Thursday, May 6, 2021

Re: Ang.:Re: [electricboats] One engine down...looking for solutions/suggestions

Alas, I didn't consider resistive loss…but then, that's difficult to figure given the lack of detail.

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of Myles Twete
Sent: Thursday, May 6, 2021 4:13 PM
To: electricboats@groups.io
Subject: Re: Ang.:Re: [electricboats] One engine down...looking for solutions/suggestions

 

Yeah, well, details matter---look at the specs on that website.

On one line claiming: "KV: 50"

On another: MaxVolt: 48S (200.6v)

On another: MaxAmp: 190a

On another: MaxPower: 40000w.

So, it appears they claim max power at around 200v, 190amp with about 40kw power.

NoLoadCurrent: Blank

Resistance: Blank

 

And not a dang thing about what the no load speed is, though they do spec:

Torque: 68Nm

Assuming 68Nm @ 190a, then Kt ~ 0.36N-m / amp

And since Kt (N-m/amp) = Kb (V/r/sec), we have Kb ~ 0.36v/r/sec

And assuming this torque is also with V~200v, then:

              W(maxpwr) ~ 200v / (0.36v/r/s) ~ 556rad/sec ~ 5300RPM

Maybe…

 

Specs matter…when missing, suspicious or non-sensical, beware.

 

-MT

 

 

 

From: electricboats@groups.io [mailto:electricboats@groups.io] On Behalf Of Carsten via groups.io
Sent: Thursday, May 6, 2021 3:01 PM
To: electricboats@groups.io
Subject: Ang.:Re: [electricboats] One engine down...looking for solutions/suggestions

 

You're right about that, Jamie.

But we can't have 50.000V on our boats, max 48 or 96 V...

I tried to look up the manufacturer, but without success. Assume it's just another Shenzhen backyard company.

Please enlighten me, if some of you have ANY experience with this kind of motors !

I am going to Guangdong Province this weekend (the center of manufacturing in China), so if any really reasonable ideas, I would be able to go for inspection of a supplier.

 

Was that a bomb to you ???!!

 

 

 

På fre., den 7. maj 2021 klokken 1:03, jamie.schlinkmann@gmail.com

I'm sure some people will cringe....but these large outrunner drone motors are very efficient. There are several manufacturers of motors like this:

 

APS 24050 Outrunner BLDC motor 50KV 40KW Paramotor

alienpowersystem.com

This motor will get into the desired RPM range at 48V and below 10kW it will be very efficient. Of course it will also be able to produce more power when needed. Also there is a series of open-source drives available on the market that are very well designed...

 

Welcome to the Home of E-Motion! What ever is on your mind, the Vesc-Environment will help you to achieve your goals faster. E-Motion is the key to success for the most innovative products of the near future.

vesc-project.com

I know many will say they are not hardened for the marine environment but they certainly can be. If I were doing this kind of conversion on a saildrive I would look hard at components like this.

 

Jamie

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