Alternator Cooling

[CaptainRivet]

Originally Posted by Mauruuru

The proper way would be to add both inlet and outlet air from outside the cabin. Route incoming ambient air over the area you are trying to cool and take exhaust from take exhaust from area across the engine room to maximize benefit.

If your engine is running hot yes optimize ventilation till engine is running fine on max load. Thats the surrounding your alternator is made and speced for. Making it cooler is super ineffective for the alternator, costs a lot and brings nearly 0 effect.
Because if its ok forget that to cool down your alternator like this.
Diodes away to reduce casing heat and temp regulating external regulator is the only way to effectively squeeze the max out off your existing alternator. The heat is generated deep in the alternator, the outside air temp makes a difference in the last 5% as your cooler air won't reach the core of your alternator where the. Origin of the heat is.. except for its so hot that your engine overheats.
You habe to prevent the alt from heating up, means you have to regulate it at the temps borders where the heat build up inside it and the self cooling ability is still in balance. Optimize the self cooling side only really works is when you significantly raise the airflow through the alternator and this only works if you raise the RPM. Problems see above.
If that gives you too less amps update the alternator to a bigger one is the only way.
Everything else is waste of money and time.

[C. Strauss]

I have the same problem. The solution I'm thinking of is to wrap the alternators with tubing bedded in thermal caulking, and run cooling water through them. Yes, I know it'd be messy and make servicing more difficult, but it'd cool more efficiently than air. Feel free to shoot this down if it's a bad idea.

[captstu]

BMW and Land Cruisers can both come factory with water cooled alternators up to 200 Amps. These are sealed, brushless, very high quality alternators with proper high power fittings that use water to dump the heat. This is what I would use rather than the Balmar and GM alternators i used last time I did this.

[PaulCrawhorn]

Porsches also, not large

[Wandering1]

Seems like a lot of expense when solar is super cheap. We live full time off solar when at anchor. We run two fridges and a freezer, icemaker, heat hot water from solar, etc. We make water with the diesel genset but never turn on the battery charger. We do all this with four Trojan T105s. They don't drop below 80% full overnight.

[hjohnson]

Originally Posted by Wandering1

Seems like a lot of expense when solar is super cheap. We live full time off solar when at anchor. We run two fridges and a freezer, icemaker, heat hot water from solar, etc. We make water with the diesel genset but never turn on the battery charger. We do all this with four Trojan T105s. They don't drop below 80% full overnight.

It all comes down to the boat and how it's rigged. On my Ericson 27, there just isn't that much room for a decent solar array. We're putting in 120W of solar, mostly to ensure our monitoring system doesn't drain the house batteries, but there's no way we could actually install enough solar on the boat to make up our actual use.

Conversely, on my friend's 46', they have easily enough room for a good 1200W of solar power, which runs most of their systems plus allows for the making of a decent Latte in the morning.

[Shay]

Most alternators come with a fan that can be used turning either direction. This is not the most efferent fan. Make sure you are using a directional fan and turning it in the correct direction. I have experimented with larger fans and have found there to be a difference. A good automotive alternator shop should be able to help with a better fan.

I have also experimented with turning the alternator faster. Running a smaller alternator pully will spin the alternator faster and produce more air flow. The faster alternator will probably yield more current at very low engine speed but the alternator is limited to the max current it can produce so you will get the same output at cruising speed with more cooling.

There is nothing wrong with trying to get the max out of the alternator as long as you don't over heat it.

[PaulCrawhorn]

And if you have the space as well as the HP to spare

some are designed to output their full rated power continuously, say 150-200A

and yes, as long as you don't let them get too hot. Special V belts & pulleys, plus the right VR for LFP if you don't want a stack of Sterlings

[SOLAR SUPPORT]

Originally Posted by Mauruuru

The proper way would be to add both inlet and outlet air from outside the cabin. Route incoming ambient air over the area you are trying to cool and take exhaust from take exhaust from area across the engine room to maximize benefit.

Just added a fan to pump extra air in to the engine room. Good air flow in to the room and second fan blows the air on to the alternator. Excessive air is flowing to the stern and exit through the ventilation windows at the back of the boat. Both fans work together when the alternator temp is over 80 C°. Alternator Charge also interrupted by an other thermostat.

https://youtube.com/shorts/2SW_gLZMJxE?

[sailingharry]

Originally Posted by CaptainRivet

Your alternators can safely output around 50% of their rating when! cooled properly. So its 60A+75A=135A and not the 200A you pull.
You need to scale down amps AND need to improve cooling and you maybe can go to 150A but never 200A if they should surive long.

If my choice is replacing my alternators annually, or doubling my engine run time --- my decision is easy!


Last summer, with a daily power demand over 150Ah/day, we ran the engine a LOT just for charging. And we went the last 60 days without a single shore power connection, so the alternators were all there was (besides useless Solbian junk, and a D400 that rarely put out more than 5A).



The alternators are out for rebuild right now. The 150 easily puts out 120-130, but the 120 won't get over 75 -- I'm hoping that the rebuild will get it back up to rated amps (I'm betting I've lost one diode pair). I hope to get closer to 225 - 250 next year.


I am currently running them on a single regulator, and so only have one temperature sensor -- which happens to be on the smaller alternator that's only putting out 2/3 of it's capacity. Wrong place to have it! LOL. I intend to go to two regulators, each with temperature sensors. So that will have the effect of reducing the output as temperature goes up. I just hope it doesn't drive engine run time up too much....

[sailingharry]

Originally Posted by Wild Geese

Out of interest what RPMs do the alternators turn at?

We have a single Powerline 120 amp alternator that never puts out more than 70 amps even when brand new. Heat was one of the questions the mechanic asked about and our fresh air input to the engine room was rerouted so the 4 inch diameter air intake hose exited at the alternator for maximum fresh cool air to the alternator to make sure.

RPM was the next question. Looking at the Powerline alternator power curve one of the reasons we can’t make the 120 is our engine does not turn fast enough. Our cruise power is 2600 RPM max and according to the alternator power vs rpm chart it can’t get more than 70 amps unless we were to take the engine to red line. Even then our red line RPM is 3200.

Is there a chance your engine doesn’t turn the alternators fast enough for the full power?

Happy sailing!

Yes, the excellent folks at Powerline have sent me the output curves. I have a few more RPM than you do, and cruise at quite a bit more. I forget the actual numbers, but I do get well up into the curve. I should be closer to 100+A at least.


On the other side, my 150 is driven by a sperpentine. I machined an adapter to put a Mack truck pulley on the front of the engine, adding about 2" to the pulley diameter -- that alternator gets way up in RPM!

[sailingharry]

Originally Posted by CaptainRivet

Best solution stack as much brand highest spec bifacial solar panels as you can and job done. clean, quiet, nearly maintenance free energy with victron mppts and you are mainly set. Alternator is just backup.

My boat came with 360W of Solbian flexible junk running through Genasun 10's. Never saw more than about 200W.


I've wrestled 3 falls out of 5 with the Admiral before sought professional mediation, and have been able to agree on removing 180W of the Sobian junk, and am putting in 480W of rigid panels, including upgrading two of the Soblian's to larger Victrons. I do hope to see closer to 300-400W of production this summer. Part of the problem is we are spending our time north of Cape Cod (this summer we'll see Newfoundland) so solar sucks to begin with.


I also have a Watt & Sea, that puts out amazing power until the cheap plastic propeller sheds blades. But I'll have a new prop on it this summer too.


So, yes, I hope to get the alternator out of primary and into secondary. Hit the batteries with 200A for a 1/2 hour in the morning, and as the current starts to back off, let renewables finis the job.


The real challenge for us is we still have AGM, which of course is about the worst possible battery for cruising. Last summer, I got about 95% charge about once a week. So painful!

[d design]

The problem is your trying to push enough current to compensate for such low voltage through small windings. I would consider going to 24V for more efficiency or consider a high voltage alternator with a step down inverter like the integral systems. You can do all sorts of technical mods but if you decide to sell the boat I guarantee the next owner will be cursing. KISS

[sailingharry]

Originally Posted by hjohnson

It all comes down to the boat and how it's rigged. On my Ericson 27, there just isn't that much room for a decent solar array. We're putting in 120W of solar, mostly to ensure our monitoring system doesn't drain the house batteries, but there's no way we could actually install enough solar on the boat to make up our actual use.

Conversely, on my friend's 46', they have easily enough room for a good 1200W of solar power, which runs most of their systems plus allows for the making of a decent Latte in the morning.

THIS!^^^^


We have a 43' boat, but she's thin (just shy of 12' beam), so not a lot of arch. And the aesthetic review board (she has 100% veto power) won't let me put the helo pad I want back there. I'm removing two 95W junk Solbian flex panels from the arch and upgrading to 480W rigid, so that will be a huge improvement -- but still only good for about 120Ah on a good day, less than my consumption. And even worse in northern latitudes...


I'd sure like to put double that on, but no idea where to put it without junking up the boat. Over the bimini is a possibility, but a split backstay makes shadows a huge problem. It also would cover the window to let me see the sails.

[PaulCrawhorn]

Those Aussie "blanket style" pretty compact folding pads can be put out, moved around and put away...