48 Volt System

[SOLAR SUPPORT]

The dc voltage level of energy storage and conversion systems affects the costs of the entire electrical infrastructure and the devices used in the boat. Pay attention to the costs of wiring, Inverter device, ac-dc charger, mppt charger, dc-dc converter devices.

Those manufactured for 12 volts dc are much more expensive than those that operate with 48 volts dc. Because energy converter devices and transmission lines working with 48 volt dc voltage are much lighter and smaller. As the DC operating voltage rises, the cost of the electrical device used decreases inversely at least a multiple of 12.

The 12/24 volt energy infrastructure, which is sufficient for the modest electrical infrastructure in small boats, may become insufficient in terms of increasing the electrical power needed as the boat sizes increase and for transferring the energy over long distances. Total costs should be compared for low and high voltage infrastructure, depending on the size of the system to be scaled for onboard electrical energy needs.

If the energy need is high, for example, when it comes to the use of appliances in a house, it makes sense to install an additional energy infrastructure with a higher voltage than the 12/24 volt dc infrastructure on the boat.

It may not be cheap to implement additional electrical infrastructure with 48 volts voltage using integrated devices that operate separately with each other. Using a 48 volt off-grid smart inverter charger can be considered as an alternative to realize the additional energy infrastructure more economically.

Hybrid type mppt, ac-dc charging and full sine inverter package working integrated with each other. Everything works integrated in a single box and monitoring, control and settings are done through the screen on this device.

To give an idea, a 7kw - 48V hybrid smart inverter costs around $1,100. It consists of full sine inverter, integrated high capacity mppt and ac-dc battery charging modules. Some models have two mppt modules. When such a device produced for terrestrial off-grid systems is used, the 48-volt system will cost much less than a 12-volt system with a 48-volt inverter of the same kWh power and a 48-volt battery bank with the same kWh capacity.

There will be some problems that you will encounter, but all of them can be solved. Problems such as how to feed the AC power input of the 48 volt smart inverter charger, or how to adapt the arrangement of your batteries to the DC voltage of the inverter, adapting the connections of the solar panels to the new mppt.

On a boat with 48 volt battery voltage you may need to use step-down converter(s) with enough power for anything powered by 12 volts. Step-down converter(s) to be used for windlass and bow thruster can be mounted near these tools.

If windlass and bow-thruster can be found working with 48 volts, these tools are likely to be much cheaper than their 12-24 volt counterparts. The long power transmission cable cross-sections required for their operation will decrease and the dc-dc converter may even cover its own cost in this way. This probability increases as the energy transmission distance increases.

It may be necessary to use a step-down dc-dc converter that is specific to other 12V consuming devices. Thanks to the inverter power chosen according to the needs, it is possible to supply and operate many home appliances working with AC power much cheaper than the dc alternatives produced for the boat.

Depending on the inverter power, devices working with 110/220VAC can be used. Such as heaters, kitchen stove, tv, air conditioner, hair dryer, kettle, laundry, dishwasher, coffee machine. Since their energy cables will be suitable for AC power, the energy transmission cable costs necessary for their operation will be much lower.

12/24VDc and 110/220VAc energy infrastructure fed by a 48VDc battery bank. Especially for newly manufactured large boats, it can be a very economical solution alternative that can run 12 volt devices on a 48 volt energy infrastructure powered by Lifepo4 battery bank(s).

[team karst]

There are few items at odds with V selection. High current semi's, copper wire size and PCB traces become problematic with low V. With high(er) V, then you may run into touch safety issues, ability to find breakers rated at higher DC Voltage, even some fuses are only rated at 32V, for instance.
But, overall, I agree that 48V should get more use and attention.

[Jammer]

The problem is that there are important power sources and loads that are unavailable in 48v:
* 48v engine-driven alternators do exist but selection, sizes, and local availability are poor. There is good availability in 24v and 12v.

* Few if any 48v windlasses exist. There is limited availability in 24v; most are 12v only.

* Bow thrusters have limited availability in 48v and then only in sizes appropriate for boats over about 50'. There is good availability in 24v and 12v.

* Engine starters for major marine diesel engines used in sailboats are for the most part available in 12v only.
* Marine pumps are available in 12v and 24v but not 48v.
* Most marine lighting, fans, refrigeration, USB converters, and freestanding non-networked instruments and sensors are available in 12v and 24v.
* NMEA 2000 networked devices that are powered by the network require 12v.



The upshot of all this is that you end up with at least a two-voltage and possibly a three-voltage boat if one of the voltages is 48v. The complexity, costs, difficulty troubleshooting, and energy losses in conversion, outweigh the benefits of 48v.


It is possible to run 24v and then have a small 12v subsystem for things like the engine controls, starter, and NMEA2000 that can't run on 24v, and on many boats this makes sense. Usually this is common at around 50' and over, though on some smaller boats with electric galleys it may make sense.



It is possible to run 48v for only the solar charge controllers and inverter/charger, and use 12v for everything else. Some boats are set up this way, though it means that the motor loads are still 12v, and it means that there are few choices for an engine-driven alternator.

[Adelie]

The way I see it the decision to go from 12v to 48v is dependent on 2 things
A. Boat size & Budget.
B. Sustained high demand uses, i.e. Electric propulsion (EP) or galley (EG).

A. When the boat gets very large it becomes more reasonable to have a 48v system, you save some in wiring costs, but have to buy 48v equipment which are generally more expensive, need step down converters to power the equipment you can't source in 48v and perhaps need to use boost controllers for your solar panels. If you can afford the larger boat you probably can afford the increased expense of the 48v system.
With a smaller boat the 48v system isn't very robust because it will probably become subject a single point failure. On most smaller boats ( less than 40' or so) it's easy to fit 4-12v or 8-6v batteries. Fitting 6-12v or 12-6v is probably doable but doesn't increase the size of your 48v bank, it just adds a 12v or 24v secondary bank. Finding room for 8-12v would be tough and 16-6v batteries probably isn't possible without making sacrifices to storage for other things that many people probably wouldn't make.
-A 48v system using 12v batteries is going to be 4 in series and 1 parallel, if you can fit 8 batteries then 4s-2p. As long as you only have 1 string, a failure in any cell in any battery is likely to bring the whole system down. If a cell goes down 48v nominal will drop to 46v nominal, which is probably OK for the short term (24hr). When you try to charge the bank you now have a safety issue, the bad cell is now a short so the other cells are all being overcharged which will damage them and lead to outgassing and perhaps overheating somewhere. If you pull the affected battery out of the string then you are left with 36v and nothing works because you haven't lost 4% of your voltage, you've lost 25%.
-A 12v system will have 4-12v batteries in parallel (4p-1s). If one battery cell fails by short circuit the other cells in that battery will overcharge and be damaged, but that whole battery was a writeoff anyway because of the bad cell. The other 3 batteries will charge properly but off the charger the system will act wonky as the 3 good batteries try to balance with the bad one until you investigate and find the bad battery and remove it from the system. At which point you are left with 12v nominal but 3/4 of capacity.
-If you have room for 5 or 6 batteries you could have 4s-1p pushing 48v for the house and have 1p-1s or 2p-1s for the engine starting. If one of the house batteries dies, then move an engine battery to take it's place (they all need to be the same size) and start the engine from the house bank. This removes the single cell point of failure scenario but is somewhat more complex.

B. EP & EG are sustained very high demand uses. 48v becomes preferred in these cases because of decreased amperage in cable which results in a significant decrease in fire risk.

1. For EP it's hard to find motors that are big enough to push the vessel that aren't at least 36v. Most are 48V. Regardless when the ICE motor and fuel tank are removed the electric motor that replaces it is generally much smaller freeing up a large volume for more batteries to be installed. In the case of an Atomic 4 being replaced there is often enough room for 8-12v batteries and the new motor in the space under the cockpit where the engine and tank used to be. And the location outside the engine room where the batteries used to be can be used for storage or even a 3rd string of batteries.

2. For EG the issues are more complex. If you have a 2 burner induction hob and a convection oven, at some point you will probably run them at the same time. This means you want a 4kW or preferably 4.5-5.0kW inverter. It appears that there are similar numbers of 48v and 12v inverters that capacity at similar prices.
a. If you stay with 12v you can install the inverter on the other side of a bulkhead from the batteries and use very short very large cables switching fusing them separately from the main panel.
b. If you have a 48v system then siting the inverter becomes more flexible and cabling can be smaller and cheaper but you run into issues of single cell failure bringing down the whole system unless you find enough room for 2 strings or are prepared to juggle a starter battery into the failed battery's spot while at sea.

[RaymondR]

I suspect that the reason for the fairly ubiquitous use of 12 volt equipment in pleasure vessel is that as they became more electrified 12 volt equipment from motor vehicles was the more readily available. Trucks and other more industrial equipment which required more battery storage and were subjected to heavier electrical loads tend to be 24 volts and I believe many aircraft, weight being more important, use higher voltages still.

I think we are probably stuck with 12 volt equipment although there would be significant advantages in moving to higher voltages.

[SOLAR SUPPORT]

The dimensions of private boats and the electrical equipment needs within them will be different for everyone. It is obvious that the energy needs of people who use their boat for hobby purposes are much different from those who use it as a home.

Planning the budget in terms of initial investment and ongoing expenses becomes more and more difficult, especially in this period of high inflation. Similar to many materials, the prices of copper metal are rising breathlessly. The cable cross-sections required for a given power decrease inversely with the multiples of 12 as the selected system voltage rises. The amount of copper contained in the cables, the sizes of the connectors, circuit breakers, fuses also change inversely with the system voltage.

The price appeal of hybrid smart inverters, which include mppt, inverter and ac-dc chargers, which have been developed for a long time and work integrated with each other in a very small box, also highlights 48 volt systems. I don't need to compare them with marine inverter/ac-dc chargers like Victron in terms of quality. However, hybrid smart inverter devices designed for off-grid terrestrial systems of the same power and voltage are even lighter and cheaper than ½ of their Victron friends, although they have extra mppt and integration.

The biggest improvement for batteries is the development of Lifepo4 technology. Compared to LA batteries, Lifepo4 batteries weigh 1/4 less for the same useful capacity. Although they have complex charging needs, it seems that their power density, performance and longevity features will continue to be the reason for choosing Lifepo4 batteries. Thanks to these powerful batteries, it is possible to use devices that consume more electricity on the boat.

It is these batteries and solar panels that help you save on kitchen gas, diesel, gasoline. I don't think it's necessary to remove the sail rigging and fill the boat with Lifepo4 batteries to make the boat electrically powered 🙂 The comfort of the catamarans cruising with the newly released rigging, electrically driven engines and large solar panels is eye-catching, but; this concept is only possible for double hull catamarans. Converting a crested catamaran doesn't make much sense either.

The news of the new large capacity 48 volt Balmar alternator also arrived yesterday. I think we will hear similar news for windlass and bow thruster soon. At least, I think that these infrastructures will start to be preferred in newly built boats.

[Adelie]

Originally Posted by SOLAR SUPPORT

….

A. Planning the budget in terms of initial investment and ongoing expenses becomes more and more difficult, especially in this period of high inflation. Similar to many materials, the prices of copper metal are rising breathlessly. The cable cross-sections required for a given power decrease inversely with the multiples of 12 as the selected system voltage rises. The amount of copper contained in the cables, the sizes of the connectors, circuit breakers, fuses also change inversely with the system voltage.

B. The price appeal of hybrid smart inverters, which include mppt, inverter and ac-dc chargers, which have been developed for a long time and work integrated with each other in a very small box, also highlights 48 volt systems. I don't need to compare them with marine inverter/ac-dc chargers like Victron in terms of quality. However, hybrid smart inverter devices designed for off-grid terrestrial systems of the same power and voltage are even lighter and cheaper than ½ of their Victron friends, although they have extra mppt and integration.

C. The biggest improvement for batteries is the development of Lifepo4 technology. Compared to LA batteries, Lifepo4 batteries weigh 1/4 less for the same useful capacity. Although they have complex charging needs, it seems that their power density, performance and longevity features will continue to be the reason for choosing Lifepo4 batteries. Thanks to these powerful batteries, it is possible to use devices that consume more electricity on the boat.

D. It is these batteries and solar panels that help you save on kitchen gas, diesel, gasoline. I don't think it's necessary to remove the sail rigging and fill the boat with Lifepo4 batteries to make the boat electrically powered �� The comfort of the catamarans cruising with the newly released rigging, electrically driven engines and large solar panels is eye-catching, but; this concept is only possible for double hull catamarans. Converting a crested catamaran doesn't make much sense either.

E. The news of the new large capacity 48 volt Balmar alternator also arrived yesterday. I think we will hear similar news for windlass and bow thruster soon. At least, I think that these infrastructures will start to be preferred in newly built boats.

A. You may save on the cost of wiring but the cost of switches and breakers goes up with voltage. That’s a small part of why the push to switch to 42v in the auto industry in the 1990s failed.

B. While there may be a price advantage to integrated charge controllers/inverters/dc-dc converters it makes all 3 subject to a single point failure. Also distributed solar controllers gives you an output advantage as well as redundancy advantage.

C. For Plug-n-Play batteries LiFePo batteries are 1/3 the weight per usable Whr compared to quality golfcart FLA batteries, not 1/4, you don’t need to fluff their performance for people to understand they have a big advantage. The same FLAs are generally cheaper per lifetime usable Whr than the LiFePos.
LiFePos occupy a bit more than 1/2 (60%ish) the volume of the FLAs, on a usable Whr basis.

D. It is perfectly possible to put enough solar and FLAs on a 34’ monohull to convert to an electric galley. That’s about 750Ahr of batteries and 1,000W or so of panels. For the panels you would need a solar arch on the stern, a solar Bimini and a couple small panels on the dodger.

What’s a Crested catamaran?

E. 48v systems may become attractive for larger boats (>45’) which are also the ones that are more likely to have a bow thruster and very large windlass which would benefit from the 48v. I don’t see it for boats under 40’unless they are also converting to Electric Propulsion (EP).

[RaymondR]

Originally Posted by SOLAR SUPPORT

The price appeal of hybrid smart inverters, which include mppt, inverter and ac-dc chargers, which have been developed for a long time and work integrated with each other in a very small box, also highlights 48 volt systems. I don't need to compare them with marine inverter/ac-dc chargers like Victron in terms of quality. However, hybrid smart inverter devices designed for off-grid terrestrial systems of the same power and voltage are even lighter and cheaper than ½ of their Victron friends, although they have extra mppt and integration.

How about come brand names for these for thode of us not familiar with non boating solar equipment.

The news of the new large capacity 48 volt Balmar alternator also arrived yesterday. I think we will hear similar news for windlass and bow thruster soon. At least, I think that these infrastructures will start to be preferred in newly built boats.

I Googled for 48 volt alternators and was delighted to see Balmar had already made them available but then noticed the price. More interested in the possibility of converting 12 or 24 volt units.

[SOLAR SUPPORT]

Originally Posted by Adelie

A. You may save on the cost of wiring but the cost of switches and breakers goes up with voltage. That’s a small part of why the push to switch to 42v in the auto industry in the 1990s failed.

The most important factor affecting the costs of materials used to create electrical installations is the reduction of their size. As the solar industry has expanded considerably around the world, inexpensive but durable electrical components can be found here.

B. While there may be a price advantage to integrated charge controllers/inverters/dc-dc converters it makes all 3 subject to a single point failure. Also distributed solar controllers gives you an output advantage as well as redundancy advantage.

Carrying all the eggs in the same basket may be more risky, but the advantages that come with collecting all devices in the same box are many. Intelligent hybrid inverter devices are also available with more than one mppt.

C. For Plug-n-Play batteries LiFePo batteries are 1/3 the weight per usable Whr compared to quality golfcart FLA batteries, not 1/4, you don’t need to fluff their performance for people to understand they have a big advantage. The same FLAs are generally cheaper per lifetime usable Whr than the LiFePos.
LiFePos occupy a bit more than 1/2 (60%ish) the volume of the FLAs, on a usable Whr basis.

You can access many resources on this subject when you search the internet. Here is a link with a volume and mass comparison:

https://www.dnkpower.com/how-to-calc...nergy-density/


D. It is perfectly possible to put enough solar and FLAs on a 34’ monohull to convert to an electric galley. That’s about 750Ahr of batteries and 1,000W or so of panels. For the panels you would need a solar arch on the stern, a solar Bimini and a couple small panels on the dodger.

Yes this is possible.

What’s a Crested catamaran?

I mentioned a masted catamaran. The new electric propulsion driven ones do not have a mast.


E. 48v systems may become attractive for larger boats (>45’) which are also the ones that are more likely to have a bow thruster and very large windlass which would benefit from the 48v. I don’t see it for boats under 40’unless they are also converting to Electric Propulsion (EP).

.....

[Adelie]

B. When coastal sailing in the developed world having a low redundancy system probably won’t result in significantly more risk to life or vessel.

On long passages or in remote areas lack of redundancy for critical systems will Significantly increase risks.

C. Cool looking graph from that link. But it shows the relative values of the underlying chemistries without any required ancillary items such as packaging and BMS.

I checked info for actual products. The following graphic was the result.

[SOLAR SUPPORT]

Originally Posted by Adelie

C. Cool looking graph from that link. But it shows the relative values of the underlying chemistries without any required ancillary items such as packaging and BMS.

I checked info for actual products. The following graphic was the result.

I need to tell you my real experience with battery replacement on my own boat. I have a battery compartment on my boat that is occupied by two 200 ah AGM batteries. Two 200 Ah Lifepo4 batteries, manufactured in the same dimensions, fit into this compartment. The weight of two 200Ah AGM batteries is 124 Kg. The weight of two 200Ah drop-in Lifepo4 batteries is 54 Kg.

The 400 Ah capacity test of Lifepo4 batteries was repeated many times with %100 result. AGM batteries were being discharged their Soc%70 usually to prolong their service life to 4 years. You can make the calculation for energy density.

Most of the Drop-in Lifepo4 batteries are manufactured in the same dimensions so that they can be placed in the places discharged from the LA batteries. I'm not sure as I haven't opened the box yet, but in some opened box videos, I saw that Lifepo4 cells are supported with thick bumpers inside the box.

.....

[Adelie]

As previously indicated, LiFePos are pretty wonderful. Comparing them to a mediocre battery though doesn’t make them any better.

On the whole AGMs are poor choice for a house battery on a sailboat.

What are they good for?
Low maintenance
Can provide high-C discharge
Vibration resistance
Can be charged and discharged on side or end.

What are their liabilities?
Poor PSoC service (not full charged almost every day)
Requires high-C charging
Mediocre cycle life, 700-800 cycles to 50% with proper high-C charging.

If access is poor or maintenance isn’t your strong suit, Gels are about the same price and will last 50% more cycles to same DoD.
House use is the opposite of High-C discharge, so high-C discharge is not needed.
Unless you sit the battery on the engine, vibration resistance isn’t getting you anything either.

Sailboats being cruised with moderate amounts of installed solar will consistently operate PSoC unless they regularly run the main engine.

High-C charging means 0.2C for bulk charging. 0.3-0.4C would be better. 0.2C for a 400Ahr bank is 80A going to that bank. Unless you upgraded the alternator you probably have not been charging at high enough C. Charging the LFP at the same time as the AGMs will make the situation even worse. Or do you separately charge the LFP.

Gels will give you 1200 cycles to 50%, golfcart FLAs are similar, solar FLAs are somewhat better.

Once again LiFePos are great.

[CaptainRivet]

48V is considered a dangerous voltage for humans. So unless you don‘t have to 24V is best compromise. 24x300A=7,2kw is more then enough for electric galley, unless you need 48V for e-propulsion there is no need for swapping security for smaller cables. The 7kw are your inverter which is normally max 1m cable length away from your house bank, so even 300A no problem and 2x70sqmm2 cable. Talking about cruising boats here, not >80ft megayachts…
Yes there is 110V/220V on boat too but that’s isolated circuit and eg in my case all 230V cabling is high above waterline while 12/24V not.

[goboatingnow]

Originally Posted by CaptainRivet

48V is considered a dangerous voltage for humans. So unless you don‘t have to 24V is best compromise. 24x300A=7,2kw is more then enough for electric galley, unless you need 48V for e-propulsion there is no need for swapping security for smaller cables. The 7kw are your inverter which is normally max 1m cable length away from your house bank, so even 300A no problem and 2x70sqmm2 cable. Talking about cruising boats here, not >80ft megayachts…
Yes there is 110V/220V on boat too but that’s isolated circuit and eg in my case all 230V cabling is high above waterline while 12/24V not.

Not so in Europe where it’s falls outside most of the scope of the low voltage directive

[team karst]

My industrial equipment has to follow this for CE (and soon to be UKCA) part of LV Directive:

5.1.5.3.2 Values under normal conditions
Values under normal conditions are listed below. Values exceeding the levels/limits of items
a) to c) below, in normal conditions, are deemed to be hazardous live. The limits of items b)
and c) below apply only if the voltage exceeds the values of item a).
a) Voltage levels: 33 V a.c. or 70 V d.c.
For equipment rated for use in wet locations, the voltage levels are 25 V a.c. or 37,5 V d.c.

But, that particular IEC standard may not be applicable to boats, but note the wet location reduction to 37.5V dc.