Ok I’m really confused. (not unusual)
You’re even considering 8 motors and talking about KISS?
Belt Drive on a system this big?
Why water cooled?
Why are you set on a 48V system?
As an example the GMS system below uses 384A at 4300RPM and 48V (then at 85% E). Let’s see 384A x 8 motors = 3000A at 48v with an 8 pack (2 strings of 210 AH, 50% SOC = 100A). You should be able to run for ooh… what 30 seconds?
You would need a 144kw Genset.
I’m sure I screwed up the calcs some place so educate me, it’s early and I’m still sleepy. :o)
Redundancy…
My motors are actually 2 motors in one case each side. I have 2 controllers for each side. If ½ of a motor goes I can run at 50% on the remaining ½ and full on the other side.
I have reverse
Direct drive = Motor, shaft, prop.
I’m at 144v system = much smaller wire sizes.
I draw a theoretical max AMPS of 150A per side (as tested by the Eng. To see at what point things smoked) Never tried nor plan to but the hull speed is reached at 40A per side so I don’t need to go there.
I have a 16KW Genset (would really like a 20 or 22kw) providing 80A.
At 60A total I can motor all day long at around 8 knots with the genset and put 20A back in the batteries.
KISS…
Steve in Solomons MD
The dual version in interesting:
Just two of them cost $11,000 dollars. Eight would set you back about $45,000. They seem to get two of the controllers to work together. I wonder how much more work it will be for you to get 8 of them to work together?
On Jan 11, 2011, at 11:11 PM, ibles_world wrote:
I am looking into Green Motorsports, The motor they produce weighs in at 37lbs and is 21 hp each They are water cooled Brush-less and completely sealed for marine environment, 48 volts, Ac not sure if its 50 or 60 cycles, 4000 rpm. I may need 6-8 of these motors, The question now is how big of a gen set would I need to continually run them at half speed? Has anyone used them or done research on them?
--- In electricboats@yahoogroups.com, Matthew Geier <matthew@...> wrote:
>
> On 11/01/11 16:57, ibles_world wrote:
> >
> > I also was on another site and it looked as if multiple motors could be setup in tandem with one another, This looked like a valuable option, I could mount 2 or more smaller drive motors with clutches to a single shaft,
> You don't need the complication of clutches to disengage motors. You
> just leave them all connected and run them in parallel at lower power in
> each motor.
> Motors are often ganged to get extra power.
>
> Even if it became necessary to cut the power to one motor (say due to
> an electrical fault) unlike an ICE there isn't much mechanical
> resistance in leaving it in line and spinning it dead. (unless it's
> shorted out and acting like a generator with a shorted output, but that
> would be unusual.) Having a motor mechanically jam would be very rare.
> Your clutch arrangement would be more likely to fail.
>
>
> Electric motors also have very large operating speed that produce full
> torque. A variable gearbox isn't generally needed. Forced cooling might
> be needed if high torque at low speed is needed as the motors may not be
> spinning fast enough to self-ventilate. Rail applications all have fixed
> gear ratios and look at the loads railway locomotives drag.
>
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