Anyone have any experience with electric engines (TW28)

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MageDK
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Anyone have any experience with electric engines (TW28)

Post by MageDK »

I am looking at building the trawler 28 and I was wondering about the feasibility of using an electric engine. Living in Miami we do get a lot of sunlight pretty consistently throughout the year.
I was wondering if anyone had any experience with electric engines? Would I be able to get the same range as I would using a Diesel engine? Would I need to load up every square inch of the boat with batteries? I know lithium batteries are expensive. Would it be worth it ?
Check out my Trawler 28 build viewtopic.php?t=66261.

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Evan_Gatehouse
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Re: Anyone have any experience with electric engines (TW28)

Post by Evan_Gatehouse »

1. Yes, experience in commercial workboats. Mostly hybrids (batteries for low load situations, diesel for high loads)

2. No. long range only if you fill the boat with batteries. Basically weight energy density of Li-ion is about 1/15 of diesel. What is reasonable/achievable is perhaps 30 or 40 miles at 4.5 knots, depending on your budget. Even still it will be costly.

Here is an example of just the cost of batteries. Say you need 10 kW (14 HP) to go 5 knots against a light chop. To go 50 miles you have to motor for 10 hours. So the battery requirement is:

10 kW motor power x 10 hours = 100 kW.hr total battery bank size

Most people know batteries in terms of Amp.hrs. A 100 A.hr / 12 V battery will have a capacity in kW as follows:

kW.hr = Amp.hr x voltage / 1000

A 100 A. hr battery can produce about 10A for 10 hrs (really it's a bit less but this makes the math easy)

Tis battery capacity in kW.hr is: (100 A.hr x 12V / 1000) = 1.2 kW.hr

So to have 100 A.hr capacity you will need the following number of batteries:

100 kW.hr / 1.2 kW.hr each = 83 batteries.

A Battleborn LiFePO4 deep cycle 100 A.hr, 12V battery retails for $874. Each.

So you will need 83 x $874 = $72,542 and 31 lbs each so 2600 lbs of batteries.

https://battlebornbatteries.com/product ... e-battery/

This does not include the cost of electric motor, controller, wiring etc etc.

3. Only you can answer "will it be worth it". Typical displacement electric pleasure boats have shorter range and lower cruising speeds to reduce power requirements.

Further thought. You won't be able to power the boat with solar panels effectively. Power/area just isn't big enough. You can sit at anchor for several days running a fridge, a stereo, LED cabin lights using just solar. Not A/C.
designer: FB11/GV10,11,13/ HMD18/
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MageDK
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Re: Anyone have any experience with electric engines (TW28)

Post by MageDK »

I was afraid it was going to be something like that. I didn't know the numbers so thanks for the detailed explanation.

I was hoping that electric might be an option given the current fuel prices and everything, but I really want the boat for long-distance trips up and down the coast, and the Keys. I guess I'll plan on going with a Diesel engine for now.

Thanks
Check out my Trawler 28 build viewtopic.php?t=66261.

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Re: Anyone have any experience with electric engines (TW28)

Post by Jaysen »

Electric is more “efficient” but storage (batteries) are the problem. Co wider a hybrid approach that uses a diesel generator to provide battery charging and “on demand peak” to the motor. Think Chevrolet Volt.

That or sails. Wind has been moving boats over water with no fuel cost for a LOOOOONG time.
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Re: Anyone have any experience with electric engines (TW28)

Post by Cbuf »

I have a done a bunch of research in this idea. The only feasible solution is to have a hybrid. Check out the Volvo hybrid drive system. It is a diesel inline power system that combines the shaft for both power generation for charging batteries and has a shaft output for running on diesel at speed. To understand the way it works check out Greenline 39 or 40 hybrid. Depending on model and batteries can go 50 miles on batteries, then flip a switch and the diesel motor kicks in to turn the screw and charge the batteries. With the solar array on top the boat can be at anchor in perpetuity.
https://www.greenlinehybrid.com/en/propulsion
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TomW1
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Re: Anyone have any experience with electric engines (TW28)

Post by TomW1 »

You might want to contact these folks to see what they can do for you. https://www.torqeedo.com/us/en-us/produ ... rid-drives

Tom
Restored Mirror Dinghy, Bought OD18 built by CL, Westlawn School of Yacht Design courses. LT US Navy 1970-1978

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Evan_Gatehouse
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Re: Anyone have any experience with electric engines (TW28)

Post by Evan_Gatehouse »

The reality of the Greenline 39: 20 mile range at 5 knots on battery power for the hybrid model (26.6 kW.hr battery pack)
designer: FB11/GV10,11,13/ HMD18/
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MageDK
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Re: Anyone have any experience with electric engines (TW28)

Post by MageDK »

TomW1 wrote: Mon Jul 11, 2022 2:09 pm You might want to contact these folks to see what they can do for you. https://www.torqeedo.com/us/en-us/produ ... rid-drives

Tom
I did look at the torquedo outboard motors for a dingy. They are pretty impressive for their size.
Check out my Trawler 28 build viewtopic.php?t=66261.

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