Alternator Cooling

[CaptainRivet]

Originally Posted by hjohnson

Are they now? Coolant cooled alternators are somewhat common in the OEM automotive market. Volvo, BMW, and a few other manufacturers use them. It would basically mean plumbing the coolant loop through the alternator. The tough part is the tight confines as the alternator seems to be right next to where the heat exchanger and liquid cooled manifold are located.

High end models so we talk about big v6/v8 or even 12 cylinder engines with min 6 times the hp then your leisure marine engine.
Then these engine have a already a sweet water colant system that already cooled down by radiators.
Marine engine has salt water cooling system with a heat exchanger but no radiatorsband no wind that cools down the radiator of the car when driving.

In marine max self cooling capability with a high temp operating capability is the key to get an economical and high current delivery (school bus or cooling truck alternator principle) with moving away the rectrifier from alternator to optimize cooling. That gets you to around 2300W max per alternator and 2700W of heat means around 5kw in total for small case alternators. With 24V 2700W and 2300W heat and finally 48V less heat and more output, around 3500W and 1500W heat.
Thats also limit for the bearings plus cost you approx 8-10hp of your engine.

[sailingharry]

Originally Posted by hjohnson

Are they now? Coolant cooled alternators are somewhat common in the OEM automotive market. Volvo, BMW, and a few other manufacturers use them. It would basically mean plumbing the coolant loop through the alternator. The tough part is the tight confines as the alternator seems to be right next to where the heat exchanger and liquid cooled manifold are located.

And I think you may be alluding to what I see as the big drawback to coolant cooled alternators -- using coolant! I think the coolant circulating in my engine is right around 185F. Is "cooling" an alternator with 185F water an improvement? Yes, it really pulls it down (good heat transfer/flow), but it has a floor of "very hot." The coolant cooled alternator starts off with no load at 185, and goes up as it gets loaded. Yes, typical alternators run closer to 250F, so it may still be a bonus.

[hjohnson]

Originally Posted by sailingharry

And I think you may be alluding to what I see as the big drawback to coolant cooled alternators -- using coolant! I think the coolant circulating in my engine is right around 185F. Is "cooling" an alternator with 185F water an improvement? Yes, it really pulls it down (good heat transfer/flow), but it has a floor of "very hot." The coolant cooled alternator starts off with no load at 185, and goes up as it gets loaded. Yes, typical alternators run closer to 250F, so it may still be a bonus.

At least on my car, the coolant temperature sits right at 90C once the car warms up. I would imagine the coolant loop on a marine engine would be similar.

Coincidentally, the max temperature for most alternators is also 90C, but that’s also the max case temperature, as it’s impractical to install the temperature sensor internally in most cases. Certain components will certainly be hotter.

The real question is whether the heat exchanger is sufficient to accommodate the additional thermal load of the alternator. I suspect you could get away with it in cold waters like the Salish Sea or the Great Lakes, but you’d probably be breaking the limits in the Med or Caribbean.

The cooling solution would need to be engineered for the whole system.

The thing we’ve considered (given that our current engine is raw water cooled anyway) is removing the rectifier from our alternator and mounting it off-board with forced ventilation. Having that extra bit of heat blowing into our cabin would actually be appreciated 8 months out of the year.

[Dan Kimblad]

Originally Posted by hjohnson

At least on my car, the coolant temperature sits right at 90C once the car warms up. I would imagine the coolant loop on a marine engine would be similar.

Coincidentally, the max temperature for most alternators is also 90C, but that’s also the max case temperature, as it’s impractical to install the temperature sensor internally in most cases. Certain components will certainly be hotter.

The real question is whether the heat exchanger is sufficient to accommodate the additional thermal load of the alternator. I suspect you could get away with it in cold waters like the Salish Sea or the Great Lakes, but you’d probably be breaking the limits in the Med or Caribbean.

The cooling solution would need to be engineered for the whole system.

The thing we’ve considered (given that our current engine is raw water cooled anyway) is removing the rectifier from our alternator and mounting it off-board with forced ventilation. Having that extra bit of heat blowing into our cabin would actually be appreciated 8 months out of the year.

The bennefit to cool down the alt with the engines cooling system is the low effeincy of the alt. When you start your car when its freezing cool the alt will warm up the water that go directly to the heat inside the car to defrost. Smart, but when we have running temp 90C it will not cool down the alt. None car manufacture use this system today. It was to much problem.

Heat exchanger in the Meds or Caribbean. No problem. The delta T is about 20C (I have measured it) If we have 30C in the sea then the alt will be 50C
I have not tested a longer heatexchanger but certainly that will reduce the temp. But I dont now yeat how much more amp I will get. I have to try this in my test bench to simulate different temperature on the cooling water. Then we have the answer and not guessing

https://youtu.be/9CrBNP1dqzs
Kimpower РGeneratorer f̦r b̴tar

[Dan Kimblad]

Originally Posted by hjohnson

Are they now? Coolant cooled alternators are somewhat common in the OEM automotive market. Volvo, BMW, and a few other manufacturers use them. It would basically mean plumbing the coolant loop through the alternator. The tough part is the tight confines as the alternator seems to be right next to where the heat exchanger and liquid cooled manifold are located.

What I know have Volvo not used a water cooled alt, but MB and the VW family.
Plumping throw the alt is not a good idea. To warm "cooling" element this.
The alt will not be cooled down by 90C. You will have exremly nice figure of the output amp for some minutes and after a while you will be disapointed.
Trust me. Developing my sytem now for five years. Have a own test bench for the alt and 500Ah LFP as load in my workshop.

[Dan Kimblad]

Coolest part you will find with a heat camera is my water cooled alternator!!!
Porsche last air cooled engine was modell 993 year 1998. That was 26 years ago.
I have noticed a significant cooler engine compartment after that I removed my less performance GenMaax to a water cooled alt that produce double of Amp.

[Dockhead]

Originally Posted by sailingharry

And I think you may be alluding to what I see as the big drawback to coolant cooled alternators -- using coolant! I think the coolant circulating in my engine is right around 185F. Is "cooling" an alternator with 185F water an improvement? Yes, it really pulls it down (good heat transfer/flow), but it has a floor of "very hot." The coolant cooled alternator starts off with no load at 185, and goes up as it gets loaded. Yes, typical alternators run closer to 250F, so it may still be a bonus.

Maintaining the alternator at a constant 90C would be fine. That's not "hot" for the components of any alternator.

But this is a theoretical discussion only. I had a few cars with the liquid-cooled BMW alternators (a 540i 6 speed; a Range Rover) and replaced a couple of them for many thousands each. I wouldn't have one of those on a boat on a bet.

Water-cooled alternators are a solution looking for a problem which does not actually exist. There are air-cooled alternators which are actually designed for producing their rated power continuously -- school bus, large case, hot-rated alternators. They cost a few hundred each, can be repaired in any third world auto-electric shop. These can crank out a couple of kW day in and day out without breaking a sweat.

The problem is not air-cooling. The problem is cruisers trying to produce bulk power out of alternators not designed for the purpose. Small-case car type alternators -- the kind which come standard on most boat diesels -- are designed to produce tiny amounts of power needed to support the engine electric systems, and recharge a starter battery which was discharged by 0.1% on the last start. They are simply not fit for the purpose of producing bulk power for domestic needs.

[Dan Kimblad]

Originally Posted by Dockhead

Maintaining the alternator at a constant 90C would be fine. That's not "hot" for the components of any alternator.. I had a few cars with the liquid-cooled BMW alternators (a 540i 6 speed; a Range Rover) and replaced a couple of them for many thousands each. I wouldn't have one of those on a boat on a bet.

Water-cooled alternators are a solution looking for a problem which does not actually exist. There are air-cooled alternators which are actually designed for producing their rated power continuously -- school bus, large case, hot-rated alternators. They cost a few hundred each, can be repaired in any third world auto-electric shop. These can crank out a couple of kW day in and day out without breaking a sweat.

The problem is not air-cooling. The problem is cruisers trying to produce bulk power out of alternators not designed for the purpose. Small-case car type alternators -- the kind which come standard on most boat diesels -- are designed to produce tiny amounts of power needed to support the engine electric systems, and recharge a starter battery which was discharged by 0.1% on the last start. They are simply not fit for the purpose of producing bulk power for domestic needs.

I agree that the alt that are equiped standard is not made for what we are trying to do, charge LFP.
When the alt get warmer then the internal Ri will rise and lower output will the result be. Keep it cooler then you get out more Amp. Best would be superconductivity. I new that company B have problem whit over-heating internaly on their performance alternators. GenMAax have moved out the rectifier and air cool it to solve this problem.

You cant use water cool alt as they are.
I am not trying to talk theoretical discussion
Build my own test bench with a 10 hpr 3 phase motor controlled by a frequens converter. I bougth 500 Ah LFP as load, only for testing.
External resistiv load of 2700 Watt. I have made so many test to find al week spots that you have find as problem whit those alt when they are standard equiped.
I have improved the construction and solved those week points.
I have removed the rectifier cause the diodes cant stand the heat.
The new rectifier is externely water coled and temp is only 42C 107F
The internal regulator is removed. I use instead a Balmar MC-618 in my yacht and also in my workshop.
Running this system now for the 5 season, and I am not alone.
Al of us have more Amp and much cooler engine compartment without any problem.


https://www.cruisersforum.com/forums...1&d=1716203925

[Dockhead]

Originally Posted by Dan Kimblad

I agree that the alt that are equiped standard is not made for what we are trying to do, charge LFP.
When the alt get warmer then the internal Ri will rise and lower output will the result be. Keep it cooler then you get out more Amp. Best would be superconductivity. I new that company B have problem whit over-heating internaly on their performance alternators. GenMAax have moved out the rectifier and air cool it to solve this problem.

You cant use water cool alt as they are.
I am not trying to talk theoretical discussion
Build my own test bench with a 10 hpr 3 phase motor controlled by a frequens converter. I bougth 500 Ah LFP as load, only for testing.
External resistiv load of 2700 Watt. I have made so many test to find al week spots that you have find as problem whit those alt when they are standard equiped.
I have improved the construction and solved those week points.
I have removed the rectifier cause the diodes cant stand the heat.
The new rectifier is externely water coled and temp is only 42C 107F
The internal regulator is removed. I use instead a Balmar MC-618 in my yacht and also in my workshop.
Running this system now for the 5 season, and I am not alone.
Al of us have more Amp and much cooler engine compartment without any problem.

https://www.cruisersforum.com/forums...1&d=1716203925

That's a beautiful project! It must have been a lot of fun.


Are these series produced?


What alternator was used as a base for this? And you made a new case for it with the water cooling jacket? Or how?



It's in any case quite a bit more complex than a school bus alternator, so I don't think I will change that, but it's good someone is pushing the state of the art.

[Dan Kimblad]

Working with small electric motors since 1989 and for the last five years have become obsessed with alternators.
Funnest project so far in my life. Learned so much after spending many nights in my workshop.
For just over 1000 hours, I have tried my way to find all the weak links in the systems. Have had access to my brother's company that manufactures water cutting machines. This means that I can quickly and cheaply get fasteners and various parts. Here I am modifying five alternators so that they can be mounted on someone's Yanmar engine that will charge LFP batteries.

[newhaul]

Originally Posted by sailingharry

The engine displacement discussion came from the post about the engine already extracting a lot of air from the engine room.


You are right that I need to push air at the alternators -- hence, the idea of inserting a vent grate in the companionway stairs right in front of the alternators, so makeup air would be right there.



I have two alternators. The smaller (120A) is in the stock position. While it is more than conventional wisdom recommends for a single belt, I have minimal belt dusting (although I have never seen it give more than 70A -- part of why it is back for rebuild). The bigger 150A is driving by a serpentine belt. It's mounted on the starboard side, and I machined an adapter to mount a multi-v pulley for a Mack Truck on the front. I'm pretty happy. This one will routinely puts out up to 130A or more, depending on the situation.



So, at 250A (let's hope I get that after rebuilds!), that's just under 5HP. Assuming 50% efficiency, that's 10HP -- so close to your 25% number. I consider that a good thing, especially if I'm running it at anchor or in neutral while sailing. Probably a bad thing when needing 100% of engine power -- might be worth considering a switch.


Pic of the install. The bracket was made by a buddy with the same boat -- and when he does ANYTHING he does several, so he had a spare.

Actually 250 amp output from the alternators is more like 15 hp. It takes approximately 1.5 hp per 25 amps output from alternators.
A cutout switch installed in the exciter wire of the alternator is something to consider if you may need the full power of the engine at times.

[donradcliffe]

Stepping back and looking at your electrical system as a whole:

Switching to lithium will reduce your daily generation requirements by about 10% by lowering internal battery resistance .

More solar is the most cost effective and least complicated means of electrical generation.

Increasing the pulley ratio of your alternators will make them run cooler. The cooling power of the fan goes as the square of the RPM, but the heat generation is more a function of amps, which saturates.

A better fan on the alternator (an the correct rotation of the fan) is a cheaper fix. But use your engineer's eyeball on the fan blades--sexier does not mean better.

If you ever want to sail the boat in the tropics, generating more cabin heat from a hot engine is a bad thing. OTOH, in Newfoundland it may be a good thing.

[Dan Kimblad]

Only one alt and charging 262Amp at 1500 rpm in the beginning.
And freezing cool after a hour.
https://youtu.be/9CrBNP1dqzs

[Dan Kimblad]

Installed one Hitachi and one Chinese copy parallell on a Benetau 55 with a Yanmar 110hpr
I noticed that the Chinese copy was only producing 75Amp when idling and Hitachi 190 Amp
When I rev it up then I got only 376Amp!
Will replace the Chinese today and hopefully I will get 450Amp and peak over 500Amp
https://youtube.com/shorts/NYbvYro3cpw

[CaptainRivet]

Originally Posted by Dan Kimblad

Installed one Hitachi and one Chinese copy parallell on a Benetau 55 with a Yanmar 110hpr
I noticed that the Chinese copy was only producing 75Amp when idling and Hitachi 190 Amp
When I rev it up then I got only 376Amp!
Will replace the Chinese today and hopefully I will get 450Amp and peak over 500Amp
https://youtube.com/shorts/NYbvYro3cpw

Only 376A...would be happy to get that...

That main battery cable is by far to small for 376A and for 450 - 500A . You need 2 in parallel minimum.