2015.05.20, 06:34 AM
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#16
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Registered User
Join Date: Jul 2012
Location: NJ
Posts: 582
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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.
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2015.05.20, 08:17 AM
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#17
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Registered User
Join Date: Dec 2014
Posts: 215
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Quote:
Originally Posted by DMALMAD
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.
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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.
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Electrical Engineer
Mini-Z/RC Enthusiast
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2015.05.20, 12:13 PM
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#18
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VE7FM
Join Date: Oct 2010
Location: Langley, BC
Posts: 629
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Quote:
Originally Posted by rojak
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.
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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.
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2015.05.20, 03:04 PM
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#19
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Curmudgeon & Moderator
Join Date: Jan 2008
Location: Kannapolis, NC
Posts: 2,549
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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.
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2015.05.20, 05:59 PM
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#20
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Registered User
Join Date: Jul 2012
Location: NJ
Posts: 582
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Quote:
Originally Posted by Jshwaa
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.
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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
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2015.05.21, 09:29 AM
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#21
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Registered User
Join Date: Dec 2014
Posts: 215
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Quote:
Originally Posted by DMALMAD
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
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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...
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Electrical Engineer
Mini-Z/RC Enthusiast
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2015.05.21, 03:23 PM
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#22
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Registered User
Join Date: Mar 2012
Posts: 56
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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.
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2015.06.10, 02:48 AM
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#23
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Registered User
Join Date: Jan 2015
Location: Malaysia
Posts: 36
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Quote:
Originally Posted by JesseT
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.
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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.
__________________
MR01->MA-020VE->MR02-VE>MB010
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2015.06.10, 04:16 PM
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#24
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Registered User
Join Date: Mar 2012
Posts: 56
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Quote:
Originally Posted by rojak
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.
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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.
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2015.06.10, 07:45 PM
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#25
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Registered User
Join Date: Jan 2015
Location: Malaysia
Posts: 36
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Quote:
Originally Posted by JesseT
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.
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Yes,you are right,after I re solder the coil, the motor is okay already.
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MR01->MA-020VE->MR02-VE>MB010
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