Add second large alternator to charge house batteries

[flyingfin]

So your plan is to run an inboard engine (basically a heat machine that can also spin a shaft) down in the hull of a vessel in order to charge high cost batteries so you can try to cool down the heated hull at night with AC?? Sounds to me like an introductory Thermodynamics course is in order. But you will make the battery salesmen happy

[Jammer]

Originally Posted by a64pilot

A Honda’s $1,000, is very reliable, puts no hours on your motor and you don’t have to modify anything.

I think it is important to mention the drawbacks of this approach even though it is increasingly common.

1. There is a carbon monoxide risk. People have died as a result of running generators on deck. In Minnesota we now have a burdensome law requiring three separate placards on carbon monoxide risk from generators because of a particularly unfortunate accident where three people died below decks on a cold rainy day.
2. There is a fire risk from the gasoline used to fuel the generator. Where will you keep the fuel? Where will you store the generator? What if there is a fuel leak while it is being stored?
3. There is an electric shock risk particularly if the portable generator is used in adverse weather or sea state.
4. Portable generators are prime targets for theft.
5. You will use more fuel. Honda generators will give you 4-6 kwh per gallon of gasoline while a typical diesel genset will give you 9-11 kwh per gallon.
6. They won't last as long. While reports vary widely, I put the useful life of the better suitcase generators at around 2000 hours. The low-speed diesel sets (Northern Lights etc) are good for 20,000 hours, and the economy diesel sets (Farymann/Entec, Next-gen) about half that.

As a result of 4, 5, & 6 over the course of years it's hard to save much money.

[69Datsun510]

Originally Posted by flyingfin

So your plan is to run an inboard engine (basically a heat machine that can also spin a shaft) down in the hull of a vessel in order to charge high cost batteries so you can try to cool down the heated hull at night with AC?? Sounds to me like an introductory Thermodynamics course is in order. But you will make the battery salesmen happy

You missed read my posted or my philosophy of power supply on my boat. I specifically stated, I own a sailboat, prefer to sail, and not run any motor. I wouldn’t use my engines or generator at all, as a charging source except, if already motoring because of no wind, or my solar and my usage haven’t stayed in proportion. I wouldn’t run any motor to run my AC, not even a generator. I’d only run my AC if I had solar or battery reserve to run them. There will be power left over from sunny days, with my solar, I can run my AC, two small AC units, in the two aft cabins, because the batteries are full.

OP asked about getting power to charge batteries from adding an alternator. It’s been established his thought of adding a second alternator that can be remotely controlled. Most have suggested not to add, but to upgrade one or both alternators to larger output ones. However, limited on doing this with motor specifications, and limited gain. His best options, so far, are to have large solar and lithium battery power, won’t need any charging from motors, or get a generator.

I’ve suggested the large solar and lithium, and large framed alternator to get the best out of the situation, should you need to assist on occasions or harvest power while you have to motor because of no wind.
As far as having an understanding of thermodynamics, I have a Mechanical Engineering degree, worked as a mechanical engineer, not specifically in thermodynamics, did have classes as required for my degree. I did acknowledge the one post regarding the Yanmar power curves, available power under different conditions, will limit size of output of the alternator. Was a good constructive fact to bring to the subject.
Finally, I can say members, me included, can say they have lengthy experience and schooling, but could be blowing smoke. I’ve even given another members thread with supporting data of close to 3 years, and rarely has to use his generator. He even has a power hungry water maker.

[69Datsun510]

Originally Posted by Jammer

I think it is important to mention the drawbacks of this approach even though it is increasingly common.

1. There is a carbon monoxide risk. People have died as a result of running generators on deck. In Minnesota we now have a burdensome law requiring three separate placards on carbon monoxide risk from generators because of a particularly unfortunate accident where three people died below decks on a cold rainy day.
2. There is a fire risk from the gasoline used to fuel the generator. Where will you keep the fuel? Where will you store the generator? What if there is a fuel leak while it is being stored?
3. There is an electric shock risk particularly if the portable generator is used in adverse weather or sea state.
4. Portable generators are prime targets for theft.
5. You will use more fuel. Honda generators will give you 4-6 kwh per gallon of gasoline while a typical diesel genset will give you 9-11 kwh per gallon.
6. They won't last as long. While reports vary widely, I put the useful life of the better suitcase generators at around 2000 hours. The low-speed diesel sets (Northern Lights etc) are good for 20,000 hours, and the economy diesel sets (Farymann/Entec, Next-gen) about half that.

As a result of 4, 5, & 6 over the course of years it's hard to save much money.

All reasons, I wouldn’t use my Honda except at anchorage, to power my Cruise RO water maker at anchor. I mentioned at the beginning of the thread, the Honda doesn’t put out enough amperage to charge large house battery banks to make a large enough difference.

I have the Honda to power my Cruise RO water maker if need be, and for emergency power for navigation electronics while on passage. Both situations being essential on a passage, and you would be glade to have them in that situation. Any responsible captain should know all of the safety risk examples you have sited, and know how to address them, and monitor the while in use. Only use when physically monitoring, not sleeping, preferably in the daytime for easier visibility.

Using any fuel burning equipment on board, has risk, and it’s up to the operator of such equipment, to be aware of the safety factors, while operating them. Even your gas stove and oven in your galley fit this risk area.

Using the Honda on anchorage, with proper safety, and proper carbon monoxide alarms in the boat, the alarms should be on your vessel already for safety. I’m not sleeping in any cabins on a boat, if not onboard.

I store my Honda in a deck compartment, not visible to attract thieves, my dingy and paddle boards get enough attention for that situation.

I would use large alternator to harvest power while already having to motor for lack of wind. The motor is already being used for a purpose, just getting some power from there, if I want. Can be externally regulated to control how much and load added to the motor.

My system doesn’t need a Northern Light or similar generator, my system is designed for not needing to run any motor for house batteries.

I also stated, I was thinking on upgrading my alternator, doing alternator modification as the OP was inquiring about. To use my boat motor, if need be at anchor, a rarity but an option. There are loads of boats on the water that already do this, but with small gains off a 80 amp rated alternator putting out 40amps at best. If I have to do it, I want a big alternator pushing at least double, or possibly triple, to cut down the time I would need to run it.

My set up doesn’t need a Northern Lights or similar generator, it’s designed to harvest and store enough power by solar and the lithium house bank. CatNewBee has such system with documentation for several years of rarely needing to run his generator, and hates running any motor. He has a power hunger all electric galley and appliances too.

[Cylon60]

Hi, I am in the middle of an exercise to add a 2nd altenator to my 45HP Yanmar.. The objective is to introduce resilience such that the engine and house battery banks are fed separately but when one alternator kick out the other will pick up both banks charging.. The reason for this is transatlantic sailing..


I've gone with a Yanmar 2nd alternator kit which includes a second 125Amp alternator. benefits of this are that it comes with brackets, adapters, belt etc. and insert for engine wiring bus. It also keeps me within warranty.


To bring some context to the origins of the thread I found that the following issues guided me in the direction I took..


1. House and engine loads translated into total amperage requirements

2. Battery capacity relative to load and rate of depletion of charge

3. Efficiency of the engine (burning diesel) with the additional load on the crank and optimal balance of the alternators torque on the engine. Would it cause an imbalance in wear and tear
4. I don't like petrol on a boat and a separate gen set is too risky .... explosion or fire (but that just a pet hate and only partly rational ;-) ).


In the final design I have each alternator wired to its own battery group. They both are rated at 125Amps. I'm also using Argo FET Battery isolators with alternator energize input..


Hope that helps..

[captstu]

I fitted a Voyage 430 with twin 200 Amp alternators - 1 factory 55 and 1 200 on each 3GM35F. The 55s charged the twin starting batteries - unmodified - and the new 200s each fed 1100Ax12V banks that were ganged together.

The setup fed the house and a 3kw inverter - that, in turn, fed a Splendide Washer/dryer, a water maker, and a 16,500 BTU/HR air conditioner. There was no auxiliary generator.

The boat was our ful-time residence for 5 years - never took on shore water and did nearly all our laundry on board.

When sailing, we did not need the a/c, but before entering an anchorage, we closed up the boat, turned on the a/c and operated the engines normally for harbor approach. After anchoring, we allowed one engine to run about 1200 rpm to support the a/c over dinner.

When sleeping, we turned off the engine and ran the a/c on the battery bank. The undervolt (11 V) shut down the inverter about 3 or 4 a.m. and we "coasted" until morning, starting up the engines if necessary depending on the heat and humidity.

We ran both engines when washing clothes if the a/c was on - generally shutting the a/c during the dry cycle.

We had a battery failure after 3 years - the AGMs just ran dry and we didn't know about adding water to AGM batteries them - we replaced the AGMs with flooded cells and had no further battery problems.

The belits were a continued source of problems. We had 2 high power "V" boats on each 200 amp alternator - factory belts on the 55s. The 200 amp starting load was to much for the belts so they slipped a bit - leading to a belt failure about every 6 months. Current setups use notched belts of various sorts that do not slip.

The ignition switch for each engine was wired to turn off the exciter current for the respective 200 A alterator. We shut off the exciter when maneuvering in an anchorage since sudden acceleration, for example to stop at a mooring, was very slow when simultaneously accelerating the alternator. With the field current off, there was no load and the engine accelerted normally.

The engines were under higher than designed load - and were always on the on the edge of overheat. As a result, we believe, both engines failed at about 5000 hours - I spent about $4500 to replace 3 of 6 pistons, both crank shafts, all bearings and gaskets, and odds and ends like rings, oil pumps and such.

This was an expected failure due ro long term overload.

The overall cost of this unit was about $8000, special pulleys (stock available now), two High Output alternators, 2 Balmar regulators, 3 alternator rebuilds (overheat killed diodes), and lots of "00" wire -direct feed from each battery bank, direct feed from the alternators (6" from alternator to fuse and "00" to battery) and some instruments to see what was going on. You must manage your voltage drop very carefully during design. We saw loads approaching 500 A during a/c startup.

Results:

1. even with the engine rebuilds, it was no more expensive than a generator
2. It was very quiet - I had no problem runnning it in an anchorage, we could eat in the cockpit without disruption.
3. Fuel consumption was undetectable - we ran up and down the ICW a few times for fun on a single engine with the a/c running - no more fuel than just running an engine.

If I did it again:

1. Notched belts to avoid slipping- a single wider belt - is essential. Must of the heat must have come from belt slippage, but I did not know since both the engine and alternator pulleys were very ot.
2. Extra engine room cooling. more extra cooling, still more cooling. Consider an engine auxiliary oil cooler for the engine.

This is not an easy upgrade. Significant cable access had to be added to get 3 separate "00" cables to the new fuse blocks protecting the battery. Battery cooling was added (enough). Extra engine and oil cooling makes space management hard.

The Voyage was stock with 8xGC2 batteries and 2X41 starting batteries. This is a minimum if you want to run a/c underway. Unless you understand watering AGM batteries, I suggest flooded cells- the use charging loads and daily discharge cycles required at least weekly watering. The flooded cells showed no signs of problem after 2+ years when I sold the boat.

Drop me a not if I can help: stu@shearwater-sailing.com

[Mystic38]

Personally i would not add a second alternator.. but simply replace the stock weedy one with (say) a 6 series 100A balmar.. its a mechanical replacement so installation would be easy, and with an external regulator you will significantly improve overall charging efficiency.
for comparison, I did this on a W38 westerbeke with a stock "50A" alternator (max'd at 32A) and cut charging time by 75%.. ran 100A at 1400rpm

and i will be doing it on both 3GM30 of my cat...

[rslifkin]

Stu, another thing that would help engine longevity in that usage is to under-prop a bit. That way the overload when motoring with a heavy electrical load is less, and you'd get better throttle response too. Only downside is you'd possibly lose some speed when electrical loads are light, as you would hit max RPM before the engines were at max power.

[Cheechako]

I'll give this a go:
Is it possible to add a second larger alternators to twin Yanmar 3YM30, 29 HP, dedicated only to charging the house batteries? If yes, what is the largest alternator that is recommended?
You might consider just using one engine existing alternator for that. With a battery switch to combine or not combine. Or in your case a larger alternator, but not a second one. You CAN however add a second alternator at some expense.
I would go with a 75 amp alternator if you are not trying to get too complicated. Or you can spend big bucks and time and get a special belt and up to 200 amp alternator etc. You can do 100 amp with one belt , but sometimes it is too much causing belt wear and squealing on start up.

Can such alternators be engaged and un-engaged at the helm station or electrical panel or navigation station.
Yes, just put a switch in the field wire from the regulator. You can turn the alternator on or off at will. (use a regulator outside the alternator, not a built in regulator)

Does having the large, second alternators partially or fully alleviate potential issues from idling the engine daily at a high enough RPM for the alternator to provide 50% of it's rated output due to the increased load of running the second laternator?
In theory yes it helps. But if you use your boat and not sit all the time, you will run the engine enough to not be a problem. ALL my boats have been alternator charged systems for simplicity. None have been an issue from idling. But be aware, batteries are the charging limiter. They heat up. A typical 100 amp alternator will start out very high, like 85-90 amps. Within 10 minutes or so it will start decreasing output. By maybe a half hour you will be down to 50% of output and it will decrease output rapidly after that. The last 10% or so of charge takes a very long time.

What are the pros and cons of this sort of set up as opposed to having a generator on a Cat that has two engines as described above to charge a large bank of lithium batteries. The boat has 1200 watts of solar and 800AH of lithium batteries at 12 volts.

As described above and with the size alternators you recommended how long would both engines need be idled to maintain output from both alternators of 50% of their rated value? is there a way to keep the alternators cool enough so that they don't lose output or at least don't lose significant output from getting hot or is it all about selecting the best possible alternator for the job? see above ref: batteries.

Another thing I will mention is with two alternators tied to the same battery bank, both will not necessarily engage. One alternator regulator might sense the output from the other alternator and shut down it's charge rate. Don't ask how I know this! I think there are devices to regulate this situation though. With all your other available charging systems, I would simply replace one alternator you have with a high output and add appropriate switching for it's output

[Augi]

Originally Posted by Jammer

I think it is important to mention the drawbacks of this approach even though it is increasingly common.

1. There is a carbon monoxide risk. People have died as a result of running generators on deck. In Minnesota we now have a burdensome law requiring three separate placards on carbon monoxide risk from generators because of a particularly unfortunate accident where three people died below decks on a cold rainy day.
2. There is a fire risk from the gasoline used to fuel the generator. Where will you keep the fuel? Where will you store the generator? What if there is a fuel leak while it is being stored?
3. There is an electric shock risk particularly if the portable generator is used in adverse weather or sea state.
4. Portable generators are prime targets for theft.
5. You will use more fuel. Honda generators will give you 4-6 kwh per gallon of gasoline while a typical diesel genset will give you 9-11 kwh per gallon.
6. They won't last as long. While reports vary widely, I put the useful life of the better suitcase generators at around 2000 hours. The low-speed diesel sets (Northern Lights etc) are good for 20,000 hours, and the economy diesel sets (Farymann/Entec, Next-gen) about half that.

As a result of 4, 5, & 6 over the course of years it's hard to save much money.

As mentioned, I plan to avoid use of a portable generator except in an emergency. A good out come is I buy one and never use it.

[darrelweb]

Go to www.hamiltonferris.com.
I upgraded my yanmar with a 125 amp alternator with their Max Charge voltage regulator...was very pleased with the results. Same engine you have.

Give them a call and tell them your needs. 508-743-9961

Another idea and my 2 cents worth.

Darrel

[Augi]

Originally Posted by 69Datsun510

In my set up, I’m suggesting to only have one alternator per engine, one a large framed 200amp, and on stock. To install a large frame 200-250amp alternator, will require a serpentine belt upgrade, too. I would only use the large alternator, as secondary charging method, if the solar wasn’t able to keep up over days of low output. Or if motoring, harvest power on a motor already being used for propulsion.
Only use the large alternator on anchorage as a backup or emergency charge because batteries are getting low.

The Honda would be to power the Cruise RO water maker, if I needed to conserve power, or in an emergency to have power for navigation equipment during a passage, should the solar or lithium battery system stopped working. I would have essential power while getting the main system back up and running.

For data on such system, read CatNewBee’s build on solar ad lithium, and well appointed all electric galley. He has been using his system for 3 years now, I think. https://www.cruisersforum.com/forums...ey-201795.html

My thoughts are, I have a sailboat, want to sail, and not rely on motors, boat or generator. Therefore, I will have a system design with enough solar and lithium to be comfortable. We are fortunate with owning catamarans, we can put up large solar panel arrays, have areas to put large lithium battery packs. The technology of these components has made it possible to do suggest task

Thanks for referring me to CatNewBee's thread. It is absolutely excellent.

https://www.cruisersforum.com/forums...ey-201795.html


I am going to head in the direction of what CatNewBee has done. That means not change to the existing alternator set up on either engine. But that means I will go with a NextGen 5.5 KW generator, similar amount of solar and lithium batteries, and same supporting equipment. All electric kitchen. Only propane will be for transom grill (to have propane cooking as back up), and to run a portable generator in an emergency. A good outcome is I never use the portable generator on the boat. I am not capable of DIYing as CatNewBee did. I need to find the right vendor(s).

[mvweebles]

I have two alternators on my 75hp Perkins 4.236. I think one is a 150A Balmar, and the other is a 75A Balmar. If you use their 612-Dual regulator, you can gang them together essentially forming a single 225A alternator to a single house battery instead of splitting between two batteries (and two regulators). Reason for this are several. First, large LFP bank can accept higher charge rates. Second, once stepped-down to say 90A, each Alternator will run at 40% each vs one at 85A and one at 5A (sample numbers, you get the idea). Finally, if one dies, the other will pickup the slack to it's capacity, so there is redundancy without battery switches.

See attached PDF from Balmar. Attached JPG is the diagram.



http://www.balmar.net/wp-content/upl...612-Dual-H.pdf

[Augi]

Originally Posted by darrelweb

Go to www.hamiltonferris.com.
I upgraded my yanmar with a 125 amp alternator with their Max Charge voltage regulator...was very pleased with the results. Same engine you have.

Give them a call and tell them your needs. 508-743-9961

Another idea and my 2 cents worth.

Darrel

Thanks for the input! What you suggest in regards to the existing alternator set up, is the most I would do if anything. Doing much more is not worth the $$, inherent limitations, potential problems and hassle.

I am going to head in the direction as what CatNewBee did as he described at the link below.

https://www.cruisersforum.com/forums...ey-201795.html

If I do as CatNewBee there is no need to change the existing alternators or add a second alternator to either engine.

[roland stockham]

The issues with very large alternators is always cost v output, allowable load on front pulley, overheating and how to reduce load when motoring. Generally belt driven alternators are not that good as generators. If instead you added a clutch driven A/C generator sized to the motors rated output you would have all the power needed, not have to worry about light engine loads and could easily disconnect it while motoring. Don't know if it has been do e this way but may be worth some research if the is space at the front of the engine. If you literally just want battery charging the are very good DC units designed for direct drive from people like Polar power in the 5-10Kw range which have the advantage of not need a fixed speed governor. DC generators are significantly more efficient than alternators.