Re: [electricboats] Controller overheating

Do you have an efficiency graph like the attached from a ME1507/ME1616? 

Is the motor intended to run with 7.5kW at 900 RPM?  Seems low RPM.   I suspect it would all sort out better with a reduction gear to get the motor going faster for the same prop RPM.  I wonder if you're simply over-loading the motor because the prop pitch it too high for the direct drive. 


Dan Pfeiffer

On 2022-01-31 6:58 pm, Mich Pop wrote:

Hi all,

 

Thanks for your suggestions.

I did check the connections with an IR thermometer and they all seem to be at the controller temp.

What temperatures do your controllers run at?

 

Thanks Dan, I noticed that my conversion underperforms.

Those RPMs are motor RPMs without any reduction gear.

Direct drive, so motor = prop RPM

 

I have a 16 /14 RH two bladed prop which is the old prop that came with the 20 HP Bukh diesel and the boat.

I swapped to a smaller 3 bladed prop just because that was lying around.

However, that ran at much higher RPMs and the old prop shaft was making a lot of noise at RPMs over 800.

The prop shaft had only ever been up to max 800 RMP with the diesel.

The prop shaft turns quite easily by hand and doesn't heat up.

So I changed back to the original 2 bladed prop.

 

I attach a graph of the 2 different props below.

 

Unfortunately there isn't any room on the keg to swing a bigger prop. Going up to a 3 bladed prop of same size would impair the sailing performance.

I'm with you, sailing comes first.

 

I guess the heat generated by the controller is not enough to explain the performance loss?

I wonder if the nearly 10 foot beam might contribute?

 

I am keen to improve the efficiency so I can feel safer out in the Pacific.

 

Thank you so much for your thoughts

 

 

Cheers

Mich

On 1 Feb 2022, at 5:25 am, Dan Pfeiffer <dan@pfeiffer.net> wrote:

Agree about checking connections That Seek sensor looks very interesting though a bit pricey?  I have Klein IR thermometer that's quite handy though not as cool as the Seek.
https://www.kleintools.com/catalog/infrared-thermometers/infrared-digital-thermometer-targeting-laser-101
https://www.amazon.com/Klein-Tools-IR1-Thermometer-Non-Contact/dp/B0873T6SGR?ref_=ast_sto_dp&th=1&psc=1


Your power consumption on the Roberts 29 seems quite high for the speeds you are reporting.   I am seeing speeds of almost 2x at the same power levels in a 6 ton 33' boat.   
At 28 amps (1300 Watts at 48V) you get 2.0 knots.  I am seeing more like 3.8 knots. 
http://dan.pfeiffer.net/10m/electric_drive_performance.htm
A shorter boat will be a bit slower but not that much?  Seems like there is something wrong somewhere. 

What are the prop dimensions and the reduction gear?  Are you running a reduction gear?   You RPM's seem quite low for the speeds if those are motor RPM.  If it's prop RPM it's fine.  But I don't know what the revs for that motor should be to get into the high efficiency range.  I know my ME1616 would be quite unhappy with those loads at that low RPM. 

You have really good battery capacity and should get excellent range from it. 

Dan Pfeiffer


Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

On 2022-01-31 12:22 pm, James Sizemore wrote:

 

Before doing more advanced trouble shooting, I would first check that the lugs on your cables are not getting hot from bad crimps and internal arcing. Also check andvmake sure the nuts are clean and snug.

 

You would be surprised how much heat a bad connection can generate.

 

I use a Seek thermal sensor to check for heat distribution, that can save lots of time trouble shooting and are fairly cheap. 

On Jan 31, 2022, at 9:48 AM, Mich Pop <michpop@gmail.com> wrote:

Hi all,

I wonder if you could please come up with some thoughts as to why my controller overheats at relatively low currents.
Once it reaches 90 Celsius it downregulates the current which can be dangerous in some situations.
Latest example: running at 450 rpm = 30 amp for an hour
when the controller downregulated to 200 rpm for 10 minutes before resuming at 450 rpm.
Ideally I would like to be able to run at 200 amps for 90 minutes.

Heat dispersal is optimised in regards to airflow and a fan that starts at 50 Celsius.

The controller is an older model and I'd be happy to get a new one.
I'd like to hear what kind of controller you suggest.

I've got a 4.5 ton 29 Roberts with a 48V 15s 4p 450 Ah 21.6 kWh LiFePo battery. (usable 360 Ah  = 17.3 kWh)

The controller is a Kelly
KAC72601-8080I
1 Minute Current600A
Continuous Curent240A
Voltage24-72V

The motor is a 7.5 KW, 4P, 415V, AHE132M4, 3PH, MEP S2
rewound to 30 VAC, air cooled
The motor doesn't get hotter than 80 Celsius

Here is the average performance I get with a hull that could be cleaner.

Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

Thank you so much for your thoughts

Cheers
Mich

[electricboats] FLIR

I have the FLIR 1 pro, = the real gear, not the low one.

Bought it half a year ago, when I bought another house.

Works very good on my 2'nd  house (!!!) , and on my boat.

I assume that device will find your heating problems very quickly.

Of couse you'll have to find out how it works properly !!

Can only recommend that thing, even useful for many other purposes ;-)

When you're dealing with an electric engine, that can find a lot of connection troubles easily.

It connects to you cellphone directly.

It's good.

I'm not advertizing it, I'm just telling you guys here, doing thermal experiments with electrics, like me.

On Monday, 31 January 2022, 18:23:21 CET, James Sizemore <james@deny.org> wrote:

Before doing more advanced trouble shooting, I would first check that the lugs on your cables are not getting hot from bad crimps and internal arcing. Also check andvmake sure the nuts are clean and snug.

You would be surprised how much heat a bad connection can generate.

I use a Seek thermal sensor to check for heat distribution, that can save lots of time trouble shooting and are fairly cheap. 

On Jan 31, 2022, at 9:48 AM, Mich Pop <michpop@gmail.com> wrote:

Hi all,

I wonder if you could please come up with some thoughts as to why my controller overheats at relatively low currents.
Once it reaches 90 Celsius it downregulates the current which can be dangerous in some situations.
Latest example: running at 450 rpm = 30 amp for an hour
when the controller downregulated to 200 rpm for 10 minutes before resuming at 450 rpm.
Ideally I would like to be able to run at 200 amps for 90 minutes.

Heat dispersal is optimised in regards to airflow and a fan that starts at 50 Celsius.

The controller is an older model and I'd be happy to get a new one.
I'd like to hear what kind of controller you suggest.

I've got a 4.5 ton 29 Roberts with a 48V 15s 4p 450 Ah 21.6 kWh LiFePo battery. (usable 360 Ah  = 17.3 kWh)

The controller is a Kelly
KAC72601-8080I
1 Minute Current600A
Continuous Curent240A
Voltage24-72V

The motor is a 7.5 KW, 4P, 415V, AHE132M4, 3PH, MEP S2
rewound to 30 VAC, air cooled
The motor doesn't get hotter than 80 Celsius

Here is the average performance I get with a hull that could be cleaner.

Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

Thank you so much for your thoughts

Cheers
Mich

Re: [electricboats] Electric retrofit for 57' Chris Craft Constellation

Hi,

I am thinking about something similar, except I plan to keep my diesel engine (135 hp Lehman) and setup the electric motor as a parallel hybrid.

Lars, I am really interested in your setup!

From your picture it looks like you added a pulley on your transmission gearbox output flange.
In other words, you've got a parallel hybrid transmission and can run either:

1. with the diesel running and the electric motor generating electricity, or
2. the electric motor running and the diesel transmission in neutral

Am I right about this?

This is what I am hoping to do with my boat. Some questions I am hoping you have some thoughts on if I am right about your setup:

• any issues with the transmission in neutral and the electric motor driving the shaft. Does the transmission overheat or are you worried about it?
• Are you worried about the lateral pulley load of the electric motor damaging the transmission bearing?
• what make of transmission is it?
• It looks like the mounting plate for the electric motor is mounted separately from the diesel engine. Any issues with diesel engine vibration and the electric drive belt?

_._,_._,_

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Re: [electricboats] Controller overheating

Hi all,

Thanks for your suggestions.

I did check the connections with an IR thermometer and they all seem to be at the controller temp.

What temperatures do your controllers run at?

Thanks Dan, I noticed that my conversion underperforms.

Those RPMs are motor RPMs without any reduction gear.

Direct drive, so motor = prop RPM

I have a 16 /14 RH two bladed prop which is the old prop that came with the 20 HP Bukh diesel and the boat.

I swapped to a smaller 3 bladed prop just because that was lying around.

However, that ran at much higher RPMs and the old prop shaft was making a lot of noise at RPMs over 800.

The prop shaft had only ever been up to max 800 RMP with the diesel.

The prop shaft turns quite easily by hand and doesn't heat up.

So I changed back to the original 2 bladed prop.

I attach a graph of the 2 different props below.

Unfortunately there isn't any room on the keg to swing a bigger prop. Going up to a 3 bladed prop of same size would impair the sailing performance.

I'm with you, sailing comes first.

I guess the heat generated by the controller is not enough to explain the performance loss?

I wonder if the nearly 10 foot beam might contribute?

I am keen to improve the efficiency so I can feel safer out in the Pacific.

Thank you so much for your thoughts

Cheers

Mich

On 1 Feb 2022, at 5:25 am, Dan Pfeiffer <dan@pfeiffer.net> wrote:

Agree about checking connections That Seek sensor looks very interesting though a bit pricey?  I have Klein IR thermometer that's quite handy though not as cool as the Seek.
https://www.kleintools.com/catalog/infrared-thermometers/infrared-digital-thermometer-targeting-laser-101
https://www.amazon.com/Klein-Tools-IR1-Thermometer-Non-Contact/dp/B0873T6SGR?ref_=ast_sto_dp&th=1&psc=1


Your power consumption on the Roberts 29 seems quite high for the speeds you are reporting.   I am seeing speeds of almost 2x at the same power levels in a 6 ton 33' boat.   
At 28 amps (1300 Watts at 48V) you get 2.0 knots.  I am seeing more like 3.8 knots. 
http://dan.pfeiffer.net/10m/electric_drive_performance.htm
A shorter boat will be a bit slower but not that much?  Seems like there is something wrong somewhere. 

What are the prop dimensions and the reduction gear?  Are you running a reduction gear?   You RPM's seem quite low for the speeds if those are motor RPM.  If it's prop RPM it's fine.  But I don't know what the revs for that motor should be to get into the high efficiency range.  I know my ME1616 would be quite unhappy with those loads at that low RPM. 

You have really good battery capacity and should get excellent range from it. 

Dan Pfeiffer


Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

On 2022-01-31 12:22 pm, James Sizemore wrote:

 

Before doing more advanced trouble shooting, I would first check that the lugs on your cables are not getting hot from bad crimps and internal arcing. Also check andvmake sure the nuts are clean and snug.

 

You would be surprised how much heat a bad connection can generate.

 

I use a Seek thermal sensor to check for heat distribution, that can save lots of time trouble shooting and are fairly cheap. 

On Jan 31, 2022, at 9:48 AM, Mich Pop <michpop@gmail.com> wrote:

Hi all,

I wonder if you could please come up with some thoughts as to why my controller overheats at relatively low currents.
Once it reaches 90 Celsius it downregulates the current which can be dangerous in some situations.
Latest example: running at 450 rpm = 30 amp for an hour
when the controller downregulated to 200 rpm for 10 minutes before resuming at 450 rpm.
Ideally I would like to be able to run at 200 amps for 90 minutes.

Heat dispersal is optimised in regards to airflow and a fan that starts at 50 Celsius.

The controller is an older model and I'd be happy to get a new one.
I'd like to hear what kind of controller you suggest.

I've got a 4.5 ton 29 Roberts with a 48V 15s 4p 450 Ah 21.6 kWh LiFePo battery. (usable 360 Ah  = 17.3 kWh)

The controller is a Kelly
KAC72601-8080I
1 Minute Current600A
Continuous Curent240A
Voltage24-72V

The motor is a 7.5 KW, 4P, 415V, AHE132M4, 3PH, MEP S2
rewound to 30 VAC, air cooled
The motor doesn't get hotter than 80 Celsius

Here is the average performance I get with a hull that could be cleaner.

Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

Thank you so much for your thoughts

Cheers
Mich

Re: [electricboats] Controller overheating

Hi Mich,

Your input into the controller is 30 amps. The output to the motor will be higher, but still under the continuous rating of the controller at 450 rmp's. Just an FYI. 

Matt Foley 

Sunlight Conversions

Perpetual Energy, LLC

201-914-0466

sunlightconversions.com

instagram.com/sunlightconversions/

youtube/sunlightconversions

On Monday, January 31, 2022, 12:23:21 PM EST, James Sizemore <james@deny.org> wrote:

Before doing more advanced trouble shooting, I would first check that the lugs on your cables are not getting hot from bad crimps and internal arcing. Also check andvmake sure the nuts are clean and snug.

You would be surprised how much heat a bad connection can generate.

I use a Seek thermal sensor to check for heat distribution, that can save lots of time trouble shooting and are fairly cheap. 

On Jan 31, 2022, at 9:48 AM, Mich Pop <michpop@gmail.com> wrote:

Hi all,

I wonder if you could please come up with some thoughts as to why my controller overheats at relatively low currents.
Once it reaches 90 Celsius it downregulates the current which can be dangerous in some situations.
Latest example: running at 450 rpm = 30 amp for an hour
when the controller downregulated to 200 rpm for 10 minutes before resuming at 450 rpm.
Ideally I would like to be able to run at 200 amps for 90 minutes.

Heat dispersal is optimised in regards to airflow and a fan that starts at 50 Celsius.

The controller is an older model and I'd be happy to get a new one.
I'd like to hear what kind of controller you suggest.

I've got a 4.5 ton 29 Roberts with a 48V 15s 4p 450 Ah 21.6 kWh LiFePo battery. (usable 360 Ah  = 17.3 kWh)

The controller is a Kelly
KAC72601-8080I
1 Minute Current600A
Continuous Curent240A
Voltage24-72V

The motor is a 7.5 KW, 4P, 415V, AHE132M4, 3PH, MEP S2
rewound to 30 VAC, air cooled
The motor doesn't get hotter than 80 Celsius

Here is the average performance I get with a hull that could be cleaner.

Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

Thank you so much for your thoughts

Cheers
Mich

Re: [electricboats] Controller overheating

Mich,
Sounds like the heatsink either isn't sufficient for the environment that you've got the controller located in or the thermal connection to that heatsink isn't working well. In either case, make sure you've got a good method to expel the heat outside of the boat. Kelly is a good controller and all controllers produce heat. My controllers are liquid cooled and the liquid is cooled via a small radiator located outside the controller cabinet.

_._,_._,_

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Re: [electricboats] Electric retrofit for 57' Chris Craft Constellation

Required propulsive power increases in proportion to the cube of the speed. 

A general rule of thumb, you double the amount of power to get 1 knot in speed. So if 8 knots requires 20kW, 9 knots = 40kW ; 10 knots = 80 kW(not actual data), just to get an idea. This is only for non planing hulls.

So setting your top speed needed down a couple knots, could lower your costs greatly.

The other big factor on power requirements will be adverse weather. If you have to head into a 20+ knot wind, you will need significantly more power. Wind resistance is exponential.

If money is not a big factor, you could look at Torqueedo's Deep Blue motors.

https://www.torqeedo.com/us/en-us/products/inboards/deep-blue-25-50i-1400/M-3302-00.html

2 of them should get you to the speed you want, with some safety room for adverse winds.

Getting the right propeller is very important, which I think they could help you figure out. You will want the biggest one you can fit. You will be constrained by the proximity to the hull. You need a minimum of 2 inches of clearance.

Another option, that might be more cost effective, is a hybrid system. Have 2 electric motors, batteries for 2-3 hours at modest speed, and a generator for when you need more power or longer distance. 

Good luck!

On Mon, Jan 31, 2022 at 3:34 PM angelo merico via groups.io <angelomerico=yahoo.it@groups.io> wrote:

Hi Dennis, I think about stern unfoldable floating solar panels, but is only an idea.

best regards, Angelo Merico

Il lunedì 31 gennaio 2022, 20:51:47 CET, Dennis Cohen <dac@theconcordance.com> ha scritto:

I am, hopefully, in the process of removing my two 8v71 Detroit Diesels (which each weigh about 4,000 pounds) and replacing them with electric motors, batteries, and a generator.
She weighs in at 32 tons.  I keep her in or close to the marina, so my desired range is probably 10-15 miles max, at a speed of 8-10 knots.
I have shore power and the capability of using either one or two 100 sq.ft spaces for solar arrays.

I have looked at several systems,  and I realize it's a big project.  I'm looking for whatever suggestions I can get on engine size, voltage, genset requirements, prop size and pitch, etc. 
Also am aware of having to add ballast to account for the large amount of weight I will be removing from the hull line.

Any thoughts are appreciated.

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Re: [electricboats] Electric retrofit for 57' Chris Craft Constellation

Hi Dennis

I have the same thoughts - have a Broom Crown motorboat, 37 feet, 12 ton, 2xPerkins 185 HP. Use it mainly on canals, so a normal speed would be 5 knots for up to 8 hours

Got some calculations/estimations made, which says 4,5 knot/4kw, doubling every 1 knot

8 hours sailing would then require 30-35 kw batteries (plan 2 banks of 20-24 kw each)

Plan to have a 10 Kw genset installed for charging away from shore power. Solarpanels also.

Currently I have a 18 kw/72v ME1616 water-cooled motor hooked up to one of the gearbox output flanges, driving a toothbelt-pulley (1:4 ratio) - next week it should be possible to measure power-consumption versus axel-rotation to get an estimate of the consumption and doability of this.

Unsure if the ratio is too low, maybe its better with 1:6-7 - but the PoC will hopefully tell me more

Will keep you posted about progress.

Motor: ME1616 18Kw/72V motor

Controller: SEVCON4

7,2 KW Lifepo4 battery

/Lars

mandag den 31. januar 2022 skrev Dennis Cohen <dac@theconcordance.com>:

I am, hopefully, in the process of removing my two 8v71 Detroit Diesels (which each weigh about 4,000 pounds) and replacing them with electric motors, batteries, and a generator.
She weighs in at 32 tons.  I keep her in or close to the marina, so my desired range is probably 10-15 miles max, at a speed of 8-10 knots.
I have shore power and the capability of using either one or two 100 sq.ft spaces for solar arrays.

I have looked at several systems,  and I realize it's a big project.  I'm looking for whatever suggestions I can get on engine size, voltage, genset requirements, prop size and pitch, etc. 
Also am aware of having to add ballast to account for the large amount of weight I will be removing from the hull line.

Any thoughts are appreciated.

_._,_._,_

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Re: [electricboats] Electric retrofit for 57' Chris Craft Constellation

Hi Dennis, I think about stern unfoldable floating solar panels, but is only an idea.

best regards, Angelo Merico

Il lunedì 31 gennaio 2022, 20:51:47 CET, Dennis Cohen <dac@theconcordance.com> ha scritto:

I am, hopefully, in the process of removing my two 8v71 Detroit Diesels (which each weigh about 4,000 pounds) and replacing them with electric motors, batteries, and a generator.
She weighs in at 32 tons.  I keep her in or close to the marina, so my desired range is probably 10-15 miles max, at a speed of 8-10 knots.
I have shore power and the capability of using either one or two 100 sq.ft spaces for solar arrays.

I have looked at several systems,  and I realize it's a big project.  I'm looking for whatever suggestions I can get on engine size, voltage, genset requirements, prop size and pitch, etc. 
Also am aware of having to add ballast to account for the large amount of weight I will be removing from the hull line.

Any thoughts are appreciated.

Re: [electricboats] Re Power for SV/Retreat Time Catamaran

Split the batteries would be my advice - keep a way to parallel the two packs. 

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Re: [electricboats] Re Power for SV/Retreat Time Catamaran

I have the same size cat 39-1/2’ x 17’. She has a pair of Motenergy water-cooled 48v PMAC motors. Top speed is 6.3 knots. I have 18”x14” 3-blade Hang Shen props and a 3:1 reduction. Max motor RPM is 2,400RPM. I chose the reduction and props after much head scratching using both empirical and tank test data. I am comfortable that I picked right - motor spins up to 2,400 - no more - no less. 

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Re: [electricboats] Controller overheating

Before doing more advanced trouble shooting, I would first check that the lugs on your cables are not getting hot from bad crimps and internal arcing. Also check andvmake sure the nuts are clean and snug.

You would be surprised how much heat a bad connection can generate.

I use a Seek thermal sensor to check for heat distribution, that can save lots of time trouble shooting and are fairly cheap. 

On Jan 31, 2022, at 9:48 AM, Mich Pop <michpop@gmail.com> wrote:

Hi all,

I wonder if you could please come up with some thoughts as to why my controller overheats at relatively low currents.
Once it reaches 90 Celsius it downregulates the current which can be dangerous in some situations.
Latest example: running at 450 rpm = 30 amp for an hour
when the controller downregulated to 200 rpm for 10 minutes before resuming at 450 rpm.
Ideally I would like to be able to run at 200 amps for 90 minutes.

Heat dispersal is optimised in regards to airflow and a fan that starts at 50 Celsius.

The controller is an older model and I'd be happy to get a new one.
I'd like to hear what kind of controller you suggest.

I've got a 4.5 ton 29 Roberts with a 48V 15s 4p 450 Ah 21.6 kWh LiFePo battery. (usable 360 Ah  = 17.3 kWh)

The controller is a Kelly
KAC72601-8080I
1 Minute Current600A
Continuous Curent240A
Voltage24-72V

The motor is a 7.5 KW, 4P, 415V, AHE132M4, 3PH, MEP S2
rewound to 30 VAC, air cooled
The motor doesn't get hotter than 80 Celsius

Here is the average performance I get with a hull that could be cleaner.

Rpm.  Amp.  Knots
350.    20.    1.5
400.    28.    2.0
450.    30.    2.1
500.    50.    2.5
550.    63.    2.7
600.    80.    3.0
650.    93.    3.3
700    113.  3.5
750.   140.   3.7
800    180
900    260

Thank you so much for your thoughts

Cheers
Mich

Re: [electricboats] Sizing batteries for a small boat

The below information was supplied by my motor vendor for my 2021 Marshall Sanderling (2200 lb. Cape Cod Cat sailboat). It's not quite what you're looking for but I think it'll put you in the ballpark.

I outfitted the boat with two Mastervolt MLI Ultra 24/5500 in parallel to a 2.5kW BLDC motor from QuietTorque. It is overkill for a daysailer but I have intentions of making a Cape Cod rounding one day in her, and I like the extra range/safety margin, so that's what I went with. I have not had the time/opportunity to verify these range numbers, my observations of hull speed to power draw are in line with the first table.  I looked into the generator option but my sailing needs have not made its purchase appealing to date. The system is mated to a Chargemaster Plus III 80/24V.

Speed & Power QT2.5 24v cooled Motor System (waterproof option available)

 

Kts Amps Watts (Calm Waters)
2.7 10 240
3.4 20 480
4.3 40 960 *This speed supported by portable 2kW generator
5.4 80 1920
2500 Max power of QT2.5 system
Hull speed 5.52

 

Range DOD to 80%
400ah 24v
Kts Hrs Nm
2.7 34.2 92
3.4 16.5 56
4.3 8.0 34
5.4 3.8 21

 

Range DOD to 80%
200ah 24v
Kts Hrs Nm
2.7 16.5 44
3.4 8.0 27
4.3 3.8 16
5.4 1.9 10

 Motor in Marshall Catboat.JPG

 180 IBLI.PDF

 

On Mon, Jan 31, 2022 at 8:50 AM Peter Ford <petersford@hotmail.com> wrote:

I am looking to repower a 22ft Norwegian wooden boat with an electric motor.  The boat weighs in the 2500-3000 lb range.  The 5kW thunderstruck kit would probably do, but their advice is to get a 10kW kit because the motor is air cooled and not sealed.  I am ok with that advice.  This is not a sailboat I am looking at continuous power draw for 4-5 hours.  On a sailboat I have used a Minn-Kota for getting in/out of the marina with good results.

The question comes to sizing the battery pack.   Does anyone have real world numbers for speed and amp draw for a small boat like this?   My goal is to be able to cruise 20nm, perhaps 30 in a stretch.   I am thinking somewhere in the 4 kt range.

Secondly, any real world experience using a regular 2000W generator to power the charger while the small boat is underway?

Any guidance or pointers appreciated.

Cheers, peter

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Christopher Greenwald

14 Manitoba Rd.

Waban, MA 02468

Cell 617-699-9189

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Re: [electricboats] Re Power for SV/Retreat Time Catamaran

S/V Retreat Time is a sail cat, intended purpose is coastal cruising, 1st season Bahamas second season Maine, third season sea of Cortez.

No particular reason for the 18KW systems, they are robust for sure, we have been caught in some 25-30 knot winds and apposing tide and our motors got hot and I do not want to be in that situation again. It was one of those times I should have waited it out, however it blew for three more days. The main reasoning for 18 kw is to electro sail, using the big props to regen while underway, and have plenty of power when needed.

I'm digging the reduced voltage and the increased amp hours approach, and I will discuss this with Brenard for the final tune, I would like to thank all who offered up their advice and knowledge and time to consider us.

John Winterrowd 702 343 1492 4.2.1. Email Disclaimer NOTICE: The information contained in this electronic transmission is intended only for the use of the individual or entity named above. ANY DISTRIBUTION OR COPYING OF THIS MESSAGE IS PROHIBITED, except by the intended recipient. Attempts to intercept this message are in violation of 18 U.S.C. 2511(1) of the Electronic Communications Privacy Act, which subjects the interceptor to fines, imprisonment and/or civil damages. If you are not the intended recipient, please delete it and notify me.

On Sunday, January 30, 2022, 09:06:10 PM EST, Dan Pfeiffer <dan@pfeiffer.net> wrote:

One reason you might choose this particular kit is to get the water-cooled motor.  I think if you want to be able to motor continuously at speed you really need more robust cooling than the air cooled units will give you.  Also at more modest speeds you will not be pushing the system so hard.   But I don't think there is enough battery reserve here. 

If I am reading the description correctly you will have a 72V 200AH AGM bank in each hull?  That will be 100AH usable capacity (50% depth of discharge).  I am sure there are some Catamaran dynamics that make the comparison problematic but for my 13,000 lb monohull 100AH of usable capacity would get me about 10 miles at 5 knots.  That would not be good enough for my purposes.  Is a 26,000 lb cat like two 13,000 monohulls?  Probably not and with the higher hull speed of 40'LWL maybe you would do better?  Still seems like too short a range for practical purposes. 

Regardless of how you divide up the battery banks you still have a total capacity (with 24 batteries) of 28,800 Whrs.  But with AGM you have 50% depth of discharge so it's 14,400Whrs usable which is marginal I think. 

I would consider running at 48V and configuring the batteries for 4S3P on each hull for two 48V 300AH banks.   Still the same Whrs total - that's the good thing about looking at it in Whrs.   The motor would be 12kW at that voltage and 2500RPM max.   I thought the ME1616 is 96 V max anyway?  So 144V banks won't be an option? 

Then again, with a CAT it might be nice to be able to run the port side from the starboard battery and higher voltage would be better for that.  But I am not so keen on the high voltage.    But it can be done.  You still have the same total Whrs and that's what the range is based on. 

Prop speed depends on the size of the props.  I have an 18" prop with a 3:1 reduction for 800 RPM max.   This has been an excellent match for me.   Bigger and slower prop will be better.  You have 19" so I would target a prop speed of 600 to 900 RPM.    This may be another reason to go 48V because max motor RPM will be 2500.  At 72 it's 3600 RPM?   That means 4:1 to get the prop rotation where you want it.  That may be more difficult to come up with regarding reduction gear parts.   You can do 3:1 pretty simply though I am not sure what those limits might be with the Thunderstruck reduction units.  

But it also depends on pitch.  You say 19deg pitch?  That is typically expressed in inches of pitch.  How many inches will the boat move forward for one rev of the prop.   Can you translate that 19deg to inches of pitch?  If that's what it was, 19 inches, then it's a pretty big pitch which also means slow RPM.    My 18" prop is set to a theoretical pitch of 13.5".   It's a feathering prop so the behavior is not exactly the same.   But if it was 19" of pitch I would need an even slower RPM.  Like 600. 

Lots of variables to work with...


Dan Pfeiffer

On 2022-01-30 4:24 pm, Carsten via groups.io wrote:

 

Is it a sail cat or just engine powered, John ??

 

I'm a bit confused, why you need 2x18KW for a cat

 

 

On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577=yahoo.com@groups.io> wrote:

 

 

Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.



Facts and figures for SV/Retreat Time Catamaran
LOA 44 '
Water line 40'
Beam 20
Draft 3.5
Propeller 19 " Diameter 3 blade
Pitch 19 degree
Displacement 26,000 lbs.
Battery bank per hull consists of 12 group 31 AGM Duracell 100AH

Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts,

Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts.

Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. 

https://vicprop.com/displacement_size_new.php
Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week. 
Thanks John

Re: [electricboats] Re Power for SV/Retreat Time Catamaran

Thank you, Dan

I'll revert in a day.

I have the same issue, with channelling to the berth.

I do not use engine when out on the sea, but winds can get so bad, so it is more comfortable to do motoring, for a while, especially when singlehanded. Then the power should be there, for sure.

My present old Volvo is useless for that.

We still need to hear what John's actual use of his cat are.

On Monday, 31 January 2022, 09:48:25 CET, Dan Pfeiffer <dan@pfeiffer.net> wrote:

I did a lot of number crunching and estimating or the performance of my electric drive before I built it.  That was mostly based on performance reports from other similar boats and some other prediction formulas and spreadsheets.  Once I was up and running I was getting significantly better performance than predicted.  I was exceeding predictions by 30 to 50%.   I predicted 5 knots would take 3600 Watts.  It takes more like 2400 (flat calm).   I attribute most of this to the excellent match of my propeller.  I am lucky to have a large diameter feathering prop (18") where I can change the pitch (not underway).  If you are simply swapping the electric for the diesel with the same fixed prop you are probably giving up some significant performance.  I would fit the largest prop that will fit and set up the reduction gear to get it spinning at the slowest practical speed.   That's harder with a fixed prop as you are committed to the pitch so it's harder to experiment.  But there are big gains in performance to be made by getting a good match with the prop. 

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

Having said all that, I would certainly give up motor performance for sailing performance.   I have a feathering prop so I get a good bit of both.  But sailing comes first.   It also depends on your use.  I am mostly day sailing these days so 25 miles of electric range at 5 knots is fine (better than expected).  I plan to get back to occasional voyaging and for that I feel the need for sustained motoring capacity to make passages up rivers and through canals from time to time.  And for now I think the most practical way to achieve that is with an inboard diesel genset.  I think I could get over 55 miles range at 3 knots but loafing along like that amidst real ship traffic is not appealing. 


Dan Pfeiffer

On 2022-01-30 9:41 pm, Carsten via groups.io wrote:

 

Hi, Dan

 

The props are probably the real key here...

And, actually, the use of the cat.

If you have a cat, then consider retractable engines in the middle.

Stupid to have a big fast cat, with fixed props hanging there, behind...

 

Many cats are not real sailboats, just double hull motoring boats. No mast.

I don't know about John's cat yet.

 

I just think, that 2x 18 KW electric is a way overkill for a cat sailboat.

It is supposed to go fast, when sail. Not by battery powered engines.

The sails are much more powerful, and can last across an ocean for years.

 

My 8000 lb old mono can sail without an engine, of course, but it helps, with even a small 10 HP outboard, when coming in waters without much sailing possibility...

 

Cheers,

Carsten

 

On Monday, 31 January 2022, 03:06:09 CET, Dan Pfeiffer <dan@pfeiffer.net> wrote:

 

 

One reason you might choose this particular kit is to get the water-cooled motor.  I think if you want to be able to motor continuously at speed you really need more robust cooling than the air cooled units will give you.  Also at more modest speeds you will not be pushing the system so hard.   But I don't think there is enough battery reserve here. 

If I am reading the description correctly you will have a 72V 200AH AGM bank in each hull?  That will be 100AH usable capacity (50% depth of discharge).  I am sure there are some Catamaran dynamics that make the comparison problematic but for my 13,000 lb monohull 100AH of usable capacity would get me about 10 miles at 5 knots.  That would not be good enough for my purposes.  Is a 26,000 lb cat like two 13,000 monohulls?  Probably not and with the higher hull speed of 40'LWL maybe you would do better?  Still seems like too short a range for practical purposes. 

Regardless of how you divide up the battery banks you still have a total capacity (with 24 batteries) of 28,800 Whrs.  But with AGM you have 50% depth of discharge so it's 14,400Whrs usable which is marginal I think. 

I would consider running at 48V and configuring the batteries for 4S3P on each hull for two 48V 300AH banks.   Still the same Whrs total - that's the good thing about looking at it in Whrs.   The motor would be 12kW at that voltage and 2500RPM max.   I thought the ME1616 is 96 V max anyway?  So 144V banks won't be an option? 

Then again, with a CAT it might be nice to be able to run the port side from the starboard battery and higher voltage would be better for that.  But I am not so keen on the high voltage.    But it can be done.  You still have the same total Whrs and that's what the range is based on. 

Prop speed depends on the size of the props.  I have an 18" prop with a 3:1 reduction for 800 RPM max.   This has been an excellent match for me.   Bigger and slower prop will be better.  You have 19" so I would target a prop speed of 600 to 900 RPM.    This may be another reason to go 48V because max motor RPM will be 2500.  At 72 it's 3600 RPM?   That means 4:1 to get the prop rotation where you want it.  That may be more difficult to come up with regarding reduction gear parts.   You can do 3:1 pretty simply though I am not sure what those limits might be with the Thunderstruck reduction units.  

But it also depends on pitch.  You say 19deg pitch?  That is typically expressed in inches of pitch.  How many inches will the boat move forward for one rev of the prop.   Can you translate that 19deg to inches of pitch?  If that's what it was, 19 inches, then it's a pretty big pitch which also means slow RPM.    My 18" prop is set to a theoretical pitch of 13.5".   It's a feathering prop so the behavior is not exactly the same.   But if it was 19" of pitch I would need an even slower RPM.  Like 600. 

Lots of variables to work with...


Dan Pfeiffer

On 2022-01-30 4:24 pm, Carsten via groups.io wrote:

 

Is it a sail cat or just engine powered, John ??

 

I'm a bit confused, why you need 2x18KW for a cat

 

 

On Saturday, 29 January 2022, 14:26:19 CET, john winterrowd via groups.io <sailorboy55577=yahoo.com@groups.io> wrote:

 

 

Greetings my fellow Electrosailors, the day has come after nearly a year of waiting for chips, motors, pumps, fans and now the final details need to be identified, she is getting repowered with Thunderstruck 18 KW kits.



Facts and figures for SV/Retreat Time Catamaran
LOA 44 '
Water line 40'
Beam 20
Draft 3.5
Propeller 19 " Diameter 3 blade
Pitch 19 degree
Displacement 26,000 lbs.
Battery bank per hull consists of 12 group 31 AGM Duracell 100AH

Before I commit to keeping the 144-volt banks, I am asking the group to consider a few thoughts,

Sacrificing a few amps by dividing each battery bank in half operating at 72 volts, this way I may be able to parallel them together for higher total amp hours? Or have two separate banks for redundancy charging would be done on 110 volts instead of 220 volts.

Prop speed remains unknown to achieve at best half of hull speed, this is where I could use your help, without the variables of current and wind, I'm looking for a laboratory answer, this is to determine what gear reductions would best suit this vessels propulsion and efficiency. 

https://vicprop.com/displacement_size_new.php
Any help or advice will greatly be appreciated as Thunderstruck is planning to program and tune and ship next week. 
Thanks John