Thanks for all the comments and info John!
I overlooked the voltage column in the excel sheet. 25v is relatively low, so I can understand that you dont have any extra power.
And again about efficiency: thanks for your links. The 3 curves on facebook supports my understanding of that DC motors (and induction motors) work less efficient with lower than rated speed (at the same power). Here is an efficiency map for a DC-motor showing this: http://www.civilengineeringhandbook.tk/electric-vehicles/images/7609_44_86.png
Therefore I suspect that motor suppliers only provide efficiency curves at rated speed. And at lower speed (at the same power) efficiency will drop. This would be evident when an efficiency map or several sets of curves where provided instead.
A comment to the Yasa motor: From what I understand of induction motor theory: They mean that the battery voltage is 700Vdc. The voltage seen by the motor is increasing (along with the frequenc)y up to 700V at base speed (approx 4000rpm).
Last night I had an idea that might turn aout to be a proper solution: I could use my 17kW motor (direct drive) AND a 2-3kW motor coupled with belt drive (maybe 1:8 ) to the shaft. The small one works alone at cruise speed. At power demand (the throttle past a certain position) the 17kW motor takes over..
I am aware of that the propeller is the most important link in the system. My boat has a relatively large and slow turning propeller allready (400rpm at 4.5knots) so I would like to try this one before changing to another propeller. At the moment the motor is in my focus.
Thanks for the tips of Steve Dashew, I will check his site!
Regards
Bendik
On Wednesday, August 10, 2016 8:48 AM, fitloose <no_reply@yahoogroups.com> wrote:
Oops forgot link, here it is
http://tinyurl.com/gqd97tf
http://tinyurl.com/gqd97tf
__._,_.___
Posted by: Bendik Vignes <bendik.vignes@yahoo.com>
| Reply via web post | • | Reply to sender | • | Reply to group | • | Start a New Topic | • | Messages in this topic (18) |
Have you tried the highest rated email app?
With 4.5 stars in iTunes, the Yahoo Mail app is the highest rated email app on the market. What are you waiting for? Now you can access all your inboxes (Gmail, Outlook, AOL and more) in one place. Never delete an email again with 1000GB of free cloud storage.
.
__,_._,___
No comments:
Post a Comment