New fuel cell. Does it change the math?

[LakeSuperior]

Originally Posted by seandepagnier

It is unfortunate you think the diesel is 30% efficient. It is no where near this good on your small boat, especially with electricity as the output. A lot of people don't really just how much they waste.

there are 40.7 kwh per gallon of diesel. You can calculate how many amps going in your battery at particular burn rate do the math. For example, if you get 70 amp charge at 2 liters per hour, this is 1.6kwh. The efficiency from fuel to battery then is 4%.

A typical small diesel is 30 to 35 percent efficient. A typical alternator is 80 percent and battery charging efficiency is 80%. Running the numbers gets me to 15% which is roughly 3X higher than your number.

[Na Mara]

It’s the BMS that regulates the current from the alternator with the CL 12V 200A Victron BMS. What fuse you use sets the max current allowed to pass. 200A fuse sets the max current to 180A and so on. With a 210A large case alternator I’d put a 210A fuse in to set the max current to 190A.

I am a little worried about the alignment with the large case alternator. It doesn’t say that it will work on 4HJ yanmar engines.

[donradcliffe]

One of the raceboats I deliver has a Yanmar 4JH4-TE engine with a side mounted large frame second alternator with a serpentine belt. It has a custom mount with turnbuckles for belt tension. It doesn't even get warm to the touch at 120 amps.

[Na Mara]

The second mount sounds ace but I have no clue who would do custom mounts for me.

[dannc]

Originally Posted by Na Mara

The second mount sounds ace but I have no clue who would do custom mounts for me.

Try a local machine shop. This stuff is not rocket science.

Later,
Dan

[Dockhead]

Originally Posted by Na Mara

The second mount sounds ace but I have no clue who would do custom mounts for me.

You have a Yanmar?


Yanmar makes factory mounts for second alternators for at least the 4JH series. I have a 4JH3HTE, 100 hp. Was fitted already in Japan with two alternators, before it arrived at the shipyard. There are mounts on the starboard side cast into the block for the second alternator.

[Montanan]

Does this fuel cell require pure water so as to avoid having the electrodes contaminated and their useful life degraded quickly. I suspect it does, so you will need to be able to source distilled water and carry such.

Simpler and less expensive to just use solar panels.

[Pete7]

Originally Posted by Na Mara

I went to that site and I cannot quite make out what you are talking about. This looks more like a bespoke job for a full electric conversion. I may get round to that but not in the next decade hopefully.

Ah sorry. Try this, aimed again at electric drive but offering the ability to charge at 5Kva:

https://www.hybrid-marine.co.uk/inde...agoing-hybrids

They switched from Lynch motors to PMAC a few years ago. However, it puts the generator above the gearbox which might be a better fit for you.

Pete

[Na Mara]

Great system Pete but probably more something I would do if repowering the boat. It also looks pretty expensive and something that company would have to do at their yard which then means a pair of delivery trips as well. Maybe not this time.

[Na Mara]

Dockhead, I’ve found a dealer who makes a kit for second alternators to the side for “most” 4jh engines. I’ve asked them whether the kit will work on my engine and about shipping. We’ll see what they say. I’ve also contacted yanmar about the possibility of fitting a second alternator to my engine and will see what they say as well.

Assuming that I can’t do such an upgrade without a custom mount, the safest course here is to do the serpentine kit with a 170A small case alt that I know fits. I’ll work on that assumption when planning what I’ll do.

[Dockhead]

Originally Posted by Na Mara

Dockhead, I’ve found a dealer who makes a kit for second alternators to the side for “most” 4jh engines. I’ve asked them whether the kit will work on my engine and about shipping. We’ll see what they say. I’ve also contacted yanmar about the possibility of fitting a second alternator to my engine and will see what they say as well.

Assuming that I can’t do such an upgrade without a custom mount, the safest course here is to do the serpentine kit with a 170A small case alt that I know fits. I’ll work on that assumption when planning what I’ll do.

The second alternator mount on my 4JH3 came from the factory. The engine was delivered from Japan with two alternators, and that was back in 2001.



If I were you I would check to see if there is a Yanmar standard bracket for your engine.


If your engine is like mine, it's got the mounts for that bracket cast into the block. It looks pretty easy.


One drawback of my setup is dual v belts instead of serpentine. I get to faff with belt tension on a regular basis, and too much tension will prematurely wear the front main bearing. Serpentine drives are brilliant.

[Na Mara]

As I say I contacted yanmar so we will see what they say but there are no obvious attachment points for a second alternator on the starboard side of my engine.

A thought that has just struck me though is that the engine is now 27 years old and with an unknown but undoubtedly low number of hours on it for its age. It’s a great engine that has been well maintained, starts every time and runs like a dream but aren’t I approaching the time when a overhaul or repower is due?

If that’s the case is not spending money on a soon to be replaced engine a bit silly?

[rslifkin]

Originally Posted by Na Mara

As I say I contacted yanmar so we will see what they say but there are no obvious attachment points for a second alternator on the starboard side of my engine.

A thought that has just struck me though is that the engine is now 27 years old and with an unknown but undoubtedly low number of hours on it for its age. It’s a great engine that has been well maintained, starts every time and runs like a dream but aren’t I approaching the time when a overhaul or repower is due?

Not necessarily. If an engine checks out healthy, is working well, and parts are available I see no reason to rebuild or repower unless you want to change to something different for functional reasons.

[Dockhead]

Originally Posted by Na Mara

As I say I contacted yanmar so we will see what they say but there are no obvious attachment points for a second alternator on the starboard side of my engine.

A thought that has just struck me though is that the engine is now 27 years old and with an unknown but undoubtedly low number of hours on it for its age. It’s a great engine that has been well maintained, starts every time and runs like a dream but aren’t I approaching the time when a overhaul or repower is due?

If that’s the case is not spending money on a soon to be replaced engine a bit silly?

Diesel engines can last 50 years or more if they are taken care of and operated in healthy regimes (not full power all the time, not near idle all the time). Why do you think you will need to replace it soon?



Which engine is it, by the way?

[Na Mara]

It was just a thought that came to me. I like the engine and trust it so changing it is not something I want to do. If it’s young at 27 then that’s dandy.

Its a 4jh2 dtbe 88hp engine mounted under the pilothouse floor with loads of space either side but not much front and back. I cruise at 2800rpm and rev over 3000 occasionally when manouvering. It’s probably got around 1-2000hrs on it as she was lightly used for 24 of her 27 years. Throttle and gearbox are electronic. A more or less new hitachi 80A alt is what sits on her at the mo. That charges a 75A lead acid starter and 5x75 lead acid leisure batteries all Banner. These are done and will be replaced this year, hence the thread.

I’m well overpowered as the boat is 12,5t loaded and only 43ft loa.