Car electrics glitching

[carlin]

Hi Guys,

Wonder if anyone can help me.

I little puzzled with my electrics in my car.

This is what I'm currently running
LRP SXX TC NEW
SP V3.0 6.5t or LRP x12 6.5t
Ko Propo Servo
Ko Propo Rec 302f - Ko esp III Handset
Lipo saddles Intellects

The problem i'm having is when the car reachs top end speed it's stuttering if you know what i mean like it's holding back.

This is what i have tried so far to cure it but still doing it.
Tried two different motors
Change Crystals
Different Servos
Diff Sensor wires

I'm little confused know, I'm sure it's something to do with the speedo but it's Brand New.

Anyone have any ideas what it could be

[Rocking Donkey]

I've had something similar where accelerating hard with a low turn brushless the BEC couldn't supply enough voltage to the receiver due to a voltage drop at the battery. The receiver would cut out but only for a fraction of a second, the voltage would come up again and then the receiver would come back online. This happened on the bench as well as on the track, so was easy to spot as the green light on my spectrum would go off. LiPo's seem to have cured this for me, but maybe the current draw is too high still for you?

The other thing I would suggest is throttle end points. With some advanced timing speed controls/throttle profiles full boost/timing advance is only activated if the ESC sees the full throttle signal for a certain amount of time, say 500 ms. A few people I know calibrate their esc's with throttle EPA set to 100% and then change it to 105-110% to make sure it gets there.

Only other thing that has caused this for me was a dodgy sensor, so it might be worth trying yet another?

Final thought, if it is juddering then maybe one of the 3 power phases has a problem? possibly one of the FET's is faulty?

Just a few ideas

Ben

[ashleyb4]

Try a spektrum reciever capacitor. Called a spektrum power boost or something.

A

[markwilliamson2001]

On the Ko Propo servo, is it 7.2v? If so, wire up a FET Choke to the positive battery connector on the speedo.
HTH
Mark

[Northy]

Originally Posted by ashleyb4

spoktrum

[carlin]

Hi Guys,

Thanks for all the advice just one thing I'm not running Spectrum so i wont be able to run one of these am i correct?

The servo I'm running is the 2413fet low profile, it's been fine for long time never had this problem before.

I've tried another sensor wire (new) & samething again.

I also re-set the speedo set full throttle at 100% then turned it up to 120% still same

I have noticed on the speedo when i apply the power, get to the top the yellow/red light flashes together that the car stutters on full power.
So looks like brand new god dam speedo is screwed already???
This is starting to really put me off these LRP's now, never had problems like this before

[Rich D]

Sounds like it might be cogging to me. Is the timing on the motor set to std ?

[Rich D]

I know that LRP have had issues with the sxx stockspec stuttering ( cogging ). They will update the firmware for free if you send the speedo back to them. I just got mine back with v3 software installed.

Ive not heard of the SXX TC playing up though. Might be worth a call to SMD to ask their opinion on it. LRP make quality products and stand by them. If you give them a chance to sort the problem out then im sure you will end up satisfied with the outcome

[carlin]

Originally Posted by Rich D

I know that LRP have had issues with the sxx stockspec stuttering ( cogging ). They will update the firmware for free if you send the speedo back to them. I just got mine back with v3 software installed.

Ive not heard of the SXX TC playing up though. Might be worth a call to SMD to ask their opinion on it. LRP make quality products and stand by them. If you give them a chance to sort the problem out then im sure you will end up satisfied with the outcome

Cheers Rich.

I aint knocking the LRP gear it's just fustrating that it causing these issues with new bit of kit. Yeah i heard about the new speedos having problems liuke this too.
Yeah Jamie (SMD) are good helping out i give them call when Glyn is in tomorrow.

The motors i have tried are SP 6.5t v3 new & X12 6.5t running now they are standard (out the box) not made any changes on the timing as i really dont know alot about this stuff tbh. How do i know if it's set at standard?

[Rich D]

The socket for the sensor cable in the back of the motor will be central in the slot. You could try retarding the timing to get you going temporarily until you have spoken to LRP ( move the socket towards the zero mark on the back of the motor )

if in doubt dont touch it until you have spoken to SMD

[carlin]

Originally Posted by Rich D

The socket for the sensor cable in the back of the motor will be central in the slot. You could try retarding the timing to get you going temporarily until you have spoken to LRP ( move the socket towards the zero mark on the back of the motor )

if in doubt dont touch it until you have spoken to SMD

Thanks Rich i will have look double check it

[Donutt]

I know the SXX is new, so have a look in the receiver;
check for any mud/earth around the pins for the servo lead connections.

Also check the speedo connection is good on all pins. I've removed the wires from the servo plug, and plugged them in to the receiver, individually (without power!) just to check they are a firm fit. I usually take the receiver board out of it's case to check everything is ok (and clean it at the same time!).

I've had this happen due to both a loose speedo connection, and on another occasion, due to a dirty receiver.

[DCM]

OK, it won't be cogging, and it won't be the sensor wire.

I would be inclined to look at the timing on the ESC though.

[Rich D]

Originally Posted by DCM

OK, it won't be cogging, and it won't be the sensor wire.

I would be inclined to look at the timing on the ESC though.

To expand my own knowledge can you tell me how you can be so sure it's not cogging from the symptoms given? Not saying you're incorrect in what you say but what Rob describes is exactly what my speedo was doing before I returned it.

Cheers

[DCM]

Cogging happens when the ESC can't determine the rotor position in relation to the three phases within the motor. Even if the sensor system breaks down, once the motor is turning, there is enough feedback through the motor wires to allow the ESC to determine rotor position.

If the sensor wire was broken, you would either get cogging and a low top end, or at least a low RPM.

As it is fluctuating at the top end, I would first look to see if the ESC is running in sensored only mode, and if it is, is it set to increase the timing, if the timing is to much, the esc might be 'over timing' the motor, making it fluctuate.

Hope that helps Rich?

[carlin]

Hi Guys,

Just let you all know the glitching has gone now

I dont know what caused it tbh.

I removed everything out the car checked everything one by one plugging it in & checking it all also stripped the rec too.

It seems fine no glitching or the lights flashing on the speedo.

So hopefully it wont happen again

Thanks

[Rich D]

Originally Posted by DCM

Cogging happens when the ESC can't determine the rotor position in relation to the three phases within the motor. Even if the sensor system breaks down, once the motor is turning, there is enough feedback through the motor wires to allow the ESC to determine rotor position.

If the sensor wire was broken, you would either get cogging and a low top end, or at least a low RPM.

As it is fluctuating at the top end, I would first look to see if the ESC is running in sensored only mode, and if it is, is it set to increase the timing, if the timing is to much, the esc might be 'over timing' the motor, making it fluctuate.

Hope that helps Rich?

Cheers DCM, broadened my knowledge a bit there with the detailed reply.

[Donutt]

Sounds like a loose connection after all, although it could be on the sensor wire, hence the cogging symptoms.

If it's slack, it'll occur again, so if it does, then next time, check connection in turn, and re-test. Eventually, you'll find the culprit and replace that wire/connection.

Good luck!