Replace Diesel with electric engine

[norbu09]

Hi, I am new here, please let me know if I post in the wrong spot or make any other rooky mistakes

We live on an Amel Super Maramu in La Rochelle, France and work through our refit at the moment. We planned to go cruising soon but the diesel died so we are now looking at an electric conversion. We did toss many ideas around and landed on a system that I hope is easy to work on, easy to find parts for and good enough to get some first experience. Then, over the coming year, we plan to build out the system so it is fit to sail us home from France to New Zealand.

The system is built around a 48V Lithium battery bank that will service the boat needs and the engine. I have some initial drawings around the idea and would love to get feedback from those who have built systems like this.



The drive system will most likely be a oceanvolt AXC which runs on 48V.

The plan for the battery bank looks like this at the moment:



cheers
Lenz

[Woodland Hills]

The obvious question is how do you charge the batteries? If solar, what is the ratio of charge time to run time. Also how much thrust will you have and is that sufficient to keep you off of a lee shore in a blow when your anchor drags at night?
If you are going to travel from marina power cord to marina power cord using the batteries to get in and out of the marina only that’s a different story.
My bad, I see you are keeping the generator, in that case why the expense of all the batteries? Why not just have a direct diesel-electric drive?

[norbu09]

Originally Posted by Woodland Hills

My bad, I see you are keeping the generator, in that case why the expense of all the batteries? Why not just have a direct diesel-electric drive?

We looked at Diesel electric drives but want to drive down the need for the genset as we add solar and understand how well the regen works from the engine while sailing. Ideally over time we don't need the genset but having it adds a layer of security.

[Adelie]

I suspect The reason for the batteries is so that they don’t need to upgrade the genset. They can install a 40kw Drive but can stay with the existing 8-20kw genset or whatever size it is.
When they need a big boost of power they can drive at all 40kw for a limited period but at cruising speed they probably only need 10-12kw which the genset can provide as long as fuel lasts.

[ttex]

Dang that is a lot of battery!

[roverhi]

Rebuilding the diesel and reinstalling will take less than a month if you push it. The electric conversion will take way way more time. Is your thought in going electric to delay your departure. The hardest part of going cruising is untying the dock lines.

Electric is great for those not going anywhere.

[ArmyDaveNY]

I am not familiar with the Amel, but I suggest you check out The Rigging Doctor on YouTube. They have an electric motor on their mid thirties foot mono. He has some good insights on it. They also have a regen. His battery bank is no where near as large as yours.

They are very happy with their set up but they are also very conscious of its limitations and are happy to live with those. In particular, they primarily use it simply to get in and out of marinas.

Good luck with what ever you decide upon.

[joelhemington]

Originally Posted by norbu09

Hi, I am new here, please let me know if I post in the wrong spot or make any other rooky mistakes

We live on an Amel Super Maramu in La Rochelle, France and work through our refit at the moment. We planned to go cruising soon but the diesel died so we are now looking at an electric conversion. We did toss many ideas around and landed on a system that I hope is easy to work on, easy to find parts for and good enough to get some first experience. Then, over the coming year, we plan to build out the system so it is fit to sail us home from France to New Zealand.

The system is built around a 48V Lithium battery bank that will service the boat needs and the engine. I have some initial drawings around the idea and would love to get feedback from those who have built systems like this.



The drive system will most likely be a oceanvolt AXC which runs on 48V.

The plan for the battery bank looks like this at the moment:



cheers
Lenz

An interesting idea that many of us are thinking about. The current problem with electric propulsion is the initial cost and many of us are hoping that technology will improve to make this more feasible in the future.

From your diagram, it looks like you have about $50,000 worth of lithium batteries there, not mention the cost of the motors and the solar. In the very long run this may end up being cheaper but it's going take years for that system to offset the cost in diesel. Which is why most folks are still doing diesel. The Super Maramu is a fairly large boat at 53' but I doubt you'd need all four modules of the motor system (100 hp seems to be overkill). With the hard rails on the Amel it's easy to add the flop up panels so real estate should not be an issue for you. Ironically, the panels themselves will be the cheapest part of this system so you may as well get enough to fully charge that massive bank fairly quickly.

Note: If you take the west route back to NZ. it's pretty much downwind so the motors aren't going to be used that much. Going east is a whole lot different. Though shorter in NM, most people would not want to head east due to the adverse conditions not to mention the Suez Canal which I'm told can be sketchy.

[skipmac]

I have been considering electric power for years but have not made the switch for several reasons.

1. Batteries. To get reasonable power and more than a few kilometers of range under power you need a lot of batteries. This can be very expensive and add a lot of weight.

2. Charging. Once you add a lot of batteries you have to add a way to put power back in after you use it. With your plan of 48kWh even if you were able to fit 1000 Watts of solar panels it would take you a week of good sun to completely charge the battery bank.

3. Power. 99% of the time when cruising most sailors use the engine for short periods and only use a fraction of the engine power. However there are times when one needs all the power possible like dragging anchor onto a reef in the middle of a storm or as happened to me once, entering a new marina to find a 3 kt current pushing me sideways into a megayacht. I read the specs for the motor you propose that said the 40kW motor would give up to 100 HP. Depending on the motor maybe for a very short burst but I think that rating may be highly exaggerated.

4. Range under power. At moderate speeds and calm conditions I'm estimating you could get 5-8 hours under power with the setup you propose but again it will take days to recharge the system after this. For most cruising 5-8 hours should be fine but would not work for cruising the canals of Europe or the US ICW.

5. Cost. Once you add batteries, charging systems, controls, etc electric can cost double or triple the cost of a new diesel engine.

[stormalong]

Originally Posted by roverhi

Electric is great for those not going anywhere.

This is a critical point. When cruising there will be times when you need dependable power. I understand your desire to be green - I just bought an electric car, when cruising you won't be able to plug in every night.

Stick with diesel, your life and your companion's lives may depend on it.

Before reliable engines many sailing ships ended up on the rocks with their crews unable to do anything. Don't put yourself in that position.

[JDMac]

Listen to @skipmac !! Wish I was a member of this forum sooner! I have done this on a Newport33. By the time you add up batteries, solar array, supports for solar array, charge controllers, backup generator, etc; cheaper to put in a new Diesel. Not to mention ALL the changes to the boat dynamics, the time, and work involved. If I had to do it all again, I would replace the diesel motor. Actually, after this past three months with limited sun, and running the generator, I am considering putting the diesel back.

[nwdiver]

I have looked at this system, with it you can drop the generator and some of the batteries, it looks like respectable regen for the speed you can travel........you have the diesel when absolutely necessary.

https://betamarine.co.uk/portfolio-i...id-propulsion/

[Popaul]

If you understand german, the magazine Palstek www.palstek.de published some very helpful and interesting articles in the past 3 magazines.

[norbu09]

Thanks for all the feedback so far. Will try to hunt down the Palstek back issues and give it a few more nights of sleep

[ramblinrod]

Title is a misnomer.

Electric propulsion is not a "replacement" for a diesel.

Electric is an "alternative" propulsion method.

Every design decision has pros and cons.

Diesel Pros:

1. Standard - What the next buyer expects.
2. Long range - Limited only by fuel carried.
3. Power - for extended periods

Diesel Cons:

1. # of moving parts (complexity / maintenance)
2. Noise and smell

Electric Pros:

1. Quiet - well fewer dB, but may be more annoying.
2. Fewer moving parts - maintenance

Electric Cons:

1. Short range.
2. May limit prospect for resale.
3. No alternator.

Remember that there is nothing "green" about electric propulsion, as the electrical energy used to power is likely produced mostly by coal, deisel, or nuclear.

It is impractical on most boats to generate enough solar power to meet full cruising speed propulsion needs unless one motors less than 20 hours / month.

Hybrids are a possible solution, but can be far more expensive than just picking up a good used diesel engine.