Hello. Great Forum. Lots of creative adventurous people here.
I want to build an electric motor for my Grumman sports boat.
15feet long. 110lbs empty. 400lbs outfitted
40 inches at its widest, 31 inches at the stern
Very low draft. Rows like a dream
I will be using this boat on the upper Sacramento River, the current is very strong.
I don’t think an 8 hp electric hangkai outboard will cut it on the river. Besides I don’t want to 35 inch shaft when all I need is a 14 inch shaft on my little canoe.
Based on max Watts
The flipsky 85135 12000watt motor looked interesting
Specifications read this motor at 10,000 RPMs
My newbie analysis:
Was hoping to use and 8 inch stainless steel prop with the proper pitch, so that my motor is spinning around 9200 RPMs
Very curious about prop selection for this Grumman sports boat and flipsky motor
Then there is that whole can of worms:
Battery selection
Power supply design
Would 60v 60amps work with this motor?
And what would a modest solution look like, around 1800 on the batteries
Honestly I will only need around 45minutes of run time
I would like to navigate confidently during the winter when the river is large. Lots of smooth power would be comfortable
This is my first boat, All input would be greatly appreciated.
Your ESC must be dimensioned to bear 150-170 amps continuous. That would mean using the following one FSESC 75200 close to its limits with a good watercooling… As it is a VESC, you a have a max current limitation feature.
Recommended 28-75.6V (6-18S) better to stay at 17s to be safe against voltage spikes with the above ESC.
Should you need to connect a bike-type throttle to your VESC :
For a big square back canoe i would probably get a used EV battery. Lots to choose from, there are several suppliers, usually you can get really good batteries for around $100 per kwh.
Would the
flipsky 85135 12000watt
Run ok at 36 volts
What are the advantages at getting a second battery pack and running at 72 vilts
And of course I should not be married to this motor choice.
Battery pack is a little bit heavy at 86 pounds.
It does seem like a great deal, for the quality of the build and 220 Amps
I imagine attenuation can be a big problem at high amperages.
To balance the boat out, I would wanna place the two heavy batteries towards the middle.
Making the cables from the motor to the power supply four feet longer than they should be, does not sound like a good idea. When 50 amps are running though the wires
For today, I will row my boat
Rowing is very healthy
Better to make the motor cables longer and keep the battery cables short-> put the esc near the batteries. The Adavantage of higher voltage is lower current for the same power, also less loss in the cables.
When considering battery voltage, consider the desired motor rpm. With a 36v battery, a 100kv motor will max out at 3600 rpm.( KV rating x battery voltage = max unloaded rpm) in practice, loaded RPM is about 70% of the theoretical max. So at 72v a 100kv motor would spin 7200 rpm. Another option, would be to use a higher KV motor with a lower battery voltage to attain the desired rpm. Desired rpm depends on your propeller motor combination. Unfortunately, it usually requires some experimentation to find the right prop unless someone has already done that with your motor.
I could easily deal with a 180lb battery system. 2 of the 86lb 36v “LG ev” batteries.
Weight capacity of my boat is 1100 pounds. The other day I took a 200 pound guy fishing with me. Barely noticed when he stepped in. Barely noticed when I was rowing my boat.
If I could run this motor at 120 A for 25 minutes without breaking a sweat.
