Alternator Selection for 30 HP

[cal40john]

You say the solar power you have is usually enough for your needs, so i don't see why you want to go up in alternator amps, which causes more costs and belt eating unless you add costs again (dual or serpentine belt).

In one of your posts you're worried about eating belts. More power is worse. If you meant that you're eating belts now, the problem is pulleys, alignment or tension, not the alternator you have now.

Does the alternator you have now have a history of failure?

I'd say just buy a drop in replacement, maybe a little higher quality if you want.

[westwinds]

Alternators are generally quite reliable and you do have two of them if one goes out. What kind of batteries do you have? The normal flooded lead acid type will only take in about 10% of what the total amp-hour rating for all your batteries combined. You can push it some with an external regulator, but not much. If you have AGM, you can do a much faster charge, but these batteries may not last as long. If you are concerned, just get a spare alternator like you have. There will be other spare parts you will also need. You have two engines so maybe not as many spare parts as for one engine. The thing that will cause you the most problems is water in the diesel. It is best to buy a Baja filter and use it whenever you buy diesel. Check the diesel tanks for water. You can have bacterial growth in diesel that really plugs things up, especially if you buy diesel that already has some water in it. Siphon some diesel off the bottom of the fuel tanks and see what you get.

[Cheechako]

Personally I would go with externally regulated 75 amp alternators on that. 100amp will eat belts likely with a good regulator.
On a budget, You might be able to have your alternators rebuilt for external regulation. You will get a lot more amps that way.
Also, Ample power used to make a regulator for dual use... not sure if it's still available and if it will work well with your engines so far apart or not.
as a reference: my 100 amp externally regulated alternators would put out maybe 85 amps for a max of maybe 15 mins before backing off. Your batteries can only take so much for so long.
I'm guessing, but suspect new 75 amp internal regulated alternators wont put out any more for a charging cycle than your current 60 amp ones if you have them rebuilt and externally regulated with a good 3 step regulator.

[colemj]

Originally Posted by Cheechako

On a budget, You might be able to have your alternators rebuilt for external regulation. You will get a lot more amps that way.

I did this on our OEM alternators and it works great, except that I was measuring 270F on the diode heat sink when they were roaring along. Putting a temp sensor on them caused the regulator to throttle them back so far that they performed just like they did when they were internally regulated.

If you want to go cheap with the OEM's, I found the best solution was to stick a Schottky diode on the sense line to give it a 0.4-0.6V drop and provide a switch to bring it inline when wanted. This makes the alternator put out more than usual, and one simply monitors the temp and return to the internal regulator when hot.

Mark

[roverhi]

Unless things have changed drastically, output of alternators will cut back quickly as the batteries take a charge with the internal regulators. External regulators allow the alternators to put out maximum safe charge all the time so you'll get faster charges. Still will cut back output fairly quickly as batteries can't safely take high charge voltages unless near totally discharged. The external regulators also taper the initial ramp up of the alternator outputs which greatly saves on belt and engine wear.

If it was me, would not spend a ton of money on high end, high output alternators but would on external voltage regulators. They will maximize the charge rate and cut down on engine run time for charging. Not a small consideration unless you like to hear your engines run. Automotive alternators are cheap. You can probably buy several for price of one high end marine type. Personally, have had no issues with alternators so don't have much concern. R&R'ing an alternator is usually one of the easiest things to do on a boat.

[Cheechako]

Originally Posted by colemj

I did this on our OEM alternators and it works great, except that I was measuring 270F on the diode heat sink when they were roaring along. Putting a temp sensor on them caused the regulator to throttle them back so far that they performed just like they did when they were internally regulated.

If you want to go cheap with the OEM's, I found the best solution was to stick a Schottky diode on the sense line to give it a 0.4-0.6V drop and provide a switch to bring it inline when wanted. This makes the alternator put out more than usual, and one simply monitors the temp and return to the internal regulator when hot.

Mark

Yeah, even heavy duty marine alternators get REAL hot. I didnt have a digital Thermometer aboard but it would have been nice to see how hot. I know this, you cant touch the case for even a second.
For the money they charge for an alternator, you'd think the "marine HD" sellers would offer a water cooled jacket.... or at least a "cooling fin" case.

[TheNomadTrip]

Originally Posted by cal40john

You say the solar power you have is usually enough for your needs, so i don't see why you want to go up in alternator amps, which causes more costs and belt eating unless you add costs again (dual or serpentine belt).

In one of your posts you're worried about eating belts. More power is worse.

I'd say just buy a drop in replacement, maybe a little higher quality if you want.

This is closer to what I should do, me thinks. But, a few more amps while I'm underway would be nice. Mostly because when I'm sailing, I don't get as much solar (sails shade solar) and have more energy needs. So... I'd prefer to go up a few amps...

Originally Posted by westwinds

The thing that will cause you the most problems is water in the diesel. It is best to buy a Baja filter and use it whenever you buy diesel. Check the diesel tanks for water. You can have bacterial growth in diesel that really plugs things up, especially if you buy diesel that already has some water in it. Siphon some diesel off the bottom of the fuel tanks and see what you get.

You forgot to take your adderall today - this thread was about alternators. Or maybe you just got done polishing your tanks, and want to keep everyone from having to relive your own recent, personal, Hell. I get it, I've cleaned/polished my tanks, it sucks...

Originally Posted by Cheechako

Personally I would go with externally regulated 75 amp alternators on that. 100amp will eat belts likely with a good regulator.
On a budget, You might be able to have your alternators rebuilt for external regulation. You will get a lot more amps that way.
Also, Ample power used to make a regulator for dual use... not sure if it's still available and if it will work well with your engines so far apart or not.
as a reference: my 100 amp externally regulated alternators would put out maybe 85 amps for a max of maybe 15 mins before backing off. Your batteries can only take so much for so long.
I'm guessing, but suspect new 75 amp internal regulated alternators wont put out any more for a charging cycle than your current 60 amp ones if you have them rebuilt and externally regulated with a good 3 step regulator.

That makes a ton of sense. Except that adds a shitload of costs. By externally regulating I'm adding two external regulators and all of their wiring/controls, then I have to run them to another thing that un-confuses them when they're both running. Just not worth it.

I appreciate all of the input. I've actually learned a ton, which is why I like this site.

Where I'm at now:

- I'm leaning toward a drop-in Leece Neville 90 AMP. I plan on using heavier-duty belts on it from Gates (thanks Mark). This increases my amps, and (hopefully) doesn't increase belt-wear too much. It's also a higher-quality alt. It's also a super-cheap upgrade (in comparison to all other options). I'm going to run this little experiment on one engine - if it works right, I'll run it on my other one.

If I can remember, I'll report back.


Side note: If I only had one engine, I'd go with a Delco 105 AMP alt, externally regulate it, and use the external regulator to downrate it. I think that's ideal, but doing that on two engines doesn't do enough for me to justify the cost.

If I had only one engine and my engine was a main charging source, I'd probably run a serpentine belt, a larger alt, and externally regulate it.

[Cheechako]

Yeah, the Big Neece or Motorolas are a good cost compromise to get quality. Not sure how much they improve your charging... it's all about the regulator. Heavy duty for sure. Not sure if the Neece come in your footprint but you'll figure that out. There are a lot of Motorola internal regulated models 45- 100 amps... if I remember right.

[Stu Jackson]

Originally Posted by TheNomadTrip

- I'm leaning toward a drop-in Leece Neville 90 AMP. I plan on using heavier-duty belts on it from Gates (thanks Mark). This increases my amps, and (hopefully) doesn't increase belt-wear too much. It's also a higher-quality alt. It's also a super-cheap upgrade (in comparison to all other options). I'm going to run this little experiment on one engine - if it works right, I'll run it on my other one.

If I can remember, I'll report back.


Side note: If I only had one engine, I'd go with a Delco 105 AMP alt, externally regulate it, and use the external regulator to downrate it. I think that's ideal, but doing that on two engines doesn't do enough for me to justify the cost.

Good ideas.

Before you posted this, I was going to suggest: What you could do is install an external regulator on ONE engine's alternator.

Great minds and all that...

Also, IIRC, an MC-614 can drive two alternators. See reply #5 here:

http://forums.catalina.sailboatowner....php?p=1103132

[dgz3]

understand your aversion to additional electronic gadgets and wire. It gets to be a bit much. But....
I bought a Balmar alt., pulley, and external programmable regulator for my old Volvo two cyl. Buying from them taps you into their expertise, so you don't have to become an expert on it all. In other words, you don't need to worry about all the stuff you're trying to figure out right now.
The regulator is very simple to wire AND to program. And it provides continuous read outs of system output. It is also programmable for the belt and drive system you have. I run mine detuned so my single v belt can survive.
Additional benefits include a temperature sensor to monitor the battery, different battery type charging profiles, and bulk and float output regulation. So you get a better quality charge in addition to just higher output.
It has all worked flawlessly in the 5 years since I installed it. And it seems to be of very good quality. The stuff is pricey. But I got a much better price by ordering at the boat show">Miami Boat Show. It was actually reasonable. So you don't necessarily have to pay MSRP.
Lots of stuff I worry about. But the charging system isn't one of them. That was worth the money.

[hellosailor]

Speaking of Balmar and "detuning" to save belts? Their "soft start" feature also can be more important than it sounds. I have seen a v-belt literally hunch up like an inchworm, and as the hunch reached to pulley on the alternator, it literally JUMPED off the pulley.


If you weren't watching it happen, you'd swear there was no reason why the belt kept getting thrown off the pulleys.


But when that system kicked in and the sudden power draw from the batteries kicked the alternator up to full output hard & fast...tremendous strain on the belt. Smaller batteries would also prevent that...but the "soft start" serves a purpose.

[model 10]

Originally Posted by Cheechako

Yeah, even heavy duty marine alternators get REAL hot. I didnt have a digital Thermometer aboard but it would have been nice to see how hot. I know this, you cant touch the case for even a second.
For the money they charge for an alternator, you'd think the "marine HD" sellers would offer a water cooled jacket.... or at least a "cooling fin" case.

Or a fan that would cut your hand off if you touched it.

[hellosailor]

Water jacketing an alternator woul dbe a disaster waiting to happen. Dissimilar metals, cooling pipes subject to constant vibration, leading to work hardening and leaks, dissimilar metals and pinhole leaks, all sorts of extra complications and failure modes and of course, more rubber hoses so the alternator could still be moved for adjustment.


Big frame alternators like the Leece-Neville will always run cooler, but auto makers and most everyone else can't afford to give up a foot-wide space in a tight engine bay.


Then there are bus and truck alternators, some quite robust. Except, you might not have room for something that fat OR that long. They're longer too.


And any "real" marine alternator will do as many automotive alternators already do, it will have twin fans. One in front, one in the rear, to ensure airflow over the frame.


Personally I've always thought that marine alternators could benefit from some long-proven technology. Take the alternator apart, give the casing to a machine shop, and have them flute it. Fluting the metal shell should roughly double the surface area, even with shallow flutes, and that's proven to double to heat transfer rate to the air flowing over it.


Ain't gonna be cheap, but that's 1940's technology and it still works perfectly well today. (You have to disassemble the alternator, to keep the metal chips & dust out of it while the fluting is going on.
Fins are great, but fluting is a much more robust compromise than gluing on stuff ripped out of hydronic baseboards. Much easier to clean, too.(G)

[Cheechako]

Has anyone ever tried one of these $145 regulators?
Marine Advanced Alternator Regulator with Upgraded Software | eBay

[DeepFrz]

Yeah, that's the Mark Grasser unit that Maine Sail has commented on. I don't remember exactly what he said but I think Maine may sell them and he also sells Balmar regulators.

Edit: http://www.markgrasser.com/regulator.htm

Edit: It doesn't have all the features of the Balmar regulators.