Re: [electricboats] Throttle control head

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Okay, I'm just going to keep spinning off my original thread with another tangential question...hope that's okay.  This question is regarding the motor "size" to go with...really just the voltage.  My boat is a 48' cat at about 15 tons fully loaded.  When I consulted Thunderstruck, not having gotten to calculating exact hull speed numbers or anything yet, they were suggesting x2 of the 24kw kits at 96v.  That seems like serious overkill to me - after all this isn't a motor yacht, it's still a sailboat.  From info on this forum and a few other sources, my gut tells me that the 12kw kit (x2) running at 48v would do the trick.  Their description even suggests that this kit is used for boats up to 15 tons - mine is twice that (probably not quite actually), two pretty efficient hulls, and of course I would be using 2 motors, so it seems logical that the 12kw would work. I also have no interest or need to achieve my "hull speed" which is probably over 9 knots.  If we get 6-7 knots full out and 3-5 knots at a more efficient power band, that's perfect. 

The middle option would be sizing up to 72v (all kits run the same Me1616 motor, kit price is the same) for 18kw per side.  A 72v pack seems fairly manageable, though maybe not as easily as 48v.  For the same money it would have to be less amp hours than a 48v pack.

So my question is - assuming the 12kw 48v motors are strong enough and the 18kw 72v motors aren't strictly necessary, is there still some benefit to going that route, but with less amp hours, money definitely being an object?  

Thanks...I'm probably overthinking it.  But I've definitely gotten into more trouble in my life underthinking things.  Lol.

Additional note - as mentioned somewhere above, we'll be running about 2000w of solar and a 6kw generator as well.

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Re: [electricboats] Throttle control head

Okay, I'm just going to keep spinning off my original thread with another tangential question...hope that's okay.  This question is regarding the motor "size" to go with...really just the voltage.  My boat is a 48' cat at about 15 tons fully loaded.  When I consulted Thunderstruck, not having gotten to calculating exact hull speed numbers or anything yet, they were suggesting x2 of the 24kw kits at 96v.  That seems like serious overkill to me - after all this isn't a motor yacht, it's still a sailboat.  From info on this forum and a few other sources, my gut tells me that the 12kw kit (x2) running at 48v would do the trick.  Their description even suggests that this kit is used for boats up to 15 tons - mine is twice that (probably not quite actually), two pretty efficient hulls, and of course I would be using 2 motors, so it seems logical that the 12kw would work. I also have no interest or need to achieve my "hull speed" which is probably over 9 knots.  If we get 6-7 knots full out and 3-5 knots at a more efficient power band, that's perfect. 

The middle option would be sizing up to 72v (all kits run the same Me1616 motor, kit price is the same) for 18kw per side.  A 72v pack seems fairly manageable, though maybe not as easily as 48v.  For the same money it would have to be less amp hours than a 48v pack.

So my question is - assuming the 12kw 48v motors are strong enough and the 18kw 72v motors aren't strictly necessary, is there still some benefit to going that route, but with less amp hours, money definitely being an object?  

Thanks...I'm probably overthinking it.  But I've definitely gotten into more trouble in my life underthinking things.  Lol.

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Re: [electricboats] Throttle control head

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On a sidenote, manufacturing parts like this is really straightforward. Just measure accurately, watch some YouTube on how to use CAD software, libreCAD is open source and free. Design your parts and upload to a platform like sendcutsend.com and choose what material you want and they cut it and mail it out promptly.

Comes in handy for many boat projects.

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Re: [electricboats] Throttle control head

On a sidenote, manufacturing parts like this is really straightforward. Just measure accurately, watch some YouTube on how to use CAD software, libreCAD is open source and free. Design your parts and upload to a platform like sendcutsend.com and choose what material you want and they cut it and mail it out promptly.

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Re: [electricboats] Throttle control head

I’m running same motors on my 12m/39’6” power cat. I have a 48v/1,000AH pack with Winston 1,000AH cells. 

1.  Going for 48v/600AH pack makes sense - you should be able to power your domestic loads plus propulsion OK. More is better than less. If you can find 600AH cells, you make installation simpler  

2. I see no value motoring with a single motor - electric motors are efficient at low RPMs - only by experimenting can you determine any power savings by using only one motor. 

3  install as much solar as space and budget permit  

4  The Chargery BMS from AliExpress is a economical solution that uses external contractors for charge bus (solar, etc.) and load bus (motors, inverter, dc/dc charger/power supply, etc.). My load bus is 500A - charge bus less.  Chargery also has a matching shore charger and a “slow-start” module to prevent contactors from welding closed (if there is an inverter on the load bus).  Victron makes components that communicate with each other and is an equally good solution  

 

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Re: [electricboats] Throttle control head

Thanks all!  Some good solutions and good points there.  Great to see some of that up close.  Somewhat unrelated question (though they're all really related) regarding batteries.  My plan at the moment for this cat is a pair of ME1616s (as part of the Thunderstruck kits) which I plan to run at 48v.  I'm trying to decide how many amp hours of battery power I should shoot for.  I've looked at the spec sheets on the motor, but I'm not sure if I'm interpreting it correctly regarding power consumption.  I'd like to run a single battery pack (unless there are good reasons I shouldn't), which I'll also charge my house batteries with using an MPPT or DC to DC converter. 

My thought was 32 of the LF304 Eve cells.  So two parallel 48v, 304 ah banks, resulting in 608 ah bank to run both ME1616 motors.  Keeping in mind this is a sailboat and we very much intend to sail as much as possible, mostly long passages...is that 608 amp hours overkill?  Other than maneuvering, we'll probably spend most motoring time with just one motor.  We'll have about 2000 watts of solar as well, plus a 6kw generator.  Hoping for but not expecting a little regen while sailing as well as through the unused motor when motoring.  I realize "how much battery power do I need" is very subjective, but I welcome all opinions since I really just don't know.

Thanks again!

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Re: [electricboats] Throttle control head

Great job.  I plan for something similar, so really appreciate you sharing.

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