48-volt house bank. Next Gen for boats?

[twistedtree]

I'm kind of thinking I'd often run with both diesel and electric. So at my usual 7.5 knots instead of burning the usual 1.5 gph I'd throttle back to 1 gph and blend in 5 kw solar and maintain the same speed. Or 0.5 gph and 10 kw if I've got excess power.

Maybe this is off base, but it sounds feasible. I hang my dinghy on the transom, and don't want outboards back there as well, plus propping etc is a concern. I have a yanmar SD on my sailboat and like it.

I was looking at this guy more recently. Two 6.0 kw units. https://www.epropulsion.com/pod-drive/

I think that makes sense because the electric is coming from solar.


If the electric has been generated via a diesel, then you will have consumed more fuel than if you had just run directly off the diesel because of all the conversion losses. So it's all about WHERE the electric came from. The challenge is typically fitting enough solar on the boat to make an appreciable contribution to propulsion needs.

 

[twistedtree]

On that thought, other than not gaining anything in the maneuverability department, what about attaching one of the inboard electric motors (ELCO and Epropulsion both make them) to the shaft so the electric and diesel drive go through one prop? That gives no extra underwater drag from the setup and you'd still have prop wash over the rudder for better steering if running electric only. Only thing I'm not sure of is whether the control systems for those motors would work well with another power source on the same shaft.

That's a parallel hybrid that you have created, or at least one form of it.

 

[rslifkin]

That's a parallel hybrid that you have created, or at least one form of it.

Exactly. I'm thinking that it would likely be somewhat more efficient than having the existing shaft plus 2 more drive appendages in the water.

 

[twistedtree]

Exactly. I'm thinking that it would likely be somewhat more efficient than having the existing shaft plus 2 more drive appendages in the water.

I would expect so too. I have always understood that the larger the prop the better, so turning the main prop would be more efficient that turning a smaller aux prop. This certainly plays out with wing engines vs hydraulic or other drives that turn the main shaft. System turning the main shaft seem to go faster with the available HP (typically from one or more generators) vs a dedicated wing engine shaft & prop, I believe because the wing prop is so much smaller. Being offset doesn't help either. What you gain is redundancy of the while drive line, not just the engine that turns it. Gee, another tradeoff in a boat. Who would'a thunk?

 

[Jeff F]

I think that makes sense because the electric is coming from solar.
...
The challenge is typically fitting enough solar on the boat to make an appreciable contribution to propulsion needs.

Right. My total energy consumed is low - right now about 10 gal/day when traveling. So if I express that as 100 kwh/day, and can collect and use 30 kwh/day solar, I can reduce fuel use by 3 gal/day, or 30%.

If I travel 200 days/yr that's a savings of 600 gal/yr, by my simple calculations, which may pay for the system. Would need about 8 kw installed solar.

 

[twistedtree]

Right. My total energy consumed is low - right now about 10 gal/day when traveling. So if I express that as 100 kwh/day, and can collect and use 30 kwh/day solar, I can reduce fuel use by 3 gal/day, or 30%.

If I travel 200 days/yr that's a savings of 600 gal/yr, by my simple calculations, which may pay for the system. Would need about 8 kw installed solar.

Think you can fit 8kw of solar? I’m in the process of upgrading my home solar to about 11kw, and it’s 4 pole mounts worth of panels. It takes a lot of space.

 

[Jeff F]

I have always understood that the larger the prop the better, so turning the main prop would be more efficient that turning a smaller aux prop. This certainly plays out with wing engines vs hydraulic or other drives that turn the main shaft. System turning the main shaft seem to go faster with the available HP (typically from one or more generators) vs a dedicated wing engine shaft & prop, I believe because the wing prop is so much smaller. Being offset doesn't help either.

Interesting. This doesn't exactly match my intuition, but I won't argue. The SD(s) seem easier to install than trying to set something up on the shaft.

What you gain is redundancy of the whole drive line, not just the engine that turns it.

That's appealing. I seriously damaged my prop twice on my last long trip. I like the driveline redundancy.

 

[Jeff F]

Think you can fit 8kw of solar? I’m in the process of upgrading my home solar to about 11kw, and it’s 4 pole mounts worth of panels. It takes a lot of space.

Maybe? I've got a lot of unused space. Or maybe a frame overhead with a large array. Need to do some measurements.

This is very much up my alley. I'd find satisfaction in implementing this sort of system.

 

[Jeff F]

New system is looking like 2x6kw pods, 15 kwh batteries, 8 kw solar, a bit over $20k in parts.

 

[mvweebles]

New system is looking like 2x6kw pods, 15 kwh batteries, 8 kw solar, a bit over $20k in parts.

Am I correct that around 200W per square meter, so 8kw is 40 square meters (20 solar panels, covering 430 square feet)? Massive!!!

Question: Leaving aside practicality of such a large array on a boat, how will you clean off the seagul guano?

Peter

 

[Jeff F]

Am I correct that around 200W per square meter, so 8kw is 40 square meters (20 solar panels, covering 430 square feet)? Massive!!!

At a guess I have 250 sq ft of empty deck space now. So maybe my scheming is impractical. But I could have an overhead array and stay within my self-prescribed height restrictions. Or maybe the system is still viable with 5 kw solar. It's interesting to play within practical limits to see what's possible.

 

[twistedtree]

At a guess I have 250 sq ft of empty deck space now. So maybe my scheming is impractical. But I could have an overhead array and stay within my self-prescribed height restrictions. Or maybe the system is still viable with 5 kw solar. It's interesting to play within practical limits to see what's possible.

As a reference point, my new home arrays are 10' x 14' (140 sq ft) and rated at 5kw. So on paper you might be able to do 8kw in 250 sq ft. But when I put panels on my flybridge hardtop, I left about a 1' "walkway" so I could get to other stuff, including tipping up the panels (they are hinged and pinned) to get under them for cleaning, and to get to stuff outboard of them. So utilization of the available space was not very good. Plus I have a lot of shading issues. Your boat looks more open, so I expect you will be able to do better, but be sure you can still get around the boat, clean it, etc.

 

[Jeff F]

Thanks for comments. I'll get out with a measuring tape this week. Cold snap has broken here.

I've got a 12x18(?) area aft of the PH that I really don't use, plus the forward cabin top. Could build a frame above the aft area and get to 300 sg ft probably.

 

[MacPhid]

The other issue is flat mounted panels are derated based on angle of the sun. At noon they are close to rated output but once you’re an hour either side of noon output drops off. Install 8 and count on 5!

James

 

[Jeff F]

The other issue is flat mounted panels are derated based on angle of the sun. At noon they are close to rated output but once you’re an hour either side of noon output drops off. Install 8 and count on 5!

Yep, understood. I'm curious about what optimum placement would look like. I had a chat recently with another TF member who suggested 15 degrees off horizontal was optimal. My intuition says flat may be as good as it gets, in a boat that's moving.

In my case I'm just concerned with daily yield rather than maximum current at midday.

 

[twistedtree]

Yep, understood. I'm curious about what optimum placement would look like. I had a chat recently with another TF member who suggested 15 degrees off horizontal was optimal. My intuition says flat may be as good as it gets, in a boat that's moving.

In my case I'm just concerned with daily yield rather than maximum current at midday.

In this part of the world, nearly flat is optimal in the summer. In the winter, nearly vertical. And always facing due south, which becomes the problem on a boat. You never know which direction is south, so pretty much the only thing you can do is mount them flat and live with it.


I've seen some instances where the panels on one side of the boat are tilted a bit that way, and the opposite on the other side. That will improve output from one side if it's facing south, but be worse for all other sides. Flat compromises all panels equally, but makes the boat direction not matter, other than for shading issues. I think it would be a pretty complicated analysis to figure out if one is better than another.


Power production over the course of a day is a bell curve, as the sun arcs across the sky. Daily production is typically measured/quoted in "full hours of equivalent sunlight", which how much daily power you can expect over the course of the whole day, expressed as hours of full output (think noon time). There are tables where you can look up what is expected for your location. 4-5 hrs is pretty typical for summer in North America, and of course it varies by season.


I don't recall for certain, but I think there is derating of the panels involved as well. The nameplate rating is based on full sun exposure, but also on a relatively low temperature. In the summer, panels get very hot and production drops quite a bit. What I don't recall is whether this derating in included in the tables for full hrs equivalency, or if it needs to be added in.


Ironically, I have seen the highest solar production in the winter, on cold sunny days. Where I am located the sun barely rises mores than 20 deg above the horizon, and is only up for 8 hrs or so. But it's COLD. Just the other day I had my highest output ever at 19kwh for the day from 3.6kw of panels. That's 5.3 full sun equivalent. More typical is 4.5 or so. This also illustrates why you need to design for 125% of the max possible output, because on sunny cold days, it will happen.

 

[MacPhid]

Jeff, Optimal placement on a boat for me means as close to horizontal utilizing available space while not restricting any normal function of the boat.
There are a number of apps that help with panel alignment, I use Simply Solar, it helps calculate and more importantly set the correct angle. Of course on a boat at anchor as TT says it is almost impossible to maintain.
It's interesting that one has to design a system for a boat to compensate for less output than rated (oversize) but also for over production on cold sunny days! Of course cold on a boat is relative, but if you were to use solar in your winter berth it could be an issue.

James

 

[rslifkin]

The panels on my forward cabin top follow the deck camber. So they're tilted slightly outwards and slightly forward. That helps water drain off them better, which likely keeps the panels a little cleaner. The angle does have a small impact on output, but not enough to worry much about. I get a little better output if the boat is facing south.

 

[mvweebles]

The panels on my forward cabin top follow the deck camber. So they're tilted slightly outwards and slightly forward. That helps water drain off them better, which likely keeps the panels a little cleaner. The angle does have a small impact on output, but not enough to worry much about. I get a little better output if the boat is facing south.

I have four 1m x 1m square panels (200w ea) on my hardtop. Hardtop has a significant camber so the panels are separated into two strings - port and starboard. I have very little tracking data, but was surprised yesterday when they both registered almost exactly the same amount of thru-put - about 0.6kw each.

Ensenada is dusty in general, and a boatyard is worst-of-the-worst. I suspect my panels will need a weekly cleaning while here. Less frequently out cruising of course, but will still require cleaning. I forget if it was this thread or another, but someone was thinking about making a rack system to slide panels into rather than a support structure that could support a person. Don't forget access to clean the panels from time to time.

Peter

 

[nwboater]

Seems like the cool kit for off grid solar is 48v. There's some 24v, and almost no 12v except Victron.

I've been seeing these all-in-one systems (Inverter/charger/MPPT/transfer switch) such as this one reviewed by Will Prowse.

3000w inverter, 80 Amp charger, and the solar controller can take up to 5000w/500v of solar panels. It's around $700. Comparable victron components would be 5x that plus a lot of space a cabling.

Balmar now makes a 48v alternator ($2600- ouch).

96-Series (48V) Alternators - Balmar

Granted it would mean a second alternator for most boats, but the components and price points seem to be approaching usable for boats.

Server rack batteries are getting pretty afforable and are designed to integrate nicely all-in-one inverters. Seems like this is coming of age. Anyone thinking of a 48v house system?

Peter

Hello Peter, I stumbled onto your post asking about 48V batteries. I purchased a "portable power station" made by Hysolis. The unit has a 4.5Kw 48V battery with a built-in 3,000 watt low-frequency inverter. I ran a 30 Amp shore power cord from the Hysolis to my boat's shore power inlet. When powered up, the unit delivers 110VAC to the distribution panel. We have been using it at anchor to run our boat's electric range, coffee maker, and other AC appliances. The Hysolis MPS3K has a built-in wall charger and an MPPT solar controller.

 

[mvweebles]

Hello Peter, I stumbled onto your post asking about 48V batteries. I purchased a "portable power station" made by Hysolis. The unit has a 4.5Kw 48V battery with a built-in 3,000 watt low-frequency inverter. I ran a 30 Amp shore power cord from the Hysolis to my boat's shore power inlet. When powered up, the unit delivers 110VAC to the distribution panel. We have been using it at anchor to run our boat's electric range, coffee maker, and other AC appliances. The Hysolis MPS3K has a built-in wall charger and an MPPT solar controller.

Looks like a nice setup. How portable is it? Spec's show 55kg/121 lbs. 4.5kw is a ton of power. Must be super handy for weekend runs. $3600 isn't a bad deal for what you get.

MPS3K (3kW / 4.5kWh)

Power your world with the MPS3K. Heavy duty. Reliable. Tons of power. An All-in-One, Plug-and-Play Solar Power Station with an Inverter, MPPT Solar Charger, AC Charger, Car Charger, Lithium Battery Bank, and Comprehensive Protective Features. 4.5 kWh Lithium-Ion Battery.

hysolis.com

Peter

 

[Lepke]

Something not mentioned about 48v use is the cable size for 48v is much smaller than the same 120/240v wattage supplied with 12v. It means your inverter and batteries can be further apart if necessary and run with smaller cables. Batteries, depending on the type used, can be tucked in wherever they fit. Originally I had 3 banks in separate locations. After moving my water tanks I brought them together and made it one big bank of 3 48v groups.
I think the best way to use the 48v bank is only for the inverter. Everything on my boat, except for starting, marine electronics, bilge pumps, and navigation lights is 120 or 240v. I do have 12v emergency lights that come on if ac fails. PO had changed the winch motor to 240v and already had house appliances. Another reason for the changeover was I found 6 burned out 12v winch motors in a storage area.
I run 2 12v and 2 48v alternators. I don't need 2 12v, but do for redundancy and run 2 48v because they supply enough amps to keep the bank charged while running so when anchoring, I start with full batteries. PO ran a generator all the time except when sleeping and had a 12v inverter for refer, freezer and house lights that lasted one night. I went to 48v and can go days. Now I only run a generator to make water, laundry, and hot water, usually every 2-3 days, or if I have a crowd on board using my Incinolet toilets and showers. My diesel use is much lower than what the PO used.

 

[socalrider]

Something not mentioned about 48v use is the cable size for 48v is much smaller than the same 120/240v wattage supplied with 12v. It means your inverter and batteries can be further apart if necessary and run with smaller cables. Batteries, depending on the type used, can be tucked in wherever they fit. Originally I had 3 banks in separate locations. After moving my water tanks I brought them together and made it one big bank of 3 48v groups.
I think the best way to use the 48v bank is only for the inverter. Everything on my boat, except for starting, marine electronics, bilge pumps, and navigation lights is 120 or 240v. I do have 12v emergency lights that come on if ac fails. PO had changed the winch motor to 240v and already had house appliances. Another reason for the changeover was I found 6 burned out 12v winch motors in a storage area.
I run 2 12v and 2 48v alternators. I don't need 2 12v, but do for redundancy and run 2 48v because they supply enough amps to keep the bank charged while running so when anchoring, I start with full batteries. PO ran a generator all the time except when sleeping and had a 12v inverter for refer, freezer and house lights that lasted one night. I went to 48v and can go days. Now I only run a generator to make water, laundry, and hot water, usually every 2-3 days, or if I have a crowd on board using my Incinolet toilets and showers. My diesel use is much lower than what the PO used.

I love this concept & would think seriously about setting my next boat up like this - current boat is 12VDC only which works for my simple systems but the 4/0 cables are a pain. Couple of questions:

48VDC alternators: where have you sourced these?

Sounds like you have a 120/240v windlass? Where did you find it?

Thanks!

 

[Lepke]

I got mine on ebay. Originally I used GM CS-144 alternators used on 1990s vehicles and modified the internal regulator. Later I used an external regulator. These were 140 amp (on 12v) 35 amp on 48v. On the plus side, they are available everywhere even junk yards. But weren't quite high enough amps. You can buy 300 amp that is 75 amps on 48v. But the problem was how long they could run near max output. Now I use the CS-144s for 12v.
So I went to native 48v that will output 60 amp continuous that would give 120 amps if needed to the bank. I paid $700 each on ebay and they work fine. Single wire connect (+ ground).
Another I considered is American Power Systems that has 48v alts up to 190 amp. Various mountings.

https://www.americanpowerinc.com/products/high-output-alternators

 

[socalrider]

I got mine on ebay. Originally I used GM CS-144 alternators used on 1990s vehicles and modified the internal regulator. Later I used an external regulator. These were 140 amp (on 12v) 35 amp on 48v. On the plus side, they are available everywhere even junk yards. But weren't quite high enough amps. You can buy 300 amp that is 75 amps on 48v. But the problem was how long they could run near max output. Now I use the CS-144s for 12v.
So I went to native 48v that will output 60 amp continuous that would give 120 amps if needed to the bank. I paid $700 each on ebay and they work fine. Single wire connect (+ ground).
Another I considered is American Power Systems that has 48v alts up to 190 amp. Various mountings.

https://www.americanpowerinc.com/products/high-output-alternators

Thanks! I remember seeing a Balmar unit but it was $$$ And the windlass motor?

 

[Lepke]

Windlass motor is just a common 120/240 ac motor bought at Graingers and many other places including ebay. But I have a larger windlass than most yachts.

 

[Portage_Bay]

Looks like a nice setup. How portable is it? Spec's show 55kg/121 lbs. 4.5kw is a ton of power. Must be super handy for weekend runs. $3600 isn't a bad deal for what you get.

MPS3K (3kW / 4.5kWh)

Power your world with the MPS3K. Heavy duty. Reliable. Tons of power. An All-in-One, Plug-and-Play Solar Power Station with an Inverter, MPPT Solar Charger, AC Charger, Car Charger, Lithium Battery Bank, and Comprehensive Protective Features. 4.5 kWh Lithium-Ion Battery.

hysolis.com

Peter

A quick read of the specs says the battery type is Lithium-ion.

Not LifePo4. Safety concern?

 

[dannc]

Some how I missed this discussion. I broke up one long post into three posts. For better or worse.

We are thinking of building a boat that can currently install 6.8KW of solar panels. We have joked that we would run power cords to other boats to give them excess power.

I really don't want a generator, and with 6.8KW of PV, it would not seem to be needed.

As we have gone through the design cycle, having this much PV opens up other areas. Power is not really an issue for normal house loads and one can be a afford more in the power budget. One of the long term design points we have discussed is to maximize the amount of battery storage to allow us to go X number of days without power generation. A minimum has been 2-3 days. More is better. As the price of LiFePo has dropped the number of non power generation days has increased greatly. Years ago, I thought we would have to spend $25,000 to $50,000 to get LiFePo batteries to get us 4-5 days of no power generation. Now, it seems for $50,000 we can get 100KWh of batteries....

This gets interesting and also started us thinking of moving from 24 volts to 48 volts.

100KWh of batteries lets one stay in place for over a week without generating power, which really is a bit of overkill since 50KWh would give us a 4-5 days which is really enough. However, 100KWh opens up hybrid....

 

[dannc]

Part 2....

We want to spend time on European canals some of which are speed limited. Running the engine at the low RPM's to stay under the speed limit would be possible but not good for the engine. Having said that, the boat normally has a CPP, so in theory, I guess one could set the prop pitch to load the engine but not go fast, which seems like going backwards.

However, hooking up a parallel hybrid to a CPP drive line seems complicated and added a single point of failure I don't like.

Then I found out aboutBlueNav(BlueSpin Inhull, retractable electric motor for boats)which makes retractable 15KW e48 volt electrical motors that can be used to propel the boat and act as bow/stern thrusters. Ah HA!

The BlueNav retractable motors solve the hybrid problem very nicely. The boat would have two separate propulsion systems. Now, the hybrid is not going to get you anywhere fast, or a great distance on battery power, but it would work for short distances and if there is a diesel engine drive line failure in restricted waters. Since the BlueName motors can be used as thrusters you really get two uses from one motor. From looking at the boat we want, we would have to have a BlueNav motor in the bow mainly for the bow thruster function but it could be used to move the boat too. Due to the design of the stern, it seems like two BlueNav motors would have to used aft. This would provide a total of 45 KW of propulsion but the numbers I keep getting is we would need only about 5KW for no current and no wind conditions.

Three BlueNav motors would require three “holes” in the hull while a bow and stern thruster would be four “holes” in the hull. It might be a small thing, but three “holes” would be a bit more efficient.

So, go with 48 volt system to handle the batteries, lower cable size, weight and cost, while maxing out the batteries to 100KWh, not only to just stay in place for a long time without power generation, but to power a separate electric propulsion system.....

 

[dannc]

Last but not least, part 3.

Another issue is stabilization. Long story short, using a Quick gyro stabilizer works seems to fit the use case. The problem with the gyro is that it might need 4.5KW to power up and maybe 3KW under most operating conditions. This means one really needs a large 48volt alternator and it might be a good idea to replace the OEM alternator to one slightly more powerful and running at 24 volts.

American Power Systems has two 48 volt alternators but the 160 amp unit has an RPM power range that does not seem to work for most engine RPMs for the engine we would likely use. The 130 amp alternator has a more useful RPM range to produce the 3KW-4.5KW needed for the gyro.

Schengen rules require us to move out of many countries at 90 days.

Looking at this solar power website, PVWatts, staying in northern Europe is problematic during the winter months from a solar power production perspective. Heading south would be the idea BUT Schengen rules makes things complicated. However, one can bounce between Ireland, the UK and Atlantic coast EU countries but then one would have to deal with the lack of solar power generation....

Which bring back the generator. The generator would provide power generation during the winter, would boost hybrid range, and provide backup power for the gyro and DC-AC inverters.

Did I mention I don't want a generator but it would seem to be "needed."