Model Boat Mayhem

Technical, Techniques, Hints, and Tips => BRUSHLESS Motors and Speed Controllers => Topic started by: cos918 on November 27, 2016, 09:41:14 pm

Title: Need some help
Post by: cos918 on November 27, 2016, 09:41:14 pm

Hi
I am looking at re motoring my model ferry Finnjet. She is 1.64m long and has a pair of 40 mm props. She will be running on a 3cell lipo battery. I have done some working out and at max speed I think I should be looking for 6000 rpm which works out at 540KV. I have found this motor on hobby king website . It is a Turnigy 3508-580kv. rated at 26ah
 https://hobbyking.com/en_us/3508-580kv-turnigy-multistar-14-pole-brushless-multi-rotor-motor-with-extra-long-leads.html


Been looking at the ESC and found 2
1 hobby king 30ah
https://hobbyking.com/en_us/hobbyking-30a-boat-esc-3a-ubec.html
2 turnigy marine 30ah
https://hobbyking.com/en_us/turnigy-marine-30a-bec-waterproof-speed-controller-with-water-cooling.html


Will the motor be ok and what of these speed controls would be best
This is going to be the first time I have use brushless motor so not clued up at all. The info I have got has been from the mayhem guide .
any help or recommendations would be very much appreciated


john

Title: Re: Need some help
Post by: derekwarner on November 27, 2016, 10:15:01 pm

John.....[as acknowledged] I know little about the black arts, however the unit of measurement or understanding  >>:-( surely is the question of the required water flow through the ESC's to dissipate the heat generated

I understand the original  Finnjet Ferry was infact gas turbine powered, however at scale speeds would she provide sufficient water to the ESC's?

Derek

Title: Re: Need some help
Post by: cos918 on November 27, 2016, 10:25:53 pm

Hobby King do do a 50ah for not much more
https://hobbyking.com/en_us/hobbyking-50a-boat-esc-4a-ubec.html
Note this is a scale boat not fast electric so I dont think there will be much current pull. I am in the same boat . new to brushless so dont know nothing at all
john

Title: Re: Need some help
Post by: canabus on November 28, 2016, 09:59:38 am

Hi COS918
I mate, I would use the car ESC 45A( part No. HK-45A)with reverse.
These do not require water plumbing and work better a low speed because of the electric fan cooling the ESC.
Your require a program card which is very easy to use.
I am running one on a 3639-750kv 600 watt motor with no problems.

Title: Re: Need some help
Post by: cos918 on November 28, 2016, 05:49:21 pm

Hi
Thanks for your input .Had a look at hobby king car esc . the specks do look good.


John

Title: Re: Need some help
Post by: cos918 on November 30, 2016, 06:15:23 pm

question . if a motor is rated 4s to 5s  and you run it on a 3s lipo . Will it just run slower ?


John

Title: Re: Need some help
Post by: kinmel on November 30, 2016, 06:55:42 pm

Quote from: cos918 on November 30, 2016, 06:15:23 pm

question . if a motor is rated 4s to 5s  and you run it on a 3s lipo . Will it just run slower ?

John

No, it won't start - insufficient torque.

If you want to run on 2S then buy a motor with that spec.