48 Volt System

[goboatingnow]

I wouldn’t hold my breath waiting for U.KCA

[team karst]

Sked live date is Jan 1 2023.

[Bowdrie]

Although 32V systems were fairly popular in motor yachts in the '50s>'60s, it just kind of died out.
Agree, once you get to 48V you're getting into shock hazard territory, and 32V is in the range of electric welding.
Years past I was on a large old-time motor yacht, at the time it was all incandescent lighting operating on 120VDC, (10 8D batts in series).

[s/v Jedi]

48VDC was first chosen for use with telecommunications equipment. This was the value considered still safe for humans.

[mako]

Plus there is a large industry of telecom equipment, surplus, used, etc.

[GrowleyMonster]

Up-volting to 48v is definitely a mixed bag of pros and cons and depends a lot on you and your boat. The best case for 48v is if it is a smaller boat and you want to be able to push your boat with kilowatts instead of gallons of diesel. For smaller boats, under say 35', a 48v bank works decently for an EP system. 48V PMAC/BLDC motors and controllers are common and you could certainly use a 5kw motor and controller for a windlass or bow thruster, depending on how the unit is made. There are a lot of 48V components in the golf cart world that will work. 48v EP systems are common enough that a lot of stuff is available cheap, such as DC/DC converters, lighting, etc. As for alternator, BLDC to the rescue. A typical 5kw propulsion motor and controller running off the diesel can be used for charging your 48v bank. You could probably run it without the controller, as a 3 phase alternator, through a solar or wind charge controller. You still want to run heavy cable where current can be high, but your losses will be much lower. There are a lot of reasons to run 48v and not as many reasons NOT to run 48v as some folks think.

If your transmission will handle being in neutral with the shaft spinning, you can couple a brushless motor to the prop shaft with a belt and pulley system. So, transmission in neutral, you can charge (slowly, this is not very efficient except at higher speeds) with the prop, and you also with the same motor have electric propulsion available from your 48v bank. Why bother, if you have a diesel? A few reasons. If you have a large solar array you get free energy to stuff into those batteries. Diesel fuel that it replaces, is not so cheap. There is the regen charging, which when you are overpowered and sailing at hull speed, is free and costs you practically nothing in speed. There is having no minimum idle speed, which once you learn to take full advantage of it, increases your maneuverability greatly when docking, etc. You have instantly available power for maneuvering, for instance in a close quarters situation or even spotting crab floats or other debris close ahead. You don't have to run the diesel entering or leaving harbor. EP is quiet. EP doesn't have exhaust. Charging from shore power can't spill and make a sheen on the water. EP is not a good choice for long distance motoring! That is where your diesel shines. Batteries don't store as much energy as a tank of fuel. But to get more diesel, you have to buy every drop. Sunshine and regen are free.

My last boat was a 48v boat. My current boat has a 12v system. Would I change? Well, I haven't yet. But I would if I had reason to completely re-do the DC system, maybe, although I would probably opt for two separate 48v banks and two 12kw motors for the electric engine. And I would most likely keep a 12v start battery for the diesel. I am sure I could probably start a smaller diesel with the electric engine but I don't know about the 4-107, might be too hard to roll over at the normal EP reduction ratio.

So maybe you might keep a 12v battery for starting, and in an emergency you could tap your 48v bank at 12v for starting the diesel. Most everything else you could run off the 48v bank directly, off an inverter, or off a DC/DC converter. You can still charge with the diesel, (I would only charge bulk stage, where it is more efficient) and top off with solar or regen. Shore power is cheap, where available. If you day sail a lot, shore power charging and EP are a great way to get in and out.

All those batteries cost money, and all those new components, too. 10A DC converters are cheap. Carry spares. More efficient to run 48v loads, though. Best bang for the buck is 6v golf cart batteries, and they are pretty tough batts. I got 8 years out of mine. The weight is significant in a small boat. The GC-2 size is convenient and you can get the duracells fairly cheap at Sams Club, of all places. A 5kw motor and controller that will run at 100 amps at 48v will cost you about $800 plus cables and connectors. Controllers are rated at peak current so you want a 300 amp controller. This, assuming you might want to run at 5kw briefly. A 1kw brushless motor and controller such as you might use on an e-bike will run about $150 for the pair. That would make a shaft generator, but wouldn't push the boat very well. So yeah it will cost you significant money to switch to a 48v system. Worth it? IMHO, no, unless you might be interested in EP, too. 48v EP works great for most 30' or smaller boats, and sorta works up to about 35' before you need to go higher voltage. If you have a dead diesel and are tired of using an outboard, pulling the engine and fuel tanks will offset much of the new battery weight. The electric motors weight is insignificant.

[RaymondR]

Originally Posted by Bowdrie

Although 32V systems were fairly popular in motor yachts in the '50s>'60s, it just kind of died out.
Agree, once you get to 48V you're getting into shock hazard territory, and 32V is in the range of electric welding.
Years past I was on a large old-time motor yacht, at the time it was all incandescent lighting operating on 120VDC, (10 8D batts in series).

In Australia a lot of islanded farm systems were 32 volt DC, they generally used a generator rigged with a knife switch to crank them with the generator. 2 volt cells were used to achieve the 32 volt, big tall monsters.

Good post Growley.

[Adelie]

Originally Posted by Bowdrie

Although 32V systems were fairly popular in motor yachts in the '50s>'60s, it just kind of died out.

Agree, once you get to 48V you're getting into shock hazard territory, and 32V is in the range of electric welding.

Years past I was on a large old-time motor yacht, at the time it was all incandescent lighting operating on 120VDC, (10 8D batts in series).

For regulatory purposes 60v and up is "High voltage" which is why many systems use 48v and under. With a 48v system you might break they 60v limit during charging in very cold conditions. That's why 42v was the target for car manufacturers in the 1990s that tried to up the voltage, even in cold conditions, it NEVER broke 60v.



Welding voltages are picked to suit the material being welded and the filler metal being used. Because it is the relatively low voltage, when you are doing major welding on a building, often the whole building frame is used as part of the conduction path. One lead from a power pak is often clamped to the building near the pak which is sited near the generator and the second lead and control wiring runs to the welding machine at the point of work. That means there is some voltage and a lot of current in the building frame. No it is not considered a risk, at least no one has brought it up to me and I've been inspecting welding for 19yr. If you accidently wind up in the circuit it might nip you a little but it won't be much.



48v might be bigger nip, but usually not enough to be dangerous.

[SOLAR SUPPORT]

The EP conversion of a sailing boat doesn't make much sense to me. Consider sailing and rigging a gigantic source of renewable alternative energy. Solar energy is another renewable alternative energy source. Sails need wind energy and solar panels need sunlight.

You need a lot of solar panels to travel long distances at sea and to power EP engine batteries. Rigging and sailing equipment is an obstacle to this. Sails are already used for the same purpose, to cover long distances at sea. On a boat with sail equipment, the solar energy that cannot be increased much and the small battery group to be used accordingly brings up the need for an internal combustion engine for supplemental energy.

For a catamaran that has lost its mast and is in bad condition, an EP conversion can be a good option if the passion for sailing can be relinquished. Similarly, EP conversion for a monohull mastless boat might be a logical option, but it won't have as much solar energy potential as a multihull.

Using 48 volt energy may be considered dangerous due to the humidity and salt water in the marine environment. In an EP conversion that gives up sailing, it is possible to sail the boat without leaning on starboard and port, since there is no sail equipment. I think this reduces the risk of the boat getting water and the electrical equipment getting wet.

[GrowleyMonster]

Originally Posted by Adelie

For regulatory purposes 60v and up is "High voltage" which is why many systems use 48v and under. With a 48v system you might break they 60v limit during charging in very cold conditions. That's why 42v was the target for car manufacturers in the 1990s that tried to up the voltage, even in cold conditions, it NEVER broke 60v.



Welding voltages are picked to suit the material being welded and the filler metal being used. Because it is the relatively low voltage, when you are doing major welding on a building, often the whole building frame is used as part of the conduction path. One lead from a power pak is often clamped to the building near the pak which is sited near the generator and the second lead and control wiring runs to the welding machine at the point of work. That means there is some voltage and a lot of current in the building frame. No it is not considered a risk, at least no one has brought it up to me and I've been inspecting welding for 19yr. If you accidently wind up in the circuit it might nip you a little but it won't be much.



48v might be bigger nip, but usually not enough to be dangerous.

I always thought the cutoff was 50v nominal.

Main danger with 48v is metal tools and the spectacular shorts they can cause. I posted a pic on here maybe 10 years ago of my wrist neatly encircled with big puffy blisters where my metal wristwatch band decided it had always aspired to one day conduct several hundred amps of DC. In a ridiculously careless instant that left me feeling like an idiot and my watch band actually in two pieces, That made a believer out of me. Except not long after that, I knocked over a coffee can full of quarters for the washing machines and unknown to me, one bounced around into the engine compartment and landed across two phase terminals and just sat there. The next time I powered up the system, it was fireworks. I blew the finals, of course. Sent it back to China for repair, they covered it under warranty.

So the moral there is you simply cannot be too paranoid when it comes to guarding live terminals against shorts, or using metal tools around big juice. 48v is unlikely to kill a human due to the resistance of the body, especially dry skin. Not saying it can't happen, but seriously unlikely, compared to say an automotive EP plant that might have a 300V battery. The real danger is the arcs and sparks, fire and explosion potential. Like you said, arc welding is done at less than 48v. A dropped wrench will eagerly and instantly weld itself across terminals that are not shielded.

[GrowleyMonster]

Originally Posted by SOLAR SUPPORT

The EP conversion of a sailing boat doesn't make much sense to me. Consider sailing and rigging a gigantic source of renewable alternative energy. Solar energy is another renewable alternative energy source. Sails need wind energy and solar panels need sunlight.

You need a lot of solar panels to travel long distances at sea and to power EP engine batteries. Rigging and sailing equipment is an obstacle to this. Sails are already used for the same purpose, to cover long distances at sea. On a boat with sail equipment, the solar energy that cannot be increased much and the small battery group to be used accordingly brings up the need for an internal combustion engine for supplemental energy.

For a catamaran that has lost its mast and is in bad condition, an EP conversion can be a good option if the passion for sailing can be relinquished. Similarly, EP conversion for a monohull mastless boat might be a logical option, but it won't have as much solar energy potential as a multihull.

Using 48 volt energy may be considered dangerous due to the humidity and salt water in the marine environment. In an EP conversion that gives up sailing, it is possible to sail the boat without leaning on starboard and port, since there is no sail equipment. I think this reduces the risk of the boat getting water and the electrical equipment getting wet.

EP in a sailboat does not preclude the use of sails. It also does not preclude the use of a diesel. EP in general is not a good choice for constant or long duration motoring. That is where a diesel is more practical. Most sailboats that have EP or hybrid drive, use the electric engine only for leaving or entering harbor, or maneuvering situations where you suddenly find yourself needing a turning prop, or for short duration tasks like clearing bridges.

The best setup for solar panels on a sailboat with EP is an array of around 300 to 500 watts. That is pretty much all you can hang on a sailboat and not be crippled by shading from sails, mast, and rigging. You will not be motoring constantly powered by such a small solar array. What it will do for you is possibly slowly charge your bank over several days, if your house loads don't use it all up. This means SAILING, not EP motoring the boat. And if it is determined that a full day of motoring is called for, then the diesel, if there is one, is used. The typical EP sailboat does not have a bank that big and about 10kwhrs is as big as you will see on a small sailboat. That is over 600lbs of batteries and a fairly large space required for the battery box.

The OP was mostly, I think, talking about using a 48v bank for house loads. I only brought up EP because it could be an incentive or advantage in up-powering from 12v to 48v, and the same motors and controllers could be used for other things besides propulsion. And we are talking about a sailboat. I thought that was clear.

[mako]

Originally Posted by GrowleyMonster

Main danger with 48v is metal tools and the spectacular shorts they can cause.... So the moral there is you simply cannot be too paranoid when it comes to guarding live terminals against shorts, or using metal tools around big juice.

Good post Growley and you demonstrate why the words "safety" and "PPE" were developed, it's why we don't wear cotton shirts when screwing around with electricity and even use LOTO tags at home, even if it's just a strip of tape over a breaker so our kids don't flip it back on.

[goboatingnow]

Originally Posted by mako

Good post Growley and you demonstrate why the words "safety" and "PPE" were developed, it's why we don't wear cotton shirts when screwing around with electricity and even use LOTO tags at home, even if it's just a strip of tape over a breaker so our kids don't flip it back on.

We live in cultures where personal injuries are no longer acceptable no more then farm safety etc. this is right and proper. Far too long poor practices and amateurish activities have propagated a propensity fir entirely avoidable injury

Whatever we do now we follow code agreed practices and use appropriate trained professionals

This is right and proper the “ plucky “ uninformed. Amateur dats are over and good riddance.

[team karst]

Originally Posted by mako

Good post Growley and you demonstrate why the words "safety" and "PPE" were developed, it's why we don't wear cotton shirts when screwing around with electricity and even use LOTO tags at home, even if it's just a strip of tape over a breaker so our kids don't flip it back on.

I think you will find the majority of FR clothing is cotton.

Mine:

Its synthetics that are trouble.

[Bali43Cat]

We have a year's worth of experience living aboard our Bali 48 Catamaran that generates and stores 42 kWh at 48V - exactly for the reasons the OP mentions. By using 3 banks of 2 - 24v MG Lithium the system is redundant, safe, and powers everything on the boat including A/C (6 - DC units) and a fully electric galley.

Power is generated by Integrel high output alternator on each Yanmar 57hp engine - capable of producing up to about 8.5 kw each (limited by operating temperatures at the alternator itself) at 48 volts. Combined with 2,500 watts of solar - we can see peak charge rates of almost 20 kilowatts. To achieve these kind of rates with anything less than 48 volts would require some seriously beefy hardware indeed. Imagine the cable(s), fuses, & busses required to handle 750 amps at 12 volts for each alternator?

By installing the 48v generating and storage system after the boat was built per factory specs - the 12v house system is already conveniently in place to power lighting, toilets, water pumps, water maker and every other common DC item. The 8 factory installed 12v. Gel house batteries remain and by simply using 3 DC/DC chargers from 48v. to 12v. the conversion process is incredibly simple and efficient. An upside is the "house" batteries are always at 100% - meaning every DC appliance always operates at maximum voltage which should result in extended life.

AC is supplied by an 8kw Victron Quadro inverting the 48v to 230v/50hz. Aside from typical wall outlet demands the largest 230v consumers are the conventional sized Samsung refrigerator, the microwave/convection oven, and the induction stove-top.

The entire electrical system is redundantly monitored by the Victron, Integrel, and MG Battery Management System all working to ensure everything is operating "normally".

Aside from moderately high installation costs - I have yet to see a downside to this approach. The system has been incredibly reliable (ie: 100% uptime) and we lack virtually none of the conventional "comforts" of home. Highly recommend this approach!