48-volt house bank. Next Gen for boats?

dannc said:

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.....

Click to expand...

BlueSpin looks interesting, but note that it does come with complexity (360 degree turning), so is probably (?) expensive and you'd want to look at warranty for something newish like that. Rather than that, there are retrofit thruster units that you can essentially hang over the transom (and bow) and have few moving parts - this would allow you to have a fixed, non-rotating electric propulsion which should be simpler and cheaper. Of course at lower speeds you have to consider steering, but since you are going for a new build then you can cater for that in the design.
Also their system it seems to use a Kort nozzle which has its own pluses and minuses for the concept, but another minus is that you may not be (easily) able to fit a larger prop to get the best efficiency for your particular boat. Of course at really low speeds (2-4kn) it probably won't make too much difference.

Since you are still at thinking stage, I'd suggest thinking of a narrow catamaran. It has all the deck space available for solar, can fit in the canals (4.9m BOA), can have two engines widely apart for steering, and can have nice internal space (IMHO). Our lovely lady is one such that was designed for the French canal system (NOT Midi ), and we're planning on 8+kW solar with a (likely) parallel hybrid on our 2x135hp diesels. We've already changed to a 48V house bank and a small starter solar array to test things, and are designing the 12-15kW electrics which will run off the existing shaft (aka parallel hybrid). I would like to change to 48V bow thrusters and anchor winch, but given the 12v are working it may be too many BOAT bucks for now.

mcarthur said:

BlueSpin looks interesting, but note that it does come with complexity (360 degree turning), so is probably (?) expensive and you'd want to look at warranty for something newish like that. Rather than that, there are retrofit thruster units that you can essentially hang over the transom (and bow) and have few moving parts - this would allow you to have a fixed, non-rotating electric propulsion which should be simpler and cheaper. Of course at lower speeds you have to consider steering, but since you are going for a new build then you can cater for that in the design.
Also their system it seems to use a Kort nozzle which has its own pluses and minuses for the concept, but another minus is that you may not be (easily) able to fit a larger prop to get the best efficiency for your particular boat. Of course at really low speeds (2-4kn) it probably won't make too much difference.

Click to expand...

BlueSpin is certainly a risk since they are a new company but so are most of the other electric propulsion providers. The advantage of Bluespin is that it is decoupled from the diesel drive line, unlike other hybrid solutions, and it would be easy to take out worst case.

Not sure spinning a large prop is really a needed since the use case is for sheltered waters at three to five knots, maybe six. The main drive line is still intact. BlueSpin is not a replacement to the CPP.

mcarthur said:

Since you are still at thinking stage, I'd suggest thinking of a narrow catamaran. It has all the deck space available for solar, can fit in the canals (4.9m BOA), can have two engines widely apart for steering, and can have nice internal space (IMHO). Our lovely lady is one such that was designed for the French canal system (NOT Midi ), and we're planning on 8+kW solar with a (likely) parallel hybrid on our 2x135hp diesels. We've already changed to a 48V house bank and a small starter solar array to test things, and are designing the 12-15kW electrics which will run off the existing shaft (aka parallel hybrid). I would like to change to 48V bow thrusters and anchor winch, but given the 12v are working it may be too many BOAT bucks for now.

Click to expand...

Don't really want a catamaran for a variety of reasons. We could put in twin diesels but have decided that is not the best approach with the boat design we are considering. More solar can be installed but they would be on the forward main deck and I don't think like that idea.

The Blue Spin looks interesting. There has been a lot of cool stuff done on retractable drives and thrusters for sailboats lately.

I think a generator still makes sense, maybe even more so with electric propulsion, when it extends get-home range. Having a generator also makes the 48v alternator optional when used with large solar

It's great to reread this thread.

Jeff F said:

The Blue Spin looks interesting. There has been a lot of cool stuff done on retractable drives and thrusters for sailboats lately.

Click to expand...

Yep, they BlueSpin drives look very interesting. What I like about them:
- Retractable so more hydrodynamic compare to thrusters. Tis a small thing though.
- From a hybrid propulsion perspective, the thrusters are completely decoupled from the diesel drive line. This is a big thing to me.
- Beta Marine's parallel system is nice in that the motor is connected to the drive line via a belt so it is not likely to cause a problem to the diesel propulsion, and if so, just removed the belt.
- Should allow more control in close quarters which is a big plus.
- It looks like BlueSpin is solving two requirements with one set of equipment, electric propulsion and bow/stern thrusters.
- With two or three BlueSpin thrusters, one should be able to operate each at a low load but still get the power one needs to go 4-5 knots.
- With two or three BlueSpin thrusters, if one needs thrust, one has plenty of reserve in the motors as long as the battery has the charge and can handle the load.
- BlueSpin works on 48 volts. I have seen other solutions where they are using 96 volts and higher which I really don't like. Just wish more navigation devices ran on 48 volts....

What concerns me about BlueSpin:
- New and small company. Will they be around for long?
- How much support will be provided, short term and long term?
- What to do if the thrusters get jammed into the down position? How easy is it to force them up? I have ideas.
- Does it really work.

Jeff F said:

I think a generator still makes sense, maybe even more so with electric propulsion, when it extends get-home range. Having a generator also makes the 48v alternator optional when used with large solar

Click to expand...

Unfortunately, I think you are right about the need for the generator. I really don't want one but after looking at the solar power generation in the winter months, not seeing how one can really load the engine, even with two alternators, and taking into account the electric propulsion, a generator seems like a good idea/requirement for our use cases.

I have long thought a small generator was all that was needed, say 5KW/6KW but after thinking this through and considering the ability to put large amount of KWhs into a LiFePo battery bank, it seems the bigger the generator the better. The price per KWh is about the same no mater the size of the geset so the more power it can produce, the less time it has to run. In other words, a 5KW/6KW genset would need three hours or so to generate 15ish KWh but a larger generator could produce the same power in an hour.

Having said that, if electric propulsion is not installed for whatever reason, the generator becomes a question again.

Jeff F said:

It's great to reread this thread.

Click to expand...

Yes, yes it was.

dannc said:

I have long thought a small generator was all that was needed, say 5KW/6KW but after thinking this through and considering the ability to put large amount of KWhs into a LiFePo battery bank, it seems the bigger the generator the better.

Click to expand...

Yep. The electric only propulsion range gets extended with a bigger genset as well.

I've wondered about 48 VDC gensets. It seems that this use case is all about feeding the batteries when required.

Jeff F said:

I've wondered about 48 VDC gensets. It seems that this use case is all about feeding the batteries when required.

Click to expand...

Found some. Marine DC Generators - Polar Power

@dannc this is a good thread to get one thinking about extended low speed putting around, which is generally not good for the mains.

When I lived in Florida that was definitely the use case of my wife and I as well. Hours spent at 5 mph on canals and in channels. She hated the ICE.

So whether you go with a huge Li pack or with a generator, for propulsion you may wish to consider switching out your marine gear to a model with a PTI. A power take in will allow you to connect a hydraulic or electric motor and drive your main prop directly.

There is a option to set up the solar panels for 48 volts to the solar controller. Then have the controller convert to 12volts to charge 12 battery bank. I have had house bank converted to 12v lithium for a couple years now.

I have a dedicated 12v lead acid bank for the 12v to 120v inverter. I want to replace that bank with lithium and add solar panels dedicated to charge this bank. I will wire 3 sets of 4 solar panels in series for 48volts to a Victron solar controller. I will wire lithium batteries in parallel for 12volts and set up solar charger to charge this 12v battery bank. This will allow me to use the existing new 12v to 120v pure sin wave inverter. This gives me the ability to run smaller wires from solar panels to controller/charger. The solar controller is in same compartment as lithium battery bank, so the run of heavy size wire will be short to the 12v batteries. I will also run a DC to DC converter from this new set of dedicated lithiums to the existing lithium house bank for house bank back up charging. Bilge pumps, lights, refrigeration ect.. on house bank.
Down the road I can replace inverter with a 48v to 120v unit rewire batteries in groups of four in series and reconfigure the solar controller for 48 v charging. It is an option for a slow conversion to upgrade that doesn't brake the bank.

Bud said:

There is a option to set up the solar panels for 48 volts to the solar controller. Then have the controller convert to 12volts to charge 12 battery bank. I have had house bank converted to 12v lithium for a couple years now.

I have a dedicated 12v lead acid bank for the 12v to 120v inverter. I want to replace that bank with lithium and add solar panels dedicated to charge this bank. I will wire 3 sets of 4 solar panels in series for 48volts to a Victron solar controller. I will wire lithium batteries in parallel for 12volts and set up solar charger to charge this 12v battery bank. This will allow me to use the existing new 12v to 120v pure sin wave inverter. This gives me the ability to run smaller wires from solar panels to controller/charger. The solar controller is in same compartment as lithium battery bank, so the run of heavy size wire will be short to the 12v batteries. I will also run a DC to DC converter from this new set of dedicated lithiums to the existing lithium house bank for house bank back up charging. Bilge pumps, lights, refrigeration ect.. on house bank.
Down the road I can replace inverter with a 48v to 120v unit rewire batteries in groups of four in series and reconfigure the solar controller for 48 v charging. It is an option for a slow conversion to upgrade that doesn't brake the bank.

Click to expand...

I've been planning a 2000 watt solar array and 10kWh 48V LFP bank for quite awhile, but have not pulled the trigger yet because I don't need it until Fall 2025 at the earliest, and it seems the longer I wait, the cheaper it gets. I plan to retain my 690AH 12V FLA GC house bank, my 12V start bank and my 12V genset start bank and continue to run the boat on 12V. I was planning to use 48V to 12V DC to DC charging and add a 120VAC to 48VDC charger, but when I priced it out, it was cheaper and simpler just to buy a Victron 48VDC to 120VAC inverter/charger and run all my AC off that when not running my genset or at the dock. The 48V inverter will power my 12V 3 bank battery charger to keep all my 12V banks topped up, and when AC is available, will charge my 48V bank, (assuming solar does not keep it full). My existing 3000 watt 12V inverter will just be backup to the 48V inverter. I realize it's not the most efficient way to keep my 12V bank topped up, but I always have my inverter running when AC is not available so I'm OK with the inefficiency.

I love that the Victron 48V inverter does automatic 50AMP 120VACx2 switching because it will interface perfectly with my existing manually-swtiched 12V inverter. The wiring that allows me to run either of them as inverters or chargers will be really simple. I can even use the 12V inverter to power the Victron inverter with 120VAC to use my 12V alternators to charge the 48V bank, if I want to, though that would likely never happen.

Jeff F said:

Yep. The electric only propulsion range gets extended with a bigger genset as well.

Click to expand...

And as usual for boat design spirals, not only is the larger generator going to dump more power into the batteries in a shorter power of time, and it also allows one to propel the boat when circumstances warrant, but it also impacts the water maker.

If one now has a big generator, one might as well put in the most GPH water maker since one now has the power, i.e., make the most water in the shortest amount of time.

Looking at one of the areas we want to visit and even stay in, trips would be short, sometimes as little as one hour, so using the generator to produce as much power as possible in a trip, as well as having the water maker as much water as possible would be very positive.

This really becomes and issue during the winter months when the solar panels are just not going to product the needed power.

Mako said:

@dannc this is a good thread to get one thinking about extended low speed putting around, which is generally not good for the mains.

When I lived in Florida that was definitely the use case of my wife and I as well. Hours spent at 5 mph on canals and in channels. She hated the ICE.

So whether you go with a huge Li pack or with a generator, for propulsion you may wish to consider switching out your marine gear to a model with a PTI. A power take in will allow you to connect a hydraulic or electric motor and drive your main prop directly.

Click to expand...

Looking at a hybrid propulsion system, I first saw the PTI transmissions. My concern with them was/is:
- Another point of failure in the drive line.
- The electric power is a back up only for the engine. One still is dependent on the transmission, prop shaft and prop.
- We want a CPP and I have not seen how one can use a CPP and PTI transmission. Maybe there is a solution out there, one would think there would be, but I have not found it.

So to use a PTI hybrid solution or the Beta Marine belt solution, one has to give up on the CPP.

What I like about the BlueSpin idea is that it is completely isolated from the diesel propulsion. The CPP can still be used and it's reliability is not at risk from the hybrid propulsion.

We have been on land where we are looking to go cruising/live and I have watched the river traffic in person but also with AIS. Much of the commercial river traffic is 7-8 knots though there are faster vessels running around. I really thought the commercial traffic would be going faster, but they are not, so even running at electric speeds on these rivers seem doable. At least when going with the current.

Hey all. Wanted to join up mostly to just watch this thread, but figured I should add my deets to it. Big blog post here for more details. But basics:
* 30 kWh of 48V batteries from ECPC
* 2x Victron Quattro 5kVA alternators running 100% of our 120/240 power
* ~3540W of solar in two banks (2550W on the roof, 990W on the front)
* 12V house running entirely off 3 Orion-Trs, with multiple backups to hardwire to other systems if something goes wrong
* Custom raspberry-pi-based solution for managing a Calex 3000W bi-directional dc-dc converter to manage sending 12V power to 48V, and visa-versa (one of the backups to the Orion-Trs as needed)
* 48V windlass, and a few other smaller 48V things, but mostly a 12V-based boat still

We have another buddy boat with the exact same setup as well. We've purchased an APS 8kW 48V alternator this winter and will be putting them on in the spring, so I'm excited to have ~.7C charge rates available to us next year if we combine solar, 2 alternators, and generator.

We've accomplished my goal of making the boat into a house -- we basically don't think about power. We leave the hot water heater on 24/7, once in a blue moon the generator automatically turns on (or I manually do it if I notice us heading toward needing it). We run the A/C on anchor at night if we want it. It's a lovely world.

I'm moderately interested in hybrid propulsion, but I'm pretty sure that it just doesn't make sense to do it on this boat, and instead will be something we focus on in whatever the next boat is.

codingparadox said:

Hey all. Wanted to join up mostly to just watch this thread, but figured I should add my deets to it.

Click to expand...

I was just reading your intro, and then your blog post. Nice to have you. You're clearly an early adopter having that up and running in 2021.