New Balmar Alternator Charging Question

[deluxe68]

We have a 50HP Yanmar that had the original 80A alternator. We just installed a Balmar 165A alternator with a serpentine kit and the 614 remote regulator. We just went out to the boat to use the new stuff for the first time this week. We have two 4D 200AH AGM batteries for the house. At idle the charging amps start around 130 and continue like that for around 5 minutes then they start dropping and after 30 minutes we are getting 40 amps. The batteries start at around 80% of capacity. I assumed the charge acceptance would cause the alternator to decrease the output but only when the batteries were closer to 95% charged.

Does this sound normal? The alternator temp is getting up to 68C, but sometimes the regulator is giving a reading of "2bc" or "3bc" instead of temperature.

[Jd1]

Originally Posted by deluxe68

Does this sound normal? The alternator temp is getting up to 68C, but sometimes the regulator is giving a reading of "2bc" or "3bc" instead of temperature.

Yes, this is completely normal. You don't see full se of your new alternator unless you are running lithium batteries that can take whatever the alternator can dish out.

2bc .... could that be 26C
3bc ..... 36C ?

[john61ct]

Originally Posted by Jd1

You don't see full se of your new alternator unless you are running lithium batteries

Going to a bigger bank and lower SoC you will see the high amps last a bit longer.

And some AGM do have a higher CAR than others.

But yes everything is working as it should; a higher output alt doesn't save that much overall time, you still want solar for the 3-5 hours long tail once past 80-85% SoC.

LiFePO4 is revolutionary in this aspect, can completely forget about getting to Full, just idle for 20 minutes rather than hours, and no solar required at all if it's inconvenient.

[DeepFrz]

I would suggest that you limit the output of your alternator to somewhere around 120 - 130 amps so that you don't damage it when you charge a much more discharged house bank. That is a setting in the regulator. Maine Sail has some interesting comments on that on the Compass Marine web site.

130 amps at idle speed sounds pretty impressive to me.

[john61ct]

Called small engine mode, also a similar feature called belt manager.

I think 614 derates for alt temp as well as the battery sensor?

But as long as the ER has decent ventilation and the fan's working well, a Balmar alt should be OK near rated output for that long, they base off pretty robust truck models.

A huge LFP bank would be more of a concern.

[deluxe68]

Originally Posted by Jd1

Yes, this is completely normal. You don't see full se of your new alternator unless you are running lithium batteries that can take whatever the alternator can dish out.

2bc .... could that be 26C
3bc ..... 36C ?

No. The temp would read 60C, next time 60C, next time 2bc, next time 60c.

[deluxe68]

Originally Posted by DeepFrz

I would suggest that you limit the output of your alternator to somewhere around 120 - 130 amps so that you don't damage it when you charge a much more discharged house bank. That is a setting in the regulator. Maine Sail has some interesting comments on that on the Compass Marine web site.

130 amps at idle speed sounds pretty impressive to me.

But it is only putting out that much for 5 minutes. By 30-40 minutes it is putting out about 40 amps and the batteries are still only around 85-90% charged. The lowest I let them get this week was 70% charged.

[deluxe68]

Originally Posted by john61ct

Called small engine mode, also a similar feature called belt manager.

I think 614 derates for alt temp as well as the battery sensor?

But as long as the ER has decent ventilation and the fan's working well, a Balmar alt should be OK near rated output for that long, they base off pretty robust truck models.

A huge LFP bank would be more of a concern.

Correct on the de-rating, I know it cuts off at around 102C, not sure if it progressively cuts output before then. I need to read up on that.

[DeepFrz]

The thermal cut off should only be used as a safety device, not an operating parameter. 130 amps at idle could very quickly increase to a much larger output at operating RPM and if the bank were discharged to 50% (which could happen, right?) then the output could reach rated level for longer than a few minutes. Anyway, just a suggestion. As someone on here says, your boat, your decision. And don't count on your engine room being properly ventilated until you verify that it is.

[HankOnthewater]

As a side issue on this thread (and many others), lots of posters use acronyms. Yes, many readers will know the meaning or what it stands for, but maybe others may not know. I wonder if it would be preferred when a poster introduces an acronym, to put its meaning in between brackets, only for the first time it is used in the thread, from thereon acronyms are fine and if readers do not read the whole thread... and miss the meaning/explanation, then it is their problem.

This thread has only 9 posts sofar and used the following ……
- SoC State of Charge (of the battery), generally expressed as a percentage of fully charged which is 100%
- ER is that engine room??
- CAR ??? charge acceptance rate??
- LiFePO4 Lithium Iron Phosphate (type of battery)
- LFP I assume same as above?

Some acronyms/abbreviations are nearly universal and may not need explaining:
- RPM revolutions per minute
- Amp ampere, unit of current
- Alt alternator
- C Celcius, degree
- AH Ampere hours (capacity of battery)
- AGM absorbed glass matt (type of battery)

Anyway some thoughts. If I come across as pedantic here...... was not intended that way, just trying to help some readers.

[Paul L]

Originally Posted by john61ct

Called small engine mode, also a similar feature called belt manager.

I think 614 derates for alt temp as well as the battery sensor?

But as long as the ER has decent ventilation and the fan's working well, a Balmar alt should be OK near rated output for that long, they base off pretty robust truck models.

A huge LFP bank would be more of a concern.

I've never seen a Balmar alternator that could run at it's rated output for any extended lenght of time. They always get to the overheat derating quickly. My 120 amp Balmar that I have set to Max at about 85 amps with the belt manager onlY delivers full output for maybe 20 mins before it derates for heat. Their output rating is more marketing than reality.

[Pizzazz]

Originally Posted by Jd1

...You don't see full se of your new alternator unless you are running lithium batteries that can take whatever the alternator can dish out.

With wet cell batteries, when they are fully charged, it is called state of charge at 100%. When charging to about 80% capacity it is called bulk charging. In this mode the battery takes as much current as is available up to about 1/3 of it total capacity (e.g. for 100 AHr battery the max charging current is around 35A. Approx. 85-90% of this current is stored in the battery (called charging efficiency), the rest goes to heat. Once the battery is 80% charges, its internal resistance increases and the charging current drops (also the battery starts to gas more). It is a very painful (meaning slow) process to charge wet cell batteries above 80% (the 80% figure can vary a bit based on temp, battery condition, etc. but it is definitely not 95%).

You have three choices:
1) Accept that your batteries will only reach a max charge of 80%. This is pretty much taken for granted in the boating world. Once you make peace with this thought you will have efficient charging (i.e. stop the engine/generator once the current drops), quick charge times, less gassing and a happy life. Your batteries will not last as long as they could but will last a long, long time. If you feel bad about using only the 50% to 80% state of charge range, feel free to discharge to 20%. It will not be as bad as some people will lead you to believe. Pretty much use the we cells as if they were lithiums and do not worry.

2) Spend the extra effort to always charge to 95-100%. This means either long generator run times, extensive motoring or massive amount of solar. Even then, assuming you start fully charged at sunset, you will quickly drop to 80% since most people consume large amounts of energy in the evening (lights, pumps, laptops, TV, like a regular house). You will constantly worry about your state of charge and will rearrange your life around your batteries. You will gain double the expected lifetime of your batteries.

3) Buy lithium batteries as suggested above. You will reduce weight, have a great and flexible system, possibly accepting higher charge rates and you will spend 5x more money than comparable wet cells.

As someone suggested in another thread, I should not recommend a solution since different people have different preferences. 95% of the boaters I know follow approach 1.

[Pizzazz]

Originally Posted by Paul L

I've never seen a Balmar alternator that could run at it's rated output for any extended lenght of time. They always get to the overheat derating quickly. My 120 amp Balmar that I have set to Max at about 85 amps with the belt manager onlY delivers full output for maybe 20 mins before it derates for heat. Their output rating is more marketing than reality.

You may be right but in my experience, more often than not the limiting factor is the battery not overheating. I have a cheap 50 amp stock alternator and an even cheaper 80 amp aftermarket alternator. Both run within 5% of their rating with an old Balmer ARS-4 regulator when charging in bulk mode.

Let's be realistic. The typical cruiser has 400 AHrs and starts charging at 50% state of charge. This leaves only 30% capacity in bulk mode charging which is about 1 hour at 120 amps, 1.5 hours at 80 amps. You really do not need long alternator runs at max capacity. It is a myth or a very special situation (i.e. you are running the engine under heavy load, so it heats up, the alternator supplies concurrent loads - watermaker, etc. and very little is left for the batteries) where you need to the full capacity of the alternator.

[Paul L]

Originally Posted by Pizzazz

You may be right but in my experience, more often than not the limiting factor is the battery not overheating. I have a cheap 50 amp stock alternator and an even cheaper 80 amp aftermarket alternator. Both run within 5% of their rating with an old Balmer ARS-4 regulator when charging in bulk mode.

Let's be realistic. The typical cruiser has 400 AHrs and starts charging at 50% state of charge. This leaves only 30% capacity in bulk mode charging which is about 1 hour at 120 amps, 1.5 hours at 80 amps. You really do not need long alternator runs at max capacity. It is a myth or a very special situation (i.e. you are running the engine under heavy load, so it heats up, the alternator supplies concurrent loads - watermaker, etc. and very little is left for the batteries) where you need to the full capacity of the alternator.

The scaling back of my Balmar is due to the alternator overheating, not the batteries. The Balmars that I've seen will not run at their rated output for an hour without overheating and needing to be scaled back. My 600ah AGM battery Bank can take a lot more for the first 1 to ,1.5 hrs than my Balmar 120 amp belt limited to around 85amps will deliver. They are oversold with marketing ratings as far as I am concerned.

[OceanPlanet]

Virtually no normal small case alternators can cool themselves enough to run high output for very long. An 80A or other low-output don't produce as much heat, so can run closer to their rated output. Small-case 180A, 160A, 140A, or even 120A will have a hard time maintaining their output, largely due to the heat produced by the diode bridge (rectifiers) that inside the unit. Bigger alts do better but some do much better than others. Often we use modified large-case units that can fit into the small case stock location. Like the American Power 42i series (especially for 24V x 160A), MGDC (Mark Grasser) for 12V x 250A, etc.


However, another great option we use with the small-case MGDC is their "remote rectifier" (RR), that takes much of the heat off of the alt. and onto a separate fan-cooled unit. This allows the small-case 160A or 180A to run at very near full rated capacity, continuously. Makes a big difference. There are 3x AC cables from the alt. that connect to the RR, which converts the AC to DC and the pos/neg DC cables go to the batteries from the RR.