is this normal? starting off problem

[james_2k 0]

hi guys, finally got all the stuff for the car and it has a weird quirk,

if you very gradually increase throttle the car wont move, it will when you push the car manually (while still holding in the trigger), it then zooms off (into a wall)

looking at the motor when you do this, it does react initially (just sort of twitches) same for reverse.

once its going its fine and can drive slow or fast no problems. its just starting off,

if you start off a bit more positively it will work fine, the problem comes if you slowly add power.

is this normal for low turn motors? (its a 4.5) or is it screwed?

reverse isnt so good, because of this issue it tends to surge when it actually starts off..

cheers!

[sosidge 624]

You say 4.5, so I assume you are running a brushless system.

If you are running a sensorless system, this kind of behaviour is typical, it is called "cogging". The only real answer is to run a sensored system.

If you are running sensored already, then it possible that your batteries aren't up to the job, a 4.5 is a very fast motor and requires a lot of power which older/cheaper batteries may not be able to provide.

If you give a list of your electrics and the car they are in it will help understand the problem.

[TA-Mark 195]

Motor not wanting to start until you give the model a push is NOT cogging. This points to a more serious issue, like a failed phase, or bad startup power setting, or extreme timing setting.

Cogging is the motor stuttering at very low speeds.

A sensorless ESC will try all phases in their order to attempt to make the motor start, as opposed to sensored which will send the phase the sensor tells it that is needed. Either way it will rotate the motor far enough to either sense the next phase by the sensor (sensored) or the back EMF of the disused phase (sensorless).

More information would be good. What ESC? What motor? What chassis? What size wheels? What gearing? What battery type/specs? What battery connector?

[james_2k 0]

thanks guys.

esc xirius race pro sensored (120A cont 700A burst)

motor xirius BL 4.5 6000+/- kv

battery 5000ah 50c lipo (gens ace)

wheels are standard as came with the ta06 pro kit

stock gearing but as i say below, makes no difference

4mm bullets.

as i said its fine when it gets moving, or if you use a bit faster application of the trigger..

also it does it whether its attached to the spur or not. (took pinion off and it shows the same symptoms.) wont spin up with slow trigger application

p.s.

the motor is very smooth at low speeds, but to get it moving in the first place it needs a 'revving' of the throttle. le wierd!

cheers!

[speedy_w_beans 4272]

The fact the motor won't start with the pinion removed makes me think you have a sensor board problem or a phase winding problem. I had a Novak Havoc system with 10.5T SS PRO that did this. It didn't matter if the motor was in the car or not; it would not start unless the shaft was spun by hand first. Then it would continue rotating as long as the throttle was applied, but it was rougher operation than a normal motor. I used a digital multimeter to measure the hall effect sensor outputs while spinning the shaft by hand, and I could see that one of the sensor phases was not switching. So I sent it back to Novak under warranty and they replaced the motor.

If you have a digital multimeter, you can check your sensor phase outputs as well with the "volts" setting. Spin the shaft by hand slowly and check to see that each sensor output it toggling between 0 V and 5 V (roughly). This is with the motor connected to the ESC and the ESC is switched on, supplying power to the sensor board. If all of the sensors are firing, then use the multimeter in the "ohms" setting to check your motor windings. Check A-B, B-C, and C-A connections with the motor disconnected from the ESC. That should tell you if there is anything unusual about one of the windings.

-Paul

[james_2k 0]

hmm well.. seems i have a minor break through..

well removing the sensor cable makes it run every time (very rough.. but it starts) .. what would this mean then

[speedy_w_beans 4272]

To be sure I would use a meter as described earlier, but based on what you're saying I would guess a bad sensor board in the motor or a bad sensor harness. If it's a new brushless system and still under warranty, it's probably time to approach the manufacturer for a replacement...

-Paul

[james_2k 0]

thought you might say that

it was only bought a couple of weeks ago so its fine to send back.

weird though because once its started it runs fine. but it is really annoying.

cheers!

[james_2k 0]

well got the system replaced and it still does it..

when its running its fine, smooth and no issues. but starting off needs a couple of blips on the throttle to get it running..

argh!! ive checked all the connections and the voltage at the esc is fine.

any other ideas?

[sosidge 624]

It's possible that it is simply the nature of the ESC/motor package. I asume you are using the Ansmann Xirius system, generally Ansmann rebadge inexpensively-produced Chinese stuff, rather than the race developed brands. So the poor sensored running may be par for the course.

It could be that lightning has struck twice and you have got another ESC from a dodgy batch (eminently possible with a lot of the Chinese stuff where QC is a low priority).

The batteries look to be of a good, capable type. I would try another pack if you have one to hand, just to check.

My only other thought is that something is assembled wrong on your TA06. If the drivetrain is very tight it may be hard for the ESC to get the drivetrain moving. Something as simple as an over-tight pinion mesh can cause problems.

[Percymon 2184]

If the new motor and esc still stutter with the oinion removed then i'd lay money on it being another bad brushless set-up. With no load on the motor from the car any charged battery should be able to power the motor. Assuming your, on paper, very capable lipo battery is fully charged you should be able to run that motor off load for several hours from that battery.

Double check the output of the battery with a meter, or run it in another car to validate its charge state.

[james_2k 0]

the esc and motor cost 150 pounds, i would hope that its not that bad

battery voltage is fine and like i said, its very fast when up and running, just lacks 'finesse' starting off without a bit of blipping on the throttle :S

p.s.

these symptoms remain even with pinion removed, so i can discount the chassis

[Percymon 2184]

these symptoms remain even with pinion removed, so i can discount the chassis

EXACTLY.

If you are confident in the battery then i'd take that £150 brushless set-up back to the shop and show them how bad it is.

I agree that at £150 it shoudl be good quality but perhaps they have a bad batch and maybe you've had two from the same batch.

Does not using the sensor cable make any difference ?

Have you tried the lowest of the start/punch/acceleration profiles (although even the most aggressive should still be fine with no pinion and hence no load) ?

Have you tested the motor/esc away from the car, hence increasing the distance of the brushless components from the radio receiver ?

[james_2k 0]

EXACTLY.

If you are confident in the battery then i'd take that £150 brushless set-up back to the shop and show them how bad it is.

I agree that at £150 it shoudl be good quality but perhaps they have a bad batch and maybe you've had two from the same batch.

Does not using the sensor cable make any difference ?

Have you tested the motor/esc away from the car, hence increasing the distance of the brushless components from the radio receiver ?

yep have tried it without the sensor cable and it 'fixes' it but obviously get cogging.

will try the other things you suggest cheers!

[speedy_w_beans 4272]

A few more thoughts:

- Are you using a good quality battery connector, like a Deans plug, on both the battery and ESC?

- Do you have the power capacitor installed? I'm looking at a picture and description on Ansmann's web site, and the capacitor looks like a loose part to be wired in during installation. This is essential for operation.

- Do you have to configure sensored vs. sensorless operation on the ESC? Is it running in the right mode?

- Have you braided your motor wires together to minimize generating interference?

- Are you running your sensor harness some distance away from the motor wires?

- I didn't see any mention of your radio system -- is it a 2.4 GHz system? AM is a definite no-go, FM might be ok, 2.4 GHz is best.

-Paul

[james_2k 0]

A few more thoughts:

- Are you using a good quality battery connector, like a Deans plug, on both the battery and ESC?

- Do you have the power capacitor installed? I'm looking at a picture and description on Ansmann's web site, and the capacitor looks like a loose part to be wired in during installation. This is essential for operation.

- Do you have to configure sensored vs. sensorless operation on the ESC? Is it running in the right mode?

- Have you braided your motor wires together to minimize generating interference?

- Are you running your sensor harness some distance away from the motor wires?

- I didn't see any mention of your radio system -- is it a 2.4 GHz system? AM is a definite no-go, FM might be ok, 2.4 GHz is best.

-Paul

hey paul,

4mm bullets throughout

it comes installed

afaik theres no way to set it to sensorless mode

not yet - have done it now and no change

no - it cant be that far away from the motor wires but even as far away as it will go same thing

2.4ghz

[speedy_w_beans 4272]

That's about all I have in my bag of tricks... Beyond that, maybe it's time to switch brands...

-Paul

[james_2k 0]

That's about all I have in my bag of tricks... Beyond that, maybe it's time to switch brands...

-Paul

oh well. ill keep you updated if i hear anything from ansmann. until then im buying nothing else from them thats for sure!!

cheers for your help!

[MadInventor 3884]

A few more thoughts:

- Are you using a good quality battery connector, like a Deans plug, on both the battery and ESC?

- Do you have the power capacitor installed? I'm looking at a picture and description on Ansmann's web site, and the capacitor looks like a loose part to be wired in during installation. This is essential for operation.

- Do you have to configure sensored vs. sensorless operation on the ESC? Is it running in the right mode?

- Have you braided your motor wires together to minimize generating interference?

- Are you running your sensor harness some distance away from the motor wires?

- I didn't see any mention of your radio system -- is it a 2.4 GHz system? AM is a definite no-go, FM might be ok, 2.4 GHz is best.

-Paul

What's wrong with using AM radio system with brushless motors ????? I use 27MHz systems with my eZrun systems without any problems at all......

[speedy_w_beans 4272]

Well, my statement on radio systems comes from three sources.

1) Bottom left of page 2 of this Novak GTB2 manual: http://www.teamnovak.com/download/instruct...2_basic_ins.pdf

2) Personal experience: I tried running a Novak Havoc 2S ESC with SS PRO 10.5T 4200 kV motor and a Futuba 2PH 75 MHz AM transmitter and RJ152E AM receiver, and the motor would hesitate and glitch when hitting the throttle hard from a low speed or standstill. I replaced the radio system with a Futaba 3PL 2.4 GHz FHSS transmitter and R2004GF receiver, and all the hesitation and glitching went away.

3) Anecdotal evidence on various RC forums.

That's not to say every AM system will glitch; maybe your 27 MHz receiver is able to filter out certain noise better than a 75 MHz receiver, or maybe the noise is more in the 75 MHz spectrum than the 27 MHz spectrum. Maybe your installation is clean -- motor wires braided, sensor harness away from the motor wires, receiver antenna away from the motor wires, etc. Maybe it's a brand/quality/engineering issue too. Hard to say for sure.

-Paul

[Backlash 481]

Ummm... Stupid question, Is the motor and ESC phased correctly?? i.e., A phase on the ESC goes to A phase on the motor, B to B and C to C... ??

It seems funny that it wont start turning on its own with the sensor cable connected, but will start turning woth the sensor cable disconnected..?

[james_2k 0]

afraid its all connected correctly.

[MadInventor 3884]

Well, my statement on radio systems comes from three sources.

1) Bottom left of page 2 of this Novak GTB2 manual: http://www.teamnovak.com/download/instruct...2_basic_ins.pdf

2) Personal experience: I tried running a Novak Havoc 2S ESC with SS PRO 10.5T 4200 kV motor and a Futuba 2PH 75 MHz AM transmitter and RJ152E AM receiver, and the motor would hesitate and glitch when hitting the throttle hard from a low speed or standstill. I replaced the radio system with a Futaba 3PL 2.4 GHz FHSS transmitter and R2004GF receiver, and all the hesitation and glitching went away.

3) Anecdotal evidence on various RC forums.

That's not to say every AM system will glitch; maybe your 27 MHz receiver is able to filter out certain noise better than a 75 MHz receiver, or maybe the noise is more in the 75 MHz spectrum than the 27 MHz spectrum. Maybe your installation is clean -- motor wires braided, sensor harness away from the motor wires, receiver antenna away from the motor wires, etc. Maybe it's a brand/quality/engineering issue too. Hard to say for sure.

-Paul

Thanks for the info. I was genuinely interested about this as I have never heard of this issue before. I am using ACOMS techniplus 27MHz AM systems (can't remember which MK, the TX has 3 colured LEDs for the battery indicator). The 2 brushless systems I have used have been a ezrun 8.5t sensorless combo with their standard 60A ESC, an ezrun SC10 speedo with a 8.5t ezrun motor, and a nosram dragon sensored system (13.5T). The only issue I've seen has been with the thundershot with the SC10 combo fitted, where I get interference at about 60-70 metres and the car sometimes stutters on the steering and the speedo. The other 8.5T has been fitted in a hotshot rere, and I've had no issues at all with that other than it isn't that quick on the batteries I'm using

It will something I will definetly bear in mind for the future though.