Water cooled, high amp 12v alternator

[kenbo]

Is a water cooled alternator that runs at 180° to 190° F much better than a hot rated truck or school bus alternator? Delco rates their line of HD truck alternators at 225° F. Seems like a solution looking for a problem.

I used to have problems with the front brake rotors on my truck until I ran a 3" hose from the grill to the brake caliper/rotor...problem solved. Sailorboy suggested the same here. Just get the outside air forced to the back of the alternator should help a lot. Also, if your really making big amps get the bridge rectifier out of the alternator and mount it on an aluminum plate. That will remove more than half of the waste heat from the alternator. Go to the Wind Blue website and read about remote rectifiers. WAI/Transpo sells 210A, non-avalanche diode rectifiers for under $30. Run them in parallel and you're good to go.

[txg]

I don't say that a Honda generator is a bad solution in general, but it's not the best solution either:

-you have take it out every time you need it and put it back into storage after that to make sure it won't get stolen. This also means it will take up space in a storage locker.

-you have to be careful with CO poisoning, when running the generator needs a place where it can vent its exhaust gasses.

-if you have a 2stroke-outboard, you need a third sort of fuel for the generator.

-a 1000$ Honda generator won't charge at 60-70A by itself. It will only power a charger and one with this output current is additional $$$.

-60A is not much, even our stock 110A Vetus/Mitsubishi will put out more.

-a portable generator can't be run when underway, except for maybe very light winds.

-a high-output alternator will charge with high output whenever the engine is running meaning nearly full batteries even if the engine has just been running for half an hour when approaching an anchorage.

-a separate generator means another internal combustion engine and therefore storage for another set of spare parts and also regular services like oil changes.

[kenbo]

I don't disagree with your points in regards to a Honda2000i but I do disagree with this:

-a high-output alternator will charge with high output whenever the engine is running meaning nearly full batteries even if the engine has just been running for half an hour when approaching an anchorage.

Not true unless you have LiFePO4 batteries.

[Cheechako]

Originally Posted by txg

Even if this thread is 5 years old, alternator heat problems are still a big problem as can be seen in several threads on this topic.

Still noone that tried using a water-cooled alternator on a boat? They are expensive, but i just found out that they can be bought used quite cheap, 14V 150-200Amps for about 150€.

Yeah, but realistically, you can only pound a high charge into batteries for a short time. The batteries are the limiting factor.
I bet a finned aluminum alternator housing with a ducted fan wold cool really well and be simpler than a water cooled alternator.

[txg]

Originally Posted by kenbo

-a high-output alternator will charge with high output whenever the engine is running meaning nearly full batteries even if the engine has just been running for half an hour when approaching an anchorage.

Not true unless you have LiFePO4 batteries.

I get your point, but this depends on what you define as "nearly full", on the SOC when beginning to charge and the type of batteries used. We have a rather small 220Ah bank, but they are AGM and can take a lot of current. When we have run the engine approaching an anchorage, batteries are at least at about 75-80% most of the time. Okay, this doesn't mean full but there is a decent charge.

Originally Posted by Cheechako

Yeah, but realistically, you can only pound a high charge into batteries for a short time. The batteries are the limiting factor.
I bet a finned aluminum alternator housing with a ducted fan wold cool really well and be simpler than a water cooled alternator.

Even if the batteries can't take all of the current it is nice to have a high-output alternator. E.g. we have an electric cooking plate running through an inverter that pulls around 130A. With a bigger alternator that can deliver 150A+ continuously, it would be possible to cook while charging the batteries at the same time.

We do cool our alternator with an external fan and while that does help a lot, watercooling would be much better.

[john61ct]

Watercooling system would be fine but IMO only worth doing if professionally designed and installed from the beginning to run off the engine cooling system.

You need to first test **that alt** for the ability to put out your desired Amp loads within target rpms for long periods of time. Most automotive can't do over 60-80A, really need large-frame truck style for higher.

For retrofitting, use forced air cooling.

Serpentine belt for sure, dual vee bare minimum for under 150A.

Single belts can't comfortably carry the torque of actually **producing** 80-100A for extended periods. The max alt rating is irrelevant.

[john61ct]

Relevant thread http://www.cruisersforum.com/forums/...d.php?t=193270

[john61ct]

On AGM higher acceptance rates.

Only relevant for a few minutes at low SoC. Still need 5-8 hours to get to 100% Full, essential for bank longevity.

Need solar to carry on, finish the long tail after your morning dino juice run.

http://www.sailnet.com/forums/showthread.php?t=241409

[a64pilot]

Water cooling an alternator should not be a real concern, it has been done, and it works. A whole lot less heat to remove from an alternator than say an intercooler, yet they are water cooled with few problems.
However if your concerned with salt water you could use a fresh water / antifreeze mix and remote mount a transmission cooler and blow air over that.
Many things are possible, however they start to become what I call a science project, sort of like the thread on a DC generator.
Of course it’s possible to build your own DC generator, just like it’s possible to build your own watermaker for instance. If you enjoy tinkering and have nothing else the Boat needs, go for it.
However I’d bet even if you consider your time worthless, your still going to spend more $$ than just buying a Commercial solution that already has the bugs worked out. However I admit there is satisfaction is setting back and thinking “I built that”. Must be why people home build boats, otherwise I believe they are insane
Now if your really cruising and don’t have an automobile to run around constantly scrounging parts and access to a decent shop, it’s really going to be more difficult than you may think.

[Dan Kimblad]

Hi all sailors
I found a picture of my alternator when I was googling on this old thread.
Have to share what I made!
Its a standard car alternator that I have build in to my Jeanneau 42 DS 2012 with a Yanmar 4JH5E
Its water cooled with at separate heat exchange from sea water to a internal system only for the alternator. The cooling water are circulated by a brush less water pump from Bosch. The multi rib belt are only for the alternator. its a separate fan belt for the water pump for the motor. This is for limiting the radial forces on the bearing for the water pump.
The alternator charge 140 Amp at idling at 800 rpm to a 540 Ah Li-Io battery bank.
In the beginning when I start up the engine it charge 190 Amp at idling but the internal heat are lowering the charge after 10 minutes (have a dream to fix that)
I have measured the efficiency of the alternator and its only 50% in a test rig. That means that you have a heating element of about 2000 Watt in the engine compartment. But I flush out that heat by the heat exchange.
I have running this solution for two year and I made the same solution on my brothers Bennetau 55 at the same time.
How everything looks like when running and charging 140 Amp
https://youtu.be/6xjsDT2OuV4

The best part are that all parts are standard car parts. The belt is standard and not as some gen fix supplier use, special belts that you cant find that easy and bring a lot of radial force on the water pump.
It took me a lot of time to fullfilled this dream.
https://www.instagram.com/p/CBgdRmjn4e1/

Waiting for another spring and summer while the Lady are on land

[team karst]

That is very cool!

[GordMay]

Greetings and welcome aboard the CF, Dan K.

[Bowdrie]

While much of the heat load on an alternator is a result of the output load, a surprising amount comes from the friction drive, and is transmitted directly into the front bearing of the alternator.
The poly-v belts are a big improvement over the traditional V-belts, but they still rely upon friction for power transmission.
If you can use an "on engine" mounting scheme and the proper pulleys are available it's a decent way to go.
In my case the only way to use a large-frame alternator was to go to an off-engine mounting arrangement,, and any kind of V-belt drive was going to get complicated.
Either V or Poly-V, they operate properly only within a fairly narrow range of tension, and with "softer", (so to speak,) engine mounts, I wanted a drive that could transmit torque without as much belt tension/friction/heat, or side bearing loads.
My solution was the Browning Gear-Belts, also known as Gilmer or Blower belts.
The little 1in wide belt, (with the pulley sizes and RPM range I use,) is good for ~10HP.
A very wide range of pulleys/belts are easily available,, although one may have to have some machine work done to mount the engine pulley.
Here is a pic of the big Leese-Neville,, this belt has over 600 hours on it and their is little wear that I can discern, and No "black powder" sprayed anywhere.

[SoonerSailor]

Much of the heat load of an alternator can be moved out by using an external rectifier. Not sure how that would compare to water cooling, but far simpler.

[Dan Kimblad]

Originally Posted by SoonerSailor

Much of the heat load of an alternator can be moved out by using an external rectifier. Not sure how that would compare to water cooling, but far simpler.

It's true that moving the rectifier externally is much easier and will certainly lower the temperature. I have not thought about that, but how much lower will the temp be?
If we have bad diodes that have 0.7 volts in drip, it will be 70 watts at 100 Amp (please correct me if I am wrong about this).
It is still type 1300 Watt heat at 100 Amp. Note that I have measured the alternator in a test bench. The efficiency is 50% I have measurement protocols but I have not yet learned how to get pictures on the forum. How much of it is the transmission that there are losses in. Source-critical, I have contacted a company that has been working with belt transmissions since 1971, Aratron AB. A good Poly V belt that is correctly mounted has an efficiency of up to 98% If we say 95% to calculate something, it is 2800 watts that the generator consumes and then there is 140 Watt losses in the belt, if we count with 98% so it is 56 watts.
Unfortunately, our alternators have poor efficiency. Everything should be as cheap as possible. When the alternator is cool, it charges almost 200 Amp when I start the engine and idle at 850 rpm. When the internal heat rises up to 47 C (measured with a thermal camera), the charge drops to 140 Amp
I do not want to master in any way, but I want to try to understand how things work and share with me what I have stated and take to heart what you others have stated.
What I will do in the next step is to measure the voltage drop on the negative cable. Today I have a 85 mm2 and is mounted at the back of the engine. Is it worth reconnect the minus cable directly on the alternator. How much losses is it throw the whole engine?