Been considering the same myself, mine never had a generator and adding one is very pricey so thought of same option.
There is a commercial solution (VERY pricey) for high end by Nigel Calder. By the way inverters have relays usually and are not Ignition Protected so it can not be in the engine room.

by me from another thread:
There is two parts to this mostly economics. A new marine generator is going to be $12-15k and while nice, you need to be able to afford it and it will ad some value to the boat but you'll not likely get it back on sale. Used half that as, but you have to find a decent one, then what do you get? Likely high hours already since it is some kind of take out from another boat. And again as mentioned any generator running at anchor in calm air will have a high CO risk. Get CO monitors if not already installed, even the main engines can lead to CO issues.

I have not started yet but my plan is this; for that $6K I can get a good sized inverter/charger 6000W ($1,200) . And a good size LifePo4 Lithium battery bank (48v 200ah) ($1,000) with a battery management system ($250). That will let me run anything I want to. Even the AC for a short period like to cool the cabin a little before turning in at night. So far that's about $3k installed. Zero noise, zero CO. This is where I am going to start.

I don't want solar panels all over the boat. So to augment shore side charging I will add later as a second phase an extra 48v PMA, Permanent Magnet Alternator ($300). PMAs have no internal brushes or regulators just plain wires so no Ignition Protected issues in a gas boat. The PMA will feed into an MPPT (charge controller - $900) next to the Inverter. Whenever my main engine is running it will charge the batteries back up. And/or I can run the AC off the engines before anchoring and really cool the cabin down. So all in I hope to be around $4500.

I plan to start this project this summer and will post how it works.
After having this basic idea my research lead to this where I admittedly got a lot more details. So its being done but I cant see their costs.
https://www.morganscloud.com/2019/02/13/nigel-calders-generator-replacement-machine-part-1-what-you-need-to-know/
https://integrelsolutions.com/

 

I think at this size boat not having a generator reduces value, it's not so much that having one increases it, if that makes sense?

At the same time, I don't think having a slick battery/invertor will add value. People generally want a generator to run the air, run the hot water heater and drink some coffee (for extended periods ). Batteries are hard pressed to do any of these reliably, repeatedly?

 

I think at this size boat not having a generator reduces value, it's not so much that having one increases it, if that makes sense?

At the same time, I don't think having a slick battery/inverter will add value. People generally want a generator to run the air, run the hot water heater and drink some coffee (for extended periods ). Batteries are hard pressed to do any of these reliably, repeatedly?

With today's systems I think it will be more common. Most large cooking loads are short term 30/45 minutes or less.

It is why I am looking at 48vdc, at 12vdc the current needed is 4x larger. This means huge battery cables and any resistance becomes an issue, cable length to inverter, the inverter internal components, alternator sizing, etc. But at the 48vdc I can get a split phase 240/120 Inverter/Charger at a reasonable price. And the PMA solves the longer term power needs; a solar panel just cant output 3000+ watts without covering the boat (64 sqft). The LifePo4 batteries 48 * 200 is 9.6kw, available at least 8kw.

Now I have made some other upgrades that fit into this plan. 30A 120 shore I upgraded to 50A 240/120.
Stove top is a modern 240 volt two burner. Hot water heater was shot so 6gal is now an 11gal 240v, but engine heats that and it hold well so far. AC will have to see how that works out.

 

What is your source for a 48V 200ah battery for $1000?

I am also considering this for when my genset kicks the bucket, but I think your price is too low.

I just purchased a 48V 90Ah battery set and it was significantly more than $1000, but it does have a specific application, and it's UL certified. Which adds value for something that I will be parking in my garage

 

slow boat from China Alibaba so we will have to see about the quality...

 

Watch this. AC and all the power for every luxury. Very interesting.

 

yep but there pricing for my load they say is $15k
Their key is just the custom MPPT controller that can calculate the load to adjust it for maximum output without stealing to much horsepower while under way. Everything else is really off the shelf Victron componenets.

 

Our types of boats don't lend themselves to be without a generator; they are not misers' of electricity even sitting at the dock, including the SR mid sized boats.
I have been planning a conversion to lithium Iron Phosphate batteries for over a year. Below are the electrical sketches for the conversion; these drawings have been in review by a marine electrical engineering company for about a year (the pandemic has delayed progress) and there are some changes needed (save review and comment from @RollerCoastr) as well as the installation drawings to be done but the general configuration is correct. This system has over 1000 amp hours of battery storage with 800 amp hours useable for boat systems and a reserve of 100 amp hours for engine starting which establishes a maximum depth of discharge of 90 percent; this will keep battery life at around 5000 cycles which will yield a minimum 15 years of service. The primary intent is to size the battery bank and inverters to enable the boat's systems (AC and DC) including air conditioning to operate nominally without generator through the night. Even with this size of a system the generator will still be needed more frequently in specific load situations like AC running and making water or hot water heater heater operating; the battery bank will deplete faster than the over night requirement. As you can see the inverters can provide a continuous 10KW which is about what the generator or shorepower supplies nominally as a peak for this boat's summertime loads here in Florida. When the battery bank reaches a depth of discharge of 80 percent (that 100 amp hours still reserved for engine start) I have an Automatic Generator Start system that brings the generator on line to recharge the battery bank then the genset shuts back down. The great thing about the lithium batteries is they can be charged as fast as the charger can pump current to them plus they have virtually no absorption phase so the generator run time is reduced significantly. Typically on a 10 day trip on my boat the generator runs 18 hours per day so that is 180 hours which is about 360 gallons of diesel. Now with the batteries as the primary AC power provider then generator is pretty much there to charge the batteries and it's run time is reduced to provide the 800 amp hours to the batteries which if the boat's systems deplete three times a day that is 2400 amp hours needed from the generator. The system is designed to provide 300 amps of charge current during the charge cycle so consequently the generator needs only to run 8 hours instead of 18 hours and the boat's systems know no difference. That is a savings of 200 gallons of diesel for the 10 day trip not to mention the quite nights of sleep which is the main reason for the modifications. This doesn't include the contribution the boat's engine alternators provide to the charge cycles or when we are at a marina and plugged in; we typically don't stay in any one location for more than a day so the genset actually runs even much less over the 10 day trip.
You may ask how does this provide 240 volts that the AC systems require? These inverters can be setup to operate in split phase; they provide 120 volts 180 degrees out of phase so voltage across the two inverters is the desired 240 volts.
Regarding photo-voltaic solar panels - Our boats simply don't have enough unused acreage to install solar panels that would make a difference in comparison to the demand on the batteries from the boat's systems. The cost trade on my boat showed overwhelmingly no justifiable investment return on the solar panels. It was like peeing in the ocean....
Anyway, the investment and scope to change to a system like this is huge and pretty much every system in the boat requires modifications, large modifications. Just to give you an idea this modification will be between $25K and $30K with me doing the installation..... This is scalable for your boat so you can get an idea of the scope and investment.
View attachment 106961 View attachment 106962 View attachment 106959

 

Our types of boats don't lend themselves to be without a generator; they are not misers' of electricity even sitting at the dock, including the SR mid sized boats.
I have been planning a conversion to lithium Iron Phosphate batteries for over a year. Below are the electrical sketches for the conversion; these drawings have been in review by a marine electrical engineering company for about a year (the pandemic has delayed progress) and there are some changes needed (save review and comment from @RollerCoastr) as well as the installation drawings to be done but the general configuration is correct. This system has over 1000 amp hours of battery storage with 800 amp hours useable for boat systems and a reserve of 100 amp hours for engine starting which establishes a maximum depth of discharge of 90 percent; this will keep battery life at around 5000 cycles which will yield a minimum 15 years of service. The primary intent is to size the battery bank and inverters to enable the boat's systems (AC and DC) including air conditioning to operate nominally without generator through the night. Even with this size of a system the generator will still be needed more frequently in specific load situations like AC running and making water or hot water heater heater operating; the battery bank will deplete faster than the over night requirement. As you can see the inverters can provide a continuous 10KW which is about what the generator or shorepower supplies nominally as a peak for this boat's summertime loads here in Florida. When the battery bank reaches a depth of discharge of 80 percent (that 100 amp hours still reserved for engine start) I have an Automatic Generator Start system that brings the generator on line to recharge the battery bank then the genset shuts back down. The great thing about the lithium batteries is they can be charged as fast as the charger can pump current to them plus they have virtually no absorption phase so the generator run time is reduced significantly. Typically on a 10 day trip on my boat the generator runs 18 hours per day so that is 180 hours which is about 360 gallons of diesel. Now with the batteries as the primary AC power provider then generator is pretty much there to charge the batteries and it's run time is reduced to provide the 800 amp hours to the batteries which if the boat's systems deplete three times a day that is 2400 amp hours needed from the generator. The system is designed to provide 300 amps of charge current during the charge cycle so consequently the generator needs only to run 8 hours instead of 18 hours and the boat's systems know no difference. That is a savings of 200 gallons of diesel for the 10 day trip not to mention the quite nights of sleep which is the main reason for the modifications. This doesn't include the contribution the boat's engine alternators provide to the charge cycles or when we are at a marina and plugged in; we typically don't stay in any one location for more than a day so the genset actually runs even much less over the 10 day trip.
You may ask how does this provide 240 volts that the AC systems require? These inverters can be setup to operate in split phase; they provide 120 volts 180 degrees out of phase so voltage across the two inverters is the desired 240 volts.
Regarding photo-voltaic solar panels - Our boats simply don't have enough unused acreage to install solar panels that would make a difference in comparison to the demand on the batteries from the boat's systems. The cost trade on my boat showed overwhelmingly no justifiable investment return on the solar panels. It was like peeing in the ocean....
Anyway, the investment and scope to change to a system like this is huge and pretty much every system in the boat requires modifications, large modifications. Just to give you an idea this modification will be between $25K and $30K with me doing the installation..... This is scalable for your boat so you can get an idea of the scope and investment.

Sorry for slow response but I cant do a long winded response using my thumbs, had to wait until I had time to get to my desk.
I agree completely with the assumptions about how boat power is utilized and how that does not lend itself to solar based charging. And a very detailed and well thought design obviously. However there are several choices you made that I believe complicate the solution and leads to the additional costs. And that is why I disagree that you need to make any changes to the boats current 12vdc systems.

The first choice was staying with a 12 volt inverter solution and charging using the standard 12v engine alternators.
Any automotive type alternator is not designed for continuous output. They are designed for flooded batteries, that discharge during statrup and then take a high charge for a short period of time and quickly taper off. Standard alternators have the diodes and regulator internal and as they heat up they cut back on output so even a 100A alternator rarely hits full output. This is why your design required Balmer externals to prevent over heating the alternators and burning them out when charging LifePo4 batteries. Also your main disconnect relays isolate the start, alternator & switched loads. This is appropriate for overcharging situations as that is the most damaging to the cells and highest risk of cell thermal runaway. You still have some "un-switched" loads that would not be disconnected on a low voltage disconnect. I assume those would be bilge pumps only. If you have a low or high voltage disconnect you lose all house functions, lights, radios, etc.

Each use case is slightly different as well, and that can drive choices. You have a generator, I never had one. So I am looking at the cost of adding a generator vs battery/inverter. I already changed my FLA battery banks. I have three separate batteries. two marine starting batteries, port independent, starboard engine & emergency bilge pumps, everything else is on a FLA deep cycle Duarcell trolling battery. I already had a three bank AC charger so that was no cost. I added a 1-both-2 battery switch for manual control and a Blue Seas ACR for normal underway charging. I will replace the ACR with a 48v to 12v DC-DC battery charger (Sterling) the manual switch will remain as a backup option if needed. So all my 12vdc systems will stay as they are and have redundant charge capabilities should I have any issues with the LifePo4 batteries/system.

Then as I already described above the inverter is a completely separate system, treated almost like a stand alone generator. The 48v split phase systems are readily available and reduce the size of so many components compared to the high amperage required at 12v. The inverters Mosfets & windings, cables, disconnect switches and relays are all significant smaller, and therefore usually less costly. Then the addition of the PMA/MPPT based charging system is akin to wind or hydro power solutions.

And finally I do plan on prismatic batteries. But have already planned the battery and box arrangement. It will be a bolted pack with separaters of aluminum plates. These plates will be wider than the cells on both sides (fins) The assembly will be inside an aluminum battery box. Ventilation will be included to dissipate heat during charging and to help isolate from engine heat.

Besides Nigel I have also gotten a great deal of marine lithium info form this firm.
http://nordkyndesign.com/category/marine-engineering/electrical/lithium-battery-systems/

 

I already have a Magnum inverter installed and have used it for a couple of years now and it does what I designed it to do...run the microwave and coffee make in the morning without the genny waking everybody up. I love it!

I ran it off my starboard house/start bank, but its time to get it it’s own battery source. I’m looking at 8 280Ah prismatic cells to make a 4P2S 560Ah @12V to feed it. These are about $1000 delivered. Google Will Prowse or DIY Solar...I’ve never seen anybody get so excited about batteries...he’s hilarious! He list a couple decent sources.

I’m watching Tom to see how his system works out, but I think you might see more of this in the future, be it retrofits, of new boats from the factory.

If money were no object, I’d get a 24V or 48V Victron Quattro, and enough battery to run the main AC all night. Or convert to DC AC units.

This is doable with enough money and engineering resources!

 

I already have a Magnum inverter installed and have used it for a couple of years now and it does what I designed it to do...run the microwave and coffee make in the morning without the genny waking everybody up. I love it!

I ran it off my starboard house/start bank, but it time get it it’s own battery source. I’m looking at 8 280Ah prismatic cells to make a 4P2S 560Ah @12V to feed it. These are about $1000 delivered. Google Will Prowse or DIY Solar...I’ve never seen anybody get so excited about batteries...he’s hilarious! He list a couple decent sources.

I’m watching Tom to see how his system works out, but I think you might see more of this in the future, be it retrofits, of new boats from the factory.

If money were no object, I’d get a 24V or 48V Victron Quattro, and enough battery to run the main AC all night. Or convert to DC AC units.

This is doable with enough money and engineering resources!

Dave - the prismatic lithium batteries bring some challenges. First and most important is they do not deal well with shock movement and jostling as we see in boats with any wave action at all; boaters that attempt to use them build reinforcing boxes to put them in. Secondly, they don't dissipate heat well at all and charge rates as well as discharge rates are a fraction of the 18XXX cylindrical LiFePo4 cells. This is why pretty much all high current batteries (Battleborn, Lithonium, Victron, Mastervolt, Testla, etc) do not use prismatic. Just a heads up..
Tom

 

What about using a 48v lithium battery. Use your inverter to 120v AC and a step down from 48v to the 12v system. I haven’t really started looking at this stuff for a boat yet, but it seems in the residential market 48v systems are more common. I just ordered a 48v, 120ah lithium system for my golf cart. My plan is to pick up an inverter before hurricane season so that I can power the house fridges and some lights/fans overnight without listening to a generator.

 

Have to upgrade the inverter. The Quattro is about $2800

The other design criteria is $$$. I only use this system sparingly for microwave/coffee brewing, so I’m not looking to spend too much.

The separate battery for the inverter is mostly driven by wanting to spare my House/Start batteries wear and tear, and the satisfaction of designing and building a system for my own personal education/gratification.

I just replaced my starboard start house bank with 2 new G31 AGM, and I’m going to repurpose the 6 year old set for the inverter bank.

I’ll consider my options until those older batteries die a slow painful death.

 

For my purposes, I have a stand alone inverter system that is not intended to be charged by the main propulsion engines. All current taken from and returned to the batteries would be via the inverter/charger using AC power from the generator or shore power. Also, this systems is not mission critical.

Here is the article from Battle Born. They used a MS2012 (2000 W) where mine is a 2812 (2800 W), but the general principles apply.

--> https://battlebornbatteries.com/can-use-magnum-ms2012-lifepo4-battery-bank/

I'd need 4 100Ah units to get full rated power out of the inverter and not exceed the BMS limits. The newer 270Ah versions are getting close at a 300A continuous load, but full power on this inverter is 373A. I'd still need 2.

Economics just don't work...yet.

 

For my purposes, I have a stand alone inverter system that is not intended to be charged by the main propulsion engines. All current taken from and returned to the batteries would be via the inverter/charger using AC power from the generator or shore power. Also, this systems is not mission critical.

Here is the article from Battle Born. They used a MS2012 (2000 W) where mine is a 2812 (2800 W), but the general principles apply.

--> https://battlebornbatteries.com/can-use-magnum-ms2012-lifepo4-battery-bank/

I'd need 4 100Ah units to get full rated power out of the inverter and not exceed the BMS limits. The newer 270Ah versions are getting close at a 300A continuous load, but full power on this inverter is 373A. I'd still need 2.

Economics just don't work...yet.

Dave - can you adjust the bulk charge voltage on that Mangum? I remember when you installed that BTW. 14.4V is too high and leaves too little margin up against the BMS. You really need 14.1 or 14.2 max. Also the absorption phase needs to be changed to 10 minutes to get out from under the excessive time to float. In looking at your existing Inverter/charger I suspect it will need to be changed if going to Li in order to reduce risk and get the most out of the batteries.
Victron is the right path but be careful; take that step and you will get sucked in to their cool product lines, can't get enough... Garmin sucked me in and Maretron sucked me in.... And now Victron has me by the short hairs.

 

This was the book I picked up to read up on the various battery chemistries and the design criteria for building them. Not a bad primer.

View attachment 107008

 

Tom, just curious why switching existing wiring/systems to lithium as opposed to just adding a large stand alone bank/system. Seems like a lot of work and expense compared to just a add on system.

I've thought about dumping the generator, and go with a 12/24v inverter system to run the coffee/ microwave, but swap out the Air Conditioning units to DC. Power consumption is a lot more reasonable using what I assume are variable speed compressors/fans.

Either way It's a lot of engineering, planning and above all...EXPENSE!

 

First it's all about useable energy density over volume and weight. To get the amount of energy to fully operate the boat in the summer over a 6 or 8 hour period isn't insignificant. Secondly, to replenish that energy into the storage system within several hours at most is important. Only the lithium technology solves these two requirements. For example to get 1000 AH of useable energy from lead acid is over 1600 AH battery rated. That, for example, is eight 8D batteries at 120 pounds each vs. four of these at 81 pounds each - https://battlebornbatteries.com/product/270ah-12v-lifepo4-deep-cycle-gc3-battery/
To charge such a lead acid bank would be 10 plus hours vs the lithium bank less than 4 hours.
Yes it is a lot of effort and expense but it's a technology leap and a cool project that will make boating much more pleasant and comfortable. Another thing is it automates and integrates the boat's electrical systems so if on shore power the system automatically configures to shore power or if shore power is removed it configures to battery power while sheading unnecessary loads then automatically when the battery bank depletes to a given level the generator comes on line to recharge the bank then shuts back down.
Regarding DC HVAC units; energy is energy. BTU's to cool are Watts and Watts are amps; it doesn't matter wither AC or DC it's the same amount of energy..... Regardless if you have one inverter for all of the boat's systems or individual inverters like on a DC HVAC unit you will still have losses due to the inverting process so for the most part a wash. The big difference is the DC cabling going to the HVAC unit gets significantly larger...

 

Amazon has some cheap lifepo4 options if anyone is brave enough to try them. I’m not there yet.
https://smile.amazon.com/gp/product/B0949CJ8VY?

 

I think you guys scared the OP off with the pros/cons of electrical science.

Perhaps we should have found out what was wrong with his generator?

 

One other question. What do you think about leaving each engine battery as a single AGM battery, and instead swap the generator battery to a large lithium bank that could be used to power all of your dc loads and your inverters.

DC - DC converters could be used to charge the large bank while the drive engines are running.

 

We have considered DC-DC converters and MPPT's but as of now there are none that can singly carry anticipated loads. The Victron converters can be ganged but then becomes a cost and space issue.

 

Have they told you why they don’t think it’s suitable for engine starting? Is it because, even though you have redundancy, it’s not diverse. So if there is an event that activates one BMS, it will activate all of them. Since they are electronic, they are susceptible to more failures than a pure AGM starter system that has no electronics built into it. With electronics, you also have to consider failures such as an EMC (VHF, Radar, cell phone, microwave) signal taking out the BMS circuitry.

Did you see my follow-up question about leaving the drive engines as a lead-acid/AGM system and then building the alternator bank into a large capacity house bank?

Another thing that I’ve noticed is that not all of the 120 Vac powered Victron equipment carries US safety certification marks. They do meet European requirements, but those requirements don’t always carry over nicely to the US. And they aren’t recognized by US inspectors or during an insurance claim.

 

Have they told you why they don’t think it’s suitable for engine starting? Is it because, even though you have redundancy, it’s not diverse. So if there is an event that activates one BMS, it will activate all of them. Since they are electronic, they are susceptible to more failures than a pure AGM starter system that has no electronics built into it. With electronics, you also have to consider failures such as an EMC (VHF, Radar, cell phone, microwave) signal taking out the BMS circuitry.

Did you see my follow-up question about leaving the drive engines as a lead-acid/AGM system and then building the alternator bank into a large capacity house bank?

Another thing that I’ve noticed is that not all of the 120 Vac powered Victron equipment carries US safety certification marks. They do meet European requirements, but those requirements don’t always carry over nicely to the US. And they aren’t recognized by US inspectors or during an insurance claim.

Our objective is to move away from lead acid; that is the technical challenge. I have the generator start on AGM which is the backup for electrical power. Cascading BMS trips is the principal risk; Charge and discharge limits that we are establishing has substantial margin on the BMS limits; we are establishing 0.2 volts on the top and bottom end beyond what the manufacturer is specifying. The Victron Cerbo GX can alarm when the set points are crossed which partially meets the intent of the new AYBC requirements. The set points allow enough time to evaluate and remove the infringing component. So, this system is set up to tolerate a single or dual BMS internal failure but reduce risk of externally caused BMS cascading trips. Again, they are moving me to keep engine starting on AGM but I don't yet see the technical reasoning to what they want.
For boats and yachts UL certification is not a requirement. Insurance is not concerned with the US UL certifications. Insurance is concerned with meeting USCG and AYBC requirements. The Victron products in this configuration meet all necessary requirements for insurability. I've already been down that road. The open item is the batteries themselves in which the individual BMS are not alarmed per AYBC; we are working on that issue.

 

They won’t tell you why?

Do they consider this battery to be mission critical? If so, I doubt they will ever sign off on just one bank to replace two.

Ironically, EMC is likely to not be an issue for you until you start sticking communication ports outside of that metal enclosure, which will increase its susceptibility to noise. That communication requirement may bring in more concerns in that regard.

 

I think that is a valid question to Battle Born. They do not have metallic enclosures.

 

To get started on my design I bit the bullet and got a copy of ABYC TE-13.
I have to say I was not impressed. It is mostly what we already know, follow the manufactures specifications for each component, you need a BMS, you need circuit protection, disconnects, etc (many things actually reference E-11 and the "normal" battery installation standards). And a lot of "should" not "shall" which is the difference between a rule and a suggestion.

As I've said before every use case is different, @ttmott has diesels, CCA could be north of 800A, @jmauld you have 8.1 gas and I have 5.7 gas, a lot less CCA. I doubt any FET based BMS will ever handle cranking a diesel.

I cant upload the whole document legally but to the last few questions:

View attachment 120143
View attachment 120144
View attachment 120145
View attachment 120147
View attachment 120148

 

To get started on my design I bit the bullet and got a copy of ABYC TE-13.
I have to say I was not impressed. It is mostly what we already know, follow the manufactures specifications for each component, you need a BMS, you need circuit protection, disconnects, etc (many things actually reference E-11 and the "normal" battery installation standards). And a lot of "should" not "shall" which is the difference between a rule and a suggestion.

As I've said before every use case is different, @ttmott has diesels, CCA could be north of 800A, @jmauld you have 8.1 gas and I have 5.7 gas, a lot less CCA. I doubt any FET based BMS will ever handle cranking a diesel.

I cant upload the whole document legally but to the last few questions:

View attachment 120143
View attachment 120144
View attachment 120145
View attachment 120147
View attachment 120148

Locked rotor is almost 800 amps; cranking is 350 amps.

 

Looks like 13.5.3 covers the push for AGM. Also, the statement about following manufacturer specs. If the engine manufacturers spec Lead-Acid/AGM, the engineers won't recommend that you deviate from that. Doesn't mean you can't, but you should make sure that you document the risks identified and how you address them.

 

In the OEM 2 bank system is the generator alternator connected into the circuit with the engine generator? I don’t see the genset alternator mentioned in my manual. The spec sheet for the 7.3ecd says that it has an alternator built in, I just assumed it didn’t.

Also, when you’re underway with the generator running, do you switch off the battery charger?

 

Do you guys mind critiquing this block diagram.

I’m not sure if the dc-dc chargers need to be switched or not. They are "smart" and are supposed to know if the engines are running in order to activate their charge circuits. There’s more separation that needs to be documented for the ignition circuits. For now, I’m just focusing on the addition of the batteries. My primary intentions are to get the heavy loads, like the windlass and the bow thruster off of the drive batteries.
View attachment 120203

 

couple of things and a couple questions...
Is the three battery charger in the middle the AC charger? Is it lithium aware (configurable per battery)?
If not don't use the existing AC battery charger

If you use the alternator on the generator to charge lithium you will likely over heat it and burn it out unless you are using an external (Balmer type) regulator with temperature sensor.

 

It is a 3 bank AC charger. My current charger will be replaced with one that has lithium profiles built in. Good point about the regulator for the alternator.

 

Personally, I'd ditch the idea of trying to use a 'one size fits all' 3 bank charger for both the starters and the lithium bank. Those are two radically different requirements, one being just a maintenance role and the other being primarily a bulk-charging role. I'd go with a fairly small two bank charger for the starters and probably use a decent inverter/charger as the main charger for the lithium. You don't really need to use the inverter feature, but it could provide some limited power for convenience when the genset is not running. Or you could just go with a dedicated charger just for the lithium (but it would probably cost just as much) that can deliver a good punch back into the lithium to get it full again.

 

Shunts are always the first device off of the battery negative terminal.
For sure you will toast the genset alternator
Having a common charger for both types of batteries will render the batteries that are either lowest charge or requiring the longest charge to be undercharged.
I don't quite understand the DC to DC converter configurations....
Sorry not enough time to really help here...
Tom

 

Having a common charger for both types of batteries will render the batteries that are either lowest charge
Tom

are you saying that a 3 bank charger isn’t configurable per bank? Victron specifically shows a diagram with two lead acid batteries and one lifepo4 charging off of the same charger.

I’m updating my diagram with the suggestions and also adding info to clarify. I initially called this a schematic when it’s really a block diagram. I am not showing the detailed connections.

 

That's a good thought.

Any thoughts on those DC-DC chargers that are charging the lithium battery from the the drive alternators (I should indicate the direction of those chargers on the diagram, for clarity) I'm curious if that constant 18A load would be an issue for the alternators.

 

That's a good thought.

Any thoughts on those DC-DC chargers that are charging the lithium battery from the the drive alternators (I should indicate the direction of those chargers on the diagram, for clarity) I'm curious if that constant 18A load would be an issue for the alternators.

Maybe in my scenario, charging the lifepo4 from just a single 120/240V charger would be enough. If I need a charge, just start the generator to top it off.

The caution is the lithium charge amperage can be far greater than the lead acid batteries and voltages can be different as you know. The challenge is to have a common charging source that can deliver the high amperage yet still ensure all of the batteries are fully charged. Lithium batteries do not enjoy constant trickle charging like lead acid and absorption is for the most part eliminated they need to be charged at bulk then the charge current shut off unless an electrical demand is on the batteries. So once the batteries are at the manufacturers specified voltage (14.4 for example) terminate further charge current. I believe the Victron DC to DC chargers can do this but their largest is 70 amps which may be Ok for your alternators but they will be working at full tilt until the batteries are charged. So, I would have a dedicated AC charge system for the lead acid batteries and another for the lithium batteries. Then all of the engines and their alternators including generator on the lead acid batteries. This way the alternators are not at risk and you can get rid of the APD on the gen. So in this format your lithium bank can be charged through the dedicated charger and/or the DC to DC chargers. What I would do is combine the two lead acid banks and have a cross-over solenoid for emergency start between the lithium bank and the lead acid bank. Then have another shunt on the lead acid bank so now you are monitoring all of the battery systems. Another thing I would do is to reduce your lead acid bank to two Gp 27 batteries for starting and operating the engines then move all of the boat's 12 volt systems to the lithium bank.

 

TT, you hate carrying around lead weight, don't you? I do too, for me it comes from years of racing cars. I was going to reduce each engine battery bank to a single Group 31 battery, but tying them together and putting the emergency solenoid to the lithium bank is a good solution as well. It still concerns me that the alternators (three of them in this case) would be fighting to charge the single bank, but I guess that's not a big issue based on everything that I can find so far. The DC-DC charger should limit the lithium charge rate to whatever rating they are set to. If I have one battery bank, I would just purchase one 12/12-30A instead of two 12/12-18A chargers. https://www.victronenergy.com/blog/2019/10/10/new-product-orion-tr-smart-dc-dc-charger/


I don't think I've seen this posted, but I understand that the LiFePO4 batteries need to be somewhere other than in the engine room. Which is one of the reasons I made the post about the Vacuum. I might be able to fit a couple of batteries in the cabin where it is currently located. I haven't decided on a location yet.

 

The alternators "competing" is a bigger problem with the lithiums due to the charge current and large swings during bulk charge. In a lead acid configuration not a big deal. To really do it right is to have external regulators and a centerfielder but now it's getting expensive. You may consider having a separate small generator start battery; now you will have true redundancy in your DC systems. The generator's alternator will maintain that battery and a lead acid two or three bank (you don't need to use all of the outputs) AC charger dedicated to the lead acid battery system. So, now we are up to three Gp 27's. You really don't need Gp 31's for starting. In fact if you are not going to use the batteries for anything but engine start and run then go to dedicated start batteries rather than dual purpose.