2021/2022 Updates on 48v for main system bus

[alaskanviking]

There is an older thread 2018/2019 talking about 48v as a system bus voltage. It was supposed to be a feasibility & work possible solutions thread but it sadly devolved into some flame war stuff.

Now it's 2021. I see more and more signs of 48v becoming a standard. Was already a standard for telecom, cars seem to be going that way, and a good number of the boat electric drive systems are 48v.

I was thinking of a 48v house battery for of the power generation or high load equipment, inverters ect, with a 24v or 12v battery and DC to DC chargers.

I have a 24v system. I converted it in 2013 from 12v. Now my old lead bank is close to kuput and Ive started my electrical system refit. I see 48v diesel hybrid series or parallel propulsion systems coming. I'm resistant to replacing my engine as I suspect those hybrid packages to be much more common in the 5-10 years a rebuild would last. Since I'm replacing a lot of the equipment anyway it would be a good time to consider changing to a 48v system.

I have seen the difference in efficiency moving from 12 to 24v. Power generation efficiency increased, and I use less power for than I did for the same item on 12v. Looking at the 48v equipment the efficiency is higher and I expect the power usage to be be similar. We are talking 2-3% but when you spread that across the whole system you save enough or generate enough more power that it does seem to make it worth it

I could just keep 24v. But I don't want to have to buy new inverters and chargers and the like. There is also some nice possibilities of using 48v motors instead of 120v or 240v, in the larger sizes needed for water makers and scuba compressors.

Looks like alternators and inverter chargers are covered. It appears you can get 48v Solar panels and mppt controllers. I seen boat wind generators that are 48v.

Safety is similar to running 120v/240v inverters. Lot of work around to that aspect.

I am having trouble finding decent sized DC to dc chargers or converters for 48v to 24v. Even the 12v versions are limited in ah. This is a bigger deal for me since a good chunk of my equipment is 24v. Thinking that even if it wasn't a fully realized system at first it would likely be a few more years down the road, and by the time hybrids are common all the kinks would be worked out and expensive equipment purchased.

Just looking at feasibility, possible solutions, is it worth the cost in 2021. Vice reconfiguring and replacing equipment in 5-10 years.

[smac999]

Unless you have electric engines I would stick to 24v

12v is still fine under 50’.

[BillKny]

What I see: You are spending an AWFUL lot of money in the expectation of saving 2-3%. Driven by the need to change out your batteries? Just keep it 24V for now, and change later IF needed.

There is no telling what the most modern systems will look like in 10 years. Guessing today is a fool's errand.

[EngineerRetired]

I actually agree that when I needed to upgrade my electrical system I would consider making the move to 48 volt.



The issue though, you are on the bleeding edge of the tech and they call it that for a reason. 100% off the shelf doesn't exist yet so YOU are going to do a ton of leg work, the components are going to be more expensive and in the end you will have no choice but to make compromises.


Second, talk with your insurance carrier. Going above 24v dc makes them nervous.

[Dockhead]

Originally Posted by EngineerRetired

. . The issue though, you are on the bleeding edge of the tech and they call it that for a reason. 100% off the shelf doesn't exist yet so YOU are going to do a ton of leg work, the components are going to be more expensive and in the end you will have no choice but to make compromises.. . .

Intriguing idea.

The biggest question is whether you can get the main components off the shelf or not.

charger/inverter is not an issue -- Victron make them in 48v.

But I don't know about windlasses, winches, bow thrusters. Watermaker shouldn't be a problem. I guess if you can get all your high power stuff off the shelf, and you don't mind swapping out, don't mind doing a certain amount of rewiring, then why not? The low power stuff you can just power off a separate bus off a dropper. I already do that with my electronics with my 24v system; it's not a problem.

As to efficiency -- you are not only saving power, but higher voltage DC stuff just works better, runs cooler, lasts longer. And you are saving on cabling, or if you're using existing cabling, then you are halving amperage so reducing voltage drop quite a lot, which will again make all the stuff run better.

Then there's the question of the battery bank architecture. If you were using lead, then unquestionably you get better architecture by less parallelling, with higher voltage. Don't know if this applies to lithium.


I had 6 volt cars in my youth (old VW busses) . I'll never forget how good it was to go to 12v in the more modern ones. All the electrical gear just worked better. My present boat is my first 24v boat. Same feeling coming from a 12v boat, as it was going from 6v to 12v in cars. I feel quite sure that 48v will be noticeably great. I am fairly satisfied with 24v, but I'd sure as hell never go back to 12v, not even on a smaller boat.

[alaskanviking]

Originally Posted by Dockhead

As to efficiency -- you are not only saving power, but higher voltage DC stuff just works better, runs cooler, lasts longer. And you are saving on cabling, or if you're using existing cabling, then you are halving amperage so reducing voltage drop quite a lot, which will again make all the stuff run better.

I had 6 volt cars in my youth (old VW busses) . I'll never forget how good it was to go to 12v in the more modern ones. All the electrical gear just worked better. My present boat is my first 24v boat. Same feeling coming from a 12v boat, as it was going from 6v to 12v in cars. I feel quite sure that 48v will be noticeably great. I am fairly satisfied with 24v, but I'd sure as hell never go back to 12v, not even on a smaller boat.

I agree whole heartedly. I wouldn't go back to 12v. Everything your saying is exactly why I keep thinking of this. At this point almost every thing on the boat is 24v. 5 years ago that wasn't as easy or inexpensive. Big push was reconfiguring the batteries and inverter charger. Slowly upgraded things over the years. There are a few hold outs, fans are very difficult to find in 24v. But that's minor stuff a DC converter works well with.

For those that think 12v is good enough, I can fully say that the higher voltages are better. I have a few old par pumps that can use a 12v or 24v motor. no difference in these motors other than the winding inside, they are really simple. In swapping over I found the motors run better, the can is cooler, and they use less power. Not a whole lot less power true, but significant enough that it's noticable. I noticed the same with a 12/24v water pump and other dual voltage devices. 24v prices have come way down, many things are the same price. The 24v specific stuff is usually more commercial in nature and the small price increase is for increased durability and efficiency. Multiply that by all the pumps and things on board and that little bit of power savings adds up. The alternator was a bit of a surprise, It also is more efficient. I get more power than I expected. Yes just a little bit, but that adds up over time. Altogether means I can stay out at anchor for longer without having to turn on the engine, and when I run the engine it charges that little bit faster. Not as impressive with my old lead batteries but it is very useful for lithium.

To another poster. No I don't have electric motors. However i see more and more evidence that that will be the way forward. Trying to think out of the box a bit. Since I'm due for upgrades anyway. The quick math suggests it will be more costly to replace stuff. I don't think it will take long for diesel hybrid motors to come into the mix, which suggests 48v. I'm rebuilding a spare Perkins 4-108, instead of getting a new engine for 15-20k for this reason alone. The rebuilt Perkins doesn't cost me as much and will bolt right back into place with little trouble or changes to my systems. True things could go a different way. A lot of fabricating and experimental stuff converting now I'm sure.

Really I guess I'm trying to figure out the best strategy. I think switching over to 48v may be similar to switching to 24v, start of with generation equipment and slowly adapt over time. But staying with 24v , sizing solar panels for a 48v system and targeted purchases that are adaptive or usable somehow with 48v is another viable option, Just more expensive equipment you have to replace at the conversion. I suppose you can use a good inverter system and switch things to 120/240 which is what the induction and electric galley types do.

I have seen the motors and such that are available. There isn't much for 24v. i can't even find fans in 24v. Larger motors are available now for 48v, including HVAC blowers and fans.

Maybe this needs a few more years to marinate and see how things shift.

[BruceS]

I ran 48V nom in a houseboat for a few years until I sold it. Have 24V in this bigger boat & wished it was 48V.
Look at how big an inverter you can run off 24V compared to 48V?
Same as charging?
I just ran almost everything off the AC just like a house. (in Australia)
240V AC spotties on the front.

The few things off 12V via a converter. Radio, depth sounder etc.
Genny 240V plugged into inverter/charger.

[mcarthur]

Originally Posted by alaskanviking

I am having trouble finding decent sized DC to dc chargers or converters for 48v to 24v. Even the 12v versions are limited in ah. This is a bigger deal for me since a good chunk of my equipment is 24v. Thinking that even if it wasn't a fully realized system at first it would likely be a few more years down the road, and by the time hybrids are common all the kinks would be worked out and expensive equipment purchased.

Have you seen the new Wakespeed 3000? or the Calex 3000? They are both buck-boost DC-DC which certainly do 12<->48 at 3kW and IIRC also do 24v.

[John_char]

Check out YouTube channel sailing Dauntless. He’s using Tesla batteries wired in 48v. Plus he made his own dc to dc converter.

Well worth the watch if your into that kinda thing.

[Jammer]

Originally Posted by alaskanviking

I have seen the difference in efficiency moving from 12 to 24v. Power generation efficiency increased, and I use less power for than I did for the same item on 12v. Looking at the 48v equipment the efficiency is higher and I expect the power usage to be be similar. We are talking 2-3% but when you spread that across the whole system you save enough or generate enough more power that it does seem to make it worth it

There is a point of diminishing returns. The real advantage of higher voltages is that it is feasible to use wire sizes that don't introduce significant resistive losses and aren't unreasonably heavy and expensive.

There is also some nice possibilities of using 48v motors instead of 120v or 240v, in the larger sizes needed for water makers and scuba compressors.

I have looked extensively and have found no difference in availability between 24v and 48v. DC motors in standard sizes up to 2 hp are readily available in either 24v or 48v in a form factor and RPM range that makes them drop-in replacements for 120v/240v AC induction motors. The larger sizes would work in scuba compressors and high-pressure pumps. See https://www.electricmotorwholesale.com/LEESON-109106/ - comparing 48v and 24v, efficiency is similar and at 24v the full load current is a relatively manageable 75 amps. DC motors larger than 2hp in these voltages are hard to find.

Just looking at feasibility, possible solutions, is it worth the cost in 2021. Vice reconfiguring and replacing equipment in 5-10 years.

* no windlasses in 48v
* no marine alternators from Balmar, Dashew, etc. in 48v
* no 48v engine starters for diesel engines in the sizes usually used on sailboats
* Chartplotters available in 24v but not 48v
* Bilge pumps and water pumps available in 24v but not 48v
* marine LED lighting available in 24v but not 48v

* microwave ovens, higher wattage cooking appliances, not available except in 120v/240v

If you run 48v then your choices are either a 4-voltage boat with 120, 48, 24, and 12 or you end up running some fairly large loads like the windlass on 12v to avoid the need for a 24v bus. The only thing you really gain at 48v is that you can run higher power and smaller cables to the inverter/charger and the bow thruster. Nothing else on the boat that can be converted to 48v uses/produces enough power for there to be any advantage.


On the other hand if you run 24v then you can run a minimal 12v system with only a handful of smaller loads, with VHF radios, HF radios, and NMEA2000 being the main areas where there isn't a 24v alternative.

[FAST FRED]

]These folks make 24-12 equalizers for decades , for the transportation industery

Ahould be able to find stuff on Craigs list , but 48V would probably have to be new.

Battery Equalizers - Vanner

https://www.vanner.com › brochures › Battery-Eq...

With Vanner VoltMaster battery equalizers, you can have an abundance of 12 volt DC power from your 24 volt battery system. Our equalizers allow operation of ...[/QUOTE]

[Dockhead]

Originally Posted by Jammer

. . .
* no windlasses in 48v
* no marine alternators from Balmar, Dashew, etc. in 48v
* no 48v engine starters for diesel engines in the sizes usually used on sailboats
* Chartplotters available in 24v but not 48v
* Bilge pumps and water pumps available in 24v but not 48v
* marine LED lighting available in 24v but not 48v

* microwave ovens, higher wattage cooking appliances, not available except in 120v/240v

If you run 48v then your choices are either a 4-voltage boat with 120, 48, 24, and 12 or you end up running some fairly large loads like the windlass on 12v to avoid the need for a 24v bus. The only thing you really gain at 48v is that you can run higher power and smaller cables to the inverter/charger and the bow thruster. Nothing else on the boat that can be converted to 48v uses/produces enough power for there to be any advantage.

On the other hand if you run 24v then you can run a minimal 12v system with only a handful of smaller loads, with VHF radios, HF radios, and NMEA2000 being the main areas where there isn't a 24v alternative.

I don't think it's as bad as you say.

Bow thrusters, windlasses, and winches ARE available in 48v.

e.g. https://www.wmjmarine.com/592502.html

https://www.vetus.com/en/blog/48v-no...ale-range.html

Balmar do make 48v alternators: https://balmar.net/96-series-48v-alternators/

There is no need for a 48v starter. Even with 24v, you keep the start and engine management all at 12v and separate.

3 voltages are no big deal. 48v is just for battery bank, charger/inverter, and very high power equipment -- thruster, windlass, winches. 24v for ordinary stuff like lighting, pumps, your chart plotters, alarms, etc. 12v for the nav system network, radios, etc.

I think it should work fine.

[codingparadox]

You don't need to run the whole boat at 48V. You run your heavy loads (windlass and inverter) at 48V, which makes for nice small wires and very safe amperages, with very quick charging. Then you use WS3000 to go to 12 or 24V for whatever your built-in house loads are.

I wrote this all up pretty extensively for our boat, and we love it.
https://www.highwind.fun/2021/04/16/...-power-system/

[C420sailor]

Honestly, I think this really all comes down to your wallet more than anything.

If this kind of stuff tickles your fancy and you’ve got a fat checking account, have at it.

[Dockhead]

Originally Posted by C420sailor

Honestly, I think this really all comes down to your wallet more than anything.

If this kind of stuff tickles your fancy and you’ve got a fat checking account, have at it.

If you're building from scratch it might not cost any more. You will save on cabling for heavy equipment, especially with a larger boat.

I think the reasons to do this are far deeper than 3% power savlings. You get:

1. Better structured battery bank (less paralleling)
2. Safer amperages in the cabling to high power equipment
3. Better running, cooler running, longer lasting high power equipment including alternator.
4. Lighter and cheaper cabling for high power equipment.
5. Less voltage drop to high power equipment, making it run better.


Sounds really good to me. If I were building from scratch or rewiring a boat, I would seriously consider this. To convert an existing boat with good wiring and equipment, however, might not be worth it.


My boat is 24v and even with a lot of high power equipment on board, it works more or less fine. I'm not burning to convert it. HOWEVER, there are two items of equipment which really would work better with 48v -- my second alternator, which I use to generate bulk power, and my charger/inverter. The alternator is a real heavy duty hot rated school bus alternator, so it will produce its rated power of about 2.5kW continuously. However, it does get pretty hot doing so and I'm not completely comfortable running big loads like my washer/dryer off it over long periods. All the more if I had lithium batteries. The charger/inverter while rated for about 2.5kW doesn't like continuous loads over 1.5kW. I think it would work better with 48v.