Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

While it may be difficult to determine state of charge of a LiFePo4 bank just from voltage, I do think if my voltage was essentially unchanged from November to the following May (according to Victron meter) that is a reasonable indication that the battery was in the same state of charge after that time.  I may not be able to say 53.25 volts is 78% charge but I think I can say that 53.25 is more than 53.20.  And if my measurement went from 53.25 to 53.24 over the winter can I take form that that I didn't loose any significant charge? 

But you are correct about the difficulty of determining state of charge from voltage.  That's why I have the shunt meter to track current in/out of the battery.  It does require that you establish a 100% reference level. 

Also, the charge curve is not flat at the bottom or at the top.  So the voltage change from 100 to 98% is much larger than from 60 to 58%.   Sort of a moot point for me as I never take the bank to that charge level preferring to operate in the 20 to 95% range for my use.  Or maybe 97%. 


Dan Pfeiffer



I don't know where this graph came from but I think it is representative...

On 2023-10-30 9:00 am, Larry Brown wrote:

So LiFePo stays fairly high voltage until it nears the very end but the older Lithium Ion chemistries have a slow drop of voltage until near the end so it's easier to determine the remaining capacity by voltage with that chemistry?  

So really we're talking about what the chemistry is.  But to my point, if you do have the LiFePo, these examples of how little loss someone had after leaving the boat in the cold for years evidenced through checking of the voltage; it's is insufficient.  They would have to have run tests after the winter to see how much energy was actually left.  (Unless they had the other chemistry.)  The only reason I keep bringing this up is that I've checked the voltage on my batteries when full and accidentally left my fridge that should have brought the batteries down and the monitor was disconnected.  I reconnected it and the voltage was the same (13.3 I believe).  I would say the battery was approximately 50% discharged based on how long the fridge had been running.  So putting my monitor back on, the voltage read the same, and the monitor either said 100% or 0%, I forget.  But that left me in an awkward position of figuring out how long to charge the batteries back up and know they are full. (The bms is built into the battery with no way to read.  Something I'll avoid in the future)  I could only let the solar panels charge them for long enough that I was confident surely they must be full and made sure the monitor was at 100%.  If I could tell from the voltage there wouldn't be so much guessing.

 

 

On Sun, Oct 29, 2023 at 6:21 PM Myles Twete <matwete@comcast.net> wrote:

Not all lithium acts like this.

While a fairly flat discharge curve is seen with Lithium Iron Phosphate (LiFePo or LiPo), it is not the case for Lithium Ion chemistries.  As example, the batteries in my pack---Fully charged they reach 49.2v.  Fully discharged voltage is about 30v (2.5vpc).  That's a nom. 40% drop in voltage making it quite easy to estimate the remaining capacity of the pack by voltage monitoring alone.

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of Larry Brown
Sent: Sunday, October 29, 2023 5:39 AM
To: electricboats@groups.io
Subject: Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

 

Unless I'm wrong, my understanding is that lithium doesn't drop in voltage as you deplete them like lead acid and the voltage stays high right up until they reach capacity.  So the only accurate way to gauge loss is through a battery monitor watching the draw from the system.  But drain from low temp which I don't even know if it's a thing wouldn't be tracked with a monitor.  You'd have to draw it down when you get it ready in the spring and watch the monitor to see how long it lasts.  That would be the sure way.  But I don't think they lose much from temp.  I just understand they perform better at optimal Temps and worst at extremes.  There are experts in this list so I'll let them chime in and maybe learn a thing or two  😁

On Oct 28, 2023, at 10:52 PM, THOMAS VANDERMEULEN <tvinypsi@gmail.com> wrote:

Very interesting, Dan.  Thank you for the information.  No doubt your batteries are of nobler pedigree than mine.  I was always over-protective of our kids as they were growing up, but it never did me or them any harm.  In any case, there's still the matter of getting one of those 48v monoliths into my motor space without a hoist and without cutting the opening bigger.
To each his own, I guess!
You're on Erie, then; what port?
Cheers!
[-tv]

 

 

--

Larry Brown

S/V Felicity

Placida, FL

~~~~~~~~~~~~~~~~~_/)~~~~~~~~

    ~     ~          ~~           ~

~           ~~_/)    ~      ~ ~        ~

     ~                  _/)          ~

Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

https://www.patreon.com/posts/83745741?utm_campaign=postshare_creator

Here's a link to how that motor and the battery pack fit into the space that used to hold a Yanmar 3GM. We have a lot of data up on that site and it's not locked for patrons only, don't worry that I'm phishing here.

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Good afternoon from the Azores! I have that exact motor. We went with Eve cells through Docan, and I've been incredibly happy with their performance while shaking down in Florida then crossing 2/3 of an ocean amd now bouncing around the central group here. Any reason you don't want to build your own pack? I'm no engineer but I was completely capable of making this work. And it's a good deal cheaper.

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

So LiFePo stays fairly high voltage until it nears the very end but the older Lithium Ion chemistries have a slow drop of voltage until near the end so it's easier to determine the remaining capacity by voltage with that chemistry?  

So really we're talking about what the chemistry is.  But to my point, if you do have the LiFePo, these examples of how little loss someone had after leaving the boat in the cold for years evidenced through checking of the voltage; it's is insufficient.  They would have to have run tests after the winter to see how much energy was actually left.  (Unless they had the other chemistry.)  The only reason I keep bringing this up is that I've checked the voltage on my batteries when full and accidentally left my fridge that should have brought the batteries down and the monitor was disconnected.  I reconnected it and the voltage was the same (13.3 I believe).  I would say the battery was approximately 50% discharged based on how long the fridge had been running.  So putting my monitor back on, the voltage read the same, and the monitor either said 100% or 0%, I forget.  But that left me in an awkward position of figuring out how long to charge the batteries back up and know they are full. (The bms is built into the battery with no way to read.  Something I'll avoid in the future)  I could only let the solar panels charge them for long enough that I was confident surely they must be full and made sure the monitor was at 100%.  If I could tell from the voltage there wouldn't be so much guessing.

On Sun, Oct 29, 2023 at 6:21 PM Myles Twete <matwete@comcast.net> wrote:

Not all lithium acts like this.

While a fairly flat discharge curve is seen with Lithium Iron Phosphate (LiFePo or LiPo), it is not the case for Lithium Ion chemistries.  As example, the batteries in my pack---Fully charged they reach 49.2v.  Fully discharged voltage is about 30v (2.5vpc).  That's a nom. 40% drop in voltage making it quite easy to estimate the remaining capacity of the pack by voltage monitoring alone.

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of Larry Brown
Sent: Sunday, October 29, 2023 5:39 AM
To: electricboats@groups.io
Subject: Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

 

Unless I'm wrong, my understanding is that lithium doesn't drop in voltage as you deplete them like lead acid and the voltage stays high right up until they reach capacity.  So the only accurate way to gauge loss is through a battery monitor watching the draw from the system.  But drain from low temp which I don't even know if it's a thing wouldn't be tracked with a monitor.  You'd have to draw it down when you get it ready in the spring and watch the monitor to see how long it lasts.  That would be the sure way.  But I don't think they lose much from temp.  I just understand they perform better at optimal Temps and worst at extremes.  There are experts in this list so I'll let them chime in and maybe learn a thing or two  😁

On Oct 28, 2023, at 10:52 PM, THOMAS VANDERMEULEN <tvinypsi@gmail.com> wrote:

Very interesting, Dan.  Thank you for the information.  No doubt your batteries are of nobler pedigree than mine.  I was always over-protective of our kids as they were growing up, but it never did me or them any harm.  In any case, there's still the matter of getting one of those 48v monoliths into my motor space without a hoist and without cutting the opening bigger.
To each his own, I guess!
You're on Erie, then; what port?
Cheers!
[-tv]

--

Larry Brown

S/V Felicity

Placida, FL

~~~~~~~~~~~~~~~~~_/)~~~~~~~~

    ~     ~          ~~           ~

~           ~~_/)    ~      ~ ~        ~

     ~                  _/)          ~

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Not all lithium acts like this.

While a fairly flat discharge curve is seen with Lithium Iron Phosphate (LiFePo or LiPo), it is not the case for Lithium Ion chemistries.  As example, the batteries in my pack---Fully charged they reach 49.2v.  Fully discharged voltage is about 30v (2.5vpc).  That's a nom. 40% drop in voltage making it quite easy to estimate the remaining capacity of the pack by voltage monitoring alone.

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of Larry Brown
Sent: Sunday, October 29, 2023 5:39 AM
To: electricboats@groups.io
Subject: Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

 

Unless I'm wrong, my understanding is that lithium doesn't drop in voltage as you deplete them like lead acid and the voltage stays high right up until they reach capacity.  So the only accurate way to gauge loss is through a battery monitor watching the draw from the system.  But drain from low temp which I don't even know if it's a thing wouldn't be tracked with a monitor.  You'd have to draw it down when you get it ready in the spring and watch the monitor to see how long it lasts.  That would be the sure way.  But I don't think they lose much from temp.  I just understand they perform better at optimal Temps and worst at extremes.  There are experts in this list so I'll let them chime in and maybe learn a thing or two  😁

On Oct 28, 2023, at 10:52 PM, THOMAS VANDERMEULEN <tvinypsi@gmail.com> wrote:

Very interesting, Dan.  Thank you for the information.  No doubt your batteries are of nobler pedigree than mine.  I was always over-protective of our kids as they were growing up, but it never did me or them any harm.  In any case, there's still the matter of getting one of those 48v monoliths into my motor space without a hoist and without cutting the opening bigger.
To each his own, I guess!
You're on Erie, then; what port?
Cheers!
[-tv]

Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

George,
Your example very much highlights the quality of "name brand" prismatics, such as CALB.  But as I'd subbested to Dan, mine are not of that quality and I feel need a little babying.  That fact aside, I don't see the problem with being overly cautious, or providing myself with some additional flexibility in the arrangement.  Two sides to every coin, I guess.
I appreciate the thoughts, though, George, as I'm sure do tohers on the discussion.
[-tv]

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Unless I'm wrong, my understanding is that lithium doesn't drop in voltage as you deplete them like lead acid and the voltage stays high right up until they reach capacity.  So the only accurate way to gauge loss is through a battery monitor watching the draw from the system.  But drain from low temp which I don't even know if it's a thing wouldn't be tracked with a monitor.  You'd have to draw it down when you get it ready in the spring and watch the monitor to see how long it lasts.  That would be the sure way.  But I don't think they lose much from temp.  I just understand they perform better at optimal Temps and worst at extremes.  There are experts in this list so I'll let them chime in and maybe learn a thing or two  😁

On Oct 28, 2023, at 10:52 PM, THOMAS VANDERMEULEN <tvinypsi@gmail.com> wrote:

Very interesting, Dan.  Thank you for the information.  No doubt your batteries are of nobler pedigree than mine.  I was always over-protective of our kids as they were growing up, but it never did me or them any harm.  In any case, there's still the matter of getting one of those 48v monoliths into my motor space without a hoist and without cutting the opening bigger.
To each his own, I guess!
You're on Erie, then; what port?
Cheers!
[-tv]

Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Very interesting, Dan.  Thank you for the information.  No doubt your batteries are of nobler pedigree than mine.  I was always over-protective of our kids as they were growing up, but it never did me or them any harm.  In any case, there's still the matter of getting one of those 48v monoliths into my motor space without a hoist and without cutting the opening bigger.
To each his own, I guess!
You're on Erie, then; what port?
Cheers!
[-tv]

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Why do you need to remove the batteries from the boat for winter storage?  I have a 48V 280AH battery that I built from prismatic cells (cost about $2,700 including BMS).  I have left it on the boat at about 90% charge for three seasons now here in NE Ohio with no charging.  Voltage drop over the winter last season was about 0.005 volts which is likely actually below the capacity of the Victron meter to accurately measure.    I don't think winter removal is necessary. 

http://dan.pfeiffer.net/10m/electric_drive_battery.htm

Dan Pfeiffer

On 2023-10-28 1:14 pm, THOMAS VANDERMEULEN wrote:

David,
You're installing batteries in a 27-foot boat, so I assume your physical space is limited.  That's certainly what I found repowering our 27-foot Cape Dory.  Living and sailing in Michigan gave rise in our case to another consideration, that may or may not apply to you, in that we want to be able to remove the batteries from the boat seasonally for storage.  The thought of building and rebuilding a full 16-cell (I use prismatics) battery back every spring and fall wasn't appealing.  In addition, the access to the motor space where I needed to install the batteries was through a narrow space behind my companionway ladder.  Maneuvering an all-in-one unit that weighs over 200 lbs, and measuring over 30"x15"x12" high, thru the narrow opening seemd an impossible feat.  So I built four 12-volt banks, but used waterproof connecters from each bank to a BMS that monitors, contols, and balances the whole assembled traction battery..
Obviously, if your sailing ground is temperate year round, and leaving the batteries on the boat is not an issue, nor is access to the installation space, then probably none of the above applies to you!
Good luck!
[-tv]

Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

That should say "are not apples to apples"

> On Oct 28, 2023, at 13:26, Ryan Sweet via groups.io <ryan=ryansweet.org@groups.io> wrote:
>
> Your life will be much simpler purchasing 48v units.
>
> The options you posted though are. It apples to apples: Dakota lithium is mined and made in the USA, has great local support, and a fantastic reputation. They are almost twice the cost of Chinese brands. The other link as near as I can tell is a low cost Chinese brand, this one apparently lower than other (warning sign) and has very few reviews (also a warning sign but not necessarily bad - everyone has to start somewhere). There is a bottom tier of low cost Chinese battery reseller companies that perennially rebrand and grow like weeds and have almost zero quality control and usually are seeded with a crop of fake reviews. The more established ones have more reviews, have been around longer, and tend to all track one another pretty closely in price. You can often find reviews on the Will Prowse YouTube channel for some of them.
>
> For a short couple of years I had a business importing Lifepo4 from Chinese factories but the market has shifted such that much larger companies are now involved at higher volume than I could match and it really drove the cost down, which is good. Eg4 from signature solar is established as a pretty reliable Chinese import brand with great us based support they have a really good price on their 48v 100ah ABS style housing batteries right now. If you want the best moned and made in USA go with Dakota or battleborn, but if you are more cost conscious look at eg4 and the raft of similar copycats (litime/amperetime).
>
>
>
>


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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Your life will be much simpler purchasing 48v units.

The options you posted though are. It apples to apples: Dakota lithium is mined and made in the USA, has great local support, and a fantastic reputation. They are almost twice the cost of Chinese brands. The other link as near as I can tell is a low cost Chinese brand, this one apparently lower than other (warning sign) and has very few reviews (also a warning sign but not necessarily bad - everyone has to start somewhere). There is a bottom tier of low cost Chinese battery reseller companies that perennially rebrand and grow like weeds and have almost zero quality control and usually are seeded with a crop of fake reviews. The more established ones have more reviews, have been around longer, and tend to all track one another pretty closely in price. You can often find reviews on the Will Prowse YouTube channel for some of them.

For a short couple of years I had a business importing Lifepo4 from Chinese factories but the market has shifted such that much larger companies are now involved at higher volume than I could match and it really drove the cost down, which is good. Eg4 from signature solar is established as a pretty reliable Chinese import brand with great us based support they have a really good price on their 48v 100ah ABS style housing batteries right now. If you want the best moned and made in USA go with Dakota or battleborn, but if you are more cost conscious look at eg4 and the raft of similar copycats (litime/amperetime).

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Replying to Thomas V and others who report removing batteries in the cold north winters-

I believe you all are being overly cautious and lithium iron phosphate cells can certainly handle extreme cold storage (when not charging).

I have 20 CALB 180AH cells that spend the winter on the boat on Madeline Island in Lake Superior. This will be the eleventh season and I am expecting the same results as previous 10 winter seasons:  measure voltages and disconnect in the fall; measure voltages and reconnect in the spring for launching. In every season the batteries were exactly the same in the spring as they were on haulout in the fall. I cannot imagine going through the bother of removing the cells to a warm storage area.

George O.

On Oct 28, 2023, at 12:14 PM, THOMAS VANDERMEULEN <tvinypsi@gmail.com> wrote:

David,
You're installing batteries in a 27-foot boat, so I assume your physical space is limited.  That's certainly what I found repowering our 27-foot Cape Dory.  Living and sailing in Michigan gave rise in our case to another consideration, that may or may not apply to you, in that we want to be able to remove the batteries from the boat seasonally for storage.  The thought of building and rebuilding a full 16-cell (I use prismatics) battery back every spring and fall wasn't appealing.  In addition, the access to the motor space where I needed to install the batteries was through a narrow space behind my companionway ladder.  Maneuvering an all-in-one unit that weighs over 200 lbs, and measuring over 30"x15"x12" high, thru the narrow opening seemd an impossible feat.  So I built four 12-volt banks, but used waterproof connecters from each bank to a BMS that monitors, contols, and balances the whole assembled traction battery..
Obviously, if your sailing ground is temperate year round, and leaving the batteries on the boat is not an issue, nor is access to the installation space, then probably none of the above applies to you!
Good luck!
[-tv]

Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

David,
You're installing batteries in a 27-foot boat, so I assume your physical space is limited.  That's certainly what I found repowering our 27-foot Cape Dory.  Living and sailing in Michigan gave rise in our case to another consideration, that may or may not apply to you, in that we want to be able to remove the batteries from the boat seasonally for storage.  The thought of building and rebuilding a full 16-cell (I use prismatics) battery back every spring and fall wasn't appealing.  In addition, the access to the motor space where I needed to install the batteries was through a narrow space behind my companionway ladder.  Maneuvering an all-in-one unit that weighs over 200 lbs, and measuring over 30"x15"x12" high, thru the narrow opening seemd an impossible feat.  So I built four 12-volt banks, but used waterproof connecters from each bank to a BMS that monitors, contols, and balances the whole assembled traction battery..
Obviously, if your sailing ground is temperate year round, and leaving the batteries on the boat is not an issue, nor is access to the installation space, then probably none of the above applies to you!
Good luck!
[-tv]

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

I agree with Simon ---- 48V is best, and you can install additional batteries in parallel for more capacity, if needed.

Here is another battery supplier for you to consider: Hi-Powerbatteries

I've had their 160Ah 48V battery installed on my Duffy Electric boat for about a year and a half, and I've been very happy with it.  There are certainly a lot of battery options.

Good luck!

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Re: [electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

Always go with the 48 volt option. No series connections. With series connections , one battery is usually chronically undercharged and prone to failure. Plus with 48 volt batteries, if you want to add more capacity , it is easy to buy and install just one battery instead of four

On Thu, Oct 26, 2023 at 8:49 AM David E Marsland <david.marsland@gmail.com> wrote:

I'm installing an Need 48v 200A for Electrictyacht 10kW motor, in my Catalina 27,
should 1 get 4 x NPP12V 200Ah Li ($2200) or 2 Dakota 48V 96Ah ($5000)?
Electricyacht says 48V is better for load balancing. 
What about safety and reliability of NPP vs Dakota?

https://electricyacht.com/product/quiettorque-10-0-sport-electric-motor/

https://www.amazon.com/NPP-12-8V-200Ah-Phosphate-4500-8000/dp/B0CL95VJ82
 12.8V 200Ah Battery, we suggest you buy 4 units and the total weight is 176.36 lbs. We had applied the best offer for you, is $550 per unit. The total price is $2200. The lithium battery are with long life and more than 4500 Cycles. Only half weight and providing twice capacity in the same size as lead-acid batteries.

https://dakotalithium.com/product/dakota-lithium-48v-96ah-deep-cycle-lifepo4-marine-battery/
The Dakota 48v 96ah batteries at a discounted price when you pair them with one of our motors.
Normal cost is $2699ea, your cost would be $2500ea.

The Lynac 48v 100ah and 48v 130ah batteries are certified grade A cells and have Bluetooth capability.
48v 100ah= $2557ea
48v 130ah= $3297ea

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[electricboats] Need 48v 200A for Electrictyacht 10kW motor, should 1 get 4 x NPP12V 200Ah Li or 2 Dakota 48V 96Ah?

I'm installing an Need 48v 200A for Electrictyacht 10kW motor, in my Catalina 27,
should 1 get 4 x NPP12V 200Ah Li ($2200) or 2 Dakota 48V 96Ah ($5000)?
Electricyacht says 48V is better for load balancing. 
What about safety and reliability of NPP vs Dakota?

https://electricyacht.com/product/quiettorque-10-0-sport-electric-motor/

https://www.amazon.com/NPP-12-8V-200Ah-Phosphate-4500-8000/dp/B0CL95VJ82
 12.8V 200Ah Battery, we suggest you buy 4 units and the total weight is 176.36 lbs. We had applied the best offer for you, is $550 per unit. The total price is $2200. The lithium battery are with long life and more than 4500 Cycles. Only half weight and providing twice capacity in the same size as lead-acid batteries.

https://dakotalithium.com/product/dakota-lithium-48v-96ah-deep-cycle-lifepo4-marine-battery/
The Dakota 48v 96ah batteries at a discounted price when you pair them with one of our motors.
Normal cost is $2699ea, your cost would be $2500ea.

The Lynac 48v 100ah and 48v 130ah batteries are certified grade A cells and have Bluetooth capability.
48v 100ah= $2557ea
48v 130ah= $3297ea

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Re: [electricboats] Electric motor size for 48' cat

***CORRECTION***
I just looked again and I had the cooling requirements and output without cooling a bit off for the ME1616.   The motor is rated for continuous operation at 140 amps without cooling (6720 watts at 48V, 13,440 Watts at 96V)  and 250 amps with cooling.   So a little higher than what I said before (125 amps).  It's not a big difference and you still need to plan for cooling.  And you would have been conservative with the numbers I gave before. 

Dan Pfeiffer

Here are some notes on the ME1616 that I had in my file...
= = = = = = =

Montenergy ME1616 Motor Details From Thunderstruck
IPM Water Cooled motor for up to 96 VDC battery systems, and 250 amps continuous. This has the same stator and rotor as the ME1507, but in a water cooled IP67 case. 7/8" keyed shaft. Provide your own small radiator and a coolant pump with a flow rate of 4-10 litres per minute. Max rpm 6000 Approx. 55 pounds. 

When used in our kits, controllers will cut power when the motor gets too hot, based on internal motor temp sensor. Coolant temp leaving the motor should be under 230F/ 110C with standard use, and up to 100C on the inlet side is allowable. If controllers are adjusted for Field weaking this rating would be lower. 


From Montenergy email 11/2020:
1)  The ME1304 is rated for 200 amps continuous with water cooling, and 125 without water cooling.

2)  The ME1616 is rated for 140 amps continuous without water cooling.  This is a lower specification as compared to the ME1507, because the ME1507 has cooling fins on the external case, and the case is thinner, in direct contact with the windings and laminations.

3)  We rate the ME1616 motor at 2 minutes, 600 amps.  This is form a cold start.  If the motor is already at maximum temperature, then this time and maximum current will be lower.

= = = = = = = 

On 2023-10-21 11:04 am, Dan Pfeiffer wrote:

The ME1616 will REQUIRE cooling at anything over 125 amps.  So without cooling you max out at 6000 watts at 48V (12,000 at 96V).  For me that's about 5.5 to 6 knots depending on conditions (waves, wind, etc).   Do NOT plan your system without cooling.  I have a sea water heat exchanger and plan to add a radiator type heat exchanger so I have 2 stages of cooling.  The radiator (basically a heater core from a car) should be fine up to 85% of hull speed.  If I need to push harder for any length of time (battery capacity limited) I will kick in the sea water system. 

Note on my cooling system
http://dan.pfeiffer.net/10m/electric_drive_cooling.htm

Dan Pfeiffer

On 2023-10-21 10:17 am, Eric via groups.io wrote:

Hey Dan and Randy,

Thanks so much and very nice to meet you.  That's very helpful and definitely gives me a place to start.  Dan I'll definitely go take a look at your FB page.  I had noticed that the motors are the same, just battery config and programming to step up to 72 or 96v which at least leaves some flexibility.  Again, just from a very general standpoint, for a sailing cat our size (around 26,000 to 28,000 lbs) and purpose, it sounds like the 48v x2-12Kw setup would likely be just fine.  Our Volvo MD-22's are 50hp, but even when both were running their power output wasn't strong and it was just fine for this boat.  I always figured a pair of good running 40hp Yanmars would be better.  Our hull speed is theoretically somewhere around 9 knots, but I have no need to ever see that with the motors.  If we can max out at 6-7 when needed and cruise at 3-5 that would be perfect.  The 12Kw kits have an option for the water cooled pieces and parts, which I assumed I'd do, plus a blower setup in the compartment.  I love the idea of merging these batteries with some new ones, but with them being close to 9 months old now, I'd be concerned about trying to do that.  We likely will just put together a decent bank for the motor(s), about 400 amp hours at 48V to run eventually 2 motors and stick with the hearty house bank using DC-DC to charge the house, plus direct charging ability from the genny if needed.

Okay, I'm getting excited!  It's looking more and more like Davy Jones might receive an offering of an old seized up MD-22 sometime soon. ;-). Now I just need to slow my roll slightly and curb my obsession since I won't be in a position to really dig into this until maybe January.  But I'm sure I'll come up with lots more questions up til then.

Eric Dove

Re: [electricboats] Electric motor size for 48' cat

Yes, absolutely.  Getting a good match of the propeller to the motor/reduction/boat is paramount to getting good performance.  And I think it is the least attended to part of these conversions.  I was lucky and had a large three bladed feathering propeller that has an adjustable pitch that I could set to match the system.  I think I am getting better performance than I initially predicted based on data from other similar conversions I had seen posted on line thanks to the better matched propeller.  This season I made a change of the pitch to one setting higher on my prop and got a very significant increase in efficiency over my initial setting.   Something on the order of 8 to 12% though I need to do some more testing to confirm that. 

So yes, spend some time/effort/money on getting the prop match correct.  Your starting point would be designing the reduction gear to match the prop RPM to what the original engine setup was if that was a good match.  But, I have a large propeller and since I could change the pitch I decided it would be better to slow the prop down with a higher reduction gear (3 to 1 in my case) and increase the pitch.   But I already had this relatively expensive and adjustable propeller to experiment with and the original diesel max RPM was about the same as the ME1616 at 2500 rpm.  

Also, I think the big prop is better for potential regen.  I have managed to get 400 watts of regen in conditions were I could sail at 6.5 to 7 knots.  But I have not explored this in any detail.  I think bigger boats are likely to be better at regen too.   A 48' cat might be very good at it.  But a 48' cat is also an ideal platform for lots of solar?  So maybe the regen is not so important?  But having a diverse set of energy inputs is a good thing? 

Dan Pfeiffer

On 2023-10-21 9:28 am, GeoG via groups.io wrote:

 

The item that rarely gets mentioned is the Propeller. How does the Propeller effect Range under Electric Propulsion in a monohull and/or catamaran while E-sailing  ? 

 

On Saturday, October 21, 2023 at 09:58:02 AM EDT, Dan Pfeiffer <dan@pfeiffer.net> wrote:

 

 

I know it's not directly comparable but I have the Thunderstruck 12kW kit in my 13,000 lb 33 ft mono hull.  It is easily as powerful as the 23hp diesel it replaced (Volvo MD11) and can power the boat to hull speed at full power.  It is an ME1616 running at 48V.  This motor can be configured to run at up to 96V (24kW) so if you got the 12kW kit it would not be all that difficult to step up to 96V operation with a reconfigured battery setup and controller re-programming (or maybe a different controller?).  Something to consider.

To run at higher speeds requires cooling.  Up to about 5.5 knots or 75% of hull speed is OK for me without cooling.  

Motor sailing is definitely a viable mode of operation.   Here's some data from a recent trip I did where I motor sailed a bit. 

Motor Sailing Data Point
TWA 93, TWS 5.2, BSP 5.38, Watts 1316

Motor Sailing Data Point
TWA 126, TWS 7.1, BSP 5.2, Watts 1024, RPM 1238 (prop RPM 412)  About 60 miles range on full battery
Estimated range 70 miles at this rate and conditions from Victon meter.  
When wind died I was making 4-4.5 at 1400 watts.  About 36 miles range on full battery
So motor sailing in these conditions about doubled the range.

Details of my installation here:
http://dan.pfeiffer.net/10m/electric_drive.htm

Dan Pfeiffer

On 2023-10-19 11:19 am, Eric via groups.io wrote:

Hello all, complete newb here, so I'll start with a very basic newb question.  First, the setup - we have a 1992 Privilege 482 catamaran with one dead diesel and the other still the original Volvo, but running well.  Light displacement about 26,000 lbs., as loaded probably close to 30,000 lbs.  With 2 old Volvo MD22's (50hp each) motoring speed was typically 7 knots at about 2000 rpm.  With just the one motor we do about 5 - 5.5.  We are full time long range cruisers so we're either at anchor or passage making - most hops are a full day, with many being multiple day passages.  We also have a 6kw Northern Lights generator which performs well and currently only about 400 watts of useable solar (this will be upgraded soon to at least 1000, possibly up to about 1600).  Our house bank is 900 amp hours of lithium, only 8 months old, but they're x3 12v 300 amp hour units, so not great for building a "master bank" for the motors from.  This being the case, if we went electric, I would be inclined to set up the motor(s) with their own unique bank and charging system(s) and keep the house as it is, controlling what gets charged when manually.

With our port motor locked up AND 30 years old, I'm very seriously considering an electric motor conversion as opposed to a rebuild (as well as several pricey parts I know it will need).  I really like what Thunderstruck Motors has to offer, but just with a very basic consultation, they're suggesting the 24kw motor kits (we would actually just do the one side at first, operating with one diesel and one electric, then once all (most? some?) wrinkles are ironed out, convert the other side as well).  However, from my trip down the rabbit hole online (which actually doesn't seem all that deep) x2 of the 24kw motors seems like overkill.  Plus, they run at 96v, which requires a monster battery setup, which is our biggest hurdle financially being in the Caribbean.  Even the fancier setups I've seen seem to be closer to the 10-15kw range for a boat roughly our size.  The 12kw motor kits from Thunderstruck run at 48v which is much more manageable and seem like they would do the trick, but again...newb.

We'd like decent potential range, but we sail 95% of the time already and when motoring, we don't have the "need for speed"...we sailed about 2000 miles already with just the one motor as mostly backup and have had no real issues getting where we needed to go.  Running a conservative 1/2 power at something like 4-5 knots would be absolutely fine, while hopefully keeping up with solar, regen, and the genny.  Heck, even motoring at 3-4 knots while waiting on wind or even just motor-sailing in the really light stuff would suit us just fine too.  That said, when entering and leaving port and anchoring, or in the situations that always happen where being able to go pedal to the metal for a little bit can get you out of a jam, we don't want to find ourselves too wimpy on power.

Thoughts?

Thanks much.

 

Re: [electricboats] Electric motor size for 48' cat

Jack, what POD System are you using ?

George

On Saturday, October 21, 2023 at 11:58:40 AM EDT, Jack Agarwal <yacht.alcazar@gmail.com> wrote:

Hi Eric,

I have a 47' sailing cat that weighs just a little less than yours that I am currently converting to EP. I can tell you I went with dual 13k (nominal) pod motors. It is powered by a 48v battery, which I prefer over higher voltages. I have yet to get the boat back in the water so I hardly have any practical feedback, but I know your boat and it's similar to my own. These motors are similar to the thunderstruck, in that, if I want, I can later up the system voltage to increase available power.

If you would like to stay in touch and hear more about how the system performs when I get the boat in; send me an email. 

Jack

On Sat, Oct 21, 2023 at 10:17 AM Eric via groups.io <sailawayvlog=yahoo.com@groups.io> wrote:

Hey Dan and Randy,

Thanks so much and very nice to meet you.  That's very helpful and definitely gives me a place to start.  Dan I'll definitely go take a look at your FB page.  I had noticed that the motors are the same, just battery config and programming to step up to 72 or 96v which at least leaves some flexibility.  Again, just from a very general standpoint, for a sailing cat our size (around 26,000 to 28,000 lbs) and purpose, it sounds like the 48v x2-12Kw setup would likely be just fine.  Our Volvo MD-22's are 50hp, but even when both were running their power output wasn't strong and it was just fine for this boat.  I always figured a pair of good running 40hp Yanmars would be better.  Our hull speed is theoretically somewhere around 9 knots, but I have no need to ever see that with the motors.  If we can max out at 6-7 when needed and cruise at 3-5 that would be perfect.  The 12Kw kits have an option for the water cooled pieces and parts, which I assumed I'd do, plus a blower setup in the compartment.  I love the idea of merging these batteries with some new ones, but with them being close to 9 months old now, I'd be concerned about trying to do that.  We likely will just put together a decent bank for the motor(s), about 400 amp hours at 48V to run eventually 2 motors and stick with the hearty house bank using DC-DC to charge the house, plus direct charging ability from the genny if needed.

Okay, I'm getting excited!  It's looking more and more like Davy Jones might receive an offering of an old seized up MD-22 sometime soon. ;-). Now I just need to slow my roll slightly and curb my obsession since I won't be in a position to really dig into this until maybe January.  But I'm sure I'll come up with lots more questions up til then.

Eric Dove

Re: [electricboats] Electric motor size for 48' cat

The ME1616 will REQUIRE cooling at anything over 125 amps.  So without cooling you max out at 6000 watts at 48V (12,000 at 96V).  For me that's about 5.5 to 6 knots depending on conditions (waves, wind, etc).   Do NOT plan your system without cooling.  I have a sea water heat exchanger and plan to add a radiator type heat exchanger so I have 2 stages of cooling.  The radiator (basically a heater core from a car) should be fine up to 85% of hull speed.  If I need to push harder for any length of time (battery capacity limited) I will kick in the sea water system. 

Note on my cooling system
http://dan.pfeiffer.net/10m/electric_drive_cooling.htm

Dan Pfeiffer

On 2023-10-21 10:17 am, Eric via groups.io wrote:

Hey Dan and Randy,

Thanks so much and very nice to meet you.  That's very helpful and definitely gives me a place to start.  Dan I'll definitely go take a look at your FB page.  I had noticed that the motors are the same, just battery config and programming to step up to 72 or 96v which at least leaves some flexibility.  Again, just from a very general standpoint, for a sailing cat our size (around 26,000 to 28,000 lbs) and purpose, it sounds like the 48v x2-12Kw setup would likely be just fine.  Our Volvo MD-22's are 50hp, but even when both were running their power output wasn't strong and it was just fine for this boat.  I always figured a pair of good running 40hp Yanmars would be better.  Our hull speed is theoretically somewhere around 9 knots, but I have no need to ever see that with the motors.  If we can max out at 6-7 when needed and cruise at 3-5 that would be perfect.  The 12Kw kits have an option for the water cooled pieces and parts, which I assumed I'd do, plus a blower setup in the compartment.  I love the idea of merging these batteries with some new ones, but with them being close to 9 months old now, I'd be concerned about trying to do that.  We likely will just put together a decent bank for the motor(s), about 400 amp hours at 48V to run eventually 2 motors and stick with the hearty house bank using DC-DC to charge the house, plus direct charging ability from the genny if needed.

Okay, I'm getting excited!  It's looking more and more like Davy Jones might receive an offering of an old seized up MD-22 sometime soon. ;-). Now I just need to slow my roll slightly and curb my obsession since I won't be in a position to really dig into this until maybe January.  But I'm sure I'll come up with lots more questions up til then.

Eric Dove

Re: [electricboats] Electric motor size for 48' cat

Hi Eric,

I have a 47' sailing cat that weighs just a little less than yours that I am currently converting to EP. I can tell you I went with dual 13k (nominal) pod motors. It is powered by a 48v battery, which I prefer over higher voltages. I have yet to get the boat back in the water so I hardly have any practical feedback, but I know your boat and it's similar to my own. These motors are similar to the thunderstruck, in that, if I want, I can later up the system voltage to increase available power.

If you would like to stay in touch and hear more about how the system performs when I get the boat in; send me an email. 

Jack

On Sat, Oct 21, 2023 at 10:17 AM Eric via groups.io <sailawayvlog=yahoo.com@groups.io> wrote:

Hey Dan and Randy,

Thanks so much and very nice to meet you.  That's very helpful and definitely gives me a place to start.  Dan I'll definitely go take a look at your FB page.  I had noticed that the motors are the same, just battery config and programming to step up to 72 or 96v which at least leaves some flexibility.  Again, just from a very general standpoint, for a sailing cat our size (around 26,000 to 28,000 lbs) and purpose, it sounds like the 48v x2-12Kw setup would likely be just fine.  Our Volvo MD-22's are 50hp, but even when both were running their power output wasn't strong and it was just fine for this boat.  I always figured a pair of good running 40hp Yanmars would be better.  Our hull speed is theoretically somewhere around 9 knots, but I have no need to ever see that with the motors.  If we can max out at 6-7 when needed and cruise at 3-5 that would be perfect.  The 12Kw kits have an option for the water cooled pieces and parts, which I assumed I'd do, plus a blower setup in the compartment.  I love the idea of merging these batteries with some new ones, but with them being close to 9 months old now, I'd be concerned about trying to do that.  We likely will just put together a decent bank for the motor(s), about 400 amp hours at 48V to run eventually 2 motors and stick with the hearty house bank using DC-DC to charge the house, plus direct charging ability from the genny if needed.

Okay, I'm getting excited!  It's looking more and more like Davy Jones might receive an offering of an old seized up MD-22 sometime soon. ;-). Now I just need to slow my roll slightly and curb my obsession since I won't be in a position to really dig into this until maybe January.  But I'm sure I'll come up with lots more questions up til then.

Eric Dove

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Re: [electricboats] Electric motor size for 48' cat

Hey Dan and Randy,

Thanks so much and very nice to meet you.  That's very helpful and definitely gives me a place to start.  Dan I'll definitely go take a look at your FB page.  I had noticed that the motors are the same, just battery config and programming to step up to 72 or 96v which at least leaves some flexibility.  Again, just from a very general standpoint, for a sailing cat our size (around 26,000 to 28,000 lbs) and purpose, it sounds like the 48v x2-12Kw setup would likely be just fine.  Our Volvo MD-22's are 50hp, but even when both were running their power output wasn't strong and it was just fine for this boat.  I always figured a pair of good running 40hp Yanmars would be better.  Our hull speed is theoretically somewhere around 9 knots, but I have no need to ever see that with the motors.  If we can max out at 6-7 when needed and cruise at 3-5 that would be perfect.  The 12Kw kits have an option for the water cooled pieces and parts, which I assumed I'd do, plus a blower setup in the compartment.  I love the idea of merging these batteries with some new ones, but with them being close to 9 months old now, I'd be concerned about trying to do that.  We likely will just put together a decent bank for the motor(s), about 400 amp hours at 48V to run eventually 2 motors and stick with the hearty house bank using DC-DC to charge the house, plus direct charging ability from the genny if needed.

Okay, I'm getting excited!  It's looking more and more like Davy Jones might receive an offering of an old seized up MD-22 sometime soon. ;-). Now I just need to slow my roll slightly and curb my obsession since I won't be in a position to really dig into this until maybe January.  But I'm sure I'll come up with lots more questions up til then.

Eric Dove

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Re: [electricboats] Electric motor size for 48' cat

The item that rarely gets mentioned is the Propeller. How does the Propeller effect Range under Electric Propulsion in a monohull and/or catamaran while E-sailing  ? 

On Saturday, October 21, 2023 at 09:58:02 AM EDT, Dan Pfeiffer <dan@pfeiffer.net> wrote:

I know it's not directly comparable but I have the Thunderstruck 12kW kit in my 13,000 lb 33 ft mono hull.  It is easily as powerful as the 23hp diesel it replaced (Volvo MD11) and can power the boat to hull speed at full power.  It is an ME1616 running at 48V.  This motor can be configured to run at up to 96V (24kW) so if you got the 12kW kit it would not be all that difficult to step up to 96V operation with a reconfigured battery setup and controller re-programming (or maybe a different controller?).  Something to consider.

To run at higher speeds requires cooling.  Up to about 5.5 knots or 75% of hull speed is OK for me without cooling.  

Motor sailing is definitely a viable mode of operation.   Here's some data from a recent trip I did where I motor sailed a bit. 

Motor Sailing Data Point
TWA 93, TWS 5.2, BSP 5.38, Watts 1316

Motor Sailing Data Point
TWA 126, TWS 7.1, BSP 5.2, Watts 1024, RPM 1238 (prop RPM 412)  About 60 miles range on full battery
Estimated range 70 miles at this rate and conditions from Victon meter.  
When wind died I was making 4-4.5 at 1400 watts.  About 36 miles range on full battery
So motor sailing in these conditions about doubled the range.

Details of my installation here:
http://dan.pfeiffer.net/10m/electric_drive.htm

Dan Pfeiffer

On 2023-10-19 11:19 am, Eric via groups.io wrote:

Hello all, complete newb here, so I'll start with a very basic newb question.  First, the setup - we have a 1992 Privilege 482 catamaran with one dead diesel and the other still the original Volvo, but running well.  Light displacement about 26,000 lbs., as loaded probably close to 30,000 lbs.  With 2 old Volvo MD22's (50hp each) motoring speed was typically 7 knots at about 2000 rpm.  With just the one motor we do about 5 - 5.5.  We are full time long range cruisers so we're either at anchor or passage making - most hops are a full day, with many being multiple day passages.  We also have a 6kw Northern Lights generator which performs well and currently only about 400 watts of useable solar (this will be upgraded soon to at least 1000, possibly up to about 1600).  Our house bank is 900 amp hours of lithium, only 8 months old, but they're x3 12v 300 amp hour units, so not great for building a "master bank" for the motors from.  This being the case, if we went electric, I would be inclined to set up the motor(s) with their own unique bank and charging system(s) and keep the house as it is, controlling what gets charged when manually.

With our port motor locked up AND 30 years old, I'm very seriously considering an electric motor conversion as opposed to a rebuild (as well as several pricey parts I know it will need).  I really like what Thunderstruck Motors has to offer, but just with a very basic consultation, they're suggesting the 24kw motor kits (we would actually just do the one side at first, operating with one diesel and one electric, then once all (most? some?) wrinkles are ironed out, convert the other side as well).  However, from my trip down the rabbit hole online (which actually doesn't seem all that deep) x2 of the 24kw motors seems like overkill.  Plus, they run at 96v, which requires a monster battery setup, which is our biggest hurdle financially being in the Caribbean.  Even the fancier setups I've seen seem to be closer to the 10-15kw range for a boat roughly our size.  The 12kw motor kits from Thunderstruck run at 48v which is much more manageable and seem like they would do the trick, but again...newb.

We'd like decent potential range, but we sail 95% of the time already and when motoring, we don't have the "need for speed"...we sailed about 2000 miles already with just the one motor as mostly backup and have had no real issues getting where we needed to go.  Running a conservative 1/2 power at something like 4-5 knots would be absolutely fine, while hopefully keeping up with solar, regen, and the genny.  Heck, even motoring at 3-4 knots while waiting on wind or even just motor-sailing in the really light stuff would suit us just fine too.  That said, when entering and leaving port and anchoring, or in the situations that always happen where being able to go pedal to the metal for a little bit can get you out of a jam, we don't want to find ourselves too wimpy on power.

Thoughts?

Thanks much.

Re: [electricboats] Electric motor size for 48' cat

I know it's not directly comparable but I have the Thunderstruck 12kW kit in my 13,000 lb 33 ft mono hull.  It is easily as powerful as the 23hp diesel it replaced (Volvo MD11) and can power the boat to hull speed at full power.  It is an ME1616 running at 48V.  This motor can be configured to run at up to 96V (24kW) so if you got the 12kW kit it would not be all that difficult to step up to 96V operation with a reconfigured battery setup and controller re-programming (or maybe a different controller?).  Something to consider.

To run at higher speeds requires cooling.  Up to about 5.5 knots or 75% of hull speed is OK for me without cooling.  

Motor sailing is definitely a viable mode of operation.   Here's some data from a recent trip I did where I motor sailed a bit. 

Motor Sailing Data Point
TWA 93, TWS 5.2, BSP 5.38, Watts 1316

Motor Sailing Data Point
TWA 126, TWS 7.1, BSP 5.2, Watts 1024, RPM 1238 (prop RPM 412)  About 60 miles range on full battery
Estimated range 70 miles at this rate and conditions from Victon meter.  
When wind died I was making 4-4.5 at 1400 watts.  About 36 miles range on full battery
So motor sailing in these conditions about doubled the range.

Details of my installation here:
http://dan.pfeiffer.net/10m/electric_drive.htm

Dan Pfeiffer

On 2023-10-19 11:19 am, Eric via groups.io wrote:

Hello all, complete newb here, so I'll start with a very basic newb question.  First, the setup - we have a 1992 Privilege 482 catamaran with one dead diesel and the other still the original Volvo, but running well.  Light displacement about 26,000 lbs., as loaded probably close to 30,000 lbs.  With 2 old Volvo MD22's (50hp each) motoring speed was typically 7 knots at about 2000 rpm.  With just the one motor we do about 5 - 5.5.  We are full time long range cruisers so we're either at anchor or passage making - most hops are a full day, with many being multiple day passages.  We also have a 6kw Northern Lights generator which performs well and currently only about 400 watts of useable solar (this will be upgraded soon to at least 1000, possibly up to about 1600).  Our house bank is 900 amp hours of lithium, only 8 months old, but they're x3 12v 300 amp hour units, so not great for building a "master bank" for the motors from.  This being the case, if we went electric, I would be inclined to set up the motor(s) with their own unique bank and charging system(s) and keep the house as it is, controlling what gets charged when manually.

With our port motor locked up AND 30 years old, I'm very seriously considering an electric motor conversion as opposed to a rebuild (as well as several pricey parts I know it will need).  I really like what Thunderstruck Motors has to offer, but just with a very basic consultation, they're suggesting the 24kw motor kits (we would actually just do the one side at first, operating with one diesel and one electric, then once all (most? some?) wrinkles are ironed out, convert the other side as well).  However, from my trip down the rabbit hole online (which actually doesn't seem all that deep) x2 of the 24kw motors seems like overkill.  Plus, they run at 96v, which requires a monster battery setup, which is our biggest hurdle financially being in the Caribbean.  Even the fancier setups I've seen seem to be closer to the 10-15kw range for a boat roughly our size.  The 12kw motor kits from Thunderstruck run at 48v which is much more manageable and seem like they would do the trick, but again...newb.

We'd like decent potential range, but we sail 95% of the time already and when motoring, we don't have the "need for speed"...we sailed about 2000 miles already with just the one motor as mostly backup and have had no real issues getting where we needed to go.  Running a conservative 1/2 power at something like 4-5 knots would be absolutely fine, while hopefully keeping up with solar, regen, and the genny.  Heck, even motoring at 3-4 knots while waiting on wind or even just motor-sailing in the really light stuff would suit us just fine too.  That said, when entering and leaving port and anchoring, or in the situations that always happen where being able to go pedal to the metal for a little bit can get you out of a jam, we don't want to find ourselves too wimpy on power.

Thoughts?

Thanks much.

Re: [electricboats] Electric motor size for 48' cat

Eric, I'm putting two of the Thunderstruck 24kw 96v ME-1616 into my 34ft catamaran rebuild. I'd suggest that you can merge your existing batteries into a single battery for both purposes with new batteries to get the range you're looking for. I went with a big 122kWh battery system but I converted from sail to 100% solar with 9.8kW of solar. But, since you're sailing, smaller batteries will work fine. I'm doing 4x 50A DC-DC converters to get 12v from the 96v. My boat is the MV Maritima and she has a Facebook page if you're interested. I'm also in a Facebook group called "ePowered Catamaran Conversions" that might help answer more specific questions. 

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