Alternator cooling

[exMaggieDrum]

This has been a very informative and helpful thread. It supports my own experience and expectations with alternators and heat. I had considered putting in additional air cooling in to the engine room but it looks like it will not necessarily help increase the alternator output very much. Too much heat is not good in a closed space though for other reasons so I may do it for that.

Re any additional concern about increased fire danger from more air from fans, it would be possible to wire up a shut down relay circuit to turn off the fans with a fire/heat detector in the engine space. But not a smoke detector as I believe there are too many false alarms with those in engine spaces. I am sure there is a heat sensor of some sort available that would work for high temps above the usual in the space.

Re thermostats, while I am not diesel expert I have been told that the purpose and function of engine thermostats is to allow engines to come up to normal engine temp quicker and that they have nothing to do with the regulation of engine heat after the engines get up to that range. I believe that they are closed when cold and open when the internal coolant reaches their rated temp.

[a64pilot]

Thermostat of course determines operating temperature of the cooling system.
You oversize a cooling system during design so that there is excess capacity to cover other than ideal conditions, so without a thermostat an engine will not hit operating temps, plus temp would vary greatly with load, environmental temps etc.,thermostat is required to maintain a steady temp with varying conditions.

Unless there is an unusual reason to do so, I would not run a thermostat other than factory recommended temp.
I don't know why, but Yanmar specs are for a 165F thermostat for my engine, seem too cool, but they had a reason.


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[a64pilot]

There are both overheat detectors and visible flame detectors for fire detection.
My Zeus touch has provisions for two video cameras, I ordered a cheap very wide angle one from EBay to try, and I have a very good Sony "lipstick" camera with different lenses.
I figure it might be worthwhile to see the engine compt, and the capability is there, why not?
I plan on putting the second camera looking at my packing gland, will probably have to have some cheap LEDs wired to the current blower power that come on with ignition power.


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[guyfromiowa]

Shall we look in a different direction? Bosch has been supplying antifreeze-cooled alternators since about 1999. If you can build the mounting bracketry and connect the coolant piping this looks like a good possibility.

BMW 540i Alternator - Car Alternators - Pure Energy USA Industries Bosch - 2000 1999 2001 2002 2003 1998 1997 1994 00 99 01 02 03 98 97 94 - PartsGeek.com

BTW-many of these installations use an overrunning alternator drive system to smooth out the belt vibrations.

Guy

[Jd1]

Originally Posted by exMaggieDrum

Re thermostats, while I am not diesel expert I have been told that the purpose and function of engine thermostats is to allow engines to come up to normal engine temp quicker and that they have nothing to do with the regulation of engine heat after the engines get up to that range. I believe that they are closed when cold and open when the internal coolant reaches their rated temp.

Incorrect. They start out as closed and then oscillate and possibly find a happy place where they are partially open. Of course if you run the engine wide open it might stay open depending on how effective your radiator is.

[Dockhead]

Originally Posted by guyfromiowa

Shall we look in a different direction? Bosch has been supplying antifreeze-cooled alternators since about 1999. If you can build the mounting bracketry and connect the coolant piping this looks like a good possibility.

BMW 540i Alternator - Car Alternators - Pure Energy USA Industries Bosch - 2000 1999 2001 2002 2003 1998 1997 1994 00 99 01 02 03 98 97 94 - PartsGeek.com

BTW-many of these installations use an overrunning alternator drive system to smooth out the belt vibrations.

Guy

Don't use that one!

I've replaced the one in my Range Rover twice, at about $2000 a pop.

Not reliable.

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[guyfromiowa]

Did you use 'Range Rover' and 'expensive' and 'not reliable' in the same paragraph? Shocked. Shocked, I am!

That's just one example of a liquid-cooled alternator. Many manufacturers have use them. You can find them on any walk through a late-model salvage yard, but you would probably pay more than buying one on-line. The last one of these that I worked with came from a Cadillac. We build mock-ups of the front plate and brackets out of plywood, cut the aluminum parts using a router and the plywood parts as templates. We plumbed the cooling antifreeze into the return side of the cooling loop. Electrically, that one was easy to connect to an external regulator. YMMV

Guy

[Dockhead]

Originally Posted by guyfromiowa

Did you use 'Range Rover' and 'expensive' and 'not reliable' in the same paragraph? Shocked. Shocked, I am!

That's just one example of a liquid-cooled alternator. Many manufacturers have use them. You can find them on any walk through a late-model salvage yard, but you would probably pay more than buying one on-line. The last one of these that I worked with came from a Cadillac. We build mock-ups of the front plate and brackets out of plywood, cut the aluminum parts using a router and the plywood parts as templates. We plumbed the cooling antifreeze into the return side of the cooling loop. Electrically, that one was easy to connect to an external regulator. YMMV

Guy

I said "that one" because I meant that particular alternator, not all water cooled ones. My Range has the BMW engine.

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[exMaggieDrum]

Originally Posted by Jd1

Incorrect. They start out as closed and then oscillate and possibly find a happy place where they are partially open. Of course if you run the engine wide open it might stay open depending on how effective your radiator is.

I think we (including a64pilot) are on the same page. My comment was that a thermostat would not prevent an engine from overheating above the rating of the thermostat, which is specific to an engine. Putting a 230 degree thermostat might allow the engine to reach that high but can't prevent it from exceeding a higher temp unless the cooling system can handle it. And that was what is needed to keep the local environment cooler. Of course, if the engine temp was fluctuating around both sides of the thermostat rating, then it would open and close to try to maintain a hot enough engine, but cannot do anything to keep the engine from overheating beyond full open.

[ErikFinn]

Originally Posted by Maine Sail

...The only way to get even close to continuous duty with a small frame alt is to rip the diode rack out and do remote rectification and even then you may not get full output for as long as you'd think..

I run a custom built 160A alt at 115A - 120A and even then I am pushing 230F and it occasionally still dips into temp compensation above and beyond belt manager. I am currently ripping the diode rack out & converting it to external rectification....

Maine Sail,
did you complete the "ripping the diode rack out & converting it to external rectification"?
If you did, how has it worked for you?
Thanks,
Erik

[wsmurdoch]

Originally Posted by ErikFinn

"ripping the diode rack out & converting it to external rectification"

In the years since this thread was current, I ran across kits to convert a normal alternator to an external rectifier alternator. https://alternatorparts.com/quicktif...rectifier.html

I also ran across this pdf of alternative rear covers for alternators http://www.metroautoinc.com/PDF%20Fi...20Domestic.pdf . My alternator is actually a GM CS130D with the field lead brought out. I considered buying the far more "porous" 46-14067 cover (p.5) to increase the rear airflow but instead had a local alternator shop order me ($6 and next day delivery) a 46-14012 (p.4) which was used on '98-'02 Cameros and Firebirds that had fresh air ducted to the back (diode end) of their alternators. I plan to use a 3" bilge blower reduced to 2" to blow bilge air into the rear of my alternator in an attempt to cool it.

[boatpoker]

Originally Posted by Maine Sail

Bingo.. While cooling will certainly help it is not the savior..

The problem is that all these alternators are rated based on automotive test criteria not a constant duty rating. Yes when the alt is hot it may produce 195A at 6000 RPM and 90C but that is just a measurement at 90C and fails to tell us for how long.....

There is no small case alternator on the planet rated at constant duty. The only way to get even close to continuous duty with a small frame alt is to rip the diode rack out and do remote rectification and even then you may not get full output for as long as you'd think..

I run a custom built 160A alt at 115A - 120A and even then I am pushing 230F and it occasionally still dips into temp compensation above and beyond belt manager. I am currently ripping the diode rack out & converting it to external rectification.... I see if that works because I can't fit a 98 series, APS or an Electrodyne...

The reality is these alts can spin at up to 17,000 RPM and we spin them at a paltry 4 - 4.5k at best. The demand for low RPM high output characteristics has led to even more issues.

Expecting the face value rating from any alternator driving LFP is really not going to happen for very long.... A big J180 type large frame brushless alt, or an Electrodyne, or even small frame with external rectification will perform much better but still bake the crap out of a small engine space.

The C-36 is a horribly tight engine box, I owned one, that really needs both input & output fans for that type of current...

Are you suggesting a larger diameter pulley might help ?

[ErikFinn]

Originally Posted by wsmurdoch

In the years since this thread was current, I ran across kits to convert a normal alternator to an external rectifier alternator. https://alternatorparts.com/quicktif...rectifier.html

I also ran across this pdf of alternative rear covers for alternators http://www.metroautoinc.com/PDF%20Fi...20Domestic.pdf . My alternator is actually a GM CS130D with the field lead brought out. I considered buying the far more "porous" 46-14067 cover (p.5) to increase the rear airflow but instead had a local alternator shop order me ($6 and next day delivery) a 46-14012 (p.4) which was used on '98-'02 Cameros and Firebirds that had fresh air ducted to the back (diode end) of their alternators. I plan to use a 3" bilge blower reduced to 2" to blow bilge air into the rear of my alternator in an attempt to cool it.

Thanks for your kind reply wsmurdoch. I am aware of the quicktifier but other than his website there is not much user experience to be found, and his video has some varied comments. The cover link was interesting, thank you for that, I read here we have one member who bought a Bosch 115a alt that had a similar integrated metal duct, but if that duct is available separately then it makes it a lot easier to build a blower system.

But the reason for me posting on this thread was to ask Maine Sail about his intention to remove the rectifier from internal to external and I would be very interested to hear his thoughts, as the few comments I found on this forum were not so much in agreement with each other.

[a64pilot]

I believe that most of us are turning our alternators slower than they can handle, higher speeds result in more cooling from faster fans, and less heat due to lower field current required to achieve the same output.
My bet is that a larger crankshaft pulley and or a small alternator pulley would help.

However we are still asking a boy to do a man’s job. If you look under the hood of a Military Humvee or truck, you will find a huge, heavy alternator. That is what it takes in my opinion to make continuous high output.
Sucks cause I can’t put a large frame in my boat, not without way more modification than I want to do, so I went with lots of Solar and a built in generator.
My 3.5 KW genset can run 185 amps of chargers continuously, but it works its guts out, to get even close to 200 out of something as tiny as a little alternator is a feat of magic.

[smac999]

Something to keep in mind is the airflow direction. I think balmars blow back to front. So you don't want a fan in front blowing in.