Is there such thing as goin tooooo big on my alternator upgrade?

[Eastward ho 24]

I have a yanmar 3gm30f. I will be getting a belt kit and high output alternator with a 300ah lithium bank this week. in the future I plan to add one more 100ah to give me 360ah useable ( if need be).I’m looking at a gen maax 215amp alternator. This I plan to run at full load at anchor to recharge and. Reduce it 50% or more under power. I guess it’s all a matter of personal preference as to how much hp. Your ok with the alternator robbing? Electromaax gen max 215 with external regulator that’s highly programmable. My concern is from what I’ve read lifepo4 will take all the charge it can get leaving you with a situation where your alternator will be running wide open most of the time and I believe this will wear it out sooner. So with the 215 and the external regulator I can program the 215 to run at say 165. This way when it’s running “wide” open it’s not really killing it. Then to further this there is a 50% reduction switch so I can have it at 80amps giving me more hp when under power. I’m no electrical guru. But this gen max is shown to run at full amps at 1000 engine rpm. Seems like a very nice unit and when paired with their regulator I don’t think it can be beat. I’ve read the horror stories with the company. I’ve been back and fourth with them for about a month and I can only say it’s the best coustomer service I’ve ever recieved. I can’t say enough good things about mr. s thus far. Does any one have a 3gm30f with a big alternator? What is the biggest I can go, is there such a thing as too big? I must confess I have 90 gallon fuel tank on my 32footer so I don’t mind running the motor. But I don’t want to slow her down too much. It’s my understanding that unlike the agms and lead which only take a percentage of recharge then a float. The lithium’s take what ever you give them up until the bms says enough? So my logic is this huge alternator will charge up the bank in very short time. And with a big old 215amp I can run an inverter as the motors running and it’ll pretty much be a generator.

[a64pilot]

Well first and this is just an opinion, but before you buy anything Electromaxx, you need to do some searching to decide.
Based on others experience I have decided to not buy anything either Xantrex or Electromaxx.
I do not have personal experience so consider that an unsubstantiated rumor or hearsay, cause it is.

But back to alternator size, it seems that a small case alternator’s continuous output is dependent on heat and not how much power they can produce, in my installation and comfort level of heat I can only get about 90 amps continuously, and that’s at cruise RPM of 1800. Lower RPM and it’s less.

The mass and cooling fans of the different rated alternators are the same or very close, so I believe their cooling ability to be about the same, so I believe that around 150 amp size is about your best bang for the buck, above that and your paying for output that you can’t use.
I’d be surprised if you could get much more than 100 amps continuously without removing diodes or adding cooling somehow or really pushing high temps. I have mine set very conservatively at 90C as I believe that will give it a real long life, and I don’t consider the alternator a primary charge source, but your foolish not to take advantage of one if your motoring anyway.

My opinion look at a Mark Grasser or Balmar kit.

When you install your temp sensor install it on the right side of the alternator if you sitting behind the alternator with its pulley furthest away from you, thats the “hot” side as the diodes are located close to there, the other side runs cooler.

[a64pilot]

If you really want to be able to turn your motor into a generator, be prepared to spend some $$$. It can be done, but not with a small frame alternator, there just isn’t enough cooling in one.
Small frame alts are like a racing motorcycle engines, yes it can make huge amounts of power, in short bursts, try it for long and it will blow. No one is lying, they can make that kind of power, just can’t sustain it.

[tkeithlu]

Love the Balmar system. Programmable to my battery bank, ever faithful. I went through a bunch of alternators learning the hard way that "Oh, I want 60 amps, here's a 60 amp alternator" is not a logical statement. Any alternator run at capacity is run without the tiny "offs" supplied by the voltage regulator, and those are what keeps it from overheating. If you want sophisticated charging, that is charging from your alternator that mimics your sophisticated battery charger, buy the right sized sophisticated alternator. That's a logical statement.

I do run two super-simply single-wire generic Delco alternators for the start batteries for the engine and the genset, but guess what? Those batteries last three years, just like on your car, and the house batteries are going well at six.

Good luck with it.

[Frankly]

I have been running a small case 100 Amp Balmar (1/2 " V belt, 612 regulator, feeding 600 AH flooded LA) for almost 15 years. If the bank is down significantly, the Alternator case will hit 190 F in about 20 minutes. Unless you can come up with a way of introducing some cooling air directly to the alternator, I don't think you will operate at anything near the rated output.

I added a small engine mode switch years back, everybody is happy operating at that level. Looking back it was a lot of money for a small increase over factory std charging. But it has all played together very well ( one set of brushes and bearings about 3 years back).

Most propping loads are well below rated engine output except at max RPM, so you are probably not going to overload the Yanmar under normal operations.

Frankly

[Eastward ho 24]

This may sound silly but does the serpentine belt conversion have anything to do with heat or efficiency?

[Eastward ho 24]

P. S. Has anyone seen the video of the electromaax?

https://youtu.be/PxGnetDZB50

I guess that's cold rating is that the catch here?

[mlydon]

I recommend you go to marinehowto.com and read his treatise on alternators. All your questions will be answered there......

Matt

[Eastward ho 24]

After reading frankly after 20mins your alt is up in temp...
I saw this and at first didn't like the idea of the cycling.

https://battlebornbatteries.com/shop...ation-manager/

Do you think this would keep your alt running cooler thus higher output?

[Dsanduril]

One factor to consider is the overhung load you will be adding. I guess because these additions have become more popular Yanmar publishes a very clear guide for the 3YM30, I’m not aware of one for the GM.

For the YM max power takeoff with 30mm overhang is 1.5kW at idle up to 4.4kW at 3600 rpm. Your proposed Electromaax is ~3kW, which could get you into that range depending on rpm. And that’s engine load, remember to account for anything else on the same shaft/bearing and for inefficiency.

Don’t know how similar the GM is in this regard, but at least seems like you’d be approaching “toooo big”.

[a64pilot]

Originally Posted by Eastward ho 24

This may sound silly but does the serpentine belt conversion have anything to do with heat or efficiency?

Not unless the V belt is slipping, then it can greatly. A slipping belt generates a lot of heat, and heat takes enormous amounts of power to generate, so there goes efficiency, then the slipping occurs on the alternator’s pulley, so a huge amount of heat is dumped into that pulley and of course the alternator, so now you have the heat the alternator makes making electricity, plus the heat from the friction to get rid of, and sometimes it’s just too much, and often it’s the alternator bearings that go out as the heat from the pulley is dumped pretty much straight into them.

Most consider about 80 amps to be about the max you can get out of a single V belt, and that’s pushing it pretty hard.

[Frankly]

Couple of years back I bought a $15 temperature controller off ebay ( been using one for years to monitor frig temp). Just connected the controller relay output in parallel with the small engine mode switch. When the SEM switch is closed then the alternator output is half. If I open the SEM switch the eBay controller takes over. Although the alternator is rated for operation in low 200s, not sure where temp spec is measured. But it will maintain the case temp between 170 and 190 just switching between full and half output.

What is real obvious, removing the engine cover and the temp heads south pretty quickly. Thought about ducting some outside air to the alternator, just never got around to it.


Frankly

[Eastward ho 24]

Marinehowto's article is a true wealth of information, it has sent me back to the drawing board unfortunately! Now it seems to me making a bracket to fit the

https://shop.marinehowto.com/products/cmi-200a-large-frame-j180-mount-extreme-duty-alternator

Seems the proper thing to do and it's actually cheaper! Anyone have a bracket or experience with this?

[Eastward ho 24]

If my reading comprehension is correct. According to marinehowtos article a small frame alternator is severely limited and I won’t see the Bennifits of super fast recharge of lifepo4 with a small frame alternator to the full extent unless I’m cooling it somehow?

[a64pilot]

Originally Posted by Eastward ho 24

If my reading comprehension is correct. According to marinehowtos article a small frame alternator is severely limited and I won’t see the Bennifits of super fast recharge of lifepo4 with a small frame alternator to the full extent unless I’m cooling it somehow?

Even then your unlikely to get close to it’s ma x output continuously. You can remove the diodes and remote mount them $$, helps, and maybe a bilge blower blowing into the back of one may help.
There are two fans, one in front and one in the back, they both suck in and blow out the middle.
The rear of the alternator is the hottest.

However to really get a lot of power, your way better off buying an alternator that is made to produce power continuously, that one Maine Sail has is an example, and there are “school bus” alternators also.
The problem is they are usually quite large, larger than will usually fit inside the engine compt.
So many of us are stuck with small frame alternators due to mounting constraints.

However as opposed to trying to turn your main engine into a generator, it may be better to use a generator, as a generator.