Very slow build from France

Jezza · February 25, 2019, 4:40pm

Nice, I found the Reissener get quite a bit hotter than my torqeedo gear. You going to put a heatsink on it?

Alexandre · February 25, 2019, 5:29pm

Yes , get some Heat from the motor too
I was thinking ( same as my first built but bigger)
Aluminium tape 38mmt to 40mm or copper
Tubing 20mm long
40 to 45mm
45 to 55mm
Then cooper or aluminium 0.8mm rolled
And another Longer with the motor 56 to 57mm

Alexandre · March 4, 2019, 9:20pm

Just a big mess and almost miss the 5.0mm but i did it , got the motor shaft from 10 to 5mm to fit the gearbox pinion

Alexandre · March 4, 2019, 10:28pm

Unit for 2019

Tubing is 60x260mm

It can be shorter but i leave room for plugs and wires

g.gregory8 · March 9, 2019, 2:05am

Have you tested a battery with the NESE modules? I was thinking of making battery with these but concerned about current draw.

Alexandre · March 9, 2019, 8:33am

Just received this week a big package from nkon

My main concern with the battery built was continious max amp draw

I wanted to use full cooper , N.E.S.E are well designed , not worried about amp draw , this built with 24 modules could support 400A , but it is mainly depending on cells temp : Max around 70c… So 30q or vtc6

Test in a few days

guldsteen · March 19, 2019, 9:37pm

What BMS are you using?

Alexandre · March 19, 2019, 11:14pm

No BMS will be used, the battery is split in to 4 x 6S 24A, charged and balanced with lipo chargers (lithium ion mode 4,1v), discharge protection by the vesc with current control

guldsteen · March 20, 2019, 9:10am

Ohh, OK. Is it the Trampa VESC PLUS 6 you use?

Alexandre · March 20, 2019, 10:21am

Waiting for @Trampa answer me , but i want to use the 75/300

agniusm · April 11, 2019, 7:06am

@Alexandre, dont forget to use extra protectors on your cells:

When inserting, get them in on an angle, positive first, negative to bare tab without compression foam.
Build is looking awesome btw!
@g.gregory8 Modules were tested over 200A discharge. Currently there is no cell to cap NESE modules @ 6P:

Alexandre · April 13, 2019, 10:36pm

thank you for the advise @agniusm, i tried a few set up and yes this one is the best:

positive on the tab with foam , inserting first, push it forward when sliding the negative down
put cells on the side then in the middle in the module

my built has been put aside for a couple week, i needed time to figure out my board: i will make my own to fit my specifications instead of trying to mod this one …

and the main reason is that for the moment i am more buying PAMPERS (again) then Efoils parts
…

i took me sometimes to understand how a brushless motor works, probably due to my combustion engine background building and mapping

i was missing the right part of a dyno chart for a brushless:

H3540at48V35ASimulator

so back to my post : rpm drop…

from : Futility of Motor Power Ratings

Flo · April 16, 2019, 9:26pm

About the torque of electric motors:
Brushless dc motors have constant torque (after the initial startup rpm has been reached so the ESC knows the rotor position). With rotational speed the voltage produced by the turning motor rises, if this generated voltage gets close to your battery voltage you can not drive the motor any faster. Thats why there is the trick called field weakening. Field weakening changes the timing of the current through your motor phase wires. Now not all current is used in the moment for optimal torque. Some of the current is used to weaken the field of the permanent magnets on your motor‘s rotor. This reduces the voltage produced by your turning motor. So your battery voltage is higher again and you can accelerate your motor further. This comes at the cost of less torque. You could also look at this as if the motors KV number was higher in this area. I think for most uses here you sould not need the field weakening/constant power area. So basically bldc motors have constant torque and therefore power rises with rpm I‘m not even sure if most ESCs implement field weakening, except maybe for the timing parameters.
I found this graph with a quick image search:
https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/902/energies_2D00_07_2D00_00961f1_2D00_1024.png

Of course the numbers differ for every motor, but the form should always be the same. I would argue that your efoils design point should not be in the field weakening area.