Buying an Electromaax alternator? I suggest not.

[aluijten]

Originally Posted by Maine Sail

This is exactly what the Balmar regulators do. They find the max temp the alt can run at

So how does that work then? How would you define the max temperature for an Alternator?

[a64pilot]

Originally Posted by aluijten

So how does that work then? How would you define the max temperature for an Alternator?

Maine Sail I hope you don't mind me answering, please correct me if I'm wrong, I learn that way


But you find max temp by testing, it's what I do for a living, testing that is, just not alternators.
Once you find that limit, you back off a conservative amount, you do analysis and further testing to see what this operating temp does for life limits, once your satisfied, you now have an acceptable operating temp, for the location you tested, then you program your regulator to not allow more than this temp.

[Maine Sail]

Originally Posted by aluijten

So how does that work then? How would you define the max temperature for an Alternator?

It depends upon the alternator but I usually limit them to somewhere between 225F to 235F and this is fully adjustable in the regulator. The regulator comes pre-set for 225F/107C but this limit can be adjusted up or down.

[aluijten]

Originally Posted by a64pilot

But you find max temp by testing, it's what I do for a living, testing that is, just not alternators.
Once you find that limit, you back off a conservative amount, you do analysis and further testing to see what this operating temp does for life limits, once your satisfied, you now have an acceptable operating temp, for the location you tested, then you program your regulator to not allow more than this temp.

Being a engineer myself I can understand that. But how do you envision that in the reality of being a boat owner looking for the best charging system for my batteries? Destructive testing is not very practical. I can't recall having seen the max.temp recommendation for the alternator on my engine.
At the same time I don't want to restrict the life of my alternator because of some poor estimate.
My point is that by pushing the system to the limits you may get more trouble than benefits. Having modest charging is better then no charging at all.

In my view if you want performance charging you should get a performance alternator that clearly specifies the sustained max output and required operating environment. Then you can adjust the smart regulator to those specifications

[Maine Sail]

Originally Posted by a64pilot

Maine Sail I hope you don't mind me answering, please correct me if I'm wrong, I learn that way


But you find max temp by testing, it's what I do for a living, testing that is, just not alternators.
Once you find that limit, you back off a conservative amount, you do analysis and further testing to see what this operating temp does for life limits, once your satisfied, you now have an acceptable operating temp, for the location you tested, then you program your regulator to not allow more than this temp.

This is another feature where you can pre-adjust the max field voltage potential to essentially de-rate the alternator by using what Balmar calls "Belt Manager".... The adaptive temp compensation then essentially becomes the back up insurance policy in-case the belt manager reduction was not enough for certain duration's..

For example I have my own 160A alternator permanently set to not exceed about 120A (feeding LiFePO4) I then have a temp limit of about 240F. Even with the BM reduction I still occasionally bump in & out of the temp limit. I am currently yanking the diode rack, and mounting it externally, and will hopefully be able to push about 145A continuously from a 160A alt.

[Stu Jackson]

Originally Posted by a64pilot

<SNIP>

Which is why I'm wondering aloud if it doesn't make more financial sense to buy a 100 amp alternator and let it run at full output, that it does to spend the $$ to buy a 200 and then turn it down to a lower output to keep the heat down?


On edit, I didn't read Maine Sails post until after I posted, I was unaware the Balmar would cut back so little, mine just drops to float voltage when temp limit is reached.

a64, your analysis is correct.

But when I got to your 100A or 200A alternator paragraph, I just started sputtering. This is exactly what Maine Sail and many others of us have been saying for years. Buy a 100A run it full bore based on your anticipated load (let's say 100A!!!) and burn it up without temp compensation, or buy a larger one and don't... I've posted about small engine mode and belt manager and so has Maine Sail. Many, many times.



The new Balmar regulators cut back in 5% increments, while the older 612s did it 50%.

[a64pilot]

I wasn't clear, sorry, by testing, I meant the manufacturer, by doing destructive testing as you say,
I didn't mean the boat owner, sorry.

But if your the manufacturer of both the alternator and the external reg, then you can test and find the spot you want to monitor the temps at on you alternator as of course there will be places that run much hotter than others, maybe machine a nice clean flat spot to mount a temp sensor and of course supply a sensor that fits there.

Note I don't have a Balmar anything so I do not know how they do things, I have a much less expensive, much less capable system.
But assuming as Balmar either actually manufactures or at least purchases both alts and external regs, then I believe it safe to assume they have done the testing to determine both the sensor location and max safe temp.
Boat owner should at that point just read and follow directions.

[a64pilot]

Stu,
What I was saying was buy a 100 amp alt, but temp protect it, but I assume it may can make 100 amps and not hit the max temp limit, where a much larger alternator can't, they have to be cut back, or they will burn up.
The cost difference between a 100 amp and a 200 amp is rather large, I mean mucho bucks.

What I am saying is that, maybe the difference in actual output from a 100 amp to a 200 amp, isn't 100 amps?


This being a bang for the buck argument for those of us that can't go in and just buy the best of everything, I try for instance to determine a cost/benefit ratio, it seems there is a point to where everything the cost escalate, for very little actual gain.
Meaning it seems it's often that you pay twice as much for something, but maybe get at most a 10% performance increase.

I'm postulating that if you can only reasonably get say 130 amps or so continuous output from a 200 amp alternator, maybe a 100 if it will give close to 100, is a better buy, or maybe 2, 100's are if you really need / want the power.

[Stu Jackson]

a64, I hear ya, but I think you're missing the point. You size your house bank for the anticipated loads you have, and in doing this you decide how long you want to be anchored without using your engine to charge your house bank.

Let's say, as many of us do, you have a 100 ah daily load and thus size a 400 ah house bank. This gives you a night or two on the hook, right?

Then, and only then, do you size your alternator. The size of the alternator is based on the acceptance of your batteries. For wet cells, we've found that a house bank of that size will have an acceptance at about anywhere from 60 to 100A, of course tapering off after an initial charging period and varying based on actual SOC.

The larger the alternator, assuming it is sized beyond the max acceptance, the cooler it will run. If the alternator size is close to the acceptance, then methods are required to essentially compensate for avoiding overheating the alternator, since the kind and physical size of the generally small frame alternators available on our modest diesel engines is limited. A 100A alternator without any cutbacks will get hot, and overheat. They are simply not made to do it.

Those methods include belt manager, small engine mode and both battery and alternator temperature compensation. These can be done automatically or manually with external regulators.

It's that simple.

If all you can afford is a 100A alternator, then to avoid overheating it with a larger battery acceptance, you have to do something, right?

BTW, I have a 100A alternator on our 390 ah wet cell house bank and have a Balmar MC-612 and I use a manual switch to induce small engine mode for initial startup periods, which I've discussed here countless times. Maine Sail does different things, as you know.

[sailorboy1]

I'm "impressed" people with sailboats even have a battery bank with enough acceptance to make enough use of these real high output alternators to make them anywhere close to the making the expense worth it.

[Stu Jackson]

Originally Posted by sailorboy1

I'm "impressed" people with sailboats even have a battery bank with enough acceptance to make enough use of these real high output alternators to make them anywhere close to the making the expense worth it.

Gee, a perfect example of

Your boat, your choice.

[sailorboy1]

Originally Posted by Stu Jackson

Gee, a perfect example of

Your boat, your choice.

more an example of believing something bigger and more expensive is better

[Stu Jackson]

Originally Posted by sailorboy1

more an example of believing something bigger and more expensive is better

WADR, not. I increased the size of my alternator and replaced the internally regulated 65A alternator with a 100A unit with external regulation. It has improved my abilities to spend more time on the hook.

I know that this is better.

For me.

Life is full of options.

Your boat, your choice.

[sailorboy1]

Originally Posted by Stu Jackson

WADR, not. I increased the size of my alternator and replaced the internally regulated 65A alternator with a 100A unit with external regulation. It has improved my abilities to spend more time on the hook.

I know that this is better.

For me.

Life is full of options.

Your boat, your choice.

I have a 100 amp alternator, but fail to understand what point you are trying to make or what this has to do with needing a 200 amp alternator. All I said is I'm impressed people could regularly make use of a 200 amp output.

[a64pilot]

Stu,
I went about it differently, I went with the largest bank I could reasonably fit, under the belief that if I am shallow cycling a bank, it will last longer.
Due to physical constraints I ended up with a 660 AH AGM bank, now I don't think there is a small frame alt made that can put out as much as that bank will accept in the bulk phase, so whatever I have, has to be temp protected.

But your statement below you sure?

"The larger the alternator, assuming it is sized beyond the max acceptance, the cooler it will run."

Your saying I believe that a small frame 200 amp alternator will run cooler producing 100 amps than the same frame 100 amp alternator, producing 100 amps will.

Why? To run cooler infers more efficient, make the same power, just less heat?


If that is true, then it would seem that as a rough average a percent of power output could be assumed for continuous power output?

Be interesting to see a continuous power output rating for alternators.

BTW, which Balmar regulator cuts back in 5% stages? I thought they only cut back by half?