Yanmar 370 Alternator upgrade
- Thread starter Kickback
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If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
IMO The modification I would consider rather than a direct replacement would be to go to an externaly regulated alt to improve charging efficiency. The stock Yanmar alt is internally regulated.
I'm interested in DavidMs point... what are you trying to gain?
There are other deficiencies in the Mainship factory install that I prioritized ahead of an alt change. I have outlined what I did & why in my Bacchus website... Projects section... Charging Mods.
Only change I have made since then is moving my eng start to my thruster bank to make my house bank a pure house vs the MS combined start / house.
I'm interested in DavidMs point... what are you trying to gain?
There are other deficiencies in the Mainship factory install that I prioritized ahead of an alt change. I have outlined what I did & why in my Bacchus website... Projects section... Charging Mods.
Only change I have made since then is moving my eng start to my thruster bank to make my house bank a pure house vs the MS combined start / house.
Last edited:
Kickback:
The stock alternator on a Yanmar 370 a Hitachi 80A is internally regulated at a fixed voltage so as a result it doesn’t charge very fast.
Balmar (Balmar.net) makes several levels of high output alternators that will fit in place of the Hitachi and have an external regulator. You will have to hook up the external regulator but that is pretty simple.
But, please tell us what you want to accomplish.
David
The stock alternator on a Yanmar 370 a Hitachi 80A is internally regulated at a fixed voltage so as a result it doesn’t charge very fast.
Balmar (Balmar.net) makes several levels of high output alternators that will fit in place of the Hitachi and have an external regulator. You will have to hook up the external regulator but that is pretty simple.
But, please tell us what you want to accomplish.
David
I doubt you will be able to do a simple "Drop in" replacement. At minimum any larger output alt will require pulley & belt mods to accommodate the higher loads. Other changes may also be required or beneficial after determining what the goal is and how best to satisfy it.
Compass Marine (Commercial Member here on TF) is a well respected resource for marine electrical info and has shared it on his website...
Some articles that are pertinent and may be of interest... scan through his site if you are not familiar.
https://marinehowto.com/automotive-alternators-vs-deep-cycle-batteries/
https://marinehowto.com/marine-alternator-installation-tips-tricks/
I will do some reading all the recommendations. We just purchased this MS40 a week and half ago, I still trying to find time to get all the systems on charging figured out. We had three day 200 mile trip home with it and I noticed that as the day went on the voltage fell. Autopilot was working along with fridge, no radar spinning. House has 3) 8d AGM , Engine 1) 8D AGM, Bow and Stern 24 volt . I found a note that the Thrusters are charged by engine Alt, via 2) charger combiners. On travel days I hardly used Thrusters leaving the dock. So I did not feel as it I drew the Thrusters down. Lowest Voltage I saw was 12.6 at which time I ran the Generator for a while. I'm just concerned that this fall when we head south I will be running Generator to help with charge. That is where I'm at at this point while I continue to research
sunchaser
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Suggest you do two things. First check volts and amps output at current alternator when cruising. Second verify condition of your existing batteries.
Do you have a good monitor associated with your inverter?
Do you have a good monitor associated with your inverter?
sunchaser
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Kickback
My wild a$$ guess is that with no inverter or battery monitor that batteries are in need of assessment. Previous owner could have drawn them down too far. Again, suggest some voltage information as measured at alternator when cruising.
My wild a$$ guess is that with no inverter or battery monitor that batteries are in need of assessment. Previous owner could have drawn them down too far. Again, suggest some voltage information as measured at alternator when cruising.
Jerry
Glad the CMS How To was helpful... lots of good info on his site.
Do some measuring. & tracing of alt output... V, A & where does it go?
You will need a clamp on DC ammeter but if you don't have one its a helpful troubleshooting tool and worth the investment.
My 2008 vintage MS34 had 2 diode isolators... 1 for alt output to house/start and thruster bank and a second that split my 3 bank shore charger to charge 4 battys. I also found what I bel I eve was a factory waiting error. The field excite wire for the alt was wired thru a set of normally open contacts on the ER fire suppression controller so the alt was essentially useless. Only reason I found it was no alt output while boat running but elec shop tested alt and reported it was fine. Reinstalled and did more tracing & measuring to find no power to field was the issue. A pain to trace back but found it run thru the Sea Fire control module incorrectly.
I had a similar issue that raised my concern early in my ownership... 1st longer cruise I had low batty warnings and that started my investigation & troubleshooting. Details of my mods & changes on my Bacchus website... projects section... charging system mods. Once I straightened out the alt charging issues the factory 80A alt has been satisfactory for extended cruises and anchoring that relied on my batty banks.
Glad the CMS How To was helpful... lots of good info on his site.
Do some measuring. & tracing of alt output... V, A & where does it go?
You will need a clamp on DC ammeter but if you don't have one its a helpful troubleshooting tool and worth the investment.
My 2008 vintage MS34 had 2 diode isolators... 1 for alt output to house/start and thruster bank and a second that split my 3 bank shore charger to charge 4 battys. I also found what I bel I eve was a factory waiting error. The field excite wire for the alt was wired thru a set of normally open contacts on the ER fire suppression controller so the alt was essentially useless. Only reason I found it was no alt output while boat running but elec shop tested alt and reported it was fine. Reinstalled and did more tracing & measuring to find no power to field was the issue. A pain to trace back but found it run thru the Sea Fire control module incorrectly.
I had a similar issue that raised my concern early in my ownership... 1st longer cruise I had low batty warnings and that started my investigation & troubleshooting. Details of my mods & changes on my Bacchus website... projects section... charging system mods. Once I straightened out the alt charging issues the factory 80A alt has been satisfactory for extended cruises and anchoring that relied on my batty banks.
Sleeping Bear
Veteran Member
Only thing I don'[t like about that engine is the single belt, better check that first, as as they wear they slip.
sailorskip
Veteran Member
Hire a reputable ABYC electrician to assess and suggest a plan.
Balmar sells single belt alternators in the 100-125 amp range. Any higher amperage, you have to go to twin belts.
But I will ask again, “What are you trying to accomplish?”
David
I have 3) 8d AGM house batteries, 1) 8d AGM engine Battery and Bow and Stern thruster AGM batteries that need to be charges will traveling. They are all being charged by the Alternator . Refrigerator, Autopilot and Plotter are on.. within a hour voltage gauges are dropping to 12.7 from 13.4 starting out. Once the hit 12.5 I run the Generator to help out. Have not been running radar trying to save power. Trying to not have to run Generator
The fridge, autopilot and chart plotter all together will draw about 15 amps. The stock Hitachi alternator should put out about double that when charging.
I would buy a decent clamp on DC ammeter and check where the current is coming and going as what you describe does nt sound right.
A decent meter can be bought on Amazon for less than $100 and a good Fluke meter for $143. See https://www.amazon.com/FLUKE-FLUKE-...&qid=1691633898&sprefix=Dc+cl,aps,125&sr=8-18
Make sure whatever meter you buy reads DC amps. Ads can be deceiving.
David
I would buy a decent clamp on DC ammeter and check where the current is coming and going as what you describe does nt sound right.
A decent meter can be bought on Amazon for less than $100 and a good Fluke meter for $143. See https://www.amazon.com/FLUKE-FLUKE-...&qid=1691633898&sprefix=Dc+cl,aps,125&sr=8-18
Make sure whatever meter you buy reads DC amps. Ads can be deceiving.
David
Cigatoo
Guru
You have a problem with the existing alternator / charging system functioning properly. Not the size of the alternator. As mentioned above get the existing system functioning as it should before making any changes. Get a professional involved.
To Don ,Carl and David
Yes I will get a good meter and confirm alternator. I do have to agree with comments that the Alternator is weak. Does anyone know what the original Hitachi alternator float charge should be ? Before yesterdays two hour run each way I had cleaned belt dust off all areas, I do not know how old that dust was since we just bought the boat a month ago. I will check on any new Dust today. Belt does look good and tension is 3/8 slack between widest spread pulleys.
Jerry
Yes I will get a good meter and confirm alternator. I do have to agree with comments that the Alternator is weak. Does anyone know what the original Hitachi alternator float charge should be ? Before yesterdays two hour run each way I had cleaned belt dust off all areas, I do not know how old that dust was since we just bought the boat a month ago. I will check on any new Dust today. Belt does look good and tension is 3/8 slack between widest spread pulleys.
Jerry
Do you have an automotive electrical shop nearby?
They after can rebuild cheaper than a new.
Most will test at no charge and give you an est to rebuild... them decide which is best. I had a local shop help me troubleshoot and find the problem was no excite V for the field so no output. Turned out the issue was, what I believe, a MS factory riring issue with the Sea Fire controller that shuts eng, gen, blower, etc off in case of fire. Alt excite was wired thru not all OPEN contacts and alt wasn't putting out. The original owner only dud short runs out on a lake and guessing the shore charger covered up the alt issue.
They after can rebuild cheaper than a new.
Most will test at no charge and give you an est to rebuild... them decide which is best. I had a local shop help me troubleshoot and find the problem was no excite V for the field so no output. Turned out the issue was, what I believe, a MS factory riring issue with the Sea Fire controller that shuts eng, gen, blower, etc off in case of fire. Alt excite was wired thru not all OPEN contacts and alt wasn't putting out. The original owner only dud short runs out on a lake and guessing the shore charger covered up the alt issue.
I ordered a new one from D&B electrical.. 89. China knock off.... I know what folks think.. But I have used these folks on Alternators and Starters on my earthmoving equip. Just one example.. I needed a special Alternator for a Linkbelt Excavator.. Dealer quoted 1400.00 and 5 weeks.. D&B talked with me and found a replacement 90 bucks and 3 days... I have had that for 8 years and works great. All the wires coming out of exisiting Alt had various ends and color wires.. the replacement was identical right down to color of wires.. So I'll gamble again.. and have old one tested and fixed.
When I was removing the alternator i found this mystery wire on the alternator. It was not hooked to anything...... Maybe this is my issue ,, Is this suppose to be connected ????
Please let me know... 2004 MS 400 with a single Yanmar 370 .Well I can't figure out how to post picture... Wire comes out of alternator case not attached to back... wire is a female push end..
Please let me know... 2004 MS 400 with a single Yanmar 370 .Well I can't figure out how to post picture... Wire comes out of alternator case not attached to back... wire is a female push end..
Here is a link to the thread on how to post pictures.
Some tachs use the Alt as the source of the signal.
My MS & Yan 6LYA- STP has a sensor on the flywheel... guessing yours does as well. Might be an unused wire for a tach?
A picture would help
Some tachs use the Alt as the source of the signal.
My MS & Yan 6LYA- STP has a sensor on the flywheel... guessing yours does as well. Might be an unused wire for a tach?
A picture would help
Don
NO link to post pictures.
When I seen that mystery wire, I thought of your post about hour issue caused by the sea fire system.... It that wire is not the issue How do I find the sea fire wiring issue, because my 2004 MS 400 also has the sea fire system... Previous owner told me he never had a voltage issue.. But some of his other statements have not been correct.. Go figure.
Jerry
NO link to post pictures.
When I seen that mystery wire, I thought of your post about hour issue caused by the sea fire system.... It that wire is not the issue How do I find the sea fire wiring issue, because my 2004 MS 400 also has the sea fire system... Previous owner told me he never had a voltage issue.. But some of his other statements have not been correct.. Go figure.
Jerry
Well New alternator , and still not charging.. At one point I remember reading about the way the sea fire was wired on Mainships... i was looking at the SeaFire unit at the helm station,, and noticed there is a switch to toggle from over ride to Normal.. I it was on over ride.. I switched it to normal , went to upper helm and that one was on override.. put that on Normal.. Started engine and it was charging 13.5 volts... Well that was good.. turned engine off and half hour later Started engine... Nope it stayed at 12 volts... So I went down in engine bay took wire off sea fire and tried start and no fire... so I jumpered it and it started .... but no charge..
What am I missing ?????????????/
What am I missing ?????????????/
More information... From the Battery terminal on Alternator the cable runs to a Sure Power Multi Battery Isolator, Model 1203 . I removed the cable battery cable from alternator to Isolator and removed one of the battery lugs off Isolator and bolted the two together Started engine and no charge .. So I get back to the Sea Fire system... DOES any have experience with a Issue like this.. I really do not want to reinvent the wheel . Looking for some help here
