Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[tizdaz]

Hi guys,

A bit of a "noob" question!

My knowledge of ESC's is very limited as i've only ever really had 2-stroke models.

If i set the EPA on my TX to around 50% for throttle stick (forward & reverse), then would this limit my motors RPM to half (ie: if my motor is rated at 4000rpm, would it now be around 2000rpm with my throttle stick at full throw?).

Ive setup the EPA on my 2-strokes to limit servo movement but obvioulsy with ESC's there are no moving parts as such so im not sure if the EPA does anything with an ESC?

I ask as its going to be for a scale Tug boat so i dont want it flying across the lake like a deep v! ..i know i can just not give it full throttle, but id prefer to have it all setup using the EPA if thats possible as im also going to be using 2 modules (sound and steam) that work via throttle movement, but im just worried that full throttle on a 4000rpm motor is going to be far too fast for a scale tug! :-(

Thanks :)

[inertia]

I can't guarantee that EPA will work with the throttle on your particular set-up but I use it with my Hitec Optic 6 and it works very well. I restrict reverse to 50%, using small brushless motors and either a Hawk or Hobbywings marine ESC. Quite whether or not 50% equates to exactly half-speed depends on the motor and the ESC.
The other way of restricting top speed in both directions is to use a lower voltage battery.
DM

[john44]

You could also use a removable blanking plate with a smaller slot, that is if your radio has not got model
Selection then you would,not have to change settings to run other boats just remove the plate.


John

[Stavros]

Personally i wouldnt bother setting epa on a speed controller simply as the tug will only go as fast as you dictate on the stick movement ...and personally i beleieve you will need 4k rpm.....aa i tried a motor with max rpm of 2k and believe you me is was pedestrian like with no power,as soon as motor was changed to a 5k motor it was spot on....your choice




Dave

[tizdaz]

thanks for info guys :)


@ Starvos
I need to be able to push the stick for throttle 100% forward as the smoke & sound module are throttle dependant ie: 10% throttle will give the sound effect of engine rpm at 10%, 50% throttle will give the sound effect of engine rpm at 50% and so on, same for the smoke module, the more throttle then the more smoke (steam) is generated, so if i was to use a blanking plate or only use 50% throttle stick movement then i wouldnt get the full benefit of modules if that makes sense :) ? So i need to be able to have my throttle range all way to 100%. But i will consider what you say about the power, so i will see how it goes with the default EPA before i make any changes :)


The radio will have EPA settings (for now will be using my current radio) which has EPA & throttle curve etc & also 10 mod memory, only downside is it is only 3 channel, but it will do for time being :)

[tsenecal]

your final reply indicates a problem.

you want the ESC to go from 0% forward to 50%, while at the same time, you want a smoker and sound unit to go from 0% to 100%.

that is not physically possible, using only the EPA of the transmitter, unless you use mixing of two different channels, one for throttle (set at 50% EPA), and one for the accessories (set at 100% EPA).  if your ESC is programmable you may be able to set the throttle max output, but only the top end models provide for that.

in addition, if you can, and need to ever calibrate the end points of the ESC, you will need to return the EPA of the radio to 100%, or you will only be setting the calibration of the ESC incorrectly.

[tizdaz]

your final reply indicates a problem.

you want the ESC to go from 0% forward to 50%, while at the same time, you want a smoker and sound unit to go from 0% to 100%.

that is not physically possible, using only the EPA of the transmitter, unless you use mixing of two different channels, one for throttle (set at 50% EPA), and one for the accessories (set at 100% EPA).  if your ESC is programmable you may be able to set the throttle max output, but only the top end models provide for that.

in addition, if you can, and need to ever calibrate the end points of the ESC, you will need to return the EPA of the radio to 100%, or you will only be setting the calibration of the ESC incorrectly.

Ah damn, never thought of that! (blonde moment lol!) .. Im going to test it as is with the epa at 100% suggested by starvos as 4000rpm might be ok (the prop size im going to use will be 15cm diamater). If i find that on full throttle it goes way too fast then my other option is a gear maybe to drop the rpm a little?


Cheers!

[inertia]

Did you miss the bit about reducing the motor supply voltage? 
DM

[tizdaz]

Did you miss the bit about reducing the motor supply voltage? 
DM

Hiya


I want to try stick to 24volt as the motor is 24 volt etc, what are the advantages/disadvantages of 12volt vs 24volt? My tug will be quite big and very heavy so i thought 24v would be best option?

[Kipper]

You can also restrict throttle to 50% by adjusting the 'Throttle curve' so that it rises to 50% then runs flat. 

[malcolmfrary]

Running a 24 volt motor on 24 volts and finding that is has about twice the power needed is generally a good clue that 12 volts will do the job.
12 volts has the huge advantage that there is lots of gear around that is designed for use on 12 volts, something to do with the fact that the auto trade has standardised on that for many years.
The downside of using EPA is that the transmitter changes the signal it can transmit.  OK in itself until you hook it up to a smart plug n play ESC at the other end of the system, which will likely work out that the max 50% that you are sending is really 100%, which could cause confusion.  Simplicity has its virtues.