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tudor_47
2014.11.14, 05:42 AM
Hi all!


i jumped on the brushless wagon and got a 10A Hobbyking ESC and teh PNracing bl motor 5500Kv V2,


i have cogging issuis, is there a fix for it?
i know that even on the kyoshos VE board there are cogging when using PNracing motors...

spektrum receiver, Hobbyking 10A ESC(XC-10A),PN 5500kv, 2cell Lipo, 10/52 gearing, chassi P28GT
Ideas?

You guys running the kyoshos VE board and motor do you experience cogging?

abasualdo
2014.11.14, 07:55 AM
I run the PN 5500 gen 1 with the VE board, runs perfect.
Think it my be the ESC?

I have tried the AMZ esc(think it's also a hobbywing) with PN 7500 gen1, also perfect.

Can you raise the starting power on that ESC? That may help.

Is the motor direct soldered to the esc or are you using connectors, if so, are the connectors making good contact?

cowboysir
2014.11.14, 10:12 AM
I'll be curious to hear the answers....I have just returned to VE's and have purchased a PN v2 5500kv.

Stupid question but how powerful are your cell packs? The limiting factor in my cogging situations is discharge....

TheSteve
2014.11.14, 11:37 AM
It is very tough to have a smooth start in an RC car with a sensorless brushless motor. Kyosho has actually done quite amazing with the VE software. I doubt the hobbyking ESC has anywhere near the software refinement.
As Cowboy mentioned though if there is a problem it is likely a lack of power from the batteries.

Rune
2014.11.14, 11:58 AM
No cogging on the VE board with PN 9500 motor if you have good batteries. It is sensitive to voltage drop.

tudor_47
2014.11.14, 02:20 PM
Thanks for all input guys!

I run Lipo so i think there is plenty of power....
I'll check connections again, they are direct soldered to the motor.

My cell is a 2 cell lipo 7,4v 300mAh with 35C discharge 70C maxdischarge,(Turnigy nano-tech)

According to the setup card (ESC) there is no limit on startup power, I can try to change that around and see if any of the settings works better.

Can there be a difference in wich cable that go on M1 at the motor?
They are on in the correct order now as the motor goes in the correct direstion but what whould happen if the cables from the ESC are in the correct order but start at the wrong place, every cable beeing in the "wrong" place. Whould this alter the 'timing' in the motor?

abasualdo
2014.11.14, 02:46 PM
Cable position does not matter, motor will just spin in the opposite direction.

In other words, if motor spins in the wrong direction, swap any of the "two" motor wires to reverse direction.

This can also be done via software on some escs, not the VE board.

gctkaz
2014.11.14, 09:11 PM
I have attempted to use that Hobbyking 10A ESC with an Atomic AMZ.

It is definitely the ESC, it just cogs really badly. The setting to adjust is the Start Power Percent. It reduces the cogging when starting from a standstill, but then it's also pretty much impossible to have any smooth acceleration as the car will just take off.

It works nicely with other small motors, but just somehow refuses to play nice with these Mini-Z brushless motors.

Jshwaa
2014.12.30, 08:49 AM
Tudor,

A good test for your cells is to put a voltmeter across them while you throttle. If you have a good meter, set up the MIN/MAX feature, because it will stop at a minimum or maximum value voltage. Throttle while voltmeter is applied, and the voltage should drop. If you are truly getting 30C discharge (21 amps for a 300mAh cell pack), then the voltage shouldn't be phased by simply throttling while unloaded(wheels off ground). If you are getting some erratic voltage dips, then this could be pointing towards bad cells.

LED
2014.12.30, 10:24 AM
Can you change the timing in the Esc? That often helps with bigger scale brushless motors. If I remember correctly reducing the timing will help with the bogging but may reduce torque a little.

yasuji
2014.12.30, 11:49 PM
I have been running the hw set up quite a bit.. 9500kv With pn batterys no cogging @ all... The ddrs start mode makes a big difference I have tested all positions and I have it set on 6 with the max timing... I think it's 8...also I run my neutral on the minimum
One thing that is very important is to set the throttle neutral and max points also the active turbo takes a little getting used to I use a throttle cushion so I can squeeze in to the turbo on the straights

Recently I have been running lithium aaa cells with great results... For that I lower the ddrs to the default... I think 5.. Every thing else the same... But I lowered to the 7500kv motor :)
BTW... The capacitor is very important!

herman
2015.01.01, 02:07 AM
Hmm... Lithium aaa cells? Do they need a special charger? Can they be used with the stock 03 board? Sorry to be off topic...

rojak
2015.05.18, 09:00 PM
Is it VE board can support 12000kV brushless motor?
Recently I upgrade my motor from 5600KV to 12000 KV,after a while run the car, then suddenly it become cogging when I full throttle. Thinking maybe the battery is weak already, i swap with fresh one,but still same.
I take out the motor and try full throttle with my tx, i fell the motor is cogging at full throttle and it becoming very hot.
Any idea?Is it I need to add more FET at my VE board?since by stock VE board got double side FET.

Jshwaa
2015.05.19, 08:16 AM
Is it VE board can support 12000kV brushless motor?
Recently I upgrade my motor from 5600KV to 12000 KV,after a while run the car, then suddenly it become cogging when I full throttle. Thinking maybe the battery is weak already, i swap with fresh one,but still same.
I take out the motor and try full throttle with my tx, i fell the motor is cogging at full throttle and it becoming very hot.
Any idea?Is it I need to add more FET at my VE board?since by stock VE board got double side FET.

You could try that. You essentially doubled the power consumption of your motor without enhancing the drive, so it stands to reason your motor is drawing so much more current that the FET's are probably dissipating.

I know the standard brushed version of the board has some overhead for FET stacking, but I'm not sure about the brushless versions. Give it a try and come back and report your findings.

JesseT
2015.05.20, 01:37 AM
The hotter motors for the VE require very good batteries, with a low internal resistance to work without cogging. This not only means that the batteries need to be of good quality, but also very recently charged and warm.

DMALMAD
2015.05.20, 06:34 AM
I would agree with Jesset, before going into incharted territory with the ve changing fets I would invest in some decent sets of batteries and a couple of good chargers and dischargers.

Jshwaa
2015.05.20, 08:17 AM
I would agree with Jesset, before going into incharted territory with the ve changing fets I would invest in some decent sets of batteries and a couple of good chargers and dischargers.

While I agree with the words of caution, I don't see how enhancing the power supply alone will solve the FET heating issue. Perhaps my suggestion should have been to purchase a higher power ESC for the higher power motor, rather than do surgery on the existing ESC. My procedure would have been to take the cells out of the equation and hook it up to a DC power supply and see if the heat issue still exists. I understand that option isn't there for most folks, so if batteries are all you have then you may have to include enhancing them as well, regardless of the FET heating issue. After all, you did double the demand of your motor, so you should double the 'fuel' too.

However, whatever you do is up to you and the decision should include your personal skill level and whatever desire you would have to find out for yourself whether or not you can get away with adding $3 worth of components to your existing, or if there are other design considerations within the brushless drives 'other than FET throughput' that are causing your heat issue. I myself haven't dissected the brushless systems to know if the KV value of the motors only include the turns of wire, or if there are programmed timing differences built into the motors that the drives have to be aware of. This could be a learning experience for me, if not for the group. Whatever you do, please share.

TheSteve
2015.05.20, 12:13 PM
Is it VE board can support 12000kV brushless motor?
Recently I upgrade my motor from 5600KV to 12000 KV,after a while run the car, then suddenly it become cogging when I full throttle. Thinking maybe the battery is weak already, i swap with fresh one,but still same.
I take out the motor and try full throttle with my tx, i fell the motor is cogging at full throttle and it becoming very hot.
Any idea?Is it I need to add more FET at my VE board?since by stock VE board got double side FET.

If the motor cogs at full throttle with no load then something is likely damaged. Either a FET or the motor itself has probably failed.

mleemor60
2015.05.20, 03:04 PM
Are you trying to pull the same gear ratio with the bigger motor? First thing i would do is go to the smallest pinion and the biggest spur and start there. With a very low gear ratio the heat load should go down. If issue goes away start adding teeth until problem comes back then back up a couple.

DMALMAD
2015.05.20, 05:59 PM
While I agree with the words of caution, I don't see how enhancing the power supply alone will solve the FET heating issue. Perhaps my suggestion should have been to purchase a higher power ESC for the higher power motor, rather than do surgery on the existing ESC. My procedure would have been to take the cells out of the equation and hook it up to a DC power supply and see if the heat issue still exists. I understand that option isn't there for most folks, so if batteries are all you have then you may have to include enhancing them as well, regardless of the FET heating issue. After all, you did double the demand of your motor, so you should double the 'fuel' too.

However, whatever you do is up to you and the decision should include your personal skill level and whatever desire you would have to find out for yourself whether or not you can get away with adding $3 worth of components to your existing, or if there are other design considerations within the brushless drives 'other than FET throughput' that are causing your heat issue. I myself haven't dissected the brushless systems to know if the KV value of the motors only include the turns of wire, or if there are programmed timing differences built into the motors that the drives have to be aware of. This could be a learning experience for me, if not for the group. Whatever you do, please share.

I think this is more of a motor issue rather then a fet issue. I have experienced ve motors overheating and breaking and the ve fets stand up to some abuse. So rather then take chances only to have to replace a 120 board I think getting a new motor ans some good batteries is a much better option. Not everyone has the skills to first know which fets would be correct for the ve (I do not even know) or the skills to put them on right without blowing the board. I have personally blown more than my fair shair of boards doing fet swaps before I became better at it and most newbs and average racers I know don't have the skill or the need to swap fets so that is usually the last recomendation I would give. Just trying to be helpful as I have made mistakes before that were pretty expensive and I would not wish those same mistakes on anyone else:rolleyes:

Jshwaa
2015.05.21, 09:29 AM
I think this is more of a motor issue rather then a fet issue. I have experienced ve motors overheating and breaking and the ve fets stand up to some abuse. So rather then take chances only to have to replace a 120 board I think getting a new motor ans some good batteries is a much better option. Not everyone has the skills to first know which fets would be correct for the ve (I do not even know) or the skills to put them on right without blowing the board. I have personally blown more than my fair shair of boards doing fet swaps before I became better at it and most newbs and average racers I know don't have the skill or the need to swap fets so that is usually the last recomendation I would give. Just trying to be helpful as I have made mistakes before that were pretty expensive and I would not wish those same mistakes on anyone else:rolleyes:

It's all good. It's better to be safe than sorry, no doubt, however it is very liberating when you can safely pull off FET jobs as easy as a 'plug and play'. The rule is to never check your work by applying power to the board. You have to check off your connections, and double-check for shorts. That is a separate discipline in itself, regardless of your skill with a soldering iron or the tools at your disposal. The videos on FET jobs don't explain this, as they wouldn't bother to show you how NOT to solder a FET, or the mistakes that are commonly made.

You wouldn't need to bother changing FETs from a performance perspective, until all of a sudden everyone else does. I think that a FET upgrade would 'possibly' allow for less heat dissipation, leaving more energy for racing, and maximizing your batteries for the long haul, as well as providing more current for less cogging when accelerating. Just a thought...

JesseT
2015.05.21, 03:23 PM
rojak,

You need to judge yourself, if the problem came directly with the 12000kv motor, or did something go wrong afterwards.
Also, do you mean with cogging, that it doesn't really start to spin properly at all, and is constantly hesitating, or is it hesitating slightly only at low speed corner exists?

If it's a constant failure, then I would check if all the three phases are working on the motor.
The FETs of the VE board pretty much accept all available motors without issues.

rojak
2015.06.10, 02:48 AM
rojak,

You need to judge yourself, if the problem came directly with the 12000kv motor, or did something go wrong afterwards.
Also, do you mean with cogging, that it doesn't really start to spin properly at all, and is constantly hesitating, or is it hesitating slightly only at low speed corner exists?

If it's a constant failure, then I would check if all the three phases are working on the motor.
The FETs of the VE board pretty much accept all available motors without issues.
Hi JesseT,
The motor start spin without problem with small throttle,but when I put full throttle,the motor start cogging. It still spinning, but hesitating and it became really hot. I change the motor to xpeed VE the red color one. No issue at all, and i think the motor itself got problem.

JesseT
2015.06.10, 04:16 PM
Hi JesseT,
The motor start spin without problem with small throttle,but when I put full throttle,the motor start cogging. It still spinning, but hesitating and it became really hot. I change the motor to xpeed VE the red color one. No issue at all, and i think the motor itself got problem.

A easy way to check a brushless motor, is to spin it with another motor, drill, dremel or something else. Then, short each phase one at a time A-B, B-C and C-A and feel if in all three cases it produces an equivalent braking effect. Better yet, use a multimeter to short it in AC current measuring mode to see if you get three equal readings. Sometimes it's the soldering of the coils that needs redoing.

rojak
2015.06.10, 07:45 PM
A easy way to check a brushless motor, is to spin it with another motor, drill, dremel or something else. Then, short each phase one at a time A-B, B-C and C-A and feel if in all three cases it produces an equivalent braking effect. Better yet, use a multimeter to short it in AC current measuring mode to see if you get three equal readings. Sometimes it's the soldering of the coils that needs redoing.

Yes,you are right,after I re solder the coil, the motor is okay already.