5 hp motor: highest reliability, highest efficiency

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blisspacket

100 W
Joined
Apr 17, 2009
Messages
102
Location
StAugustine FL
I'll preface this:Endless Sphere is a great forum where braincells run rampant and wild. Thanks.
My dilemma: how to win an all-electric boat race, the Wye River Electric Boat Challenge. The race starts on the first friday in October each year, out of St. Michaels, MD. Or more accurately, from the Miles River Yact Club. The challenge is overseen by Tom Hesselink and the Electric Boat Association of America.
So far,most recently, Torqeedo 4.0 electric outboards have dominated. Charlie Illif demo'ed mind-blowing speed with a forty foot rowing shell that can do 20mph--and even more. He's powered by AGM's and aan electrified lower outboard unit. He holds a course record, but has dnf'ed of late. The race is 24 miles long! That demands a LOT of battery.
I've been the RC outrunner motor route. I've combusted ESC's and motors. It's not pretty, it costs, and I'm happy to be alive and uncharred.
I have Nissan Leaf modules for power, but am bewildered (and pretty ignorant) of the array of motors out there.
I might have a thousand bucks to spend. From what I've seen (having been in the race 4 times) I'll need 5hp, about 4kw, of motor. I have 30 Leaf modules. Each is rated at 500kw, with 8volts nominal output.
Any suggestions for reliable, efficient powerplants??? (And implied in powerplant is motor as well as controller)
 
You're also not greatly restricted by the size or weight of the motor, so that should leave quite a few options.
 
I'm limited to 6hp without advancing to the Extreme class. Boats might be able to carry more weight, but lighter is still better. I had my own 200lbs, 240lbs of Nissan Leaf modules, 45 lbs of Torqeedo Cruise 4, and 160 lbs of boat. The Torqeedo drew between 80 and 100 amps at 48 volts for the 2 hours and 40 minutes of the race, seldom going over 10.5 mph. I'd rather do it in 1 hour and ten minutes....
 
say 90amps average for 2 hours 40min is 234amp hours


google says leaf modules are 38ah each

with 30 of them in 5 series, 3 parallel configuration (for your 48v)

you have 114ah
(at about 48v)


I think you need more batteries !

unless I've miss understood something ?


is your prop matched to the RPM of the motor ?

you could run at a different voltage so the motor rpm perfectly suits the optimum rpm of the prop ?
(voltage change = rpm change)


also, what's your boat like ? - as long as possible and as thin as possible is best, because you run higher in the water
 
How is the 6HP rated? If the organisers are smart it will be defined as at the battery output.

If it's the motor manufacturer's continuous output power rating then, as long as you're allowed to modify the motor cooling, you are effectively unlimited.
 
Ahoy Knighty! I don't know where Google comes up with those meager Ah. Each Leaf module has stamped on it 500W. Each mod is 8v, so that figures to 62Ah.

I ran the race Oct 3 with 30 modules. 6 of them were in reserve, not hooked up. With 24 of them pumping out power, 48volts, I got to within 200 feet of the finish line and the Torqeedo said "oops sorry the voltage is too low, we quit". My own voltage was too low also, so I just sat dead in the water for about five minutes, let some juices in the batteries restore themselves, and did not tap into the unused 6 modules. I finished the last 200 feet at about 6mph, I've forgotten what amps I was drawing.

The volts on the cells after the race were around 3.62. One table I have shows that to be 30% capacity. The state of charge at the beginning of the race was 24.9 to 25.

The prop was matched by the Torqeedo folks, their standard planing prop as opposed to the workhorse prop. For next year's event, I think I want to go the "Thai Panga" route, just a long shaft off the stern that swivels for steering and can be set at any depth, eminently tunable.

It's the motor that I remain in a quandry. I lean towards brushed DC, which seems archaic. But I do like the notion of a simple brushed dc controller.

Long and thin works: a 19' canoe with agm batteries beat me handily! 24 miles!!
 
To PunxOr: yes, motors are rated per mfg's specifications. And yes, with seawater right there, cooling is eminently do-able. I was briefly intrigued with Nuts&Volts' offering of a Malibu motor-generator from the GM hybridized; it has a cooling housing surrounding the motor. But the electronics are baffling to this tyro, and the m-g got sold thankfully...

The Torqeedo is limited, so I read, to 1300 rpm. I think I'd like a motor of 5hp and 2400 rpm
 
http://www.electricboats.org/2010-Wye-Island.html
Class 2, Advance batteries: Any single hull with a length to beam ratio less that 6 to 1 and utilizing non-lead/acid batteries, or running off a fuel cell. Because of the likelihood of these boats running the entire course at planing speeds, this class will not be handicapped by waterline length. (note, motor/s must be rated less than 8kw)
Click to expand...
 
blisspacket said:
Each Leaf module has stamped on it 500W. Each mod is 8v, so that figures to 62Ah.
Click to expand...

500W, or 500Wh? Very important distinction.

500W means they can output 500/8 = 62.5A of current (presumably constant, but could be peak, depends on how the W rating is marked/determined), presumably at the nominal voltage of 8V.

500Wh means they have a capacity of 62.5Ah at the nominal voltage of 8V.
 
LITHIUM BATTERY MODULE LiMn2O4/LiNiO2

60a/h rated - 7.6V - 500 W/h - max continuous power 1875W or 240A
Peak current 540A

Measured 62Ah from 4.2 to 3V, and 64Ah (4.2-2.5V)
Made in Japan from Nissan for LEAF EV CAR

Maximum voltage 4.2V per cell / 8.4V per battery
Average voltage 3.8V
90% of the capacity voltage - 4.2-3.7V
 
dnmun, sorry, I was abbreviating "module" and just calling it a mod. Nissan packages their electricity in large boxes--mods, modules--approx 8x11x1.25 inches. Those are 500Wh, within which are packaged 2s2p lithium bags; elsewhere on the forum, Icecube has taken them apart and re-oriented them. Anyway, at 2s2p, there are two main terminals from which you get 8 volts; there's a smaller terminal from which
you can monitor the 2p voltage of 4, or 3.86, or....

Here's a shot of my setup, 12 modules midship, another 12 hidden under the seats. oops, file too big, i'll try in a minute
 
Twelve mods(modules) sit midships; under the seats there's another 12. The Torqeedo 4.0 is in trailer store position.
 

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I'm looking on ebay at this item
http://www.ebay.com/itm/360375769745?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Other than the very basic info in the listing, I haven't been able to search out anything more. What does it weigh? does it have permanent magnets? In fact, I don't even know if permanent or wound field is better in terms of efficiency and weight...
 
blisspacket said:
I'm looking on ebay at this item
http://www.ebay.com/itm/360375769745?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Other than the very basic info in the listing, I haven't been able to search out anything more. What does it weigh? does it have permanent magnets? In fact, I don't even know if permanent or wound field is better in terms of efficiency and weight...
Click to expand...

That is a 6.6 inch diameter series wound DC commutator (brushed) motor from the Ft. Wayne GE factory I believe. It is a good solid motor and a deal for the price. Likely used in industrial utility carts like Taylor Dunn or Cushman. It is totally enclosed non ventilated so is rated at 3.25hp probably for one hour continuous run duty. It will certainly put out higher power, in fact much higher, but then would need shorter duty cycle or extra cooling.

If you're not familiar with series wound motors, beware they have an infinite no load speed. So should your prop leave the water or dislodge unloading the motor, it could overspeed and disassemble itself rapidly (explode). If this possibility exists, a speed cutout control circuit can be employed. Also series motors are torque monsters on start up and used by the EV drag racers. I'm not sure how important that would be for your application. Efficiency would be a few percent lower than a PM motor at rated power and below but higher at overloads. Weight of this motor is probably about 50-60 pounds.

Hope that helps.
 
Valuable insights, thank you major. The high startup torque I don't really need. I think I'll search for a brushed PM motor that has more ventilation, and try to incorporate water cooling as well. Good advice re an unloaded prop, which is sure to happen sometime or other on the water. Much appreciated.
 
You will find that better speed and efficiency will be best gained by improving your hull design rather than increasing the motor power.
 
How about the "5kW" brushless motor here: http://www.goldenmotor.com/frame-bldcmotor.htm

I don't have any experience with it, but it's water cooled and some research should turn up useful user reviews.
 
teslanv said:
You will find that better speed and efficiency will be best gained by improving your hull design rather than increasing the motor power.
Click to expand...
I'd agree with that... which class are you planning on running in? The rules on the site say 8 KW limit. In the class 2 they expect the boats to be on plane for the entire race. Was your boat able to plane with your setup?

Curious what RC motor setups you have tried? I like the dragon tail idea... I spent a year in Thailand where virtually all boats used that arrangement.... even with huge inline 6 cylinder car engines.

Where I work they use fuel cells that run off hydrogen on all their fork lifts and tuggers that would normally have a lead acid type battery. They are fairly large though.... would be cool if you could borrow or rent one for the race.
 
I don't have any Racing experience per se, just general boating knowledge and a love of wooden boats. :D
How about some pictures of your hull? Maybe we can make some recommendations for how to reduce your hull drag. That would be where I would start.
 
Do you need one motor or 2, so you can run counter-rotating or contra-rotating props? The efficiency gain of contra-rotating seems good enough to give it a go for a competition like that, and pulling it off with a solid shaft inside a hollow one seems relatively straight forward to DIY as long as you're versed in stuffing boxes.

I have some extra motors stateside that suit your needs, and the project is interesting enough that I'd do a results guaranteed arrangement in exchange for sharing build info for promo purposes. The motor diameter is too big to do an outboard, so it would have to be an inboard drive setup, and I don't know how an angled driveshaft impacts overall efficiency, but we're talking about far more economical than anything else capable of 5-10hp continuous with high efficiency.
 
Regarding the hull: what I'd planned to run has a 44" beam, is 15', has about 3" of rocker. I couldn't get the motors to perform, and opted to run the race in the converted sailboat you saw above. Much more roomy.... At 10mph I think you could say it was not on plane.
Here's a foto in my testtank of the boat that I'm looking to power for next year....
 

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to John in CR, that's an intriguing proposal. The Wye Challenge is NOT heavily attended. We had 12 entrants or so, and about as many spectators. The event is followed on Saturday at the Chesapeake Bay Maritime museum, where the MidAtlantic Small Craft Festival is held. THAT event draws great crowds, and the electrics are there on show.

Here's a foto of the stern of Elektra, then powered by outrunner RC 6374's and puny ESC's. They torched in trials. The props will be the challenge, and I do intend to provide vertical slots to pull the motor/prop assembly readily. Yes, these are counterrotating. I'd been thinking of a single drive, but dual does add pizzaz and maneuverability....
 

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"dragontail" is a better term, thanks, I'll use that. I'd think it would be the simplest way to go. And the GoldenMotor site is very good, with motor wiring etc. I don't get their table in one of the pdf's, where I think the lefthand column is supposed to be rpm. Not sure what it means. Their pricetags are good enough, the technology is there. There's another hundred bucks and more in shipping.... I'll wait for reviews at this point. The fact that they have controllers engineered for the motors is good. Presumably you can wire in just a throttle and a F-R switch and leave it at that. I'm assuming the Hall sensors are wired in, but the schematic doesn't show that full detail.
 
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