With lithium do we actually need a dedicated starter battery?

[CaptainRivet]

Originally Posted by more

what lithium/AGM/lead have with a dedicated starter battery for engine,nothing.house bank is only reserve if starter battery die.
and lithium starter batery is good backup for lead starter battery

Thats exactly the point i wrote above and that in a lot boats the cheap dropins BMS won't allow to start the engine as boaters calculate BMS does 100A, 200A peak and i have 2 so 200A and 400A peak and this starts my 1500W starter using 130A and 400A surge...i might work or not but for sure not cranking it over for 10min because you got fuel problems or allike.

[CaptainRivet]

Originally Posted by more

what lithium/AGM/lead have with a dedicated starter battery for engine,nothing.house bank is only reserve if starter battery die.
and lithium starter batery is good backup for lead starter battery

But your reserve must be always able to start the engine and as described by able to crank it for 15 or 30min means a BMS hardly covering the surge with its peak load won't make that!!!
Block the fuel line and try to start engine for 15min straight on your house, thats the test you should do regardless if the house is your primary starter or the backup...that MUST work!!!

[CaptainRivet]

Originally Posted by Donahue

If you're going to remove your lead starter bank, make sure the BMS that you're relying on will allow you to crank the engine for much longer than a normal start--for example, if it's really cold or you need to bleed the engine--without going into shutdown/protect mode.

Due to some poor advice from a guy selling LFP batteries (and perhaps some bad math on my end) I removed my starter battery when installing an LFP bank that was spec'd with sufficient cranking amperage for my Perkins. It worked fine for a normal 2-3 second crank when I tested it the first couple of times. About two hours into a gulf stream crossing from Marathon to Bimini, however, the engine died due to a clogged filter and when I went to give her a bit longer crank to bleed the engine, the BMS shut things down and the boat went dark. Couldn't crank sufficiently to get the engine started without the BMS kicking in. Luckily the breeze was picking up and we had a great sail for the rest of the trip into Bimini and onto the dock. I eventually got the engine bled and running through a series of 2-3 second cranks followed by BMS shutdown and reset. I think this led to the premature death of one of the LFPs (replaced under warranty by the LFP seller who gave bad advice).

Eventually bought a $50 dollar starter battery for $250 dollars in Georgetown and installed a DC-DC charger. This has worked flawlessly for years.

In short you have no backup, just a 50$ starter that will fail on you as lead are unreliable, murphy is waiting...you fixed nothing, just put a bandage on a wound....

Means you need to add another drop in to the get the BMS current capability to start or exchange the BMS.

[Fore and Aft]

After reading this thread the other day I was in my engine room and noticed my AGM start battery was marked with the purchase date 3/21. It easily started the engine after being idle for a month. I doubt most of my customers and myself would consider it a band-aid fix.
This thread reminds me of the compost toilet threads and once the participants have drunk the Kool-aid there's no going back. Right or wrong Lithium is king, we just need to see the light. Maybe I can't see because I have to spritz a little too wipe the poo of the bowl.
Cheers

[CaptainRivet]

Originally Posted by Fore and Aft

After reading this thread the other day I was in my engine room and noticed my AGM start battery was marked with the purchase date 3/21. It easily started the engine after being idle for a month. I doubt most of my customers and myself would consider it a band-aid fix.
This thread reminds me of the compost toilet threads and once the participants have drunk the Kool-aid there's no going back. Right or wrong Lithium is king, we just need to see the light. Maybe I can't see because I have to spritz a little too wipe the poo of the bowl.
Cheers

Its a band aid fix because you have no relaible backup as you figured out yourself your house cannot start the engine, that why you got the lead.

This thread is because technology changed from lead where you from technology cannot have both high current delivery and high current delivering capacity, you can have just one or the other but not both without massive compromise/consequences. Additionally you cannot monitor a lead reliably and figure out its SOC.

Different with Lifepo4, that can naturally deliver its capacity constantly in current, most can do twice or even 3 times now.
Means every 200AH lifepo4 cell in 1p4S can start a leisure boat engine up to 100hp. Whats limiting is often cheap 5$ mosfet BMS in the dropins crumpling what the cells can do.

[s/v Jedi]

I have been asked to voice my opinion here too so brace yourselves

First of all, even though not in the way one may think, I fully agree that the starter battery is history.

My engineering rules for boats:

1. As simple as possible.
2. As reliable as possible.
3. Able to cope with component failures without outside help.
4. Only at the bottom of priority, the cost of it.

So we first come to the main system that is most important for living aboard: the house batteries and power systems around it. When you eat beans cold and straight from the can then this isn’t for you. Living aboard for me means equal to living ashore and includes an all electric galley, washing machine and air heating/cooling depending on climate.

So this means high power. To get high power, as simple as possible and as reliable as possible, we need to leave 12V and go higher to 24V or 48V. For now I am still recommending 24V but I am only a couple product launches away from changing that to 48V.

One of the major advantages of higher voltage is that you can easily build reliable high quality batteries from cheap components like the 280Ah prismatic cells. The reason is that instead of 4S, you double it to 8S or even quadruple to 16S for multiples of energy storage while still having only cells connected in series.

Then there is cost and weight savings: cables become 2x or 4x as light. You only need half or a quart of the MPPT controller capacity etc.

But we normally come from 12V systems and this change is what scares people. Unfortunately this blocks their path to long term success and wastes lots of effort and money. I know it can be done with 12V. We had an 1,800Ah 12V battery bank, enough alternators bolted to the engine to double it’s dry weight and dual 4/0 cabling through the boat. It’s possible but it is suboptimal, expensive, heavy and not as safe.

So with higher voltage house battery, inverter/chargers, MPPT controllers etc. we still have 12V systems that need power. For this I recommend to create a second power system around one or more 12V batteries. This sounds like the good old starting battery, doesn’t it? Yes, we simply convert it to the 12V service bank.

My diagrams show this. Simply add some DC-DC chargers and go. I have a single Odyssey TPPL AGM battery running this show and the system not only starts the engine and generator, it also powers huge electric winches and even our large windlass. I have 60A available from DC-DC chargers and any peaks higher than that come from the single battery, which is optimized for high peak loading (with a 5,000 Amperes short circuit rating).
I do recommend to change the windlass motor to run off the house bank and I have the motor aboard… but this 12V system works so good that it is low on my project list.

As you work on systems, move them from 12V to 24/48V where possible. Water pumps, toilets, windlass, lighting (especially navigation lights), bilge pumps etc. For this you need to modify your breaker panel, which probably has a busbar mounted to one side of all the breakers. You need to remove that and install two small busbars separately: one for 12V and one for 24/48V and run each breaker to the power voltage of choice for that circuit.

I even recommend more batteries. A minimum of two house batteries, preferably with only one being enough to be able to run the boat (redundancy). But also a (small) battery for an isolated power source for the electronics aboard so they are protected against surges from lightning. I used to have another battery on my list for VHF radio (required for commercial installations) but the good handhelds have made me take that off the list. I do use isolated versions of DC-DC converters for the VHF radio and AIS transceiver, taking power from the 24V bank and making sure that the radio antenna/coax does not connect to the common DC negative.

People often say that multiple voltages breaks the #1 rule of being simple. The thing is that when you need a high power system, this automatically means the electrical part is a bit more involved, however you completely eliminate the propane installation which makes up for it plus the boost of extra safety and eliminating a fuel supply aboard.

[CaptainRivet]

Originally Posted by s/v Jedi

I have been asked to voice my opinion here too so brace yourselves

First of all, even though not in the way one may think, I fully agree that the starter battery is history.

My engineering rules for boats:

1. As simple as possible.
2. As reliable as possible.
3. Able to cope with component failures without outside help.
4. Only at the bottom of priority, the cost of it.

So we first come to the main system that is most important for living aboard: the house batteries and power systems around it. When you eat beans cold and straight from the can then this isn’t for you. Living aboard for me means equal to living ashore and includes an all electric galley, washing machine and air heating/cooling depending on climate.

So this means high power. To get high power, as simple as possible and as reliable as possible, we need to leave 12V and go higher to 24V or 48V. For now I am still recommending 24V but I am only a couple product launches away from changing that to 48V.

One of the major advantages of higher voltage is that you can easily build reliable high quality batteries from cheap components like the 280Ah prismatic cells. The reason is that instead of 4S, you double it to 8S or even quadruple to 16S for multiples of energy storage while still having only cells connected in series.

Then there is cost and weight savings: cables become 2x or 4x as light. You only need half or a quart of the MPPT controller capacity etc.

But we normally come from 12V systems and this change is what scares people. Unfortunately this blocks their path to long term success and wastes lots of effort and money. I know it can be done with 12V. We had an 1,800Ah 12V battery bank, enough alternators bolted to the engine to double it’s dry weight and dual 4/0 cabling through the boat. It’s possible but it is suboptimal, expensive, heavy and not as safe.

So with higher voltage house battery, inverter/chargers, MPPT controllers etc. we still have 12V systems that need power. For this I recommend to create a second power system around one or more 12V batteries. This sounds like the good old starting battery, doesn’t it? Yes, we simply convert it to the 12V service bank.

My diagrams show this. Simply add some DC-DC chargers and go. I have a single Odyssey TPPL AGM battery running this show and the system not only starts the engine and generator, it also powers huge electric winches and even our large windlass. I have 60A available from DC-DC chargers and any peaks higher than that come from the single battery, which is optimized for high peak loading (with a 5,000 Amperes short circuit rating).
I do recommend to change the windlass motor to run off the house bank and I have the motor aboard… but this 12V system works so good that it is low on my project list.

As you work on systems, move them from 12V to 24/48V where possible. Water pumps, toilets, windlass, lighting (especially navigation lights), bilge pumps etc. For this you need to modify your breaker panel, which probably has a busbar mounted to one side of all the breakers. You need to remove that and install two small busbars separately: one for 12V and one for 24/48V and run each breaker to the power voltage of choice for that circuit.

I even recommend more batteries. A minimum of two house batteries, preferably with only one being enough to be able to run the boat (redundancy). But also a (small) battery for an isolated power source for the electronics aboard so they are protected against surges from lightning. I used to have another battery on my list for VHF radio (required for commercial installations) but the good handhelds have made me take that off the list. I do use isolated versions of DC-DC converters for the VHF radio and AIS transceiver, taking power from the 24V bank and making sure that the radio antenna/coax does not connect to the common DC negative.

People often say that multiple voltages breaks the #1 rule of being simple. The thing is that when you need a high power system, this automatically means the electrical part is a bit more involved, however you completely eliminate the propane installation which makes up for it plus the boost of extra safety and eliminating a fuel supply aboard.

thank you Jedi, much appreciated


i see we are actually not far from each other.


your concept is basically using the old 12V starter as new 12V hybrid starter house and have a 24V house powering the higher loads which has a 12V emergency take off from the 24V bank to act as emergency starter. then you add a buffer battery to isolate nav electronics from spike and also be able to seperate it in case of lighting.



i am just one step before taking a 12V boat with a 12V starter bank to 12V liefpo4 hybrid starter/house with 12V buffer. so you don't have exhange inverters...

the house is normally quite close engine room or at least has then a big cable to it, to get the charge there.
So with Lifepo4 house its the most simple to just connect directly the starter and alternator and charge with all the alternator has.
then i place a lifepo4 or a LTO at navstation, there is your 12V main for the whole switchboard anyhow and a thick power cable from your old house. Who doesn't wanna go bigger in the future can place eg 20AH LTO or the 40AH WInston and interrupt the old power cable with a DC2DC converter or charger. only thing you have to do run a big enough cable from the nav station close to the house and put a transfere switch, chosing start from house or buffer.



next step is then exactly your setup by adding more capacity and buffer becomes the 12V hybrid/house (you just flip the transfer switch to start from old buffer now 12V hybrid) and convert house to 24V plus add 24/12 DC2DC converter or charger to 12V hybrid house.


Thats exactly my next step already prepared, just reconfigure the 4P4S into 2P8S and exchange the Multi with Studers and replace the DC2DC 12/12/30A to a DC2DC 12 to 24V converter. all other stuff MPPT, BPs..work both voltage. Actually will use the DC2DC 12/12/30A to isolate the nav electronics from the peaks and distrotion of the 12V hybrid house. 12V hybrid Starter/house will be a 40AH LTO bank from 2p6S LTO Toshiba scrib cells with electrodacus BMS and active balancer.
but till no need as the 12V system runs really well and cannot get the LTOs to my location, cables for 600A are already there but i normally use 350A max.

[s/v Jedi]

Originally Posted by CaptainRivet

thank you Jedi, much appreciated

i see we are actually not far from each other.

your concept is basically using the old 12V starter as new 12V hybrid starter house and have a 24V house powering the higher loads which has a 12V emergency take off from the 24V bank to act as emergency starter. then you add a buffer battery to isolate nav electronics from spike and also be able to seperate it in case of lighting.
I
i am just one step before taking a 12V boat with a 12V starter bank to 12V liefpo4 hybrid starter/house with 12V buffer. so you don't have exhange inverters...

the house is normally quite close engine room or at least has then a big cable to it, to get the charge there.
So with Lifepo4 house its the most simple to just connect directly the starter and alternator and charge with all the alternator has.
then i place a lifepo4 or a LTO at navstation, there is your 12V main for the whole switchboard anyhow and a thick power cable from your old house. Who doesn't wanna go bigger in the future can place eg 20AH LTO or the 40AH WInston and interrupt the old power cable with a DC2DC converter or charger. only thing you have to do run a big enough cable from the nav station close to the house and put a transfere switch, chosing start from house or buffer.

next step is then exactly your setup by adding more capacity and buffer becomes the 12V hybrid/house (you just flip the transfer switch to start from old buffer now 12V hybrid) and convert house to 24V plus add 24/12 DC2DC converter or charger to 12V hybrid house.

Thats exactly my next step already prepared, just reconfigure the 4P4S into 2P8S and exchange the Multi with Studers and replace the DC2DC 12/12/30A to a DC2DC 12 to 24V converter. all other stuff MPPT, BPs..work both voltage. Actually will use the DC2DC 12/12/30A to isolate the nav electronics from the peaks and distrotion of the 12V hybrid house. 12V hybrid Starter/house will be a 40AH LTO bank from 2p6S LTO Toshiba scrib cells with electrodacus BMS and active balancer.
but till no need as the 12V system runs really well and cannot get the LTOs to my location, cables for 600A are already there but i normally use 350A max.

Keeping the house bank at 12V is okay as long as the galley keeps propane. As soon as we enter the 5kW+ power requirement, it is much better to switch to 24/48V. It isn’t a problem that this requires a new inverter/charger because you need a new one anyway to get up to that power level. I actually recommend two 3kW models instead of one 5kW model for redundancy and extra features.

On using lead acid for the 12V: the thing that matters is that you need a technology that doesn’t mind an endless float charge of around 13.2V or even more. If that is LTO then that’s fine, but I don’t think LFP is suitable.

If people want the alternator to charge the house battery then they must buy one for 24/48V plus the protection mechanism to shut it down before HVC. This can be as simple as a BMV if people don’t mind not charging to 100% (just stop the alternator at 95%)

[CaptainRivet]

Originally Posted by s/v Jedi

Keeping the house bank at 12V is okay as long as the galley keeps propane. As soon as we enter the 5kW+ power requirement, it is much better to switch to 24/48V. It isn’t a problem that this requires a new inverter/charger because you need a new one anyway to get up to that power level. I actually recommend two 3kW models instead of one 5kW model for redundancy and extra features.

On using lead acid for the 12V: the thing that matters is that you need a technology that doesn’t mind an endless float charge of around 13.2V or even more. If that is LTO then that’s fine, but I don’t think LFP is suitable.

If people want the alternator to charge the house battery then they must buy one for 24/48V plus the protection mechanism to shut it down before HVC. This can be as simple as a BMV if people don’t mind not charging to 100% (just stop the alternator at 95%)

inverter agree with you on 5kw at 12V and also to get 2x3kw instead 5kw. but actually real 3500W is all you really need.

Here you can easy run a Multi 3000W (that a lot have) and eg use a phönix 800W or 1200W as boost inverter to real 3500W, that still works ok in 12V and is actually all you really need running a full electric galley. i see it on mine, the boost one starts at 2400W load and it maybe runs once per week when i make a roast in the oven and make rice or pasta in parallel on the induction stove for maybe max 15min. then we are at around 300A plus 20A for the rest=320A...thats the limit on 12V installs and also common install material but works well.
mine was a simple exception that absolutely everything high power was 12V already and new or max 2 years old incl. inverter plus new volvo drivetrains where its not so easy to replace alternator with external regulator. cheaper to do high current install which i know how to but design it to be able to move 24V step by step...massive cables don't hurt then :-)


why does the 12V hybrid Service been charge to 100% and floated, just treat it like your normal house, if LFP just use eg an Electrodacus BMS and let it cut the charge of the 24/12 or 12/12 DC2DC converter at 3,55V and the recharge parameter at 3,25V, like this its cycled between 70% and 98% SOC. no need for any floating as you use it, its not just sitting around. 70% SOC is more then enough to always start and support eg whinch or simply whatever you have on 12V eg fride/freezer. same with the buffer battery.

why should they buy a 24/48V alternator, its an economical question.
sure if you have an older engine and dumb 12V alternator go to 24/48V, no question but if you have newer capable 12V one there is a different way.
just let your 12V alternator charge the 12V service/house and use EasyAs relay with a 12/24/70A DC2DC converter. you anyhow need it to move power from 12V to 24V (and vice versa), so extra is just 80Euro for the relay.
As soon as your 12V alternator runs the easy as relay shuts on the converter and transfer the 12 to 24V and if full BMS shuts off the converter via remote. if alternator stop the EasyAs relay switches off the converter. done.
that makes sense if you already have a regulated 12V alternator or eg the 115AH mitsubshi or 125A Valeo with internal temp protection that deliver good charge of 80A and cut when 95% SOC via BMS or regulator. especially if you have a volvo with D+.


sure if you have a blank sheet i will also go right away 24V but a lot have well working legacy equipment in 12V. inverter are normally very close to battery so a thick cable 1 or 1,5m is ok instead of buying new inverters add a 2nd small for 300-500Euro is a better and less complicated option for a lot. Additionally you get the small victron ones often used in very good condition for a bargain. sure if you need to replace inverter or other high power stuff right away get the 24V one.

[s/v Jedi]

Originally Posted by CaptainRivet

inverter agree with you on 5kw at 12V and also to get 2x3kw instead 5kw. but actually real 3500W is all you really need.

Here you can easy run a Multi 3000W (that a lot have) and eg use a phönix 800W or 1200W as boost inverter to real 3500W, that still works ok in 12V and is actually all you really need running a full electric galley. i see it on mine, the boost one starts at 2400W load and it maybe runs once per week when i make a roast in the oven and make rice or pasta in parallel on the induction stove for maybe max 15min. then we are at around 300A plus 20A for the rest=320A...thats the limit on 12V but works well.

why does the 12V hybrid Service been charge to 100% and floated, just treat it like your normal house, if LFP just use eg an Electrodacus BMS and let it cut the charge of the 24/12 or 12/12 DC2DC converter at 3,55V and the recharge parameter at 3,25V, like this its cycled between 70% and 98% SOC. no need for any floating as you use it, its not just sitting around. 70% SOC is more then enough to always start and support eg whinch or simply whatever you have on 12V eg fride/freezer. same with the buffer battery.

why should they buy a 24/48V alternator, its an economical question.
sure if you have an older engine and dumb 12V alternator to go to 24/48V but if you have a capable 12V one there is a different way.

just let your 12V alternator charge the 12V service/house and use easy as relay with a 12/24/70A DC2DC converter. you anyhow need it to move power from 24V to 12V, so extra is just 80Euro for the relay.

As soon as your 12V alternator runs the easy as relay shuts on the converter and transfer the 12 to 24V and if full BMS shuts off the converter via remote. if alternator stop the easy as relay switches off the converter. done.
that makes sense if you already have a regulated 12V alternator or eg the 115AH mitsubshi or 125A Valeo with internal temp protection that deliver good charge of 80A and cut when 95% SOC via BMS or regulator. especially if you have a volvo with D+.

sure if you have a blank sheet i will also go right away 24V but a lot have well working legacy equipment in 12V. inverter are normally very close to battery so a thick cable 1 or 1,5m is ok instead of buying new inverters add a 2nd small for 300-500Euro is a better and less complicated option for a lot. Additionally you get the small victron ones often used in very good condition for a bargain. sure if you need to replace inverter or other high power stuff right away get the 24V one.

See, here is where our different opinions pop up:

- an electric galley can’t work on 3.5kW. Even just two induction hobs can go up to 3.6kW. You want a minimum of three 1.8kW appliances, for example a cooktop plus microwave plus coffeemaker. It should just work.

- playing tricks like one Multiplus with another inverter inputting power to utilize it’s PowerAssist feature that is toying around. Not simple, not reliable, no redundancy, nothing except it’s cheap. Propane is cheaper.

- Controlling things with Electrodacus BMS is a big NO. It’s not simple, not reliable, no redundancy, nothing. BMS must manage the battery, that’s it, like how it was named.

- Running 12V from battery? No way! We don’t want that inefficiency! We run 12V straight from the DC-DC chargers without charging/discharging any batteries.

- Chargers must be able to charge batteries without being told by BMS when to stop. That is not simple, not reliable and doesn’t allow redundancy.
The only thing the BMS needs to do is make sure the battery is happy and prevent damage to it. It must be able to accept an unlimited amount of other battery with BMS’ses in parallel. This means it shouldn’t really be MOSFET based but rather solenoid based, although I am testing LiTime MOSFET based which allows four parallel batteries.

- Struggling with 12V house batteries with an all electric galley is never a better option. If one can’t afford an electric galley then keep with propane. You have two or three hobs plus an oven and can run it all simultaneously. You need comparable performance with electric otherwise it’s a step back instead of forward.

[rslifkin]

For boats with a generator there's somewhat of a middle ground. Support 90 percent of cooking on battery power, but for the occasional time you really want to use everything in the galley at the same time, crank up the generator.

[CaptainRivet]

Originally Posted by s/v Jedi

See, here is where our different opinions pop up:

- an electric galley can’t work on 3.5kW. Even just two induction hobs can go up to 3.6kW. You want a minimum of three 1.8kW appliances, for example a cooktop plus microwave plus coffeemaker. It should just work.

- playing tricks like one Multiplus with another inverter inputting power to utilize it’s PowerAssist feature that is toying around. Not simple, not reliable, no redundancy, nothing except it’s cheap. Propane is cheaper.

- Controlling things with Electrodacus BMS is a big NO. It’s not simple, not reliable, no redundancy, nothing. BMS must manage the battery, that’s it, like how it was named.

- Running 12V from battery? No way! We don’t want that inefficiency! We run 12V straight from the DC-DC chargers without charging/discharging any batteries.

- Chargers must be able to charge batteries without being told by BMS when to stop. That is not simple, not reliable and doesn’t allow redundancy.
The only thing the BMS needs to do is make sure the battery is happy and prevent damage to it. It must be able to accept an unlimited amount of other battery with BMS’ses in parallel. This means it shouldn’t really be MOSFET based but rather solenoid based, although I am testing LiTime MOSFET based which allows four parallel batteries.

- Struggling with 12V house batteries with an all electric galley is never a better option. If one can’t afford an electric galley then keep with propane. You have two or three hobs plus an oven and can run it all simultaneously. You need comparable performance with electric otherwise it’s a step back instead of forward.

just need the right equipment for 3500W:
i have 3 burner induction cooktop Bartscher IK3342, commercial grade coil burners optimized for catering (not the cheap pulsing types) and mobile use. that has 3500W and regulates all 3 burner to max use 3500W, 95% cooking with 2 in average one is on 7 eg boiling water for pasta and the other on 4 making meat and thats 2000-2400W. never used 2 burner simultanious on full power till now...
my panasonic 4 in 1 mircrowave, convection, steamer , BBQ needs max 130A at 12V, eg on/off running at 200degrees for 45 min so i can run all in parallel with 3500W total.i though i use much more and can up to 6,5kw but in reality the 2nd staged inverter shuts on once a week for short time and in total 3500W range...not trying to optimze usage...ok i don't run wasing or dishwasher additional when cooking, even i could but thats not necessary. but i can run both and make coffee plus porridge or eggs simulataniously and be again in 3500W range...
- instead "playing with multi within its specs" you can also take 2x2kw Multi and parallel...don't like paralleling and its issues (ask TerryT1, he explained in detail whats all the issues but like staging the inverter (using power assist and the generator relay )so only one runs, the 2nd is basically working spare...also more efficent as only one is in standby. economic not cheap, its safe as within parameters and for the rare occasions I need that much power more then sufficent and can live with the inefficency in this rare cases.

-for me its simple when one source=BMS steers all, one set of parameters and to optimze battery usage can based on SOC switch on off loads or chargers. that is very simple, easy to troubleshoot and robust done via remotes tested by victron R&D to last >10 years 24/7/365 and switching on low power side...safer, cheaper and more efficent based on effective cell voltages and not regulation on fooled total voltages thats then complicated corrected by measured voltage drops.
but thats ok you have your view on that, i have mine. Without that we would all drive trabbis and have 3 boat types to chose...
2nd BMS plug&play changed in under 1min at sea on seperate cabling in case existing has a problem.

- running on 12V, yes i don't want inefficency either but well if its installed and run well its ok. and if switching to efficency costs double and complex compared to simple means add 3 cables (2 power, 1 ac from boost to multi), i chose inefficency (that only matter in rare cases) and economic and a lot will do the same...

[CaptainRivet]

Originally Posted by rslifkin

For boats with a generator there's somewhat of a middle ground. Support 90 percent of cooking on battery power, but for the occasional time you really want to use everything in the galley at the same time, crank up the generator.

fully agree on that. trend goes to big alternator and big bank and dump generator...


also you don't have only the galley...eg washing and diswasher, some watermaker (my runs DC), AC....but yes galley contains normally the most power honks beside AC.

[Fore and Aft]

Jedi that is an interesting system and shows how our lifestyle has completely missed the modern bus. We still cook with gas at home and have no air-conditioning in the house. I can honestly say the only time I have eaten cold beans was in a cafe in Hong Kong and the language barrier made it to hard to get them heated.
I can see how your system is all part of the wave of new sailors that want and have everything onboard and consider any boat under 40 feet camping.
I still like the separate start battery as any luddite can go to the local store pick up a battery and install it. Knowing that as long as the alternator is working then this system is foolproof. That's why I think there is always going to be the die-hard AGM crowd who just want simplicity.
To be honest my eyes start glazing over reading what you and CaptainRivet have written.
Cheers

[Fuss]

Why do you have to make it so complicated and even more so with the constant thread drift. I told you rivet more than a year ago that 12v 280ah Eve lifepo4 is starting my 6liter diesel and you said it would last at most a month and would burn the boat down.
That says it all, advice should be based on you own personal experience not what you imagine or read on these forums and then re parrot.
Start your motor with the same type of lifepo4 cells that you have for your non drop in house bank, that is the only way to do it if you are space limited and plan long term cruising. The benefit, I will say in a later thread as there is enough thread drift on here already.