Solar panel

Thanks Porta, I thought that the back EMK or EMF would synchronize the 3 motors. I did a test with 2 in the meantime, it seems to work, however I don't know the torque distribution load when doing it in this way. Yes, I would have 1 ribbon belt and 3 gears at the top , which would create one torque on the massive 4:1 reduction gear via the middle motor to get the approx up to 1000 rpm. (the middle motor has the gear mounted to the outrunner magnet holder to allow for greater torque) I most likely will have to find a way to measure whether the 3 motors are in sync or not. Thanks for your reply, again it gives me the confidence that 3 motors running in sync is not a bad option.

With respect to the ESC, the attached photo shows the cooling plate with the 6 x 4 Mosfets ( 4 x 114 Ampere) However, the pcb I made, allows for up to 8 Mosfets x 6. The power loss for 8 Mosfets is : 150 Ampere x 150 Ampere x 8 milliOhm divided by 8 and then multiplied by 2 for the upper switching set of Mosfets and for the lower set of Mosfets. Not taken the switching losses into account, it means a total of 45 watt, which is easy to be cooled by the aluminum plate, touching the water. I will first see whether one ESC will do, in view that I did not hear great objections from the forum members to use only one ESC . I feel, that should I make and use 3 ESC, the torque distribution may not be equal distributed over the 3 motors. Thanks for your help. Bert

 

92 mph was peak speed but lost too much in the turns, runs 85 86mph now with lower lap times. 10,000 mah battery and I use 6,500 to 7,000 in a race leaving 30% left in the batteries and the are on third season now.

 

Hi Jim,
Very impressive and a nice speed.
Jim, maybe this would be better shown in a forum for model boat designs. Except if we can learn from your experience and apply this to larger boats with crew. Your battery is I assume, 10Ah x 33 Volt = 330watt. You stated that you draw 180 ampere. i.e. 3 minutes of pleasure, that at 92 mph = 1,5 mile per minute = 4,5 miles. You state 6 rounds of 1/4 mile = 1,5 miles, thus your battery should still have 2/3 energy in it. However in the above thread you state 30% left . I think that your efficiency is worse than the 92% as you think you have. The figures don't tie up. I think you have losses in your ESC and cabling not taken into consideration. What do you think.
Bert

 

I am guessing you are timing in a trap, Jim. If you time from standing stop, that is incredible acceleration!

Here is a link to the PC motors that are efficient and the fastest up to speed though cooling might be an issue in your application: http://www.popularmechanics.com/home/reviews/news/what-drives-cores-quiet-gasless-motors-15558520

Bert, note that these have been made up to 1000 hp, and should come way down in price once mass production kicks in.

Porta

 

Bert, this is most likely battery pak loss due to Peukert effect, quite severe at extremely high discharge rates.

On your ESC, you may need a tight seal to keep the aluminum heat sink water section away from the electronics. Even just vapors of salt water can quickly cause corrosion to printed circuits that are not encased in a marine sealant. I like the simplicity, lightness and the high torque of these Core motors, may eliminate need for gears configured in the large diameters: http://coreoutdoorpower.com/technology/

Porta

 

Hi Porta, Incredible clever and logic, to use multi layer printed circuit boards to do the copper layers of windings. It may be a problem when a 1000hp motor is made that way. But somebody may have a bright idea to do super thick multilayer copper pcb's. You are right, pancake motors are the future. I must see how I can modify (One day!! I have enough on my plate) the metal casing to accommodate pancake brushless motors.
In the meantime I use the 3 outrunners to make a higher power output. Bert

 

Indeed you are right. In anyway the 92% efficiency (what a dream) will not be able to be achieved.

Yes, I have sprayed the pcb with a special coating, the seal is also water tight. Although, due to the low power dissipation at the 24 Volt and 36 Volt, it is only about 15 watt and it is not under water, but the waves which are more often splashing against the aluminum and cool it. What you see on the photo is only an experimental system on which I do some programming and experimenting.

Absolute, it will be the future for a lot of applications.
Bert.

 

Hi Ron,
My apology for deviating from your original question and hijacking your thread. Basically you had closed it already and what followed should be of an interest to you. If I was you, I would investigate whether you cannot get a pancake motor and see whether you cannot make a shaft and casing with propeller yourself. Even if you need to make a long shaft and the propeller at the end. Solar panel? It depends whether you have 300 sunshine days or only a few days like in Great Britain. I am quite fond of solar panels, I am busy mounting 2 large panels , each 245 watt behind the transom. However , I am in South Africa, plenty of sunshine.
Bert

 

Those are some of the numbers my 8 channel data logger have given me over the last 10 years.
I posted this info just to show what is possible.