Visit our Popular Forums

ArranP · 15-11-2020, 23:18

Having installed my home off-grid solar system and built an e-bike....

I am in the process to replace existing Yanmar 110 4JH110 engines on a Lagoon 560 ( shaft drive ) with electric propulsion sytem and am considering the various specifications to select the electric motor....

Power Curve & Torque Curve of the Yanmar 110 4JH110

Diesel Engine
Rpm - 3200 engine, factor in gearbox-ratio 2.48:1 reduces rpm to 1300 at the shaft
Torque - 150-270nm
Power - max 57-78kW @ 110HP, factor in gearbox loss 5% reduces the power to a max 54-74kW at the shaft

Electric Motor
kW - Several sources indicate 40-60kW, the higher seems to be inline with the stated power of the Yanmar engine.
VDC - I am seeing anywhere from 96VDC to 350VDC, some are quoting as high as 500VDC+ I doubt this high a voltage is necessary.
Rpm - I am seeing as high as 4000 rpm quoted, I am currently being told to simply reduce power to reduce rpm ? I think I need to see a Torque/Power curve for the motor to decide if the motor has enough torque at the suggested lower power/rpm setting.
Cooled - I understand liquid cooled is a must
Type - PMAC-PMSM Brushless

This is where I'm up to, I am in the process of reviewing the specifications from the various suppliers to select a motor, and I welcome any comments from personal experience or knowledge of.

Regards
Arran.

Nidnoi_V · 16-11-2020, 00:17

Hi OP

Will be following your thread have you looked at www.kraeutler.at they look like a really solid option if your search my name you will see I have been seeking advice on battery banks

Quote:

Originally Posted by ArranP

Having installed my home off-grid solar system and built an e-bike....

I am in the process to replace existing Yanmar 110 4JH110 engines on a Lagoon 560 ( shaft drive ) with electric propulsion sytem and am considering the various specifications to select the electric motor....

Power Curve & Torque Curve of the Yanmar 110 4JH110

Diesel Engine
Rpm - 3200 engine, factor in gearbox-ratio 2.48:1 reduces rpm to 1300 at the shaft
Torque - 150-270nm
Power - max 57-78kW @ 110HP, factor in gearbox loss 5% reduces the power to a max 54-74kW at the shaft

Electric Motor
kW - Several sources indicate 40-60kW, the higher seems to be inline with the stated power of the Yanmar engine.
VDC - I am seeing anywhere from 96VDC to 350VDC, some are quoting as high as 500VDC+ I doubt this high a voltage is necessary.
Rpm - I am seeing as high as 4000 rpm quoted, I am currently being told to simply reduce power to reduce rpm ? I think I need to see a Torque/Power curve for the motor to decide if the motor has enough torque at the suggested lower power/rpm setting.
Cooled - I understand liquid cooled is a must
Type - PMAC-PMSM Brushless

This is where I'm up to, I am in the process of reviewing the specifications from the various suppliers to select a motor, and I welcome any comments from personal experience or knowledge of.

Regards
Arran.

**tkeithlu** · 16-11-2020, 07:45

DC motors produce a whopping torque, which is why diesel electric systems are used on minesweepers. By reversing the field with a big switch, minesweepers can stop in 1 1/2 lengths from flank speed.

You've done a careful analysis on the replacement motor. What do you intend as the power source?

ArranP · 17-11-2020, 03:12

Quote:

Originally Posted by tkeithlu

DC motors produce a whopping torque, which is why diesel electric systems are used on minesweepers. By reversing the field with a big switch, minesweepers can stop in 1 1/2 lengths from flank speed.

You've done a careful analysis on the replacement motor. What do you intend as the power source?

Battery bank / Solar Panel / Generator

ArranP · 17-11-2020, 03:47

I think I found what I was looking for to size the motor.

https://youtu.be/5A30HpBtEqw

Power ( kW ) = ( Speed ( rpm ) x Torque ( Nm ) ) / 9550

Therefore :-

37 kW = ( 1300 rpm x 270 Nm ) / 9550

Apply a Maximum Continious Rate ( MCR ) 85%

= 44 kW

ArranP · 17-11-2020, 03:55

I have just realiesd the reduction gearbox will conversely increase torque.

https://www.engineeringtoolbox.com/g...er-d_1691.html

Therefore the reduction ratio 2.48:1 will increase the torque from 270Nm x 2.48 = 636Nm at the shaft.

Now re-calculate the power using 636Nm as the torque.

87 kW = ( 1300 rpm x 636 Nm ) / 9550

Apply a Maximum Continious Rate ( MCR ) 85%

= 101 kW

I'm uncertain as to wether the MCR is necessary as PMSM motors are rated continuous use at a certain rpm, also they can be liquid cooled that prevents a shortened lifepsan from overheating.

Therefore 80kW may suffice.

Scaramanga F25 · 17-11-2020, 09:48

You realize that you will be destroying your Lagoon's resale value. Straight from 2 family catamaran brokers. " kiss of death on resale " exact words.

ArranP · 17-11-2020, 14:46

Quote:

Originally Posted by Scaramanga F25

You realize that you will be destroying your Lagoon's resale value. Straight from 2 family catamaran brokers. " kiss of death on resale " exact words.

Noted.

RexSnr · 17-11-2020, 16:23

I like the concept as I am also into solar powering everything.......and not checking any of your calcs, but surely you are going to be using the generator nearly full time to power this? You have a heavy, wide hulled boat already and you will surely need to add huge battery banks and huge gensets (big weight increase) to have some life with 80 odd kW out per side. You have limited space for solar panels, remembering only one side of panels can reasonably work at any time when sailing, so it seems to me you will be running the generator reasonably full time to drive this big, even heavier boat??
I would go past the fun stuff (the engineering), and work on genset sizing. I think you will need one (or two) big ones.

When you consider the mechanics of installing huge gensets (if you have enough room), covering your decks in solar panels, trying to find a home for two obviously huge battery banks - it does sound like horrific modifications to your boat, add the expense that will be breathtaking - and then the previous comment of smashing your boats value rings doubly true, I would just ask - Why???

Surely, there has to be a positive in there somewhere? Savings? I would suggest you could never get a return on this "investment". Small boat maybe, but one so large??

ArranP · 17-11-2020, 16:59

Quote:

Originally Posted by RexSnr

I like the concept as I am also into solar powering everything.......and not checking any of your calcs, but surely you are going to be using the generator nearly full time to power this? You have a heavy, wide hulled boat already and you will surely need to add huge battery banks and huge gensets (big weight increase) to have some life with 80 odd kW out per side. You have limited space for solar panels, remembering only one side of panels can reasonably work at any time when sailing, so it seems to me you will be running the generator reasonably full time to drive this big, even heavier boat??
I would go past the fun stuff (the engineering), and work on genset sizing. I think you will need one (or two) big ones.

When you consider the mechanics of installing huge gensets (if you have enough room), covering your decks in solar panels, trying to find a home for two obviously huge battery banks - it does sound like horrific modifications to your boat, add the expense that will be breathtaking - and then the previous comment of smashing your boats value rings doubly true, I would just ask - Why???

Surely, there has to be a positive in there somewhere? Savings? I would suggest you could never get a return on this "investment". Small boat maybe, but one so large??

I am considering but as yet not decided :-

2x 60-80 kW Motors ( in place of existing engines )
2x 75 kW battery banks ( in place of existing fuel tanks )
10-17.5 kW Solar Panel array ( in place of existing bimini top )
100kW generator ( in place of existing genset )

Solar Panel Array 17.5kW and 10kW

5 sun hours per day @ 10 kW = 50kW using half the array = 25-35 kW

Most trips are short trips cruising at 4-6knots ie hoping from island to island, then at anchor for a few days, for this I think it maybe feasable for solar to provide the energy without the need to consume deisel fuel. For the seldom long trans-ocean passage, the generator will need to provide the energy. At least this is the rationale behind my motivation. That said, the sails can be used when there is wind...

As regards to cost there are significant cost differentials between the cost from total soluation providers and the cost from diy solutions.

For example the cost of my off-grid solar system at home that I procured and installed myself cost 5k USD, its been installed more than a year now and working just fine...

5kW inverter 700 USD
4.5kW solar panels 1,900 USD
10kW lithium battery bank 1,900 USD
cables / fuses / switches 500 USD

Dirk01 · 18-11-2020, 13:10

Rough Calc says 60% of Diesel power is sufficient. You are totally overpowered! Consider the torque! Consider the efficiency! Consider the Low Voltage Directive LVD (Insurance)!
Genset at 25% power for long range cruising.
Consider the reality. When and how long do you need full power? Max. 30 mins.! DON'T forget the sails.
Only my 5 cts...

GALAWA · 18-11-2020, 14:10

With your present YANMARs you have 2*100 HP
Any power set up, wether diesel or electric, should meet the following specs :
1- deliver 2*100 HP on the shafts for 30', and preferably 1 hour
This could be done with your 100 KW generator + batteries
2- deliver half power, say 2* 50 HP, for 48 hours
This mean using your 100KW generator continuously (Batteries will drain out after 2 hours, Solar panels are useless during the night and during the day if cloudy)

Did you compute the total weight of 2 electric motors + batteries + 100KW generator, + fuel tank ?
Did you compute the acreage of 17.5 KW worth of solar panels ?
And where on deck they would fit ?

Dirk01 · 22-11-2020, 00:34

Quote:

Originally Posted by GALAWA

With your present YANMARs you have 2*100 HP
Any power set up, wether diesel or electric, should meet the following specs :
1- deliver 2*100 HP on the shafts for 30', and preferably 1 hour
This could be done with your 100 KW generator + batteries
2- deliver half power, say 2* 50 HP, for 48 hours
This mean using your 100KW generator continuously (Batteries will drain out after 2 hours, Solar panels are useless during the night and during the day if cloudy)

Did you compute the total weight of 2 electric motors + batteries + 100KW generator, + fuel tank ?
Did you compute the acreage of 17.5 KW worth of solar panels ?
And where on deck they would fit ?

@GALAWA I totally agree with your explanation, BUT (there's always a but) :
Electric motors have a totally different torque diagram. 100% const. torque up to cruising speed and 100% const. power above (don't mix that up!).
The power curve is the quadratic-shaped field weakening part of the diagram and clines to the requirements of the yacht according to the conditions.
The above mentioned curve fits perfect for max. thrust in bad weather with higher waves and strong winds where you never can reach top speed but you've to sail & motor with heavy force. THAT is the reason why you can reduce the power but still have the torque and therefore the force to fight in emergency.
It is much better to calculate with (electric) current (equal to torque) than just to compare power. Search the web ...
Additional, electric motors can be overloaded for minutes (depending on thrust you need). So 115% in average is a common rule for 10 minutes and 140% for 5 minutes.
For long cruise at reduced speed the water friction decrease quadratic-shaped. THAT is the reason why you don't need such a big generator. The best efficieny is at ca. 80% load. And that is also the best working point for a diesel to keep it healthy. Permanent underloaded diesel engines suffer on bad combustion (sooting).
But I agree with your 30' full TORQUE (not power, as I already explained). And maybe up to 45' or 60' depending on need for security.
And I agree with your solar panel objection. Other cruisers confirm the same. To feed daily needs you need about 3kWp solar power for two crew and the boat itself. Add 500Wp per add. crew (if constantly on board). Add. a little generator of 2-3kW as a spare (maybe gas, as you need it for your outboarder anyway).
To have BIG housebanks means you can totally electrify the complete boat, incl. A/C.
I'm gonna do the same. Or deeply think about. And I already did the search and math...

mvweebles · 22-11-2020, 01:22

Quote:

Originally Posted by ArranP

I am considering but as yet not decided :-

2x 60-80 kW Motors ( in place of existing engines )
2x 75 kW battery banks ( in place of existing fuel tanks )
10-17.5 kW Solar Panel array ( in place of existing bimini top )
100kW generator ( in place of existing genset )

Solar Panel Array 17.5kW and 10kW

5 sun hours per day @ 10 kW = 50kW using half the array = 25-35 kW

Most trips are short trips cruising at 4-6knots ie hoping from island to island, then at anchor for a few days, for this I think it maybe feasable for solar to provide the energy without the need to consume deisel fuel. For the seldom long trans-ocean passage, the generator will need to provide the energy. At least this is the rationale behind my motivation. That said, the sails can be used when there is wind...

As regards to cost there are significant cost differentials between the cost from total soluation providers and the cost from diy solutions.

For example the cost of my off-grid solar system at home that I procured and installed myself cost 5k USD, its been installed more than a year now and working just fine...

5kW inverter 700 USD
4.5kW solar panels 1,900 USD
10kW lithium battery bank 1,900 USD
cables / fuses / switches 500 USD

Ummmm..... Have you checked the size of a 100kw generator? These are typically powered by 6-cylinder 5.9 liter engines producing over 100 hp. Sound enclosure is over 5 feet long, and 30" x 30" square, roughly the size of a household refrigerator. Weight is almost 3000 lbs. Probably requires at least 4 inch exhaust and easily consumes 3 gph.

Guessing the electric motors themselves are not exactly svelte either.

Peter