Hi Andrew.
I'm not sure what you're trying to say. It's been proven multiple times that the 5-6kW rated drives (48V x 120A) are drop in replacements for gas and diesel engines up to 20hp.
Ever since cars have been available, people have been trying to adapt the engines into boats (and airplanes too). While automotive engines are well suited for the demands of driving, they often don't translate as well to marine duty. Another issue is physically converting the engine to marine duty. Many engines that have looked promising for this type of conversion (in the last 10 years, the VW 1.9L TDI comes to mind) have not performed well and have had reliability issues when installed in boats. By the time one does all of the modifications to prepare the engine for real marine duty (new ECU, new cam, new cooling system, corrosion control, etc.), a proper marine engine looks more attractive.
For the conversion that have been discussed here, the most common motors in use on this group have more than enough torque to do what they are being asked to do.
As far as standing up to sustained amperage, that's the point of rating the motors. The Motenergy ME0913 that is in my boat is rated to 125A continuous. In my performance testing, operating my motor at 106A for more than 30 minutes resulted in maximum motor temperatures of less than 100 deg C (measured with the internal temp sensor). Motenergy says to keep the motor below 150C, so I could run the motor at this output for as long as I can supply power. Even though the motor is rated to run at 420A for one minute, I'm already just about at hull speed at 5100W, quadrupling the power won't increase my speed hardly at all.
Going back to your first comment, this 35 lb motor at 5100W (6.8hp) drives my boat 1/2 kt faster than the full throttle 12hp Yanmar diesel that I took out for the conversion. Even with the 8kWh battery pack, my entire electric drive system weighs 100 lbs less than the 160kg dry weight of the Yanmar SVE12 alone.
So perhaps you can be more specific about what you're stuggling with. Since the website in your signature line focuses on electric "R/C Boats, Marine, Airplane, Helicopter, Car and Truck Equipment", I would assume that you're thinking more about racing than cruising. If that is the case, check out some of the John Paramore's posts in this group. His experience with full size electric boat racing might be more of what you're looking for.
We're here to help.
Fair winds,
Eric
Marina del Rey, CA
PS. If you want usable torque, check out John Wayland's electric car, White Zombie. His 0-60mph time is below 2 seconds now. His latest proplems have been with the controllers, not the motors, he has been melting custom 2000A units.
--- In electricboats@yahoogroups.com, Andrew Gilchrist <andrew@...> wrote:
>
> This is annoying the small motors and battery voltages cannot get near
> to duplicating even small engines
>
> Prius are not going to be 10G they give you pack and CVT (brilliant for
> electric ) motor and controll unit for a few thousand dollars
>
> A Mercury leg maybe sdifferent by the cars powwer steering could be used
> here too
>
> For power generation the motor is light efficient and has a ECU
> controlled fuel and ignition uystem which can be remapped to give much
> better efficiency at lower rpm higher torque figures
>
> Tourque is what is missing from the little power units - they simply
> wont tolerate being flogged at high amps for long
>
>
No comments:
Post a Comment