Electric sailboat conversion - 2 steps forward 1 step back

luckybeanz

New Member
Hi all, firstly thanks for all the amazing information, though it is all this information that has my head in a tangle...

I am currently in Italy and looking to convert our 37ft sailboat (https://www.luckybeanz.com/2018/09/23/realising-a-dream/) which we live aboard to an electric drive. I have been researching this for about 3 years now and I want to take the plunge this winter, ordering components in the next few weeks. The question is not whether it is a good idea or not, that decision is made. Though every time I think I am there with the system I seem to find some new information which makes me reconsider. The biggest question is around the battery setup, since it will require a high amp draw.

I started a thread here with the batteries I was looking at https://diysolarforum.com/threads/d...igh-c-cells-any-experience.14159/#post-158002 and have stumbled upon this thread https://diysolarforum.com/threads/lifepo4-bow-thruster-batteries-which-bms.4668/page-2 which is ever so useful, and has me thinking of using the electrodacus BMS with a relay (I know nothing about relays so will be heading down that research path now too)

So hence this post. I am interested in anyone who has done a similar conversion and anyone who has thoughts/recommendations on the battery setup.
The motor will likely be

Here is what I am looking at :
N50 motor here http://www.fimea.it/index_eng.htm I was looking at a Golden Motor 10KW, but I can get this one locally and it supports direct drive.
250 / 300AH 48v bank- for engine and inverter
200AH 12v bank - for boat living electrics - fridge, lights etc
1.2KW solar using sunpower panels - https://sunpower.maxeon.com/uk/site...3-400-395-390_ds_en_a4_mc4_1mcable_536423.pdf
Charger/Inverter - still to be decided, but needs to be about 3kw.
DC/DC converter to run windlass and keel pump - both 12v

Interested to hear any /all thoughts one this, especially from those who have done it and have a list of components they care to share.
Thanks
 

svetz

Works in theory! Practice? That's something else
Staff member
Moderator
Welcome to the forums!

I'll move this thread over to the Marine section to see if anyone can comment on you components as you hope!
 

luckybeanz

New Member
Thanks, been scanning through that section, looks like one or two might have some input if they see it.
 

Samsonite801

Solar Enthusiast
Firstly, let me say hehe, that I am not an expert in marine EV, let alone automotive EV. I do have some pretty good experience with yachting and marine repair and maintenance. If I was going to build an EV boat, I would have to look at all the factors involved. Probably similar to an automotive application in certain regards since any portable vehicle has many constraints not found in a stationary application (mainly size and weight, vibration, weight transfer, temperature extremes, corrosion, etc).

I would probably start with battery chemistry, and how much energy density I need based on constraints of size footprint and weight footprint. In a marine application, you might also want to consider weight transfer (battery weight location on boat). Will too much weight fore or aft of center cause issues with the performance or handling of the boat? Where are all the available locations on the boat to situate the batteries? Do they all need to be in one place or are there multiple locations where they can be distributed to balance any potential weight transfer problem?

LiFePO4 has lower energy density for its weight and size than some of the cobalt chemistries. Is it significant enough to matter here for your desired level of performance?

Next we get into power requirements, EV cycle duration, and performance requirements. Speed costs money, how fast do you want to go? And how far do you want to be able to travel without shore charge. Will this solution include hybrid function, like fueled generator, supplemental solar, wind generators?

If you have your heart set on that N50 motor, I would see if I can first get a more detailed spec sheet on it, so you could hopefully get some better idea of how much power it may use under various 'partial speed' loads less than it's max power consumption, to get a feel for how much juice it may require at different speeds like normal cruise vs max speed. Do you have any idea about the present horsepower requirements for your boat? Like if you have a conventional gas or diesel engine now, how much horsepower / torque does it have and at what RPM, and how many knots can you get up to at max RPM? What is the propeller RPM at that engine RPM? Will you plan to spin the electric motor at that same cruise or max RPM, or will you need to change prop pitch to optimize to the new electric motor's characteristics? How many kW of electricity is required to spin the electric motor at the target RPMs and load points? If we can get some better idea of how much actual electricity will be required, then we can start looking into how much battery amps we need to provide, and for how long durations (kW/h).

Lots of other things involved, but it's doable, if we think like a Tesla engineer though, you can build it right to start with, which would save you money in the long run. We also want to make sure it is safe and well engineered for reliability.

As far as batteries go, for more amps, you can string up more 48v banks in parallel if you are hitting BMS current constraints and get more juice, as I would rather over-engineer it to keep temperatures under control, otherwise you might have to start adding in cooling solution (say for example if you have cobalt chemistry for smaller, lighter footprint, with high energy density, discharging at high rates).

Just some food for thought is all...
 

luckybeanz

New Member
Firstly, let me say hehe, that I am not an expert in marine EV, let alone automotive EV. I do have some pretty good experience with yachting and marine repair and maintenance. If I was going to build an EV boat, I would have to look at all the factors involved. Probably similar to an automotive application in certain regards since any portable vehicle has many constraints not found in a stationary application (mainly size and weight, vibration, weight transfer, temperature extremes, corrosion, etc).

Firstly thank you for the detailed response and for taking the time and energy to put your thoughts down. My response here is as much for information for those interested it is to respond to your points.

As I stated I've been researching this for a good three years with the better part of them actually living on and sailing the boat I am intending to convert. There are so many reasons why electric makes more sense on a small sailboat. The only downsides are the upfront cost of batteries and the perceived range anxiety. There are plenty of sailing youtubers (sailing UMA, Rigging Doctor and Beau and Brady to name a few) tat have done the conversion and here in Europe there is more of a push to get rid of diesel, especially in inland waterways, which is on our agenda.

I would probably start with battery chemistry, and how much energy density I need based on constraints of size footprint and weight footprint. In a marine application, you might also want to consider weight transfer (battery weight location on boat). Will too much weight fore or aft of center cause issues with the performance or handling of the boat? Where are all the available locations on the boat to situate the batteries? Do they all need to be in one place or are there multiple locations where they can be distributed to balance any potential weight transfer problem?
Considering that I'll be removing a 160kg diesel and all its components including a 180l diesel tank and replacing it with a 60kg electric, there is room to play with weight, also the space isn't much of a concern as they will all fit in the existing engine compartment which is fairly centered in the boat.
LiFePO4 has lower energy density for its weight and size than some of the cobalt chemistries. Is it significant enough to matter here for your desired level of performance?
LiFePO4 make sense from a safety perspective. I was originally looking at two Tesla model S modules and while I am sure they would not be an issue, especially with forced cooling (as the engine will have too) bats have come down in price so much in the last 3 years that I think it would make more sense to go with LifePO4 for simplicity sake.
Next we get into power requirements, EV cycle duration, and performance requirements. Speed costs money, how fast do you want to go? And how far do you want to be able to travel without shore charge. Will this solution include hybrid function, like fueled generator, supplemental solar, wind generators?
Here is where the fun conversation always starts when talking to other boaters... It seems most people buy a sailboat to motor around and occasionally put up the sails. I bought a sailboat to sail and go slow, no need to rush when you have your home with you. Looking at others with similar boats (
) I was very interested to see that they could motor without pulling anything from their batteries at 1 /1.5 knts. This may sound slow, but where it comes into its own is when one is able to sail at 2kts and add the extra speed using the motor and not drawing on the batteries. The charging sources:
  • 1.2KW of solar - possible to extend if needed.
  • Motor regen when sailing, probably on at speeds of 5kts, but this is one of the reasons for the N50 as it is likely able to start generating at lower speeds.
  • Generator - I'd like to start without and test how we go before purchasing ( trying to rid of the fuel burning and need to fill up)
If you have your heart set on that N50 motor, I would see if I can first get a more detailed spec sheet on it, so you could hopefully get some better idea of how much power it may use under various 'partial speed' loads less than it's max power consumption, to get a feel for how much juice it may require at different speeds like normal cruise vs max speed. Do you have any idea about the present horsepower requirements for your boat? Like if you have a conventional gas or diesel engine now, how much horsepower / torque does it have and at what RPM, and how many knots can you get up to at max RPM? What is the propeller RPM at that engine RPM? Will you plan to spin the electric motor at that same cruise or max RPM, or will you need to change prop pitch to optimize to the new electric motor's characteristics? How many kW of electricity is required to spin the electric motor at the target RPMs and load points? If we can get some better idea of how much actual electricity will be required, then we can start looking into how much battery amps we need to provide, and for how long durations (kW/h).
Yes, they do have a very nice package at an attractive price, but this is the one piece of information that I can't seem to get out of them.

Having looked at my existing usage with the diesel. I see that my average speed motoring is around 3.5knts with the engine at 1500rpm about 4knts at 1700rpm ( see datasheet for diesel here http://minardsdiesel.com/media/superseded/hm_series/brochure/3hm35.pdf). I have never actually pushed the engine at max rpm for any significant time at 2400rpm I get about 5knts, another reason I don't feel the need for a giant,clunky diesel. The sailboat's hull speed is only 7knts anyway and I've never pushed the motor to that, only under sail. Obviously the electric is a lot more efficient than this and also the torque starts at zero, so it should push the boat at the desired 3/3.5 knts using much less power. I have a 4 blade variprop with adjustable pitch so should be able to tweak it for optimum performance and balance between performance and regen.

The aim is to have a decent range at 3kts say 10hrs without any solar input.

I'm not actually set on the N50, other than they offer a nice package designed for the marine environment and it is sourced locally. I'm looking at a curtis controller and they are the local supplier hence how I found them. The motor is also direct drive and should offer a little bit better regen than a PMDC motor such as the golden motor I was looking at here https://www.goldenmotor.com/eCar/HPM48-10000Curve.pdf
Lots of other things involved, but it's doable, if we think like a Tesla engineer though, you can build it right to start with, which would save you money in the long run. We also want to make sure it is safe and well engineered for reliability.
I like your thinking. It seems to figure out all the pieces one needs some sort of engineering degree. So many variables.
As far as batteries go, for more amps, you can string up more 48v banks in parallel if you are hitting BMS current constraints and get more juice, as I would rather over-engineer it to keep temperatures under control, otherwise you might have to start adding in cooling solution (say for example if you have cobalt chemistry for smaller, lighter footprint, with high energy density, discharging at high rates).
Thanks for confirming this.
Just some food for thought is all...
Thanks again, all very useful and nice to discuss it without people telling me I am crazy for thinking electric is better than diesel.
 

Luthj

Solar Addict
With 10kw and 48V nominal, you are running around 210A. For this type of application I would suggest avoiding FET based BMSs. Instead choose a BMS which can drive an external relay/contactor. This seems to be the path you are considering. There are numerous options that can handle 200A continuous, and 300-500A for short periods. Gigivac is a good place to start, they have some dual coil (low power) relays.

The electrodacus isn't really intended for an EV application. So it can't communication with your motor controller. I don't know if that's an issue for you or not. Depending on your application you may want to have your motor controller de-rate your output at low SOC or temperature. In an EV application I would also want a BMS which can monitor each cells internal resistance. High internal resistance is often the first warning of a cell failure, or a bus bar issue.

What kind of current do your windlass and keel pump use? High current DC-DC converters which can run motors are not cheap. It may be easier to design your 12V bank to accommodate those loads, and use a DC-DC charger to keep it topped up from your traction pack.

Do you do deep water sailing or go far from shore? Depending on your risk, you need to evaluate what systems are critical. Rough seas require more care in mounting a pack. Same goes for powering your navigation, radio, other mission critical items, you need to asses reliability and fault tolerance if your life depends on these systems.
 

SeptemberMorn

New Member
Hi Mark,

A big thumbs up for your decision.
We are doing the exact same thing on our 42 ft Moody.

Our plans are:

18kW motor
Victron Inverter 5kW
LiFePO4 48Volt 600AH (3x200AH)
48 Volt Watermaker
DC DC for 12 Volt (Fridge, Instruments, Lights)
1600 Wp Sunpower Maxeon 3 (400Wp x 4)
Induction stove & electric oven
electric Outboard

Remove Diesel Engine, 260 Liter steel diesel tank, Generator and old AGM Batteries will easily compensate for weight of batteries 48 cells a 4kg, 40kg engine, 35kg Inverter and 80 kg Solar.

No more Diesel and Gas onboard

I split the battery in 3 to reduce individual amp load / requirement on BMS.

I did ask Oceanvolt for an offer which nearly put the project to an end before it even started; their cost estimate nearly matched the price of the boat.

Nevertheless, as to "power needed" and what range to expect I found their offer pretty usefull. It kind of matches calculations I found on Fischer Pandas electric drive concept.

This is what they came up for on my boat (42ft, 10to):

1605198354050.png

1605198562068.png

1605198658009.png
I am building the batteries right now and plan to test them this COVID winter with a temp rigged solar panels and charge my EV from the inverter...... and if Covid allows all goes into the boat in spring next year (boat is in Belgium, I am living in Germany, crossing borders is difficult these days


Rgds
Frank
 

luckybeanz

New Member
Hi thank you for the response.
With 10kw and 48V nominal, you are running around 210A. For this type of application I would suggest avoiding FET based BMSs. Instead choose a BMS which can drive an external relay/contactor. This seems to be the path you are considering. There are numerous options that can handle 200A continuous, and 300-500A for short periods. Gigivac is a good place to start, they have some dual coil (low power) relays.
The motor supplier will be providing a contactor so I'll look to do a 2 bank battery of around 200ah each. That way I'll have a bit of redundancy too. Still not sure on BMS.
The electrodacus isn't really intended for an EV application. So it can't communication with your motor controller. I don't know if that's an issue for you or not. Depending on your application you may want to have your motor controller de-rate your output at low SOC or temperature. In an EV application I would also want a BMS which can monitor each cells internal resistance. High internal resistance is often the first warning of a cell failure, or a bus bar issue.
Thanks for the tips.
What kind of current do your windlass and keel pump use? High current DC-DC converters which can run motors are not cheap. It may be easier to design your 12V bank to accommodate those loads, and use a DC-DC charger to keep it topped up from your traction pack.
On further reading I realize this, there is a whole thread somewhere on here discussing it. So I think I'll probably just keep a 12v bank to power these and the house items. They don't draw that much, the windlass is only a 1000w and the keel pump is similar but I'll make sure to check the keel pump.
Do you do deep water sailing or go far from shore? Depending on your risk, you need to evaluate what systems are critical. Rough seas require more care in mounting a pack. Same goes for powering your navigation, radio, other mission critical items, you need to asses reliability and fault tolerance if your life depends on these systems.
I found this interesting. Personally I think the new system will be be much more reliable than what is there at the moment. My diesel engine has failed me twice and once in a pretty hairy situation. The batteries will be mounted low and solid so should not get much shake in the boat. I did see on Will's latest video,
that he mentioned something about vibrations and am wondering why that is? Just because of the limited thread?
 

Luthj

Solar Addict
You just need to assess failure modes and your tolerance of each type. For example, do you need a redundant way to power your navigation and radio? Water maker? Look at each component, and asses the failure modes in order of likelihood. Then look at the failure consequences. A failure tree is a good idea. Then asses how each failure can be repaired at sea. If spare parts are needed or not, etc. You might find that you are okay with a single traction pack, or that you need more than one way to power critical electronics/safety equipment.

Loosing drive is a big deal, but getting stranded off shore with no radio or water could be as bad, or worse.

Vibration wise, you won't experience high frequency vibration on a sailing boat, but big swell can produce high g-force shock loads. As long as your pack is well secured, and the cells can't move relative to each other, its fine. But if the cells are allowed to move at all, even a couple mm, it can eventually cause failure of bus bars or cell casings.

Having two separate packs with their own independent BMS provides good redundancy. You just need to have a method (ideally automatic) to limit your motor controller if one pack drops out. Otherwise you over current the remaining pack (unless both packs can carry the max load). With two packs you will need two contactors/relays. You will also need a method to manually bypass the BMS for emergencies. With two packs you will want an independent switch for each contactors manual override.
 

Samsonite801

Solar Enthusiast
You just need to assess failure modes and your tolerance of each type. For example, do you need a redundant way to power your navigation and radio? Water maker? Look at each component, and asses the failure modes in order of likelihood. Then look at the failure consequences. A failure tree is a good idea. Then asses how each failure can be repaired at sea. If spare parts are needed or not, etc. You might find that you are okay with a single traction pack, or that you need more than one way to power critical electronics/safety equipment.

Loosing drive is a big deal, but getting stranded off shore with no radio or water could be as bad, or worse.

Vibration wise, you won't experience high frequency vibration on a sailing boat, but big swell can produce high g-force shock loads. As long as your pack is well secured, and the cells can't move relative to each other, its fine. But if the cells are allowed to move at all, even a couple mm, it can eventually cause failure of bus bars or cell casings.

Having two separate packs with their own independent BMS provides good redundancy. You just need to have a method (ideally automatic) to limit your motor controller if one pack drops out. Otherwise you over current the remaining pack (unless both packs can carry the max load). With two packs you will need two contactors/relays. You will also need a method to manually bypass the BMS for emergencies. With two packs you will want an independent switch for each contactors manual override.

When I sailed with my step dad a lot back when I lived in Washington State, one thing I always realized on every boat he ever owned while I hung around, was that in addition to his high horsepower main drive, he always had a 'kicker' on one side, like a 10hp outboard as a backup drive (just connected to a little carry tank with a quick-disconnect fitting). One time he needed it too, when his input shaft coupler failed once on one of his boat's outdrives. He's like 83 now but boy does he have some sailing stories!
 
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luckybeanz

New Member
Hey Frank, big props to you on leading the way. How many people have you spoken to that dismiss you as crazy and think electric can't replace a diesel?

Thanks for the info below, sounds like we are planning something pretty similar, that motor looks rather nice.


Hi Mark,

A big thumbs up for your decision.
We are doing the exact same thing on our 42 ft Moody.

Our plans are:

18kW motor
Have you already got it? What I like about the one I'm looking at is they actually provide a nice setup:
a) N50D2LC 10kW S2 48V liquid cooled motor with stainless steel supports;
b) 48V Curtis controller cable and mounted in a stainless steel case
with dc converter and cold plate;
c) wig wag single lever;
d) model 840 display;
e) liquid cooling kit (heat exchanger, reservoir, pumps);

is 2.960 eur + VAT, delivery approx 8 weeks.
- it looks super clean and while the induction motor may not be as efficient as your 96%, it does offer the ability to go direct drive and I think there will be a bit better regen... I'm just trying to convince myself it is still the right option after seeing the 14kw one on the site you linked.
https://www.boostech.de/en/produkt/set-32-kw-electric-motor-96-nm-sevcon-gen4-size6-48v/
Victron Inverter 5kW
Can't go wrong with victron. Is that the inverter/charger? I was trying to compare them to Will's' favorite EPever. Still undecided, but probably fork out for a 3kw victron in the end.
LiFePO4 48Volt 600AH (3x200AH)
Ye, I think I have settled on a split bank too. What cells have you got and what BMS. I was just watching Will's latest video and he did a bigbattery teardown which he mentioned Lishen batteries,
. A quick search on ali and I find they are currently doing a deal with 20% off on these 273AH https://www.alibaba.com/product-det...title.2d3972b65Ks2aF&s=p&fullFirstScreen=true - so reckon those will be the way to go unless someone here stops me in the next 24hrs.
48 Volt Watermaker
DIY or off the shelf. I'd like to get one, but I am actually waiting on the technology as I think we are about to see some now humidity generators hit the market https://www.watergen.com/product/automotive-solution/ I've messaged them but not received anything back.
DC DC for 12 Volt (Fridge, Instruments, Lights)
1600 Wp Sunpower Maxeon 3 (400Wp x 4)
Good choice. Be keen to see how you mount them. I am going for 3 of the same with the potential to add flex.
Induction stove & electric oven
Looking at the same. The oven is the killer, but seems there are some decent toaster ovens on the market now. What are you using?
electric Outboard
If you have not got one yet, I highly recommend the epropulsion ones. I use one with our seahopper folding dingy and only charge it once a week.
Remove Diesel Engine, 260 Liter steel diesel tank, Generator and old AGM Batteries will easily compensate for weight of batteries 48 cells a 4kg, 40kg engine, 35kg Inverter and 80 kg Solar.

No more Diesel and Gas onboard
Not to mention the amount of space gained. I actually forgot about the weight gains from removing the AGMs!
I split the battery in 3 to reduce individual amp load / requirement on BMS.

I did ask Oceanvolt for an offer which nearly put the project to an end before it even started; their cost estimate nearly matched the price of the boat.
Tell me about it, pretty crazy. If you aren't a professional youtuber or got hot pockets they are just a bit hard to justify.
Nevertheless, as to "power needed" and what range to expect I found their offer pretty usefull. It kind of matches calculations I found on Fischer Pandas electric drive concept.

This is what they came up for on my boat (42ft, 10to):

View attachment 27333

View attachment 27334
View attachment 27335
Very interesting, thanks for sharing. Our boat is 6ton but with the lifting keel I think it might actually make it more efficient. The people I am talking to about the motor did have a look at the yanmar specs and came back with this which was helpful.
Based on the motor performances curves, we can see that at 1600rpm the
propeller power needed is 6hp- approx 4.5kW.

Please note that at this speed, the ICE motor is still capable to
deliver the mechanical power of 10kW (1600rpm x 60Nm equals 10kW). Only
it is not using it.

Now about the rpms/power.

With the motor at 1600rpm, the propeller runs at 747 rpms with 4.5kW of
draw power.

With the motor at 2400rpm, the propeller runs at 1121 rpms with 10kW of
draw power.

I attached a graph that shows the rated mechanical power of the N50
electric motor and the battery current draw from 0 to 1500rpm. We
assumed a linear behaviour since the motor is not overloaded.


So at 750 rpms the electric motor can deliver 5kW mechanical with a
battery electric power consumption of 50Vx110A=5.5kW- approx 90% efficiency.

Since we need 4.5kW on the propeller shaft, we expect a battery
consumption of approx 4.5/0.9=5kW . So your 48V 250Ah 12kWh pack can
last two hours at 3-3.5knots.

A PMAC/PMDC motor will gain only few % of efficiency. We are
manufacturing PMAC 5-10kW prototypes for boats where the motor weight
and volumes must be limited e.g. outboards. However, we think that the
induction motor is still a great choice for propeller direct drive at
reasonable speeds (750-1000-1200 rpms).


I am building the batteries right now and plan to test them this COVID winter with a temp rigged solar panels and charge my EV from the inverter...... and if Covid allows all goes into the boat in spring next year (boat is in Belgium, I am living in Germany, crossing borders is difficult these day

Rgds
Frank
Again thank you for the info and really keen to follow along and see how your setup goes. As I said I have been thinking and planning this for a couple years, but just haven't been able to bit the bullet due to lockdowns and cost. Though I am hauling out in Jan and hope to have everything in place to do the conversion whilst on the hard. Will order batts in next couple days.
 

Jan Gils

New Member
The motor supplier will be providing a contactor so I'll look to do a 2 bank battery of around 200ah each. That way I'll have a bit of redundancy too. Still not sure on BMS.
You've had already some great tips from other forum members. I live in Belgium and own a 55ft sailboat, which I'm converting to LifePo4 batteries. I'm no specialist and don't have an electric engine or induction cooker or stove, but 2 kids with iPads and all electric winches and a power hungry and heavy (32ton) sailboat.

Concerning the battery, I'm currently building a 24V system, 3 batteries of 8 cells in series (EVE 280Ah cells). This setup is a 8s3p, and the reason is
  1. Weight to be able to pre-build the batteries and mount them in the boat as a unit
  2. Redundancy if a cell goes bad.
  3. High amps are possible, because the load is split over 3 batteries.
The whole setup will have 3x280Ah = 840Ah @ 24V. Take into account you want to avoid the knees of the cells, the capacity is about 670Ah realistic.

If you're discharging at high amps, you should avoid the popular chines mosfet BMS systems as they will get hot even if they are rated for 200A. After some weeks of research, I decided on a Batrium BMS system with seperate contactor / shunt. My chargers are Victron Quattro 24V/5000VA/120A and Skylla i+i 24V/100A and the Batrium BMS can also talk to the chargers through the CANBUS protocol. Additionally the Batrium is a centralised BMS, so I only need 1 controller to monitor all cells in the 3 batteries. By using this setup, there are 3 layers of security:
  1. Max voltage setting in the charger profiles
  2. Canbus communication to throttle down the chargers, based on the BMS information (temp monitor, cell voltage, ...)
  3. Trip of contactor if 1) and 2) fail
For high amp systems, take a factor of x2 when engineering the system. My chargers can put in 220A continuously, but the contactor is designed for 400A continuously, with a breaking power of 20kA. Also choose a contactor with low power usage (Gigavac GV200MA for a 24V system or Gigavac GV200NA for 48V). Specs are here:


As for the BMS, there are some good alternatives as REC or ORION. If you're using parallel banks, you'll find that you need multiple BMS systems. I talked to REC for my setup, and they said I needed 4 BMS systems (1 master, 3 slaves) so the whole system could still talk to Victron equipment. Mind you, these BMS systems are not cheap.

See here for my setup:

 

SeptemberMorn

New Member
Hey Frank, big props to you on leading the way. How many people have you spoken to that dismiss you as crazy and think electric can't replace a diesel?
Most common reply is "interesting" followed by "how fast and how far can you go" ....... and normally ends in "not for me" "I want to be able to push me out of bad weather". I think the crucial bit is the concept of living aboard and not having to make it home to go to work on Monday.......
Following some of the electric boats on youtube like Sailing Uma or Beau & Brandy the key is to sail and not to motor......



Have you already got it? What I like about the one I'm looking at is they actually provide a nice setup:
a) N50D2LC 10kW S2 48V liquid cooled motor with stainless steel supports;
b) 48V Curtis controller cable and mounted in a stainless steel case
with dc converter and cold plate;
c) wig wag single lever;
d) model 840 display;
e) liquid cooling kit (heat exchanger, reservoir, pumps);

is 2.960 eur + VAT, delivery approx 8 weeks.
- it looks super clean and while the induction motor may not be as efficient as your 96%, it does offer the ability to go direct drive and I think there will be a bit better regen... I'm just trying to convince myself it is still the right option after seeing the 14kw one on the site you linked.
https://www.boostech.de/en/produkt/set-32-kw-electric-motor-96-nm-sevcon-gen4-size6-48v/
Not ordered yet; but I have been in contact with the guy from Boostech. I would love to make use of the -3% VAT and buy this year, not sure whether it will work out.

https://www.boostech.de/en/produkt/set-32-kw-electric-motor-96-nm-sevcon-gen4-size6-48v/
Can't go wrong with victron. Is that the inverter/charger? I was trying to compare them to Will's' favorite EPever. Still undecided, but probably fork out for a 3kw victron in the end.
It is the inverter/charger. I was looking at individual components vs the integrated and settled on this one.

Ye, I think I have settled on a split bank too. What cells have you got and what BMS. I was just watching Will's latest video and he did a bigbattery teardown which he mentioned Lishen batteries,
. A quick search on ali and I find they are currently doing a deal with 20% off on these 273AH https://www.alibaba.com/product-det...title.2d3972b65Ks2aF&s=p&fullFirstScreen=true - so reckon those will be the way to go unless someone here stops me in the next 24hrs.
Those cells look good to me, decent price. I bought similar looking 202 AH cells from Deligreen on ali and a BMS that Will had in one of his videos. Cells with plastic casings like Winston cells might be a little easier to assemble as a pack.

DIY or off the shelf. I'd like to get one, but I am actually waiting on the technology as I think we are about to see some now humidity generators hit the market https://www.watergen.com/product/automotive-solution/ I've messaged them but not received anything back.
I am looking at a SeaWaterPro with a 48V motor; their system is easy, modular and the guy who runs it is really helpful

Good choice. Be keen to see how you mount them. I am going for 3 of the same with the potential to add flex.
The Maxeon 3 are kind of the only ones I found with a high enough voltage to charge a 48V Battery without using a boost charger. I want to be able to mount two of them with their individual solar charger (one on each side of the boat) and two on the stern arch.
They were sold out for some month now and when I saw them available this week I placed my order. They have shipped today and just need to arrive :)
Looking at the same. The oven is the killer, but seems there are some decent toaster ovens on the market now. What are you using?
We are thinking of a regular small domestic one; not finally decided.
If you have not got one yet, I highly recommend the epropulsion ones. I use one with our seahopper folding dingy and only charge it once a week.
We bought a epropulsion one last year
Very interesting, thanks for sharing. Our boat is 6ton but with the lifting keel I think it might actually make it more efficient. The people I am talking to about the motor did have a look at the yanmar specs and came back with this which was helpful.
Based on the motor performances curves, we can see that at 1600rpm the
propeller power needed is 6hp- approx 4.5kW.

Please note that at this speed, the ICE motor is still capable to
deliver the mechanical power of 10kW (1600rpm x 60Nm equals 10kW). Only
it is not using it.

Now about the rpms/power.

With the motor at 1600rpm, the propeller runs at 747 rpms with 4.5kW of
draw power.

With the motor at 2400rpm, the propeller runs at 1121 rpms with 10kW of
draw power.

I attached a graph that shows the rated mechanical power of the N50
electric motor and the battery current draw from 0 to 1500rpm. We
assumed a linear behaviour since the motor is not overloaded.


So at 750 rpms the electric motor can deliver 5kW mechanical with a
battery electric power consumption of 50Vx110A=5.5kW- approx 90% efficiency.

Since we need 4.5kW on the propeller shaft, we expect a battery
consumption of approx 4.5/0.9=5kW . So your 48V 250Ah 12kWh pack can
last two hours at 3-3.5knots.

A PMAC/PMDC motor will gain only few % of efficiency. We are
manufacturing PMAC 5-10kW prototypes for boats where the motor weight
and volumes must be limited e.g. outboards. However, we think that the
induction motor is still a great choice for propeller direct drive at
reasonable speeds (750-1000-1200 rpms).
Sounds pretty reasonable. I am looking at very similar prop speeds with my 17x10 3 blade prop. I plan on keeping my prop and shaft and a roughly 2:1 reduction setup, or maybe even closer to 3:1. Need to speak to boostech about their opinion and the programming......

Again thank you for the info and really keen to follow along and see how your setup goes. As I said I have been thinking and planning this for a couple years, but just haven't been able to bit the bullet due to lockdowns and cost. Though I am hauling out in Jan and hope to have everything in place to do the conversion whilst on the hard. Will order batts in next couple days.
You may be a little earlier as we plan on hauling around April (it is a little colder in Belgium :) )

Rgds
Frank
 

luckybeanz

New Member
Thanks for the detailed response Frank...

I think the crucial bit is the concept of living aboard and not having to make it home to go to work on Monday.......
Following some of the electric boats on youtube like Sailing Uma or Beau & Brandy the key is to sail and not to motor......
This is so true, though interestingly you don't hear them talk much about motor sailing, which I think is where the electric will really comes into its own. As Beau and Brandy found, with their 800w of solar they could motor at about 1 /1.5kts without drawing on the battery. So in light winds if sailing at 2knts one can use the electric to almost double one's speed without drawing down the battery much at all. This could make the difference between a 10hr sail and a 5hrs sail.
Those cells look good to me, decent price. I bought similar looking 202 AH cells from Deligreen on ali and a BMS that Will had in one of his videos. Cells with plastic casings like Winston cells might be a little easier to assemble as a pack.
I made my order for these https://www.alibaba.com/product-det...73.html?spm=a2700.12243863.0.0.664d3e5frgYe56 at that price I just couldn't pass up and it allowed me to get 40 so that I can make a 2P16S 48v bank of about 550AH which will just be used for motoring and a 2p4S 12v bank for everything else.

I'm still looking for the right BMS, but might have to splurge a bit and go for the EMUS or the Thunderstuck which both support CAN.

The Maxeon 3 are kind of the only ones I found with a high enough voltage to charge a 48V Battery without using a boost charger. I want to be able to mount two of them with their individual solar charger (one on each side of the boat) and two on the stern arch.
They were sold out for some month now and when I saw them available this week I placed my order. They have shipped today and just need to arrive :)
Where did you get them from? I have been looking and placed an order from an Italian site, but they only accept bank transfers and I can't get them to answer the phone or email so don't feel confident doing the transfer. Since I assume you got them from a EU site, I can get from the same and shipped to Italy.

You may be a little earlier as we plan on hauling around April (it is a little colder in Belgium :) )
Sounds like it. Batteries ordered, motor being made and could be an early xmas present. I'll keep you posted 😁
 

seadog

New Member
Hi all, firstly thanks for all the amazing information, though it is all this information that has my head in a tangle...

I am currently in Italy and looking to convert our 37ft sailboat (https://www.luckybeanz.com/2018/09/23/realising-a-dream/) which we live aboard to an electric drive. I have been researching this for about 3 years now and I want to take the plunge this winter, ordering components in the next few weeks. The question is not whether it is a good idea or not, that decision is made. Though every time I think I am there with the system I seem to find some new information which makes me reconsider. The biggest question is around the battery setup, since it will require a high amp draw.

I started a thread here with the batteries I was looking at https://diysolarforum.com/threads/d...igh-c-cells-any-experience.14159/#post-158002 and have stumbled upon this thread https://diysolarforum.com/threads/lifepo4-bow-thruster-batteries-which-bms.4668/page-2 which is ever so useful, and has me thinking of using the electrodacus BMS with a relay (I know nothing about relays so will be heading down that research path now too)

So hence this post. I am interested in anyone who has done a similar conversion and anyone who has thoughts/recommendations on the battery setup.
The motor will likely be

Here is what I am looking at :
N50 motor here http://www.fimea.it/index_eng.htm I was looking at a Golden Motor 10KW, but I can get this one locally and it supports direct drive.
250 / 300AH 48v bank- for engine and inverter
200AH 12v bank - for boat living electrics - fridge, lights etc
1.2KW solar using sunpower panels - https://sunpower.maxeon.com/uk/site...3-400-395-390_ds_en_a4_mc4_1mcable_536423.pdf
Charger/Inverter - still to be decided, but needs to be about 3kw.
DC/DC converter to run windlass and keel pump - both 12v

Interested to hear any /all thoughts one this, especially from those who have done it and have a list of components they care to share.
Thanks
Hello
You may want to look into EXRO a small startup that has some very interesting electric motor solutions
 

Canuck_123

New Member
Hello
You may want to look into EXRO a small startup that has some very interesting electric motor solutions
@seadog EXRO is very interesting - real-time series & parallel switching based on torque requirements from what I understand. I'd love to see them working with a company like OceanVolt with their Servoprop - could be excellent for regen.
I also happen to have bought EXRO at their low 2 months ago so I've been a very happy guy, especially this week!
 
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