Alternator Choice Advice

[SailRedemption]

Hello friends,

I have a 540ah Lifepo4 bank and a stock Yanmar 4HJ4-TE 75hp engine. I'm currently only set up to charge through our Victron Phoenix battery charger because I want to replace the stock Hitachi alternator to hook up to the Balmar 614 regulator. I do have a serpentine belt on my engine to clear that up and have fuses and proper wire ready to be installed.

The choice I am stuck between is whether or not to get a Balmar AT 165A alternator for a $1000 or a Mark Grasser 180A alternator for $900. Which one will give the best service life and the highest amps? I know both will need the belt manager but which one will produce more amps safely?

I appreciate any advice on these two alternators.

See more @ redemptiverepair.com

[exMaggieDrum]

He is a distributor of the Mark Grasser alternators so perhaps not completely unbiased but Rich Boren on SV Third Day has some comparison writeups that you might find interesting. He is on the forums daily (or so).

[a64pilot]

From my limited experience it seems that who sells a small frame alt is sort of irrelevant, the real limit as to how much power you will get out of it is temp related, I don't mean short bursts, but sustained like battery charging.
I can only get about 80 out of my 125 amp alternator, and cannot understand how I could get more out of a higher rated alternator that is the same frame size and has the same cooling fans, and have not yet had anyone explain how, what would be required of course would be an increase in efficiency, make more power with less heat, and I do not see how that is possible.

I don't know how relevant this is, but I'm running a Mark Grasser alternator and have been well pleased.
Mark does I believe make his own serpentine kit that overdrives the alternator, that is the only way that I can see to realistically increase output, increase speed which of course increases cooling and should increase efficiency a little


Sent from my iPad Pro using Cruisers Sailing Forum

[Dockhead]

Originally Posted by a64pilot

From my limited experience it seems that who sells a small frame alt is sort of irrelevant, the real limit as to how much power you will get out of it is temp related, I don't mean short bursts, but sustained like battery charging.
I can only get about 80 out of my 125 amp alternator, and cannot understand how I could get more out of a higher rated alternator that is the same frame size and has the same cooling fans, and have not yet had anyone explain how, what would be required of course would be an increase in efficiency, make more power with less heat, and I do not see how that is possible.

I don't know how relevant this is, but I'm running a Mark Grasser alternator and have been well pleased.
Mark does I believe make his own serpentine kit that overdrives the alternator, that is the only way that I can see to realistically increase output, increase speed which of course increases cooling and should increase efficiency a little


Sent from my iPad Pro using Cruisers Sailing Forum

I agree completely. For LiFePo batts you really want a large frame, heavy duty alternator, suitably derated. The acceptance rate of those batts will murder a normal alternator. Plus you really want robust output to take advantage of that acceptance rate. All that money on batteries - it's worth spending just a bit more on a worthy alternator installation. That engine will take a second, large frame alternator on the stb side. It's not that bad even.

Sent from my SGP521 using Cruisers Sailing Forum mobile app

[SailRedemption]

Originally Posted by a64pilot

From my limited experience it seems that who sells a small frame alt is sort of irrelevant, the real limit as to how much power you will get out of it is temp related, I don't mean short bursts, but sustained like battery charging.
I can only get about 80 out of my 125 amp alternator, and cannot understand how I could get more out of a higher rated alternator that is the same frame size and has the same cooling fans, and have not yet had anyone explain how, what would be required of course would be an increase in efficiency, make more power with less heat, and I do not see how that is possible.

I don't know how relevant this is, but I'm running a Mark Grasser alternator and have been well pleased.
Mark does I believe make his own serpentine kit that overdrives the alternator, that is the only way that I can see to realistically increase output, increase speed which of course increases cooling and should increase efficiency a little


Sent from my iPad Pro using Cruisers Sailing Forum

Thanks for the information and the first hand experience with the Grasser alt. I see good reviews on his alternators which is why I'm only down to just those two particular brands and models.

See more @ redemptiverepair.com

[SailRedemption]

Originally Posted by Dockhead

I agree completely. For LiFePo batts you really want a large frame, heavy duty alternator, suitably derated. The acceptance rate of those batts will murder a normal alternator. Plus you really want robust output to take advantage of that acceptance rate. All that money on batteries - it's worth spending just a bit more on a worthy alternator installation. That engine will take a second, large frame alternator on the stb side. It's not that bad even.

Sent from my SGP521 using Cruisers Sailing Forum mobile app

Hey Dockhead,
If I remember correctly, you have the one up from my engine, the HTE 110hp? I know Yanmar makes a second alt kit for this engine but it said a 125A so I assumed it was another small case alt. Am I incorrect on that? I tried searching Google for a Yanmar 4hj4-te large case alternator setup but didn't find anything for a couple hours. I'm pretty sure I have enough room for one on either side of the engine. That being said I still would probably get something close to 200A and not go much bigger with a large frame.

If you have any information on putting a large case on my engine I would love to hear about it. Or point me in the right direction at least.

I chose the Balmar AT because it does do excellent at high amp rates constantly and has gotten good praise on here and other sites(we've been on standby for 3 weeks on my ship so I have had time to sit and surf the Internet).

Also, didn't really plan to have two alternators as I'll be starting from the Li house bank and it would be one less thing I have to maintain.

See more @ redemptiverepair.com

[Dockhead]

Originally Posted by SailRedemption

Hey Dockhead,
If I remember correctly, you have the one up from my engine, the HTE 110hp? I know Yanmar makes a second alt kit for this engine but it said a 125A so I assumed it was another small case alt. Am I incorrect on that? I tried searching Google for a Yanmar 4hj4-te large case alternator setup but didn't find anything for a couple hours. I'm pretty sure I have enough room for one on either side of the engine. That being said I still would probably get something close to 200A and not go much bigger with a large frame.

If you have any information on putting a large case on my engine I would love to hear about it. Or point me in the right direction at least.

I chose the Balmar AT because it does do excellent at high amp rates constantly and has gotten good praise on here and other sites(we've been on standby for 3 weeks on my ship so I have had time to sit and surf the Internet).

Also, didn't really plan to have two alternators as I'll be starting from the Li house bank and it would be one less thing I have to maintain.

See more @ redemptiverepair.com

Well, two alternators is a really good thing because you can keep your engine start bank utterly separate from domestic system. There's really nothing to maintain. I highly recommend it. If the two banks are the same voltage, the two alts can even back each other up (not my case -- I have 24v and 12v respectively).

All the 2000cc 4-banger Yanmars are the same [within the same generation of course] except for the amount of turbocharging and intercooling. Yanmar makes brackets for a second alternator, for all of them. You also need the crank pulley.


A heavy duty alternator is probably the most joy, for the least money, you can possibly have on a boat. It's a simple, cheap, dirt cheap device, which can be completely rebuilt for $200 if needed. And functions like a 2.5kW generator which is working whenever your main engine is running. In my opinion it's a total no-brainer; I wouldn't have another boat without one of these.

I don't think you need to go to Balmar or one of the specialized marine shops. Just go straight to Leece-Neville, which is a division of Prestolite. My alternator costs like $500 brand new -- in the UK. Or about 1/30 of what my generator cost.


Simple, cheap, reliable, extremely effective -- and can be repaired in any third world auto electric shop with a hammer and pair of pliers. It's like an AK-47. I wish more gear on board were like this.

[Jd1]

Originally Posted by a64pilot

cannot understand how I could get more out of a higher rated alternator that is the same frame size and has the same cooling fans, and have not yet had anyone explain how, what would be required of course would be an increase in efficiency, make more power with less heat, and I do not see how that is possible.

Larger or more efficient fan(s), heavier wire, higher temperature rated wire and other components, diodes with lower forward voltage drop, better heat sinks on the diodes.
A minor technicality - not more power with less heat but more power with the same (or only slightly higher heat). My Balmar AT200 for example has square wires which allows more copper in the same space compared to standard round wires
thus reducing resistance and thus reducing heat generation.

Having higher temperature rated insulation on the wires in the winding will easily allow an increase in safe operating temperature. Since cooling is more effective with a higher delta between ambient and winding temperatures, you get not only the extra temperature range but also better cooling efficiencies. (hope that makes sense)

[CAELESTIS]

As Dockhead said, go with the Leece Neville. Balmar does not make alternators, they rebrand Leece Neville and others.

I have your identical engine with a Leece Neville 140A @ 24v on the serpentine belt system. 620 trouble free hours.

[Dockhead]

Originally Posted by Jd1

. . . Having higher temperature rated insulation on the wires in the winding will easily allow an increase in safe operating temperature. Since cooling is more effective with a higher delta between ambient and winding temperatures, you get not only the extra temperature range but also better cooling efficiencies. (hope that makes sense)

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.

[SailRedemption]

Thanks for the information Dockhead, Caelestis.

I contacted Balmar about their 94 series large frame alternator as they have one listed for the Yanmar 6LY engine but it still has the 3.15" mount. Hopefully I hear back from them.. I was looking at the dimensions of the 6 and the 94 series alts and it's only a little difference so I'll look on my boat and see if I have the room for it. It would be great if I could use a large case in the stock position and not have to pay twice as much for a second alternator kit plus a new alternator.

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.

I'll contact Rich tonight as well, I know he's a great guy and honest.

See more @ redemptiverepair.com

[a64pilot]

The issue is cooling I believe, one day maybe somebody will market a high amp water cooled alternator, and that I believe is about the only way to get a bunch of amps out of a small frame.

I had to install a dedicated ammeter on my alternator, without that, how can you tell what your output is? Do those amp counter battery gauges do that?

[a64pilot]

Originally Posted by Dockhead

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 it's relevant, assuming of course somehow or another your case isn't insulated and is used as a heat sink, then eventually your case will get hot, likely pretty darn hot.
The small frame, automotive alternators its pretty obvious that the frame itself is a heat sink and part of the cooling scheme, then of course the frame is also where the temp probes are mounted.

I think the average sailboat alternator is under driven RPM wise, I think they need to turn quite a bit faster to get sustained high outputs, I think airflow off of a fan is not linear, that increase RPM by a few tens of percent and you can double airflow, then of course if your trying to cool your alt and have a hot engine compartment, it's tough to cool.
I keep meaning to run a blower hose to the bilge to get cool air and blow it on the backside of the alternator, it's my impression that blowing air on the backside is more effective, there is a front and a rear fan, and the rear of the alternator is where most of the heat is made.

I can only assume these high rated small frame alternators are not continuous duty?

I learned about duty cycle in 1981 when as a contract welder in the oilfield in Oklahoma, I watched someone's nearly new welder's windings melt out of it, up until it melted I marveled at how that little thing could make more power than my old fashioned Lincoln Pipeliner could.
He tried to take it back, and they explained duty cycle to him, for every 5 min of welding, he was supposed to let it rest for 5 min.

[ColdEH]

Originally Posted by a64pilot

No it's relevant, assuming of course somehow or another your case isn't insulated and is used as a heat sink, then eventually your case will get hot, likely pretty darn hot.
The small frame, automotive alternators its pretty obvious that the frame itself is a heat sink and part of the cooling scheme, then of course the frame is also where the temp probes are mounted.

I think the average sailboat alternator is under driven RPM wise, I think they need to turn quite a bit faster to get sustained high outputs, I think airflow off of a fan is not linear, that increase RPM by a few tens of percent and you can double airflow, then of course if your trying to cool your alt and have a hot engine compartment, it's tough to cool.
I keep meaning to run a blower hose to the bilge to get cool air and blow it on the backside of the alternator, it's my impression that blowing air on the backside is more effective, there is a front and a rear fan, and the rear of the alternator is where most of the heat is made.

I can only assume these high rated small frame alternators are not continuous duty?

I learned about duty cycle in 1981 when as a contract welder in the oilfield in Oklahoma, I watched someone's nearly new welder's windings melt out of it, up until it melted I marveled at how that little thing could make more power than my old fashioned Lincoln Pipeliner could.
He tried to take it back, and they explained duty cycle to him, for every 5 min of welding, he was supposed to let it rest for 5 min.

Duty cycle , never heard it to revered to that way.

100% duty cycle , thats what you need for charging large house banks

Alternator manufactures should rate there alternators HOT and its Duty cycle , not maximum output , you know as well as I do they don't put that much out for very long .

Regards

[barnakiel]

With your batteries, I would use a BIG alt and hot rated big best. 200A and upwards.

Something like delco remy 55si brushless, etc.

b.