Big dc alternator

[FF]

For folks with massive battery banks that can require 200- 300+ amps of DC to have a reasonable charge time, getting an alternator can be expensive.

For those that prefer to "Roll their Own" and want to create a noisemaker that will operate at slow speeds for minor loads (inverter required) a big DC alt is also required.

This is a video of belting a coach direct drive unit.

These come in 12 & 24V up to 300AH output and rare available rebuilt , or just used , operating , at modest cost.

http://youtu.be/WvuT2ZSO2QI

 

[Ski in NC]

Can't make out much from that vid, but it is clearly a Detroit Diesel. One neat feature of those is that the alternators can indeed be direct/gear driven. The big bus alternators are even more unique in that they had step-up gears internally so it really made some serious rpms and thus power, even at idle. Should be a neat feature for a trawler, but never seen one installed on a boat. Not sure if that alt is available with belt drive??? If so, could be an option for non Detroit boats....

 

[choppywater]

With out getting out a calculator or looking it up...
300 amps at 12 volts is around 4.8 to 5hp to keep it spinning.
I'm not sure if you could make it work with a 6 rib serpentine belt.
I'm thinking a high performance notched drive belt would be the way to go.
I have more thoughts on just the HP and starting side under load, but think it might be better to keep my moth shut.

To me the question would be what the proper charge rate for the batteries your charging OR just say “charge it” and pump in as many amps as possible and fry your battery bank.

I have a large house battery bank and I use a 100 amp 24 volt permanent magnet alternator.

 

[ksanders]

Lots of us have large alternators on our main propulsion engines for charging a house bank. All it takes is a external multistage regulator.

What is interesting is what was inferred in the original post. You could use a engine to spin a dc alternator. The challenge there is that you would have to come up with a governor that would sense the need for current and increase engine speed to match.

 

[mbevins]

Can't make out much from that vid, but it is clearly a Detroit Diesel. One neat feature of those is that the alternators can indeed be direct/gear driven. The big bus alternators are even more unique in that they had step-up gears internally so it really made some serious rpms and thus power, even at idle. Should be a neat feature for a trawler, but never seen one installed on a boat. Not sure if that alt is available with belt drive??? If so, could be an option for non Detroit boats....

I actually looked into mounting one of those on my boat. Would have been perfect for my 6-71. Only problem was real estate. It wanted to go right where my turbo was.
It was a great thought on paper.
Ended up with a big as@ Balmar up on the front instead. Seems to do a nice job.

 

[Doug H]

Elelctrodyne makes some very heavy duty units that wiill put out impressive watts at low RPMs. We installed a 350A unit in a boat with a 12 x group 31 bank that would put out about 75% at barely over idle. Ask for the output vs. rpm curve for any alternator you are considering -- they vary quite a lot.

 

[FF]

"To me the question would be what the proper charge rate for the batteries your charging OR just say “charge it” and pump in as many amps as possible and fry your battery bank."

The fiels current draw is low enough so a normal aftermarket cruising boat V regulator will do the job.

The std bus V reg is as bad as the std auto or truck V regulator and should be avoided.

 

[Bendit]

Lots of us have large alternators on our main propulsion engines for charging a house bank. All it takes is a external multistage regulator.

What is interesting is what was inferred in the original post. You could use a engine to spin a dc alternator. The challenge there is that you would have to come up with a governor that would sense the need for current and increase engine speed to match.

Got a 12hp Kubota (600cc) driving a 24V 120A bus alternator via two belts.
I have fixed the stop control (cable) so that it also acts as a speed control and just set it by ear so there's a reasonable load on the engine. I have an external Ample Power SAR V3 regulator with a current limit pot which I've set to 90A. More current than this and the belts shred noisily and messily.
It has been suggested, on this forum, that I could increase the size of the sheaves on both the alternator and the engine flywheel to prevent this but I can live with it as is. 90A at 28.8 V(charging Voltage) is 2.6Kw which is plenty.
Two inverters supply 230V AC for hairdryers etc...this is probably not a solution if you need aircon, but we run a small fan heater in winter OK.

 

[Mule]

Got a 12hp Kubota (600cc) driving a 24V 120A bus alternator via two belts.
I have fixed the stop control (cable) so that it also acts as a speed control and just set it by ear so there's a reasonable load on the engine. I have an external Ample Power SAR V3 regulator with a current limit pot which I've set to 90A. More current than this and the belts shred noisily and messily.
It has been suggested, on this forum, that I could increase the size of the sheaves on both the alternator and the engine flywheel to prevent this but I can live with it as is. 90A at 28.8 V(charging Voltage) is 2.6Kw which is plenty.
Two inverters supply 230V AC for hairdryers etc...this is probably not a solution if you need aircon, but we run a small fan heater in winter OK.

230 volt hair dryer? This the European version or is it the Whrlpool brand for Texas Big Haired Women?

 

[kulas44]

The 50DN is available as a belt driven unit. It was primarily gear driven on the DetroitDiesel powered busses, but was converted to belt when turbo's were introduced on the 6V92s. It is pressure lubricated from the engine (cooling it also) and the stepup gearing is internal to the rear bellhousing on the gear driven units. A big gear on the cam and small gear on the alt. kinda like a sun gear arrangement. On most of the belt drive units the tensioner is a hydraulic cylinder actuated by engine oil pressure to give adequate belt tension. These are very robust and durable alternators, far exceeding anything one could get thru normal channells. And can be picked cheaply if you know someone in the bus bidness. I just happen to have friends in that area. If you can use one it would be a great investment.

 

[FF]

"I have fixed the stop control (cable) so that it also acts as a speed control and just set it by ear so there's a reasonable load on the engine"

Lazier folks install a speed control from a welding unit to make this automatic .

Not "marine" labeled so no stoooopid pricing.

 

[O C Diver]

With out getting out a calculator or looking it up...
300 amps at 12 volts is around 4.8 to 5hp to keep it spinning.
I'm not sure if you could make it work with a 6 rib serpentine belt.
I'm thinking a high performance notched drive belt would be the way to go.
I have more thoughts on just the HP and starting side under load, but think it might be better to keep my moth shut.

To me the question would be what the proper charge rate for the batteries your charging OR just say “charge it” and pump in as many amps as possible and fry your battery bank.

I have a large house battery bank and I use a 100 amp 24 volt permanent magnet alternator.

Simple answer is to go with an additional 8 groove crank pulley as opposed to multiple belts. The specialty shop truck and bus shop I use for alternators etc., told me the below 8 groove serpentine belt setup would be fine for up to a 350 amp alternator. 220 amps with an external sterling regulator should meet my needs nicely with out cooking the battery bank.



Ted

 

[fryedaze]

Simple answer is to go with an additional 8 groove crank pulley as opposed to multiple belts. The specialty shop truck and bus shop I use for alternators etc., told me the below 8 groove serpentine belt setup would be fine for up to a 350 amp alternator. 220 amps with an external sterling regulator should meet my needs nicely with out cooking the battery bank.

View attachment 46805

Ted

Ted, are you using the alternator temp monitoring on the Sterling regulator? I have smaller frame 120/150 amp alternators. The Sterling alternator shut off turns them off when they reach 194F. When the batteries are low and getting charged hard the alternator is turned off and on as the temp rises and then cools off. Your big frame alt may not have the issue. I have dedicated blowers on my alts and it still does it.


The 8 groove belt with at least 180 degrees of contact is the ticket. If the contact is less, say due to an idler pully setup they can still slip.

 

[O C Diver]

Ted, are you using the alternator temp monitoring on the Sterling regulator? I have smaller frame 120/150 amp alternators. The Sterling alternator shut off turns them off when they reach 194F. When the batteries are low and getting charged hard the alternator is turned off and on as the temp rises and then cools off. Your big frame alt may not have the issue. I have dedicated blowers on my alts and it still does it.

Hi Dave, yes I wired both the alternator and the battery bank temp monitoring. Am curious to see if it cycles on an off with the large frame alternator. What is your duty cycle (percentage off versus percentage charging) when charging the depleted battery bank? How long does it take for the alternator to cool down before switching back on?

Ted

 

[Ski in NC]

Ted- A larger diameter pulley on the crank will give you better alt performance and better alt cooling. If you have issues with running low engine rpm, consider that.

You'll know how well it works after splash day. Which is when??? Exciting...

You should see the crank pulley driving the alt on a Cat 3176/3196: It's like a foot in diameter!! Alt on that beast spins plenty fast at idle..

 

[fryedaze]

Ted, it takes about 7-10 minutes for the alternator to cool off and start charging again. At the beginning of hard charging (about 200 amps total, 2 alts) it will charge about 15 minutes and then be off 7-10 minutes. Before I put the blowers on it was on for 5 min off for 10min. If I pull 300 amp-hrs out they put it back in 3-4 hrs. The Sterling guys and the alternator supplier told me to take the temp protection off. The alternator supplier says "Wenormally see between 270 and 330* at the stator core when charging at90-300A." Thats a long way from 194F.

 

[Ski in NC]

Fry- Alts should be able to handle well over 194F, but only alt supplier will know what the actual limit is. Also, you should be able to set current limit, either sensed at stator or exciter, so thermal limit will not be reached.

Is temp limit cutoff adjustable?

I'd find that on/off behavior annoying. Gots to be a better way...

 

[O C Diver]

Ted- A larger diameter pulley on the crank will give you better alt performance and better alt cooling. If you have issues with running low engine rpm, consider that.

You'll know how well it works after splash day. Which is when??? Exciting...

You should see the crank pulley driving the alt on a Cat 3176/3196: It's like a foot in diameter!! Alt on that beast spins plenty fast at idle..

Hi Ski, thought about going with a bigger crank pulley. Have this same setup on my Cummins 6CT 300 in the charter boat. Alternator really doesn't put out until the engine reaches 900 to 1,000 rpm. With the trawler, I expect the John Deere to cruise between 1,400 and 1,800 rpm (6 or 7 knots), and WOT 2500 rpm. So I'm guessing very little output and heat production at or near idle, and plenty of rpm / cooling at cruise. Guess we will see what happens when I go from theory to reality.

Splash day should be around December 15th.

Ted

 

[O C Diver]

Ted, it takes about 7-10 minutes for the alternator to cool off and start charging again. At the beginning of hard charging (about 200 amps total, 2 alts) it will charge about 15 minutes and then be off 7-10 minutes. Before I put the blowers on it was on for 5 min off for 10min. If I pull 300 amp-hrs out they put it back in 3-4 hrs. The Sterling guys and the alternator supplier told me to take the temp protection off. The alternator supplier says "Wenormally see between 270 and 330* at the stator core when charging at90-300A." Thats a long way from 194F.

Hmmm, was hoping you were getting a better duty cycle. Maybe you need to move the temp sensor to a different bolt, like the mounting bracket.

Actually moving the sensor to a different bolt my allow a moderately higher alternator temperature without it getting too high. Might be worth trying and verifying results with an infrared temp gun.

Ted

 

[fryedaze]

It is annoying. The twins get out of sync when the alt load changes. I may remove the protection on one and see what happens. It may end up as a $350 experiment if the alt fails.

 

[ksanders]

Got a 12hp Kubota (600cc) driving a 24V 120A bus alternator via two belts.
I have fixed the stop control (cable) so that it also acts as a speed control and just set it by ear so there's a reasonable load on the engine. I have an external Ample Power SAR V3 regulator with a current limit pot which I've set to 90A. More current than this and the belts shred noisily and messily.
It has been suggested, on this forum, that I could increase the size of the sheaves on both the alternator and the engine flywheel to prevent this but I can live with it as is. 90A at 28.8 V(charging Voltage) is 2.6Kw which is plenty.
Two inverters supply 230V AC for hairdryers etc...this is probably not a solution if you need aircon, but we run a small fan heater in winter OK.

Sometimes a human ear is better than anything else.

I've been pondering how to govern a engine with a DC alternator and it just has not clicked yet. The problem is that if you increase rpm, you increase output on a alternator up to a point. Lower rpm would be great when you do not need the higher output.

The easiest method would be to govern the engine for the speed at which the alternator reaches it's max output capability. That would provide for good cooling air as well. The problem with that method is that when current needs are lower, for example as your batteries reach different stage set points in the regulator you do not need the engine screaming along at a higher rpm.

This will take some more pondering...

 

[alesnloggers]

I've had this bookmarked for a while. If you scroll down he makes his own Arduino based controller for his DC generator.

mv.VikingStar: Kubota DC Generator

 

[fryedaze]

Fry- Alts should be able to handle well over 194F, but only alt supplier will know what the actual limit is. Also, you should be able to set current limit, either sensed at stator or exciter, so thermal limit will not be reached.

Is temp limit cutoff adjustable?

I'd find that on/off behavior annoying. Gots to be a better way...

Hi Ski, no the temp set point is not adjustable. They wouldn't tell me what it was (thermocouple, RTD, etc) so I could find something higher. They told me to remove the temp protection.


Yes it is annoying.

 

[fryedaze]

Hmmm, was hoping you were getting a better duty cycle. Maybe you need to move the temp sensor to a different bolt, like the mounting bracket.

Actually moving the sensor to a different bolt my allow a moderately higher alternator temperature without it getting too high. Might be worth trying and verifying results with an infrared temp gun.

Ted

Went through moving the sensor around with minor improvement.They are actually on the mounting bolt. When you consider that the mounts are bolted to an engine block that runs 180 -185F, the 194F set point doesn't stand a chance.

 

[Ski in NC]

Hi Ski, no the temp set point is not adjustable. They wouldn't tell me what it was (thermocouple, RTD, etc) so I could find something higher. They told me to remove the temp protection.


Yes it is annoying.

Take the sensor off and go for a run. Monitor stator core temp with an IR gun. I'd say if it got to 250F I'd back off the alt load. Where'd I come up with that 250F number?? Don't ask, but you could probably guess!!

 

[Pack Mule]

This is what's on mine , not sure what it does for me . Tag says 14v . I guess the PO did what needed to be done to mount it this way (facing the engine ) . I know very little about alternators.

 

[djones44]

I'm dealing with battery charging issues at the moment (2xDD8.2L with Balmar) and I am downgrading the Xantrex 40a Truecharger to 20A. I don't want to boil my batteries (further) and I view 20A as a capable trickle charger, all I need betwixt weekend cruises for 4x8D new batteries. Or so I hope.

One question: My starboard engine when running makes a loud ticking sound somewhere up around my tachometer. It's a PITA when cruising and I have to track it down, but can't seem to do it using just audio, a steel rod, etc.

Could this is be an electrical noise generated by an alternator-based tach, or is it as mechanical as it sounds?

 

[FlyWright]

I'm dealing with battery charging issues at the moment (2xDD8.2L with Balmar) and I am downgrading the Xantrex 40a Truecharger to 20A. I don't want to boil my batteries (further) and I view 20A as a capable trickle charger, all I need betwixt weekend cruises for 4x8D new batteries. Or so I hope.

One question: My starboard engine when running makes a loud ticking sound somewhere up around my tachometer. It's a PITA when cruising and I have to track it down, but can't seem to do it using just audio, a steel rod, etc.

Could this is be an electrical noise generated by an alternator-based tach, or is it as mechanical as it sounds?

If that 40A charger is a smart charger, you should have nothing to worry about regarding an excess charge. Once the battery reaches about 80-85%(Absorption stage), the acceptance rate has stepped down enough to only allow enough measured current flow.

Why are you downgrading?

I have alternator based tachs but hear no mechanical ticking. Don't know if your engine could handle this, but have you tried a brief engine run with the alternator disconnected to note any sound differences?

 

[djones44]

If that 40A charger is a smart charger, you should have nothing to worry about regarding an excess charge. Once the battery reaches about 80-85%(Absorption stage), the acceptance rate has stepped down enough to only allow enough measured current flow.

Why are you downgrading?

I have alternator based tachs but hear no mechanical ticking. Don't know if your engine could handle this, but have you tried a brief engine run with the alternator disconnected to note any sound differences?

The boat is on shorepower 95% of the time (tied up) and I am nursing a 1500W heater over the winter. I don't feel that I need 40 amps when I have Balmars, and an 8000 KW diesel generator, and the Xantrex is stackable and smaller now, I can add one with 60A alongside for 80A if I need to. I guess I'm from the old trickle charger generation, and on 30A shorepower.

Thank you for the suggestion re: disconnecting the alternator, I suppose that must come. Maybe when I put the new Xantrex in (the Statpower was dead) things will resolve themselves from there.

 

[C lectric]

Does your regulator have a max. output adjustment. Many do.

You may actually do better to turn down the max. output current to a lesser level avoiding overheating. If you are only getting a 70% duty cycle ,on/off, then less output may actually improve overall charging if the current is constant.
Try something like 80% output and test.