted $150.00 plus shipping. Half that of the local dealer with the nicely painted alternator. Thanks.

Phill T37 #101 October 2001

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Phill,

As I recall, the unit I bought was specifically stated to be marinized. I think it was black, but who knows if that is significant. If it is the same unit as the one I bought, then $150 is indeed a good price. Does that include the drive wheel? I think that was an additional $15-20, which is what made the total $210. Make sure that it is the same diameter as your present pulley wheel. I think the main thing about the marinized unit is that it has a spark preventer. This is critical if you have a gas engine, not so much so if you have diesel. But I would still check it out. I vaguely recall that the model number had an "M" in it to signify that it was designed for a marine environment. I was also told that I should stick with the 90-amp unit to prevent overload on the Perkins, though perhaps it could have slightly higher output at higher RPM. But perhaps they have improved the output efficiency. I won't be down to our boat for several days, but I can try to find the actual model number, if that would help.

Make sure that they are selling you a new unit, not a rebuilt one. The difference in price is relatively small, but definitely worth getting a new factory unit.

regards, Harvey October 2001

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Subject: Alternator size needed for various battery bank sizes

When charging a bank of 4 six-volt batteries with a 3-stage regulator (with batteries run down 150-amp hours), the voltage will start off around 13.9, decrease a little as charging continues, and then slowly ramp up to 14.4 VDC. The charger then holds this voltage and the amps begin to drop off. When the amps go down to 10% of the original charging amps, the charger drops the voltage back to 13.2. When the batteries are full (which only happens when motoring a long time), the charger still holds float voltage - 13.2 VDC. This voltage is the same voltage used by 110 VAC battery chargers for long periods of time. This can not only extend battery life but diminish the amount of water needed during maintenance. In fact, it may well be in many cases that excessive water loss due to bubbling of the electrolyte at 14.4 VDC is a primary cause of premature battery failure.

The above only applies to my 450 amp-hour battery bank. I have a 225 amp-hour bank of 2 six-volt batteries that reach 14.4 volts in just minutes and then the amps start ramping down immediately. The original 55-amp alternator that came with my boat would charge this bank as fast as my 120-amp alternator. Small battery bank = small amps to achieve 14.4 VDC.

My six Surrette 6-volt batteries lasted eight years before a lightning strike put long, half-inch wide cracks in the top of 3 of the batteries. I replaced the batteries even though the batteries performed just fine. My 4 Rolls 6-volts only lasted 7 years before one failed. I now use the GC-2 6-volt batteries from West ($99 each) that are a direct replacement for the Rolls size-wise although 10 amp-hours smaller.

The problem with batteries is that when one goes, you need to replace all in that bank. Therefore, I agree with you that sometimes cheaper can be better. Many standard golf-cart batteries have the exact same size and post configuration as the West GC-2's. Changing out batteries is easy if the new ones don't require changing/lengthening battery wires.

Wayne Strausbaugh V-42 C/C RESTLESS October 2002

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The Dunlops (Freya of Clyde) have a Perkins 4-108 and need to find a double pulley for their crankshaft and water pump (new high-output alternator causing belt slippage). Crankshaft is no problem.
However, two diesel experts I've spoken to recommend that they NOT use a double pulley on the water pump (load, of course). They have been advised NOT to use two different belt lengths. Quandary: two belts of different sizes or double pulley on the water pump?

Tad McDonald June 2003

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A smaller alternator may be the most sensible advice that you can give them! Sounds as if either of the choices are bad for the engine. I received the same advice regarding our 4-108. The 4-108 will safely handle a 90 AMP Leece-Neville or Balmar on a single pulley.

Problems emerge when trying to drive an alternator larger than 105 Amps with the 4-108, according to the sources I consulted. Apparently produces too much side loading, and the engine is only 50 HP.

Harvey Karten June 2003

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I recently installed a 125-amp (small case) alternator on my 30! hp Yanmar (3QM30F). Jack (Jack Rabbit Marine) assured me it was ok via numerous emails.

I also talked to Jack this morning about Freya's setup (boat was formerly owned by Erik Hammerlund (sp?) and Jack remembered the setup for Freya). Jack says a single pulley is OK for that alternator/engine (even though it's a large case). He also said he's seen the double water pump pulley setup and it worked. He professes to have been "amazed."

Tad McDonald June 2003

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Thanks to all (especially Tad and Harvey) for their help in our problem with the alternator belt slippage. We have just received 2 brand new top of the range Top Cog Belts from Dayco who assure us that this belt will do the job. We will fit it this weekend and give it a try and let you know what our results are. We've had no problems over the past week but the batteries have been pretty well fully charged so we wait with baited breath ....

Alan and Anne Dunlop Freya of Clyde (T42) June 2003

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You can also get V-belts reinforced with Spectra fiber (same stuff as used in ultra high tech boat rope) that can be loaded to much higher horsepower than conventional 'balata' belts. Their lifespan is much longer than a conventional V or cog belt. Most tractor / farm implement / lawn mower shops sell them. What kills a V-belt is improper tension. NAPA automotive parts supply shops carry a nifty ~$25.00 belt tensioning gauge for precise tensioning.

Rich Hampel June 2003

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I have found the Goodyear hi-miler belts last pretty well and they come with a lifetime warranty...If and when they break, I just take them back to PEP Boys and get a replacement....

John Lewis June 2003

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Interesting concept regarding belt replacement. However, I've rarely found a PEP Boys offshore...

Anne and Alan have a belt called "Top Cog" that was specifically recommended by Jack Csenge (sp?) at Jack Rabbit Marine. I called him to discuss their slippage problem and he gave me the contact information. I believe I found them in Indiana and they shipped some belts to Anne/Alan quickly. A simple Internet search should find them (I have it written down someplace I'm not so I can't help out).

Rich makes a good point about tension. Right after helping Anne and Alan with their problem, I found myself with low batteries (cruising New England with 3 kids seems to discharge batteries faster/deeper than normal) and I started up to recharge and the alternator belt SCREAMED bloody murder. I had just upgraded to a larger alternator (125) and I was gun shy as a result of my experiences with Anne/Alan. I immediately checked the tension, retightened, and I've had no problems. I use Gates Greenstripes.

The two keys to belts: tension and belt size. Be SURE the belt fits properly in all pulleys. The inside of the belt should NOT come in contact with the pulleys...contact is ONLY supposed to occur on the "sides" of the belt (the "V"). As the belt wears, it moves further and further into the pulley thereby becoming "looser" and requiring tensioning. Once the inside of the belt comes in contact with the pulley, REPLACE THE BELT.

Clues that something is wrong: fine black dust in the engine compartment (especially on the alternator or on stuff around it), jerky voltage readings when charging (belt slipping), and, of course, a high pitched scream.

Tad McDonald June 2003

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I carried three Goodyear hi-miler belts on my last boat. I replaced a belt once in the 15 years I owned the boat. The engine had a 100-amp Balmar alternator and got used a lot since the boat was small and the battery bank small, too. The boat was used a lot. I’m sure I put 4-5 thousand hours on it over the years....

I think the reason the hi-miler performed well was that the alternator was well aligned with the engine pulley and I had a special bracket fabricated that held the alternator firmly in plane...Some of the extender brackets (like the ones west marine sells) are flexible enough that the alternator can move around when its pulling hard on the belt. This is especially true if the required adjustment position for adequate tension is near the end of the bracket’s travel... If the alternator moves out of plane (even a little), the alignment of the belt is lost and excessive wear results.

Another thing I did on that boat that I think helped was I put a switch in the line to the alternator regulator so I could switch the alternator off when the engine was first started. This kept the alternator from loading the engine before it had a chance to warm up and get lubricated.

Someone I know took that idea a step farther and installed a manual alternator regulator in parallel with the automatic one. When his batteries are really dead, he flips a switch that allows the manual regulator to take over control. That way he can control the output and avoid overloading the engine during the first few minutes of charging deeply discharged batteries... After about 15 minutes, he can switch control over to the automatic regulator since it is only a short period of time that the alternator output stays very high.

The Balmar max charge that I put on my new boat has a temp sensor for the alternator. If an overtemp condition exists, the regulator cuts the alternator output in half. The manual mentions that the user can wire a shorting switch across the temp sensor and manually cut the output in half if desired. This is useful for the reason mentioned above and also if you want more power for propulsion on boats with smaller engines.

John Lewis June 2003

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Someone mentioned a few posts ago that NAPA has a nifty belt-tensioner for about $25. My local NAPA dealer became glassy-eyed when I mentioned it. Any specifics here? Model number? Etc?
FYI, I also just installed a new Balmar 612H Max Charge regulator on Prudence and a Link 20 is sitting in the box ready for install. Previously I had a, gulp, automotive relay-type alternator. That wasn't bad enough - it wasn't even wired up properly.

The new Max Charge 612 has a digital display which shows, amongst other data, alternator voltage out and regulator voltage target. There is also a built-in delay to allow the engine to come up to speed before the alternator is engaged. My two cents....

John Kalpus S/V Prudence Tayana 37 San Diego June 2003

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Tell your NAPA dealer it’s in the TOOL catalogue.... part no. is a simple: T-50 or something like that.

Rich Hampel June 2003

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I've saved a part number from years ago for a Napa part tension checker. This may be different than the tensioner that is mentioned. Here is the tension checker part number: Napa belt tension checker part #7401-0101.

fyi, John Hovan s/v Celtic Dream June 2003

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George Ingram asked at the end of June if we could let him know who the supplier of our fan belt was.

It was Middle Atlantic Warehouse of Indianapolis, IN 46226. Telephone number 3178974499 - use '4' on the menu so you don't get some daft lassie who won't help at all!! They are Top Cog V-Belts Part No 17400.

Anne Dunlop July 2003

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Freya has now run her Top Cog Engine Belt (Fan Belt) for approximately 80 hours without any trouble. We are still very cautious when we start up the engine and allow the alternator to charge for a short period of time at low engine revs to help take the load off the engine/fan belt. This seems to be working and we hope it's one problem less. Thanks again to those who helped with the problem.

Alan and Anne Dunlop Freya of Clyde V42 August 2003

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After 1 year messing with a 100-amp alternator on a single pulley, I ended up switching back to a 72 amp. I had researched some on the Internet, and many sites don't recommend anything more than 80 amps on a single belt. I had a LOT of trouble with a single belt on a 100-amp, slipping and burning. Even went to a slotted belt; that helped, but didn't eliminate the slipping if the alternator needed full power. We have the 3 cylinder Yanmar and love the engine!

Any input??????? I have used Delco for several years, that's what was on the boat, and so far (5 years) it has done well.

Mark s/v Querencia T37 April 2005

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My engine (Perkins 4-108) starts without problems, but quite often, my tachometer needle jumps to about 700 RPM and sits there even when I increase the engine speed quite high. Then after varying periods of time, from 30 seconds to many minutes, the tachometer will suddenly kick in, and provide seemingly correct readings. During this time, the Ammeter needle indicates that the alternator is charging - i.e., needle on the Ammeter moves over to the charging (+) side. This has been happening for a few months, though until recently, it would kick in after about 30 seconds. Recently it may take as long as 5-10 minutes.

If it is pegged at about 700 RPM and I stop the engine, the Tach needle immediately drops to zero. If I restart, it again moves to about 700 and sits there. It always (until now) eventually seems to come alive.

Before I tear into the system, perhaps someone has a suggestion? Bad lead from alternator? Tach gauge itself? Could it be something in the alternator. (Alternator is about 5 year old Leece-Neville. Output seems robust, and seems to recharge the batteries with ease, but I have only been doing a bit of day sailing lately).

regards, Harvey April 2005

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Tracked down the tachometer problem. Belt appeared loose, but I couldn't get it to maintain proper tension. I then found a very fine, but complete crack, across the tensioning arc arm for the alternator. Too late in the day to get a replacement at the local Perkins dealer, but I could modify the manner of mounting using a Balmar Universal Arm (ca. $20 at West Marine). Shazam! It woiks!

The original arm has a dogleg bend, and had apparently broken once before and been welded. The new crack was just 1/4" below that, and was a lovely clean break in the metal. No corrosion, just a sharp break, with a glistening surface and sharp edges, almost like a break in a piece of thick crystal. The nearly flat faces of the two sides of the break provided sufficient surface stability that the belt remained in place and had just enough tension that it was able to run the water pump, so that the engine remained cool (165-170 degrees F.) and the tachometer eventually kicked in.

regards, Harvey April 2005

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I've been watching this alternator thread for the past few days. Interesting thing on my Perkins 4-108. I too have a problem with intermittent charging. The tach sometimes would indicate 700 RPM and not change with increasing RPM's. It would some times read zero and then would suddenly jump up to normal readings after a few minutes. All the time not charging the batteries. If the tach was working 'normally' the charging seems to work great. I can't wait until I get back to the boat and check out my alternator bracket.

If that is the problem I would have never guessed that the cause of my intermittent tach and charging problems was based on the alternator bracket. Thanks for starting the e-mail thread.

Andy Hemlin Union 36 Mariposa II Toronto April 2005

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Andy,
You also should check the leads to/from the alternator and tach. If that is all OK, it would be best to remove the alternator and take it to a specialty shop and have it bench tested. It only takes about 5 minutes to remove the alternator. The original units on the Perkins 4-108 were Delco-Remy with about a max output of 45-amps at high RPM. Most of the time, it is much lower. The voltage regulator as well as the bearings, contacts, etc., should be checked. The alternator on our engine was the original 25-year-old unit, and after trying to go with a rebuilt unit and all the hassle, about 5 years ago I finally gave up and bought a new Leece-Neville.

regards, Harvey April 2005

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The tachometer on most Perkins engines is electric and receives its signal only if the field to the alternator is energized. The field current determines how much amperage the alternator should produce. When using three stage, smart alternator controllers, it is common for them to cut off the field current completely when switching from bulk charge to float charge. The tach will suddenly drop to zero. Although disconcerting, it doesn't mean anything is wrong. In fact, this type of tachometer provides a beneficial indication since it let's you know that your alternator belt is still on the pulleys and driving your fresh water cooling pump.

A slipping belt can be due to a number of reasons. It can be as simple as having the wrong width belt. Belts do not get their friction from contacting the bottom of the groove of the alternator pulley. They should only touch the pulley on the sides of the grooves. It is the shoulder of the belt that provides the drive friction. But the most common reason for a slipping belt is when battery charging requires the alternator to put out max amps. A slipping belt always gives a low indication on the tachometer. Tightening the belt is needed.

I use a turnbuckle vice an alternator-tensioning arm to make this job a little easier. It can keep the belt from slipping with 120-amps of output but I usually regulate it to 100-amps or below since I have a single pulley setup. I have a three-way switch installed in the path of the alternator field current that enables selection of a smart controller, a standby external voltage regulator, or OFF. You can really hear the engine bog down when you turn the switch on and ask for over 100 amps. Usually, I would get a squeal if the belt was slipping. Experience finally made me decrease my amp draw. It became obvious that I was overtightening the belt to achieve more than 110 amps. Plus, I had to overhaul the alternator three times (over 5500 hours of engine time). The alternator lasts longer when not being fully loaded.

Wayne V-42 C/C RESTLESS April 2005

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The reason I like a three-way switch is to disconnect the alternator electrically until I start and warm up my engine. A hundred amps uses a lot of horsepower. The other reason is because of belt slippage with a large alternator load. Belt slippage never seems to occur when engine RPM's are steady. It always began slipping and squealing when I was jockeying the throttle when leaving a slip. A bad time to have a howling engine! A flick of a switch and that problem was solved. Or switch to my standby voltage regulator that I always set to a much lower initial charge voltage (hence, lesser amperage). The only gauge lost with the switch off is the tach (and any charging from the alternator), not the engine gauges (oil and temp).

Wayne V-42 C/C RESTLESS April 2003

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Hey Group...

Interesting thread. On Prudence, I've installed a Balmar 612 Max Charge three-way regulator for Pru's 100-amp alternator. The Max Charge, though expensive, has worked flawlessly. First, there is NO current sent to the alternator field windings for at least 45 seconds. Then, gradually, the field current is increased so prevent slipping of the single belt. The 612 is also user programmable to adapt to charging wet cells, AGM, etc. It's a completely sealed unit and has a digital readout to confirm settings. New settings are programmed with a magnetic probe included with the regulator. I've installed the unit behind the breaker panel. On Prudence, that's behind the entry stairs.

I've also installed an alternator field cutoff switch in the cockpit - one of the push-pull Cole Hersee (sp?) switches. When necessary (if ever), I can completely shut off the alternator draw on the Perkins in an emergency situation. The switch is really foolproof because when it's pulled OUT, the cutOFF position, I can't close the plastic cover to my engine instruments in the cockpit. The same goes for my fuel shutoff knob. I purchased the Balmar 612 on eBay a year ago and easily saved $100 over West Marine.

Regards... John Kalpus Prudence San Diego April 2003

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I have posted a couple of pics of an alternator with a turnbuckle in place of an adjustment arm on a Perkins 4-108. I have used this setup successfully for about 4000 engine hours. Please go to John Hovan's excellent site, www.tayanaowners.org . Look under Owners Posts, then Perkins Engines.

Wayne V-42 C/C RESTLESS April 2005

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Subject: Tachometer problem/alternator belts

If you turn off the field wire to shut down alternator output, do you still generate the Tachometer reading? Or does that also turn off the tachometer lead?

Harvey J. Karten, M.D. April 2005

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I believe that turning off the field wire to shut down alternator output will result in the tachometer falling to zero. The tachometer must look at cycles/second or some other parameter off of the field wire. John Kalpus on Prudence might confirm this using his setup. His Balmar unit sounds really slick.

Wayne V-42 C/C RESTLESS April 2005

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All of this information has led to a question. I have a Perkins 4-108 on my T-42 CC. I talked to Balmar today and they say that in order for me to charge 4 golf cart batteries (225 amps each = 1000 amp/hr), I have to have an extra large casing alternator driving dual belts. May I ask what others are using for batteries, alternators, and how long have you had the setup?

Jon and Renne' Siewers (aboard JonNe', a T-42CC) April 2005

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JS,
Are you using six volt batteries wired in series to achieve 12 volts? The most common way of using 4 golf cart batteries is to wire two in series to give 12V (but only 225 AH) and then to wire those two in parallel to two other series-wired batteries to give a total AH of 450 at 12V. Am I wrong, or missing something? I use 4 Trojan 6V golf cart batteries wired as described and I am using a Balmar 100 Amp alternator with a Balmar smart regulator. My engine is a 40 hp Yanmar and I have no trouble using a single belt alternator.

Jim (SMILES) April 2005

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JS,
I agree with Jim Smiley. I have had an identical setup as far as battery size, alternator, etc for 18 years. A 100 to 120-amp alternator is a good size for this size of battery bank and can be driven from a single pulley. It sounds like you have a 450-amp bank (4 X 225 amp, 6-volt batteries). The reason that a larger alternator may not be needed can be illustrated by the following:

I also have a bank of 2 X 225-amp, 6 volt batteries = 225-amps. When I run them down to 50% and then recharge with 100 amps, I only charge for 5 minutes before the battery reaches 14.4 volts. Then the amperage is slowly decreased to keep the battery from exceeding 14.4 volts. What this means is that the rated output of a large alternator can only be used for 5 minutes. After 10 to 12 minutes, the amperage is usually down below 75 amps. After 15 to 20 minutes, it takes less than 50 amps. When the same alternator charges the 450-amp bank, it stays at rated output for over half an hour before the 4 batteries hit 14.4 volts.

I would definitely go with a double pulley setup if the alternator was larger than 120 amps.

Wayne V-42 C/C RESTLESS April 2005

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We also have a CT-41 with a bank of 4 golf carts and a Powerline alternator (105-amps I think). It has been working fine, however I really got to worrying when the Balmar guy said I would wear it out quickly. I was concerned about what I was going to do with the Tayana, as I wanted to duplicate the set up. Sounds like it is okay to me.

Jon April 2005

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I have a Perkins 4-108, a Balmar 90 with a single belt, their regulator (an older model), and 4 golf-cart batteries. At anchor, I do 90% (or more) of the charging with an Aerogen 6 wind-generator and 3 solar panels. I recently hooked up a Xantrex Link 2000 battery monitor and the Xantrex 250 Pathfinder battery combiner and a 5th golf cart battery just for starting the engine (it is bank 2). I'm surprised at what Balmar is saying. I've had no problems on my boat - between me and the previous owner this setup has worked fine since the year 2000 and for about 1/2 of that or more at anchor.

Steve Wolfer s/v Island Girl April 2005

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It's very difficult for alternators to put a lot of amps out at low rpm. The alternator he is quoting probably has a dual winding causing more resistance at lower rpm which could cause belt slippage. Thus, the dual belt setup.

I would ask to see a power curve before purchasing any alternator. It will show how much power you get at each rpm level.

John Hovan April 2005

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JS
If I remember correctly, I have one of the Balmar series 70 alternators with a Balmar ARS-4 regulator. Balmar should be able to advise you as to which of their alternators fit your engine. I have always found them to be most helpful (and no I don't own Balmar stock) Their web site at www.balmar.net is very informative and does provide power curves for all of their alternators. When looking at the power curves one must realize that the RPM figures (vs. amperage) are RPM’s of the alternator pulley which typically is smaller than the take-off pulley on the engine. Most high output alternators have only a 2.5" deep-V pulley. This means that the alternator is turning quite a bit faster than the indicated engine PM indicates.

Jim Smiley (SMILES) April 2005

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Jim,
I agree with your comments about most high-output alternators having a 2 1/2 inch pulley. This is significantly smaller than the OEM alternator pulley provided by Perkins. This means that the tach will read a totally different RPM range. Very few people take the time and effort to fix this anomaly. When I went to the smaller pulley, my RPM's read much higher. The Perkins tach is not adjustable. I replaced it with a VDO tach with a trim pot on the back to adjust RPM. Someone loaned me a mechanical tachometer that could be placed on the center of the main engine pulley. By directly reading RPM, the tach could be set precisely.

I doubt that many of the Perkins engines out there are really showing the correct RPM if the OEM alternator has been replaced. This may explain the widely varied results that everyone reports about prop size versus RPM versus speed.

Wayne Strausbaugh V-42 C/C RESTLESS April 2005

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