outrunner to replace 45cc gaS engine ?
 

hI !

I know this is not about crawler Electronics :ror:
But mabe some one can help me any way ?

i'd like to build an brushless weedwacker powered by a outrunner that puts out min 2000w and runs on 12s lipo.
i know that hobbyking sells lot's of big outrunner do they have one that will fit my needs ?

It chould be equal or mor powerfull compared to a gas 45ccengine.
i'd like 25-40min of worktime on one charge !
Will 12s 5000mah be enough ?

Re: outrunner to replace 45cc gaS engine ?
 

That battery combo is sufficient for an average of 444W for half an hour. (10A * 12*3.7V)

2kW continous or peak?
I suppose that means 2kW peak.

There are quite a few motors that should fit your needs, even if most of them can't handle 12S directly. Just limit the max output voltage from the ESC.

Re: outrunner to replace 45cc gaS engine ?
 

Not to be a buzz kill, but save yourself time and money...

Toro | Cordless Trimmers

Re: outrunner to replace 45cc gaS engine ?
 

Please pardon, and correct me if I am wrong here... I thought I had read somewhere that brushless esc's and motors do not work by varying the voltage but yet by varying a "pulse" to get the throttle? Then the voltage would be a constant from the esc to the motor. I think you would have to limit the number of cells to get the right voltage you require.

I know my terminology is way off here. Please forgive. :mrgreen:
BTW, I have a Ryobi 40v and it kicks @$$!!!!"thumbsup"

Re: outrunner to replace 45cc gaS engine ?
 

Those toro trimmers are gutless brushed direct drive. I have one, can't cut in before mowing. Gotta mow and then finish the edge.

A 63mm outrunner is a good start, something at least 50mm long with a nice low kv 250 or less. You will need to make an adapter for the line spool.

Re: outrunner to replace 45cc gaS engine ?
 

That's a bit of misunderstanding...

1. The difference in feed between brushed and the type of brushless motors we use is that the brushed motors have two leads in where one is "positive" and the other "negative" whereas the BL motors have three leads the function of which change with the position of the rotor.
So a brushed motor (while rotating in one direction) has the current fed in only one direction through the input leads.
A BL motor has the ESC chop and alter the current fed to the three leads as the rotor turns.

2. "Voltage" is in all modern designs is regulated by pulse width modulation (PWM), which means that a high steady voltage is chopped and then distributed as a square wave where the peak voltage is (almost) the input voltage and the average is the desired output voltage.
This output signal is often smoothed a bit using a capacitor or two.

So running a BL motor designed for up to 10S on 12S is no sweat if:
- The ESC can handle a 12S input, and
- the max throttle is set to 83% (10/12) or less.
(The limiting factor isn't the impulse peak voltage, but the average power generated over time.)