Buying an Electromaax alternator? I suggest not.

[a64pilot]

Originally Posted by sailorboy1

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.

I'd be willing to bet that you never see 100 amps out of it.
Mine is a 140, I have seen 110, but not for long, as it hits its temp cut back point, seems it good for mid 80's as a continuous rating

I should note however that the non-adjustable temp cutback point seems awfully conservative, when it cut back the highest temp I could measure with an IR thermometer was 150F

[Stu Jackson]

Originally Posted by 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."

Hi again. IIRC, you also chose AGMs because of your space conditions. So you ended up with a huge bank with high acceptance, right?

Given any defined acceptance, why wouldn't a larger alternator run cooler if it is larger than the load? That, as I understand it, is the entire reason behind sizing an alternator.

I agree that shallower cycling will extend the life of a bank. And that tenp compensation is a good idea.

Originally Posted by a64pilot

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.

I agree. I don't have that info, perhaps Maine Sail has it. But doesn't logic indicate that an alternator rated for 200A will run cooler with a 100A load, just as a 100A will run cooler at a 50A load?

Isn't this the entire concept of small engine mode and temp compensation?

Originally Posted by a64pilot

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

Maine Sail has noted many times that the MC-614 does this with its newer programming. The MC-612, which I have, doesn't.

[Jd1]

Originally Posted by a64pilot

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.
But Mark says something better is coming

Seriously, .... you leave us hanging with that ????? Spill the beans man !

BTW, something that most people don't think about: You have an engine compartment that is 80C at operating temperature (well mine is) and your alternator is set up to limit it's temp to 100C. So while it may sound like the alternator is getting very hot, it is actually only getting 20 degrees C hotter before current limiting happens. No wonder that they can't output full power.
I still haven't changed my ventilation but just imagine if you were to decrease the temperature of your engine bay from 80C to 60C ... you could increase alternator output drastically while extending alternator life!

[a64pilot]

If by spill the beans, you mean what Mark said, I'd have to say call him as I did not get specifics, and don't want to start rumors, and he is just too easy to get on the phone.

I agree on temps myself, one of my projects is to run a bilge blower from the lower part of my bilge to the backside of my alternator with the idea of cooling it.

Removing the Diode pack as Maine Sail is doing would be I believe far more effective as it's my understanding they generate an appreciable amount of heat.

[sailorboy1]

Originally Posted by a64pilot

I'd be willing to bet that you never see 100 amps out of it.
Mine is a 140, I have seen 110, but not for long, as it hits its temp cut back point, seems it good for mid 80's as a continuous rating

You're right, rarely even see 70 amps out it. But it's because the battery acceptance wouldn't take more. Guess if I let my batteries discharge more I could get more out of the alternator, but I would have to turn off the solar etc. and go out of way to do it.

So my point is:
- you don't want to discharge your batteries low
- you you install a large bank ($)
- you you need to recharge them
- but you want to do it faster
- so you get some AGM batteries that accept a higher charge ($$)
- now you can have a larger alternator ($$) with a good external regulator ($$) and a serpentine belt kit ($$$)
- and you need larger cabling ($)
- and you need to cool the alternator so you need a fan system ($$)

so that's $$$$$$$$$$$$$

BUT

In real use you rarely run down your batteries low enough to get that $$$$$$$$$$$$$ out of the full system so use $$$$ of the system.

So for the most part what's the point of spending the money on a large charging system that you don't really get to fully use?

[a64pilot]

Stu,
I was initially very suspicious when I saw that the same sized alternator was available from 70 to 200 amps.
Early in my career as a Welder I learned what duty cycle meant when I saw a fellow welder's windings melt.
Now if you have ever seen a Lincoln pipeline welder, it's a big, heavy thing, is a 225 amp machine at I think 24VDC or so, don't quote me on volts, I never measured it.
Anyway I pick up one of these small frame alternators that will make 200 amps? I'm thinking "remember duty cycle" . I can't believe that big old monster Lincoln would make just a little more than twice what this thing I'm holding in my hand and is driven by a belt will?


Now what I'm thinking is that two nearly identical items as far as mass and cooling systems are laying on the table, power output is based on cooling, and somebody is telling me that one will produce twice the power of the other?
I'm thinking, Wow, twice the power, same heat? Must be a really efficient thing then, to produce twice the power and no more heat.
Remember duty cycle

Now about the same time I got my 140 amp alternator I got suspicious of all this and wanted a way to monitor power output as I'm the curious type, so I installed a Blue Seas shunt and meter on the output side of the alternator

[Jd1]

Originally Posted by a64pilot

If by spill the beans, you mean what Mark said, I'd have to say call him as I did not get specifics, and don't want to start rumors, and he is just too easy to get on the phone.

I agree on temps myself, one of my projects is to run a bilge blower from the lower part of my bilge to the backside of my alternator with the idea of cooling it.

Removing the Diode pack as Maine Sail is doing would be I believe far more effective as it's my understanding they generate an appreciable amount of heat.

Too bad you didn't get details

I don't want to mess with removing the diode pack but it could become an option in the long run. A more efficient blower and a hole for cooling air are easier to do then messing with the alternator itself.

[a64pilot]

Saliorboy, I have two 120VAC chargers, one 60 amp and one 125 amp.
When I'm on generator or shorepower, the AGM batteries will accept the combined total of 185 amps, for quite awhile, So I have use for a big charging system.
Plus, if I'm motoring, often that means little to no wind, and often it's hot.
With a 2800W inverter, I can run the front AC and my wife can lay down in airconditioned comfort, why not I'm running the engine anyway, but the AC if you assume 0 losses in conversion, pulls 60 amps of DC current, so I need 60 continuously, just to keep up.
Average current draw on my boat is around 10 amps DC, so add that 10 to the 60 and I'm at 70, and not charging anything.
So yes, I do at times have use for rather more power than I believe any small frame alternator can make

[sailorboy1]

[QUOTE=a64pilot;2089409
So yes, I do at times have use for rather more power than I believe any small frame alternator can make[/QUOTE]

We all find ways to talk ourselves into whatever choice we spend money on. The question is whether "at times" above equals 13 $ signs.

Don't get me wrong, just like in what type of boat people like, it doesn't really matter to me what they decide to spend their money on.

[aluijten]

For the 24 Volt people amongst us, Bosch seems to have improved quality alternators https://www.boschautoparts.com/en/co...ul-alternators

Not sure if they have these also for 12 Volt

[a64pilot]

No, you were questioning why would anyone need more DC generating power than you have.
I gave you a reason, you didn't like it is all.
I'll give you another, I don't yet, but will have a high output watermaker when we go as I want to spend the money I guess
Anyway with a big alternator assuming it makes good power, I will be able to make make water when the generator breaks, cause everything breaks.


Sent from my iPad Pro using Cruisers Sailing Forum

[aluijten]

Saw this page
Alternators HD-H: Hot Environment - Bosch I-Business

These are alternators specifically for hot environments. As you can see an ambient temperature of 85C reduces the expected lifetime significantly compared to an ambient temperature of 65C. I'm not sure what kind of loads are used in these measurements but its clear to me temperature affects the expected lifetime quite a bit

[Dockhead]

It's asking a lot of a small frame alternator, no matter how its regulated, to produce the kind of bulk power we need.

I realize not everyone can fit it in, but a large frame heavy duty alternator is much better suited to this purpose -- because they are designed to dissipate all the heat produced at their maximum rated power, without overheating. Because they are specifically made for bulk power production, rather than the kind of duty they get as a car alternator.

Such alternators are not even that expensive. But the brackets and new pulleys to fit them might be.

[Dockhead]

Originally Posted by a64pilot

No, you were questioning why would anyone need more DC generating power than you have.
I gave you a reason, you didn't like it is all.
I'll give you another, I don't yet, but will have a high output watermaker when we go as I want to spend the money I guess
Anyway with a big alternator assuming it makes good power, I will be able to make make water when the generator breaks, cause everything breaks.

You need a big alternator to charge a big battery bank. And here "big" is really anything more than one, which is what car alternators are designed for.

If you have a good inverter on board, you can run the whole ship off the alternator, so that it's like having shore power, when you're motoring. I even run my washer/dryer off the alternator. This is really useful especially in very calm weather, when it's possible to do different things on board, motoring in a calm, as if you were docked.

As A64 says, this is also very good backup to a generator.

[SvLetitgo]

To get back on the original subject, we had the same experience with the company. And we finally got rid of them after too many wild chase

Electromaax it will be for the alternator. – SV Letitgo