Visit our Popular Forums

ArranP · 15-03-2021, 01:58

Quote:

Originally Posted by barryglewis

Can you clarify?
The controller (couldn't find it's details on their web page) converts the DC from the batteries into AC?.
How does the regeneration work?

Here is the link to the controller
https://www.evwest.com/catalog/produ...b8da3d7f7651fe

The regeneration - I have no specific details other than it states that it can do regenerative braking... therefore if the propellor or deisel engine is turning the electric motor then the motor will produce the power to charge the battery.

Here is an exmaple of a Hybrid propulsion system from a total solution provider
https://hybridmarine.co.uk/index.php...ur-hybrid-work

valhalla360 · 15-03-2021, 04:26

Quote:

Originally Posted by Dirk01

@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.

HP = Torque * RPM

If both motors have the same HP driving the same prop, by applying an appropriate reduction gear, you wind up with roughly the same torque regardless of the power source.

The lower electric motor HP comes from the automotive world where it does make sense. Cruising down the highway a small car might only need 40-50hp but to get good acceleration from a stop, you need low RPM HP.
- With a gas engine, they do this by spec'ing a 200hp (peak) engine.
- With an electric motor, they can downsize to maybe 70-100hp and the peak torque from 0rpm compensates.

With a displacement cruising boat, acceleration isn't a big concern. Motor size is driven by the need to power the boat at constant speeds. At that point the ICE has gotten up into it's peak torque range, so there is no advantage to electric.

valhalla360 · 15-03-2021, 04:34

Quote:

Originally Posted by ArranP

Its been sometime since my last post, I thought I would share my latest findings... it appears I have found a suitable and economical motor & controller :-

HPEVS Curtis AC51 motor & Controller 1239E-8521 (144V 500A)

It's peak power is 65kw 144VDC nominal upto 500A, there is the option of an oil cooling system to both the motor and the motor controller for marine applications.

It appears to be suitable for regen braking for the purposes of marine this means it maybe possible to be used as a hydro generator or deisel generator to recharge the batteries.

The cost for 1 motor and 1 controller is circa 5000USD, additional items need to be purchased marine display, marine throttle, contactor, cables.

https://www.hpevs.com/index.htm

Peak Power Graph
https://www.hpevs.com/Site/images/to...peak_graph.pdf

Oil Cooling Continuous Power Graph
https://www.hpevs.com/Site/images/to...%204-15-15.pdf

HPEVS do mostly EV car kits but they make an oil-cooling system as an option for marine applications. They are based in USA and have alot of support and technical guides to help with the setup. They seem like a good-bet at a reasonable price from what is out there

Battery - LiFePo4 cells 3.2V 202Ah put 45 in series = 144V per 30kW pack. Cost is 75USD per cell or 3,300USD per pack. Parallel 6 to 9 packs to make a 180 to 260kW bank.

These cells can be purchased from China and assembled in the hulls to best suit the internal space that is available. Buying the batteries pre-assembled would mean having to find space for several large black boxes when compared to the size of the cells.

BMS - use a master / slave BMS solution.

Regards
Arran.

A pair of 65kw motors seems reasonable.

What did you settle on for a generator? 180-260kwh of battery bank is likely only to buy you 2-3yr at cruise speed.

Also, what is the weight of those battery banks. I recall tesla 80kwh batteries being up around 1200lb. As a DIY bank, I would expect it to be higher with cabling and racks to hold them in place. That could easily push you up around 3000-5000lb for batteries. If you have to maintain the diesel tanks for the generator and the generator itself, do you start running into weight problems.

ArranP · 15-03-2021, 05:46

Quote:

Originally Posted by valhalla360

A pair of 65kw motors seems reasonable.

What did you settle on for a generator? 180-260kwh of battery bank is likely only to buy you 2-3yr at cruise speed.

Currently I am inclined to go the Hybrid propulsion route... retain the Yanmar 110s to propel the boat and/or turn the electric motors, the electric motors produce the power to charge the battery. This is the generator, 2 of them one in each hull.

Quote:

Originally Posted by valhalla360

Also, what is the weight of those battery banks. I recall tesla 80kwh batteries being up around 1200lb. As a DIY bank, I would expect it to be higher with cabling and racks to hold them in place. That could easily push you up around 3000-5000lb for batteries. If you have to maintain the diesel tanks for the generator and the generator itself, do you start running into weight problems.

I am planning to do a DIY build of the battery, placing individual cells rather trying to find space for a whole battery in one of those large black boxes, this will I think allow me to make better use of the space available.

I plan to keep the existing diesel engines and would prefer to retain the fuel tanks as they are and work the battery at a cell level into the spaces available within the hulls.

Weight is 6kg / 13lbs per kWh.

I figure 2 hours of motorsailing will require a full day to re-charge from the solar panels... which if I do 8 hours of electric-motor sailing per week I calculate that the electric propulsion system will pay for itself in 6 years assuming it costs circa 50k USD using a comparion cost of 1 USD per 1 litre of fuel.

SunReef 60 E equipped with 60kW motors and a 160kWh battery bank claim that 10 hours of sailing with hydro regen will fully recharge the battery from empty... This means that each motor must be producing 8kW of energy per hour. I won't be able to substantiate this until later if at all depending if the electric motors I am planning to install can produce that much power from brake regen.

https://www.youtube.com/watch?v=iRTPXCV-ksA&t=190s

GrowleyMonster · 15-03-2021, 14:48

For the size and cost of your repower, if you really want to optimize your regen charging, you ought to think about controllable pitch props. Tweak the pitch for most efficient propulsion when motoring. Tweak the pitch for most efficient charging, when in trail shaft regen mode. For a 30' monohull and a 10kw motor, no biggie anyway. For your application, CRP props might pay for themselves. Plus you can set the pitch to max, in effect, feathering the props for minimum drag, when desired.