New alternator for boat diesel - what make should I look for?

[Jens]

I am starting to turn my thoughts to a bigger alternator for my boat. I have a Kubota M35B engine in there and at my cruising speed of around 2300 engine RPM I get a measly 30 amps of charge into my batteries. I haven't yet figured out what the current alternator is but it could be as small as a 60 amp rated unit. At this point I am not sure why I see only 30 amps max charge even with the batteries down to 50% SOC but all will be revealed in time ... I hope.
Anyway, the marine alternators from Balmer as sold through Defender Marine are VERY dear and can be well over $1k once you approach 100A units. I imagine that this is because they are rated to be ignition proof? Since I run a diesel engine, do I need to be concerned with that or can I run something much cheaper? Casual browsing shows new alternators between $200 and $300 on ebay which seems much more reasonable.

Anyhow, I am wondering if there is any reason to spend a fortune on a marine rated unit or will an automotive unit give me similar reliability (key is reliability). Which alternators are considered the best as far as reliability is concerned ?

Thanks !

[Henry W]

Bob or Lloyd should be able to help. I wonder if a automotive alternator can be marinized.

Henry

[Henry W]

Learned something new.

Here it is:  http://www.cruisersforum.com/forums/f54/marine-or-automotive-alternator-52508.html

It looks like Automotive alternators can be used with diesels. Never knew about screened alternators.

Henry

[Jens]

Thanks! Good thread pointer.
Let's say I currently have a 60 amp alternator that only pushes 30 amps into the batteries when they are roughly 50% charged.
How much of that reduced charge rate could be related to the fact that the batteries are getting a bit iffy and how much can be explained by the built-in regulator rather than a fancy external regulator such as the Balmer 614?
In other words, would it be a good idea to hang on to the old alternator for now and try an external regulator first ?
What would be a good source for a Balmer 614 regulator ... ebay ?

[Lloyd]

I am starting to turn my thoughts to a bigger alternator for my boat. I have a Kubota M35B engine in there and at my cruising speed of around 2300 engine RPM I get a measly 30 amps of charge into my batteries. I haven't yet figured out what the current alternator is but it could be as small as a 60 amp rated unit. At this point I am not sure why I see only 30 amps max charge even with the batteries down to 50% SOC but all will be revealed in time ... I hope.
Anyway, the marine alternators from Balmer as sold through Defender Marine are VERY dear and can be well over $1k once you approach 100A units. I imagine that this is because they are rated to be ignition proof? Since I run a diesel engine, do I need to be concerned with that or can I run something much cheaper? Casual browsing shows new alternators between $200 and $300 on ebay which seems much more reasonable.

Anyhow, I am wondering if there is any reason to spend a fortune on a marine rated unit or will an automotive unit give me similar reliability (key is reliability). Which alternators are considered the best as far as reliability is concerned ?

Thanks !

Jens,

I'll help you work through what ya need. First how big is your bat bank=amphr size? How do you use the boat, is it power or sail, how much motor time?, and how long to you anchor out? Finally what is your total amp hrs used per 24 hr when unplugged from shore charger? Do you have any SOLAR.

By the way you never contacted me about the trojans, can I ssume you have replaced your bats with new?

Llloyd

[Lloyd]

Thanks! Good thread pointer.
Let's say I currently have a 60 amp alternator that only pushes 30 amps into the batteries when they are roughly 50% charged.
How much of that reduced charge rate could be related to the fact that the batteries are getting a bit iffy and how much can be explained by the built-in regulator rather than a fancy external regulator such as the Balmer 614?
In other words, would it be a good idea to hang on to the old alternator for now and try an external regulator first ?
What would be a good source for a Balmer 614 regulator ... ebay ?

It could be bats, highly sulfated bats come up to voltage very fast. They also drop voltage very fast, the 2 go hand in hand. Use a good hydrometer after a full charge and 24 hour resting voltage.

Bob's favorite triple nickel is a good bet for an alternator, along side an Balmar controller.

Also the new square wire hair pin alternators from Denso, and Remy are excellent, both of these alts can run 75-80% efficiency, and they're a wound field alternator

Lloyd

[Jens]

Jens,

I'll help you work through what ya need. First how big is your bat bank=amphr size? How do you use the boat, is it power or sail, how much motor time?, and how long to you anchor out? Finally what is your total amp hrs used per 24 hr when unplugged from shore charger? Do you have any SOLAR.

By the way you never contacted me about the trojans, can I ssume you have replaced your bats with new?

Llloyd

Thanks for jumping in here Lloyd!
I currently still have my 2 old 4D's (they are actually not that old, probably 3 years or so). I tried buying golf cart batteries from Costco about a month back but apparently they pack up this kind of stuff for the winter so no luck. I have a Catalina 36 sail boat and no solar (Solar is something else to look at but not until well into next year at the earliest). I am guessing here but I think the 2 4D 's add up to around 320 AH total capacity when new. I am operating under the assumption that I can pull about 100AH before I start to get worried. In the summer this isn't much of an issue but I run into problems when it gets cold. The diesel hot water heater on the boat takes a fair chunk of current to run and I like running it during the entire night (it of course modulates output based on interior temperature). It is not unusual for me to see a 10 amp current drain and I can be down 100 AH by the time I get going in the morning after anchoring out. When in my home port I hook to shore power and fully charge my batteries.
So far my excursions have been short ones with fall sailing limited to one night at anchor. I am concerned what things would look like with 3 or 4 days at anchor. With a charge rate of 30 amps (and it doesn't take long before that drops), I can't really do meaningful recharging of the house bank. Also, being a sail boat, I prefer not running the engine (or minimizing run time) when there is sufficient breeze to move under sail.
What I am doing at the moment is trying to figure out how to go about enabling me to stay out for multiple days without going paranoid about battery condition. I do not have enough room to install a dedicated DC generator.
Replacing the 2 4D's with 4 6V golf cart batteries is one thing I can do but I am not sure if this will help out if I can't recharge the batteries reasonably quick. Trying to figure out what my charging system is doing and if it needs to be upgraded is the other end of the puzzle. Until such time as I figure out how the overall system should look like, I am flying kinda blind.
Although I am likely to stay with flooded lead acid for now, there is the possibility of going with lithium cells in a few years when the technology has matured a bit.

As you can see, I have not made much progress in regards to power since we last talked batteries. I have replaced some of my lights with LED's to reduce current draw, I am waiting on a boost dc-dc converter to allow running my laptop directly from the battery instead of powering the big inverter for 120V and then using a wall wart to feed the laptop (I use the laptop for anchor watch so it's on for the entire night). Babysteps here and there.

I really don't like the idea of getting a small Honda generator which was another thought I briefly entertained.
Wind power is probably marginal in the PNW and solar is of little help in the winter when I have the big current draw of the diesel heater.
I can count on one or two hours of motoring on a lot of days but try to avoid motoring much more than that.

Hopefully this gives you a reasonable picture of where I am coming from

Jens

[Jens]

It could be bats, highly sulfated bats come up to voltage very fast. They also drop voltage very fast, the 2 go hand in hand. Use a good hydrometer after a full charge and 24 hour resting voltage.

Bob's favorite triple nickel is a good bet for an alternator, along side an Balmar controller.

Also the new square wire hair pin alternators from Denso, and Remy are excellent, both of these alts can run 75-80% efficiency, and they're a wound field alternator

Lloyd

I don't recall for sure but I think I amat around 12.2 or so volts in the morning after having pulled between 80 and 100 AH's during the night. I have to run a few tests and also measure the specific gravity of the cells.

"Triple Nickel" ?

Jens

[mike90045]

what to look for - explosive atmosphere rated, if those conditions exist in the compartment.  But I think, all the mucking around with regulators, is for naught, if your pulley ratios are not right. Set pulley size for charging at your commonly used RPM, but below where the alternator will grenade  if you redline the engine.

[mobile_bob]

the triple nickel

110-555jho, and i believe it is also marine capable, as it has a sealed brush set so that no sparking to ignite fumes if they exist.

priced at about 180 bucks or so and available from any heavy truck dealer

they are rated at 160amps and will deliver ~120 amps continuous for a very long time.

there are many marine aux power units using this alternator.

bob g

ps. watch out for knock offs of this alternator on ebay for maybe 20-40 bucks cheaper, i am not at all sure they are as good as the real deal which is marketed by leece neville/prestolite.

[Jens]

Cool! Thanks for clarifying Bob!

A couple of related question if I may ...
Besides some windage losses on a larger alternator, am I going to loose anything else by going to an oversized alternator compared to let's say a 100 amp rated unit? Would there be a significant difference if I charge at 50 amps in the power to run a 100 amp rated alternator compared to a 160 amp rated alternator?

Balmer claims that marine rated units have better bearings and fans to put up with the extra demands of marine applications. Is that marketing speak or is there any truth to it? I hear that Leece-Neville actually makes the alternators for Balmer but do they modify the design for them or does Balmer take a standard unit and powdercoat it white and sell it as theirs ?

[Henry W]

I think automotive applications are tougher than marine. Alternators next to radiators and under the hood with turbo's and exhaust in summer days get very hot. I could be wrong but my guess it gets hotter than lots of marine applications.

Henry

[Lloyd]

Cool! Thanks for clarifying Bob!

A couple of related question if I may ...
Besides some windage losses on a larger alternator, am I going to loose anything else by going to an oversized alternator compared to let's say a 100 amp rated unit? Would there be a significant difference if I charge at 50 amps in the power to run a 100 amp rated alternator compared to a 160 amp rated alternator?

Balmer claims that marine rated units have better bearings and fans to put up with the extra demands of marine applications. Is that marketing speak or is there any truth to it? I hear that Leece-Neville actually makes the alternators for Balmer but do they modify the design for them or does Balmer take a standard unit and powdercoat it white and sell it as theirs ?

Most alternators are going to operating most efficiently at about 2500 alternator rpm and about 50-60% loaded. This doesn't mean that the engine is going to operating most efficiently, especially if its a large engine/small alt..

On a sail boat we typically see 9 to 20 hp auxiliaries. This make a perfect solution, with no gen required. Size the alt and battery bank to 2-3 days load, make sure you consider Peukert, and bat temps. If your bats are cold they won't have near the voltage of warm bats, nor the amp hr availability. In the NW fall to spring period I find it's not uncommon for the bat temps to be low 50's to low 60's. This really effects voltage and amp hr., so you need to size the bank to the loads at temp.

With a small sailboat auxiliary, it can be both a generator and drive motor. Setup with a Balmar MC controller when at anchor you can run a large alternator that closely matches the available engine HP. Like a dc generator, then when you need to motor, setup a toggle switch and just flip it into small engine mode. You need to be mindful of the power take off requirements of the engine drive pulley/crank loads, and make sure you have an proper sized drive belt.

Lloyd

[Jens]

Did a fact finding mission to the boat:
On trickle charge the batteries are resting at 13.45 Volt. After turning charger off and about 30 minutes voltage was at 13.3V. I will let it sit overnight and check voltage and specific gravity tomorrow afternoon.
The engine has a 50 amp alternator (Westerbeke 41017) and a 3/8 " belt.
Any increase in alternator capacity would require a new water pump pulley, crankshaft pulley and alternator pulley in order to accommodate a wider belt. I am assuming these are available but I need to figure out costs.
Physically, the alternator can't be bigger than the stock size unless I want to do major surgery. The biggest limitation seems to be depth which can't be more than about 6" from the inside edge of the pulley flange to the end of the electrical studs at the back of the alternator.
Mounting is via a 2" boss on the bottom of the alternator.

[Jens]

Most alternators are going to operating most efficiently at about 2500 alternator rpm and about 50-60% loaded. This doesn't mean that the engine is going to operating most efficiently, especially if its a large engine/small alt..

On a sail boat we typically see 9 to 20 hp auxiliaries. This make a perfect solution, with no gen required. Size the alt and battery bank to 2-3 days load, make sure you consider Peukert, and bat temps. If your bats are cold they won't have near the voltage of warm bats, nor the amp hr availability. In the NW fall to spring period I find it's not uncommon for the bat temps to be low 50's to low 60's. This really effects voltage and amp hr., so you need to size the bank to the loads at temp.

With a small sailboat auxiliary, it can be both a generator and drive motor. Setup with a Balmar MC controller when at anchor you can run a large alternator that closely matches the available engine HP. Like a dc generator, then when you need to motor, setup a toggle switch and just flip it into small engine mode. You need to be mindful of the power take off requirements of the engine drive pulley/crank loads, and make sure you have an proper sized drive belt.

Lloyd

The engine is a 35 Hp unit, cruise RPM is between 2000 and 2300 RPM, engine pulley is 4 1/8 " diameter, Alternator pulley is 2 7/8" diameter so we are looking good there. The downside is the tiny 3/8" belt. Yes the batteries will be cold, probably in the 50-60 degree range you mentioned. Without major surgery, there is no room for additional batteries so I am stuck with 4 golf cart 6 volt units.
I actually have plenty power to operate the alternator when cruising but I like the idea of 'down shifting' (presumably via the temperature probe wire on the Balmer 614 regulator).
Are there good aftermarket sources for the bigger pulleys required or would they best be ordered through Westerbeke or Kubota ?