RCCrawler Forums

bruteforce · 09-12-2009, 05:55 PM

Hi again everyone. I just got a used Rooster 12t esc but it didn't come with the cap. I put it in anyway just to get a feel for the difference and I absolutely loved it. Then I started worrying about the cap and installed one. The novak replacement part is a 680 mf, 16v. I found a 1000mf, 16v in an old computer psu and put it on. Now i don't like the esc. It is alot faster but I lost the super slow, smooth power delivery. Not to mention that the cap gets damn hot. I am using the stock Axial 27t motor.

Now, will a 55t or 45t motor get that smooth control back for me with this setup? How long would I expect this esc to last without a cap? It doesn't get any warmer than the stock axial esc and doesn't glitch without a cap. And are there any caps built into the axial motor at all? I don't see any on the outside.

Thanks in advance

bruteforce · 09-13-2009, 06:55 PM

Nobody has any info? Ok, well, I pulled the cap off and it will be my test subject. I will see how long the esc will last without it.

YJ_Driver · 09-14-2009, 12:14 PM

The cap should definitely not get hot. From the symptoms I would guess that you connected it at the wrong place like the motor output, or wrong polarity.

There is another possibility, that the ESC requires a low ESR (equivalent series resistance) cap and the one from the computer is high ESR. The higher ESR plus the extra current needed to fill the higher capacitance would cause more heat. You might want to just order a Novak cap.

Oh, and those caps should be labeled 680 uF and 1000 uF, 1000 mF (or 1 Farad) @ 16 V would be bigger than your ESC

Richard

Greatscott · 09-14-2009, 05:13 PM

The caps should only get as hot as the motor, not any hotter.

bruteforce · 09-14-2009, 05:46 PM

Thanks for the info. I wrote "mf" cause I didn't have the little squiggly looking "u" on my keyboard, sorry for the confusion. As for the low vs high esr values, I tried looking up some info on this, but I couldn't find anything too informative on how to know. How would you tell? I thought the ceramics where high and the standard aluminum plate canister type where low...

YJ_Driver · 09-14-2009, 06:47 PM

ESR varies even in the same type of capacitor, electrolytic in this case, so you have to track down the exact manufacturer part number or series and read the datasheet to find out all the nitty gritty details. In the case of the Rooster it's a Samxon GC series:
http://www.manyue.com/?pg=products&bd=SAMXON&SearchEnter=1&CategoryID=1&TypeID=&Series=GC&Temperature=&Voltage=4~50&Capacity=100~2200&LoadLife=

The datasheet states it has low impedance or ESR. This doesn't mean this is the cause of your problems, just a possibility.

Richard

bruteforce · 09-16-2009, 06:04 PM

Thanks for the info guys, I swapped it out with another cap and it seems to be doing fine. I really appreciate the responses.

09-12-2009, 05:55 PM	#1
bruteforce Newbie Join Date: Sep 2009 Location: Scappoose Posts: 32	Capacitor or die? Hi again everyone. I just got a used Rooster 12t esc but it didn't come with the cap. I put it in anyway just to get a feel for the difference and I absolutely loved it. Then I started worrying about the cap and installed one. The novak replacement part is a 680 mf, 16v. I found a 1000mf, 16v in an old computer psu and put it on. Now i don't like the esc. It is alot faster but I lost the super slow, smooth power delivery. Not to mention that the cap gets damn hot. I am using the stock Axial 27t motor. Now, will a 55t or 45t motor get that smooth control back for me with this setup? How long would I expect this esc to last without a cap? It doesn't get any warmer than the stock axial esc and doesn't glitch without a cap. And are there any caps built into the axial motor at all? I don't see any on the outside. Thanks in advance

09-14-2009, 12:14 PM	#3
YJ_Driver Quarry Creeper Join Date: Apr 2009 Location: Ottawa, ON, Canada Posts: 251	The cap should definitely not get hot. From the symptoms I would guess that you connected it at the wrong place like the motor output, or wrong polarity. There is another possibility, that the ESC requires a low ESR (equivalent series resistance) cap and the one from the computer is high ESR. The higher ESR plus the extra current needed to fill the higher capacitance would cause more heat. You might want to just order a Novak cap. Oh, and those caps should be labeled 680 uF and 1000 uF, 1000 mF (or 1 Farad) @ 16 V would be bigger than your ESC Richard Last edited by YJ_Driver; 09-14-2009 at 12:17 PM.

09-13-2009, 06:55 PM	#2
bruteforce Newbie Join Date: Sep 2009 Location: Scappoose Posts: 32	Nobody has any info? Ok, well, I pulled the cap off and it will be my test subject. I will see how long the esc will last without it.

09-14-2009, 05:13 PM	#4
Greatscott I wanna be Dave Join Date: Jul 2005 Location: North Idaho Posts: 3,648	The caps should only get as hot as the motor, not any hotter.

09-14-2009, 05:46 PM	#5
bruteforce Newbie Join Date: Sep 2009 Location: Scappoose Posts: 32	Thanks for the info. I wrote "mf" cause I didn't have the little squiggly looking "u" on my keyboard, sorry for the confusion. As for the low vs high esr values, I tried looking up some info on this, but I couldn't find anything too informative on how to know. How would you tell? I thought the ceramics where high and the standard aluminum plate canister type where low...

09-14-2009, 06:47 PM	#6
YJ_Driver Quarry Creeper Join Date: Apr 2009 Location: Ottawa, ON, Canada Posts: 251	ESR varies even in the same type of capacitor, electrolytic in this case, so you have to track down the exact manufacturer part number or series and read the datasheet to find out all the nitty gritty details. In the case of the Rooster it's a Samxon GC series: http://www.manyue.com/?pg=products&bd=SAMXON&SearchEnter=1&CategoryID=1&TypeID=&Series=GC&Temperature=&Voltage=4~50&Capacity=100~2200&LoadLife= The datasheet states it has low impedance or ESR. This doesn't mean this is the cause of your problems, just a possibility. Richard

09-16-2009, 06:04 PM	#7
bruteforce Newbie Join Date: Sep 2009 Location: Scappoose Posts: 32	Thanks for the info guys, I swapped it out with another cap and it seems to be doing fine. I really appreciate the responses.

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