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Old 25-07-2016, 17:33   #16
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Re: Alternator Choice Advice

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Do you have a view on what safe operating temperatures are for normal alternators? I see alternators rated for different ambient temperatures, but nothing about winding or core temperatures.

I have started monitoring the core temperature of my large frame alternator, and have been surprised to see that the core is much hotter than the case -- I see 120C at full output when the case is almost room temperature.

Sorry, a bit off topic, but maybe relevant.
No I do not. I have my MC614 set to limit at 100C. As you noted, core temperature is quite different from the temperature where the sensor is located so I tend to be a bit on the conservative side. Only the manufacturer would be able to give you more details and even then it is just a guess. Since the temperature measuring point is on the outside of the frame, the temperature gradient to the core depends on air flow and ambient temperature.
I would GUESS that 155C would be an average rated insulation varnish but I know for a fact that when measuring 100C by the temperature sender I had somewhere around 130C at the outside of the core and who knows what on the inside.
Insulation temperature rating goes by classes and the highest class is 180C and above.
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Old 25-07-2016, 17:56   #17
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Re: Alternator Choice Advice

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I went to the Prestolite website and it's not exactly the easiest thing to navigate. I don't know their alternator models which are which so I will do some more looking into that tonight.
Call ASE Supply, talk to Bob, there are actually TWO Bob's, both very nice. One of the neat things they do is say: "Here's our phone price, but order on the website for 15% LESS." So, why not?
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Old 26-07-2016, 01:32   #18
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Re: Alternator Choice Advice

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Originally Posted by Jd1 View Post
No I do not. I have my MC614 set to limit at 100C. As you noted, core temperature is quite different from the temperature where the sensor is located so I tend to be a bit on the conservative side. Only the manufacturer would be able to give you more details and even then it is just a guess. Since the temperature measuring point is on the outside of the frame, the temperature gradient to the core depends on air flow and ambient temperature.
I would GUESS that 155C would be an average rated insulation varnish but I know for a fact that when measuring 100C by the temperature sender I had somewhere around 130C at the outside of the core and who knows what on the inside.
Insulation temperature rating goes by classes and the highest class is 180C and above.
Thanks, that's all very interesting.

Do you think temperature limit is related to insulation? Or bearings?
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Old 26-07-2016, 02:23   #19
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Re: Alternator Choice Advice

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Do you think temperature limit is related to insulation? Or bearings?
Insulation.
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Old 26-07-2016, 02:38   #20
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Re: Alternator Choice Advice

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Insulation.
OK. Leece Neville alternators are rated for 110C -- ambient temperature. So I don't even know what kind of internal temperature you would have if the engine room is that hot. I would guess that we must have a good bit of reserve capacity there, since a yacht engine room would not normally see more than 40 or 50 degrees.

Another good thing about heavy duty alternators is that when they do get hot, they are typically regulated in a way which does not just shut them down, like car type alternators.

This is what LN say about it:

"'These units are true high temperature alternators approved for extreme applications, and will not falter at maximum rated temperatures.' Beirne explains. 'There are competitive alternators in the marketplace that claim to be high temperature, but that claim is achieved by clamping down the alternator output when the unit gets hot. In effect, those alternators crawl into a shell to protect themselves when the going gets tough. Our philosophy has been that the alternator should always try its best to supply the system with as much power as it can, even when it gets hot. We donít believe that putting our alternators into a self-protect mode, while allowing the rest of the electrical system to fail, is in the best interest of the customer.'"

http://news.prestolite.com/220-245-high-amp-altenators
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Old 26-07-2016, 06:26   #21
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Re: Alternator Choice Advice

Keep in mind that all this is advertising talk which tells you precisely nothing. Kinda reminds me of the famous "Sears horse power" .... which was the instantaneous power output of a tool/appliance at the instant it blew up.
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Old 26-07-2016, 06:35   #22
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Re: Alternator Choice Advice

Still you have to look at a product that is half the size and one third the weight of the old standard, yet is claimed to produce more power and be a little suspect.
Marketing, you know I was going to go into marketing, but when they found out my Parents were Married to each other, I was disallowed
You know you can now buy an Automotive Stereo amplifier that claims an output power of 1000W, yet has a 10 amp fuse? I guess this thing makes electricity?
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Old 26-07-2016, 06:40   #23
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Re: Alternator Choice Advice

Eco-Tech

I know Im the only one here that has one , and have mentioned this Eco-Tech before , but when you look at the prices of some of these big alternators and what you get the Eco-Tech shines .

My batteries love this alternator .

Eco-Tech Alternators | Oustanding Alternator Performance



Look at the RPM on this alternator , I have mine running at 1800 RPM and get a steady 200amps when fully hot .
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Old 26-07-2016, 06:48   #24
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Re: Alternator Choice Advice

And my Install.

Look at the amps at startup. , when it gets hot it still pumps 200 amps



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Old 26-07-2016, 06:50   #25
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Re: Alternator Choice Advice

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Keep in mind that all this is advertising talk which tells you precisely nothing. Kinda reminds me of the famous "Sears horse power" .... which was the instantaneous power output of a tool/appliance at the instant it blew up.
It's definitely advertising talk, so has to be taken with a grain of salt, but there are chunks of facts in there, which I doubt they're lying about.

For example, the approach to dealing with a high temperature condition -- shut the alternator down, or regulate the output to keep it putting out something.

Advertising talk is also useful, despite the spin, for knowing what the aspirations of the company are.
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Old 26-07-2016, 07:00   #26
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Re: Alternator Choice Advice

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Eco-Tech

I know Im the only one here they has one , and have mentioned this Eco-Tech before , but when you look at the prices of some of these big alternators and what you get the Eco-Tech shines .

. . .
That's a very cool alternator. From what I've heard, these are actually the best you can buy. And for the particular situation of LiFePo batteries, which have almost unlimited acceptance rates and so will greedily suck full power out of an alternator for extended periods of time, that's probably the right alternator for this application despite the high cost.

I am working up the specification for a new boat, and seriously thought about those alternators. So far, though, I'm planning to stick to LN because they are so much cheaper and easier to repair -- repairability in a third-world auto electric shop is part of my design brief.

But if I end up with LiFePo batteries -- which will happen if there's enough progress in development of these systems by then -- that solution won't work, and probably Echo Tech will be the thing.


That's a very, very slick installation, by the way. Did you build the generator yourself? If so, did you post details about the design and build? I'd love to read more about it.
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Old 26-07-2016, 07:11   #27
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Re: Alternator Choice Advice

Hey Dockhead ,

Thanks . Yes I did . A little bit of a long read and the original design was with lead acid batteries. Changing to Lithium was the best thing I ever did .

DC Generator - The Smart Way to Go

There are more photos and information in my profile pages of my setup as well.



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Old 26-07-2016, 07:13   #28
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Re: Alternator Choice Advice

Funny thing , the little alternator on the generator is not connected to any thing , its just used to tighten the belt for the water pump, same on my main engine . LOL

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Old 26-07-2016, 07:59   #29
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Re: Alternator Choice Advice

As others have said, with a 540 amp hour LiFePO4 bank, it would be a shame to pass up a large case alternator when your engine has the mounts for it. You can pick up a 300 amp large case alt, down regulate it to 200 amps with the MC-614, and it will pump those 200 amps all day long. Cheaper and more powerful than a small case alt. How can things get better than that? Plus, you can keep your old alt to power the tach (the large case can do this, but you'd need to recalibrate) and charge a starting lead acid (less necessary with a well designed LiFePO4 bank, but some still like the safety blanket).

To toss out another brand, take a look at Zena, who makes welding alternators. They claim the alts can output their full rated amps for the entire time (ie, up to 300 or 400 amps). However, you'd probably still want to down regulate them to save your belts and your engine might not be happy with 10+ hp being sucked from the crank's side. Note, the ABYC won't be excited about these alts because I don't think they are ignition protected as they aren't built specifically for marine applications. I haven't actually called to ask, so it is worth confirming.
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Old 26-07-2016, 08:27   #30
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Re: Alternator Choice Advice

I'm sold.

Can someone help me choose a Leece-Neville alternator for my Westerbeke 55B-Four?

I've got 600aH of AGMs, 12 volt system.

I like Dockhead's reasoning for dual alternators, but with my Seafrost compressor/etc on the stbd side, I just don't have the room in that engine compartment. I'm pretty sure I'll have to remove the existing alternator to make some room for the big new one.

I imagine I'll need to come up with a custom mounting strategy much like how my Seafrost mounts... (in that case, gusseted angle iron bolted somehow to the engine block.)
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