Alternator advice needed

I have a 160A alternator on my 3306 CAT engine. It was a replacement for a dead 120A alternator about three years ago.
See photo.
Recently, I do not see charging on the voltage gauge in the pilot house. The needle goes down to yellow, close to red. I am single handed, so I cannot go to the engine room to check the voltage on the cranking battery directly.
If I run my generator, the charge happens and I can see normal voltage on the gauge. Both the alternator and the generator can charge the cranking batteries.
Sometimes, the charge happens even from the alternator alone, but it takes a while this to happen. I could be underway for 30-40 minutes already, when the charging from the alternator appears. Sometimes, it does not happen at all.
I cannot tell, if the alternator has issues, or it is dying. My knowledge is limited on this.
Do you recommend a replacement, testings, or a larger capacity alternator? If yes, which one would you buy? Thanks.

The fact that the voltage does increase after running the main engine for awhile indicates that the batteries you are charging with the alternator are drawing the alternator voltage down because they are absorbing as much current as the alternator can produce. Once the battery current draw slows up as they get charged, the voltage goes up. This is normal, especially when charging a big battery bank.



A battery state of charge monitor with a shunt will tell you the state of the batteries and the amount of current coming out of them or going into them. Would be a worthwhile improvement to any cruising boat IMO. I love the Blue Sea System stuff.

Second the suggestion for monitoring. 160A is a lot of alternator.
Questions are state of batteries when leaving the dock? it sounds like they are charging, delivery amps from the alt at this time and 1 hour later?

I agree with Mischief Managed that it would seem the alt us capable as it does come up and excess batty draw could brinf V down.
I have to wonder if that would happen with a goid alt and start bank. I would test alt output w a clamp on DC ammeter to see if alt is putting out close to its capacity or is weak. Should be able to check at dock or anchorage in neutral. I would check start batty V before starting. Start and check alt V & A output.
Do you have a cross connect between start & house bank? I would think it more likely a hi draw from large house bank more likely than replacing the hi A but short time reqd to start eng needing to be replaced in start batty.
If start batty V is low it would be a sign of bad batty... any issue w slow cranking at start?

160 amps is a reasonable sized alternator, I don’t know your whole setup though. From the picture it looks like it internally regulated?
Could be the regulator is going out, or something in the alternator itself. A clamp on amp meter is useful here to check amp output, there are inexpensive ones that work good enough.
You’re probably looking at rebuilding or replacing it though. Finding places to rebuild alternators is spotty anymore, my local guy is long gone now.
Maybe in your area there’s still someone doing it?

Bmarler said:

160 amps is a reasonable sized alternator, I don’t know your whole setup though. From the picture it looks like it internally regulated?

Could be the regulator is going out, or something in the alternator itself. A clamp on amp meter is useful here to check amp output, there are inexpensive ones that work good enough.

You’re probably looking at rebuilding or replacing it though. Finding places to rebuild alternators is spotty anymore, my local guy is long gone now.

Maybe in your area there’s still someone doing it?

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Yes, it is internally regulated. I have not messed around it. It has been like this since install.

The cranking batteries are separated from the house bank. They have their own charger from shore power, and the alternator charge underway. So these batteries are always charged. Plus they are only a year old cranking lead acid batteries.

I don’t think I can have this rebuilt. I could not find anyone in the area, when my previous alternator went out. This one is still working, but I cannot tell, if 100% ?
I don’t mind investing in a new one and keep this as an emergency backup. It would be nicer to have an alternator, which can be adjusted/measured while in use. This one does not.

Bacchus said:

I agree with Mischief Managed that it would seem the alt us capable as it does come up and excess batty draw could brinf V down.
I have to wonder if that would happen with a goid alt and start bank. I would test alt output w a clamp on DC ammeter to see if alt is putting out close to its capacity or is weak. Should be able to check at dock or anchorage in neutral. I would check start batty V before starting. Start and check alt V & A output.
Do you have a cross connect between start & house bank? I would think it more likely a hi draw from large house bank more likely than replacing the hi A but short time reqd to start eng needing to be replaced in start batty.
If start batty V is low it would be a sign of bad batty... any issue w slow cranking at start?

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The cranks are a year old and individually wired. All they do is starting the main engine. Nothing else. The house bank is lithium now, with a separate setup and wiring.
Cranking and starting the main is not a problem. The batteries handle the cranking well, as long my generator, or shore power is available to recharge. There is no issue there.
My problem is the recharging the start batteries once I leave the dock. I’d prefer to see the charge coming on immediately and see the progress of feeling them up by the alternator. I am not sure how to do that. If it is true what you are saying that the voltage goes down at first, until the batteries are charged up, I’d like to see the charging curve.

Turtle Blues said:

Second the suggestion for monitoring. 160A is a lot of alternator.
Questions are state of batteries when leaving the dock? it sounds like they are charging, delivery amps from the alt at this time and 1 hour later?

Click to expand...

Yes that is my puzzle. If the alternator is charging from the start, but the gauge does not show it, I’d like to know why? Why does it take the gauge to show any normal voltage after a long time, or nothing at all? Also, why does the charging voltage shows immediately on the gauge, when I run my generator in addition to the main engine/alternator?

Mischief Managed said:

The fact that the voltage does increase after running the main engine for awhile indicates that the batteries you are charging with the alternator are drawing the alternator voltage down because they are absorbing as much current as the alternator can produce. Once the battery current draw slows up as they get charged, the voltage goes up. This is normal, especially when charging a big battery bank.



A battery state of charge monitor with a shunt will tell you the state of the batteries and the amount of current coming out of them or going into them. Would be a worthwhile improvement to any cruising boat IMO. I love the Blue Sea System stuff.

Click to expand...

State of charge monitor from Blue Sea? I will look it up. I have shunts from my old house bank, so can use that. I’ll look up the monitor you are recommending. If not too expensive, I’ll invest in it.

You have a very good quality alternator that is only a few years old.
There is always the chance that the diodes were accidentally harmed,
but if you are getting charging current out of it, it is probably OK.
I would look at upgrading to an external regulator such as a Balmar or the like.
I have done something similar and it is great to have more charging control.

KnotYet said:

You have a very good quality alternator that is only a few years old.
There is always the chance that the diodes were accidentally harmed.
I would look at upgrading to an external regulator such as a Balmar or the like.
I have done something similar and it is great to have more charging control.

Click to expand...

External regulator means, it will over ride the internal controls? Or you will have to do some wiring to eliminate the internal control elements?

LeoKa said:

External regulator means, it will over ride the internal controls? Or you will have to do some wiring to eliminate the internal control elements?

Click to expand...

Yes, the external regulator replaces the internal one with some wires.
Just guessing but that alternator may be easy to convert.
It looks commercial. Leece Neville sells them for ambulances, etc.
Balmar may be able to guide you as to what to do and what would work best.

LeoKa said:

The cranks are a year old and individually wired. All they do is starting the main engine. Nothing else. The house bank is lithium now, with a separate setup and wiring.
Cranking and starting the main is not a problem. The batteries handle the cranking well, as long my generator, or shore power is available to recharge. There is no issue there.
My problem is the recharging the start batteries once I leave the dock. I’d prefer to see the charge coming on immediately and see the progress of feeling them up by the alternator. I am not sure how to do that. If it is true what you are saying that the voltage goes down at first, until the batteries are charged up, I’d like to see the charging curve.

Click to expand...

I would do some tests & monitoring at the dock.
Measure start batty V before start and then after start - If battys are fairly new & good the V should recover a short time after start. If they start the main eng w/o hesitation I'm guessing the battys are not the problem. I'm suspecting something with the alt. That alt has a lot of A for only recharging eng start as most OEM alts roughly half that size.
Some measurements of V & A should provide a clue to whether the alt is putting out anywhere close to what it should. I also suspect if the alt is the problem it could be rebuilt cheaper than replacing. I'd look for an auto / truck electrical shop to check it out. Could be worth a drive even not close by.
When gen is running (assuming your shore charger is on) the batty V gauge is reading the charger output to the battys. My guess is if battys were weak and drawing the alt output down you would see something similar w shore charger as I'm guessing your shore charger isn't larger than the alt.

Bacchus said:

When gen is running (assuming your shore charger is on) the batty V gauge is reading the charger output to the battys. My guess is if battys were weak and drawing the alt output down you would see something similar w shore charger as I'm guessing your shore charger isn't larger than the alt.

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Good point and agreed. The generator run should show the same behavior as the alternator no charge/low charge business. When the generator is on, the volt meter shows the healthy charge and the needle is in the green immediately. There is no delay. My generator is a 11.5KW Perkins and the alternator on it puts out 15A.
Yes, the main engine alternator should do something similar.

I was,reading the Balmar web site and I will invest into a smart regulator and monitor for my alternator and crank batteries. I want to know what is happening all the time and no guessing game. I cannot risk my crank batteries ruined, or not able to start the main engine.
Generators can die without warning, and I’ll be stuck at the dock. Almost happened yesterday, thus the need for solution come up. I started my generator as usual before the main engine. It was running fine, so I cranked up the main, too. While the main was warming up, I did some tests on the hydraulic steering, when I heard the generator started coughing and later stopping completely. I did not see any relationship between the generator and the hydraulic motor for steering. I tried to start the generator few times, without any luck. I went out sailing for couple hours and after my return, I looked into the generator. Since it was cranking fine, it was not electrical. It seems that the fuel lift pump is not working. I’ve ordered a new one.
All the time while out in the water, the voltage gauge has not shown any charge. Once back in to the dock, the shore power took care of the batteries.
To avoid situation like this, I do need a proper monitor and regulator setup. It is possible that my main alternator is fine, maybe needs repair. I cannot tell for sure, until I have more data. If it needs repair, I will buy a new alternator first. The damaged one can be repaired anytime later.
Let see what Balmar recommends and I will post updates.

Regarding starting batteries and how many Ahrs it takes to start an engine:

Imagine that it takes 1000A to start your engine and it will crank for 3.6 seconds before starting. The draw from your battery is: 3.6 sec x 1000A = 3600Asec. With 3600 seconds in an hour, the draw is 3600Asec/3600sec/hr = 1Ahr. Just to put recharging reasonably good starting batteries in perspective.

CharlieJ said:

Regarding starting batteries and how many Ahrs it takes to start an engine:

Imagine that it takes 1000A to start your engine and it will crank for 3.6 seconds before starting. The draw from your battery is: 3.6 sec x 1000A = 3600Asec. With 3600 seconds in an hour, the draw is 3600Asec/3600sec/hr = 1Ahr. Just to put recharging reasonably good starting batteries in perspective.

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You have a valid point.
My problem is that I only see charging when the generator runs, or shorepower, after the main engine started. I do not see the charge from the alternator.
My batteries are new and there is no issue with starting the main.

These online dealers all have parts for your alternator. Or replacement alternators. The have some trouble shooting info.
I have bought from all 3 w/o problems.

https://alternatorparts.com/
https://www.dbelectrical.com/alternators/
https://www.aspwholesale.com/


Personally I'd buy a GM alternator because there's millions made and available everywhere. That's what I use on my boat.

"Recently, I do not see charging on the voltage gauge in the pilot house. The needle goes down to yellow, close to red. "

From your description I am puzzled that you would expect to see how much charging you get from your alternator.
You are measuring voltage at the instrument panel without identifying its source.
When you are on shore power, your charge is not going through the instrument panel, as your engine is not on.
When charging from the generator, your meter is likely reading the same input as when on shore power, so is independent of whether the engine is on or off.
Why, then, do you expect this voltmeter ti tell you the health of your alternator?

koliver said:

"Recently, I do not see charging on the voltage gauge in the pilot house. The needle goes down to yellow, close to red. "

From your description I am puzzled that you would expect to see how much charging you get from your alternator.
You are measuring voltage at the instrument panel without identifying its source.
When you are on shore power, your charge is not going through the instrument panel, as your engine is not on.
When charging from the generator, your meter is likely reading the same input as when on shore power, so is independent of whether the engine is on or off.
Why, then, do you expect this voltmeter ti tell you the health of your alternator?

Click to expand...

i would think that most likely, the panel volt meter is essentially connected to the start bank and would show any charging source voltage influence on the batteries. doesn't matter if the engine is off or on. he may or may not need to turn on the ignition for the gauge to respond at the panel depending on how it's wired, but the source would (should) always be the battery bank itself.
so yes, he should immediately see voltage rise when the engine starts and the alternator is spinning. there might be a small delay depending on how the internal regulator is set up but he should be seeing voltage rise almost immediately, even if the bank is almost fully charged. the fact that the voltage isn't climbing right away leads me to think the alternator isn't putting out. it looks like a pretty new, beefy, leese-neville unit, so i suspect the internal regulator as do some other folks here. or possibly, there's a bum volt sensing wire that should be exciting the alternator. not sure how that alternator gets it's signal to charge.
if the house bank is charging off the alternator/starting bank through a dc-dc charger he'd greatly benefit installing an external regulator like a balmar or wakespeed.
i use my panel volt meter for "at a glance" monitoring of the alternator output, but also have two separate other meters to show actual amp output and voltages/state of charge on the various other battery banks.

koliver said:

"Recently, I do not see charging on the voltage gauge in the pilot house. The needle goes down to yellow, close to red. "

From your description I am puzzled that you would expect to see how much charging you get from your alternator.
You are measuring voltage at the instrument panel without identifying its source.
When you are on shore power, your charge is not going through the instrument panel, as your engine is not on.
When charging from the generator, your meter is likely reading the same input as when on shore power, so is independent of whether the engine is on or off.
Why, then, do you expect this voltmeter ti tell you the health of your alternator?

Click to expand...

Everything I said earlier was about the situation when I am sailing and the main engine is running alone. When this alternator was first installed, it showed the charge on the voltmeter. Besides, the voltmeter shows any voltage only, when the ignition key is turned. So, shorepower is not the subject.
I just mentioned the generator, which does provide charge and the voltmeter displays it correctly. As soon I turn off the generator, the gauge needle drops, although the main engine is running.

Bmarler said:

i would think that most likely, the panel volt meter is essentially connected to the start bank and would show any charging source voltage influence on the batteries. doesn't matter if the engine is off or on. he may or may not need to turn on the ignition for the gauge to respond at the panel depending on how it's wired, but the source would (should) always be the battery bank itself.

so yes, he should immediately see voltage rise when the engine starts and the alternator is spinning. there might be a small delay depending on how the internal regulator is set up but he should be seeing voltage rise almost immediately, even if the bank is almost fully charged. the fact that the voltage isn't climbing right away leads me to think the alternator isn't putting out. it looks like a pretty new, beefy, leese-neville unit, so i suspect the internal regulator as do some other folks here. or possibly, there's a bum volt sensing wire that should be exciting the alternator. not sure how that alternator gets it's signal to charge.

if the house bank is charging off the alternator/starting bank through a dc-dc charger he'd greatly benefit installing an external regulator like a balmar or wakespeed.

i use my panel volt meter for "at a glance" monitoring of the alternator output, but also have two separate other meters to show actual amp output and voltages/state of charge on the various other battery banks.

Click to expand...

First, the house bank is not wired in this setup. That is totally separated from the crank batteries. These are two 12v batteries, less then a year old.
I do agree with you that the alternator charge should show up on the voltmeter. It used to, and sometimes still does, as I’ve mentioned this earlier. The voltmeter is only showing the crank batteries voltage, nothing else. Either from the alternator, or from the generator, if I run that, too.
I do suspect that the alternator needs some troubleshooting. It could be the wiring, the internal regulator, or the belts. Here is a guide from the manufacturer.

https://www.prestolite-eu.com/wp-content/uploads/2018/05/PP1154_doc.jpg

The first step to look at are the belts, before any measurements. So that is what I will start with. New belts.
From there, I will follow this guide and make measurements.

I also called Balmar. A set of external regulator, monitoring gauge display, and an extra display for the pilot house will cost around $800. Not cheap. I am willing to invest that money to be safe, but first I will do the basics. The Balmar set would be very useful for the future, but I do want o know what happened to the existing alternator? Can it be fixed? I like to understand things.

Maybe the alternator is not self-exciting until it reaches a higher rpm?

Charging RPM

From your description, I doubt the following is the issue. But just in case...

Our new high-amp alternators don't have charging output at low rpm. Then at something like 1200 rpm, charging starts. Its a fairly steep curve (rpm vs charging amps) up to full charging amps.

LeoKa said:

First, the house bank is not wired in this setup. That is totally separated from the crank batteries. These are two 12v batteries, less then a year old.
I do agree with you that the alternator charge should show up on the voltmeter. It used to, and sometimes still does, as I’ve mentioned this earlier. The voltmeter is only showing the crank batteries voltage, nothing else. Either from the alternator, or from the generator, if I run that, too.
I do suspect that the alternator needs some troubleshooting. It could be the wiring, the internal regulator, or the belts. Here is a guide from the manufacturer.

https://www.prestolite-eu.com/wp-content/uploads/2018/05/PP1154_doc.jpg

The first step to look at are the belts, before any measurements. So that is what I will start with. New belts.
From there, I will follow this guide and make measurements.

I also called Balmar. A set of external regulator, monitoring gauge display, and an extra display for the pilot house will cost around $800. Not cheap. I am willing to invest that money to be safe, but first I will do the basics. The Balmar set would be very useful for the future, but I do want o know what happened to the existing alternator? Can it be fixed? I like to understand things.

Click to expand...

Any alternator can be repaired, but you need the tools, know how, and parts supply. Minus that, you could throw parts at it. Maybe if you can source a new regulator for it it will solve your problem. Maybe you could just take it apart and have a look for a flaky connection inside.
Alternators themselves are not complicated, it’s the regulation side of things that can be tricky.
It’s a real shame that the traditional repair shops have all gone away. Nobody repairs alternators anymore, nobody repairs radiators any more, everything gets thrown away and replaced, unless you have the skills to do it yourself.

LeoKa said:

First, the house bank is not wired in this setup. That is totally separated from the crank batteries. These are two 12v batteries, less then a year old.
I do agree with you that the alternator charge should show up on the voltmeter. It used to, and sometimes still does, as I’ve mentioned this earlier. The voltmeter is only showing the crank batteries voltage, nothing else. Either from the alternator, or from the generator, if I run that, too.
I do suspect that the alternator needs some troubleshooting. It could be the wiring, the internal regulator, or the belts. Here is a guide from the manufacturer.

https://www.prestolite-eu.com/wp-content/uploads/2018/05/PP1154_doc.jpg

The first step to look at are the belts, before any measurements. So that is what I will start with. New belts.
From there, I will follow this guide and make measurements.

I also called Balmar. A set of external regulator, monitoring gauge display, and an extra display for the pilot house will cost around $800. Not cheap. I am willing to invest that money to be safe, but first I will do the basics. The Balmar set would be very useful for the future, but I do want o know what happened to the existing alternator? Can it be fixed? I like to understand things.

Click to expand...

Don't be discouraged by posts like the above. Repair shops exist.
There is a possibility that your alternator's diodes were damaged by a
momentary open circuit while the engine was running. This is a
fairly common occurrence that can be avoided with an external regulator.

I would try these guys in Bremerton but I don't know your area:

Romain Electric - Bremerton, WA
ALTERNATORS GENERATORS & STARTERS SALES & SERVICE IN BREMERTON, WA
2165 Erlands Point Rd NW Bremerton, WA
(360) 377-6111

Bmarler said:

It’s a real shame that the traditional repair shops have all gone away. Nobody repairs alternators anymore, nobody repairs radiators any more, everything gets thrown away and replaced, unless you have the skills to do it yourself.

Click to expand...

They're still out there. NAPA is always a source for info on local shops if they don't do the work. I've has starters, alternators, radiators qnd heat exchangers repaired in recent years.

Sent from my SM-T500 using Trawler Forum mobile app

Mike H said:

From your description, I doubt the following is the issue. But just in case...



Our new high-amp alternators don't have charging output at low rpm. Then at something like 1200 rpm, charging starts. Its a fairly steep curve (rpm vs charging amps) up to full charging amps.

Click to expand...

I thought about this reason myself. The problem is, it is not consistent. Sometimes it comes on and charges, sometimes not. Even at high rpm.

Bmarler said:

Any alternator can be repaired, but you need the tools, know how, and parts supply. Minus that, you could throw parts at it. Maybe if you can source a new regulator for it it will solve your problem. Maybe you could just take it apart and have a look for a flaky connection inside.

Alternators themselves are not complicated, it’s the regulation side of things that can be tricky.

It’s a real shame that the traditional repair shops have all gone away. Nobody repairs alternators anymore, nobody repairs radiators any more, everything gets thrown away and replaced, unless you have the skills to do it yourself.

Click to expand...

I agree. I wish old skills and crafts were still high priority. I like taking things apart, too. The problem starts when I have to put it back together.
I might end up taking it apart, if I know what I am suppose to look for. But for that, I will need a spare alternator, just to be safe.

KnotYet said:

Don't be discouraged by posts like the above. Repair shops exist.
There is a possibility that your alternator's diodes were damaged by a
momentary open circuit while the engine was running. This is a
fairly common occurrence that can be avoided with an external regulator.

I would try these guys in Bremerton but I don't know your area:

Romain Electric - Bremerton, WA
ALTERNATORS GENERATORS & STARTERS SALES & SERVICE IN BREMERTON, WA
2165 Erlands Point Rd NW Bremerton, WA
(360) 377-6111

Click to expand...

I looked on the map, but I did not see these guys. Thank for the info.
I bought my present alternator from Blachard in Bremerton, but they are closed down now. They moved to south of Tacoma.
I might call these people you’ve recommended.

Wow so much information. After everything that I've read, I would suspect your internal regulator is not working. First thing to check. Good luck. Jack