Brushless, ESC and LiPo #confused

[Problemchild]

Ha - yeah

i meant between the T and the R 

has anyone used the fake BL hobby wing rip offs on ebay

the hobbywing ESC I currently have seems pretty nice with the waterproof/dust proof switching

i know ESCs are all of different rating, quality, capability but maybe it's the fault of the motor spec sheet not stating peak or standard. 60A is already massive current and would warm up a hefty spanner quite nicely - 100A is crazy  

im not dismissing the advice - just asking questions to understand like I do with the uber high voltage activities I deal with at work.

If a 3000W kettle draws 12.5A then you fit a 13A fuse so if a motor draws 55A and you have a 60A ESC am I not covered?

can massively over engineer if that's deemed safest  but am I missing a bit? Is it just about the additional heat generated from being close to the rating?

JJ

[Nitomor]

I don't blame you for questioning everything, it's how we learn, first principles and all that. Take the advice as a guideline, no one is going to actively recommend you sail that close to the wind in case it fails so people will always err on the side of caution, I personally take the view that I like to do my own testing so you can speak from experience. I've monsterised various buggies and there was lots of concern regarding gearing and overheating but in reality it has been absolutely fine. Theory takes you so far and it's a sound basis, on my WT01 4x4x4 build, I'd pretty much worked out the Amp draw on specifying the system because I was running 2 ESC's and 2 servo's off one battery. The reality ended up pretty close to the initial calculations. You may find the esc continually cuts out, or it might be fine. I say go for it and let us know. If you deal with electricity you know what you're doing and you're well aware of the risks (which are minimal - fried esc at worse, unless your whole model goes up in smoke in a petrol station, next to a dry forest surrounding a housing estate  ).

 

[Backlash]

1 hour ago, Problemchild said:

 

can massively over engineer if that's deemed safest  but am I missing a bit? Is it just about the additional heat generated from being close to the rating?

JJ

What it basically comes down to is that all of the manufacturers seem to come up with their ratings in a different way.. Some stay on the safe side of things, whilst other over exaggerate their ratings..

Duty Cycle is another thing that is important, but rarely listed on RC electronics.. Quite simply, yes you can use this ESC with a 12 turn, but how long will it run for before it overheats (if at all).. I was told by an electronics tech that the duty cycle of electronic components is calculated over a 1 second period....

As for the motor, I'm not quite sure how they came up with that Maximum current rating.. Is it the Stall current?  Max current at full load?  Peak current? What?

The current drawn by a motor is proportional to the load.. More Load, the more current the motor draws.. But the load on the motor in an off road RC car is not linear like it is when driving a propeller in a plane for example.. The load on the motor will not only change as the car is being driven, (stop, slow, fast) but also according to the surface being driven on (eg concrete, dirt, soft sand, grass), and how rough the terrain is...

Advancing the timing (be that at the motor or by the ESC software) can also increase or decrease the current drawn by the motor.. Gear ratio is another factor that needs to be taken into consideration.. Battery type and voltage is also a concern..

The point that I'm trying to make is that it isn't an exact science..

If you add some cooling holes in the body and add a cooling fan to the ESC and fit a smaller pinion you may get the TBLE02S ESC to work just fine with your 8.5T motor..

But in doing that, will you be getting the best performance from the motor?? 

[Problemchild]

who knows

there is no base line as i doubt there is another chassis, set up the same, running the same same motor, esc, battery combo

it'll be fun and thats the good bit about all this

JJ

[Problemchild]

ok - all in and running BUT, as with the model before, i couldn't get it to run forwards 100% as it was only available in reverse.

Easy fix with the brushed as swapping the motor wires worked 

on the sensored brushless thats not possible

reversing the transmitter does not solve as it just reverses the trigger and it still goes faster backwards (just when trigger is for accelerate)

ESC reverse is on

JJ

[Nitomor]

Try swapping the two outside wires over.

edited to say mine aren't sensored but that works with unsensored brushless.

[Problemchild]

i'm pretty sure thats not allowed on sensored

JJ

[Problemchild]

yup - it just has a fit 

seems a common problem from googling (motor and ESC agnostic)

JJ

[Nitomor]

Perhaps try fitting the esc plug in the receiver the opposite way around?

warning, might fry receiver...

[Nitomor]

Actually that might fry the receiver.

[Nitomor]

Is the ESC programmable to reverse the motor in that?

[Problemchild]

had a go reprogramming it all day

BUT

after failing with the electrical solution i took out BOTH diffs and flipped them and now it runs fine

yay mechanical engineering triumphs over electrical once again haha

 

JJ

[Problemchild]

p.s. swapping the plug in the receiver just makes it beep and not register the input

JJ

[Problemchild]

the instructions for the ESC have instructions for reverse BUT this is about switching the reverse function on and off

looking on the internet, it seems like a VERY common problem and when it comes to sensored brushless motors there is no real solution unless the ESC has a reverse (the paired speed passion isn't able to resolve this either simply)

I tried setting the ESC up with full throttle and reverse but didn't help tbh

seems v complex for something simple

JJ

 

[Nitomor]

Did you try calibrating the throttle from scratch after you reversed the transmitter function?

[Problemchild]

No - the instructions for the receiver tells you to always have the plug the one way round with the black wire in a certain position - this is confirmed by them having the little tab

it doesn't say anywhere in the guides or the web to try the "servo" plug round the other way

seems silly and probably something really simple but I followed all the set up processes

there were a few posts on here about it actually but the solution was to swap wires to the motor which only works on non sensored motors

oh well

 

JJ

[Nitomor]

No I mean the channel reverse switch on the transmitter, did you recalibrate the esc after trying that?

[Problemchild]

yes - tried all sorts

set up says to put channel in reverse mode initially

do the throttle position set up (tamiya ESC states full throttle and full reverse in set up mode)

JJ