9920 Thermal - Cogging
 

Hey Guys,

I am running an 8XL with 9920 controller. I have had 2 or 3 thermal shutdowns and pretty bad cogging.

Do thermal shut downs happen to protect the esc or am I messing it up?

More Detail:

66 / 18 I have larger pinions on the way
12 cells
40 series tires
Stock receiver

I sure hope I didn't fry it. I will post some video soon if I can.

Thanks!

:002:

im pretty sure that a esc goes into thermal shutdown to protect it

Yes but heat can also make the electronics become badly efficent making it stutter too but if your running only on 12 cells for a 8XL it can't be to do with heat.

check gearmesh and to see if the truck rolls freely

That is what I have read here in the forums. I don't have a temp sensor, but I could not hold my finger on it for more than a couple of seconds. It also runs well for the first couple of minutes starts cogging, then it stops responding until it cools.
:020:

Seems OK.

Thanks.

Do you have a pic of how itis mounted? Have your tried other receivers? Check your wires and stuff as well. Did you try some other batteries? It should not be a heat problem with the setup unless something is not right. But If the cogging can cause heat problems as well.

I have posted some High Res pictures.
Warning - Pictures are Huge
http://www.rustyonline.net/html/rchirez.html

Thanks to everyone for the help!

the pictures are a little big but they are good quality
i would recommend getting rid of those rpm arms

I plan on replacing the RPM stuff. I just want to figure out this cogging issue first.

Thanks

try getting the receiver off of the aluminum. that could very well be your problem.

I will give it a shot.

I posted a video at the site where the pics are.

Thanks

Pictures and video posted
http://www.rustyonline.net/html/rchirez.html

I have gone through the wires and checked solder. Seems to be OK.

I have tried multiple sets of batteries.

Thanks!

Steam???
 

I believe there was steam coming out of the caps (516K0).
Is that what they do when they cook? Funny thing is that it still works???
I thought it was smoke, but it wasn't. I stopped running it and the steam stopped. Ran it again steam started to come out again.

http://www.rustyonline.net/assets/images/9920-1.jpg

Hello. I don't have any experience with BL ESC's, but I do with electronics in general and those caps look bad. See how the tops are rounded? That means the electrolyte has expanded. This can be caused by age (usually 5-10 years, sooner if they are run at very close or just over their rated voltage), running a higher voltage than they are rated, or reversing polarity. The "steam" you saw was probably electrolyte gas escaping.

Capacitors are used to either pass a certain range of frequencies, or to smooth out voltage transients for a more constant current and voltage. I don't know of their function in that circuit, but since they are where the battery wires enter, I would guess they are being used to filter out noise entering the battery wires. They are too small to provide the transient function judging by the amperages the controller will require. Either way, they are needed and that is very likely what is causing your problem.

There are two ratings for a cap: voltage and "farads" usually expressed as uF. All I can see in the picture is 516k0, but on the other side, you should see the ratings I'm talking about. Most electronics shops (RadioShack) should carry those if you feel like replacing them - just be sure they are installed correctly. The white stripe denotes the negative lead.

I had problems with my 9L in my Savage cogging badly when geared 16/49, went to a 52t spur and it got better. You might also have to roll the throttle smoother, I've had that be an issue on a few cars.

Wow, great post. Thanks for taking the time. I am learning a lot!
50v 470uf
http://www.rustyonline.net/assets/im...aprating02.jpg

The controller is only a couple of weeks old. It couldn't have more than 45 minutes run time on it and It cogged or shut down every time.

I wonder if it was bad to start, or If something else caused it. Anyway, I wouldn't want to replace the caps until I knew why it happened. I hope I can exchange it. I would hate to wait months sending it back to Germany.:020:

Thanks again for the great post!!!

Good point. If I was really gentle on the throttle I wouldn't cog as bad.

Thanks for the reply!

NP.

The caps in the first picture you posted looked like they had rounded tops (especially the upper cap), but now the latest picture above seems to show they are flat (like they are supposed to be). Do you see how the tops are sort of "preforated"? This is so if the gas expands, these areas will split and release the gas without exploding. Do these look like they have been split? I really can't tell now from the pics.

If they are rounded/split, it can't be from excessive voltage as they are rated for 50v. Age is apparently not an issue either. The controller was never attached to the batteries in reverse polarity I suppose? I would think that if that were the case, you'd have a LOT more issues than just a couple of bad caps. I dunno...

Maybe the whole issue is as simple as dabid pointed out, but I don't like the fact that you saw "steam" from the caps at one point...

I hope the solution is simple for your sake.

No REverse Polarity.

Caps don't look split, but 2nd picture had time to cool.

Simple would be nice.

Hey Mike, any ideas?

try emailing mike or sending him a pm he might not see this thread

I would try to move the receiver away from the motor some. Put it back where the atenna is. see if that helps. The steam don't sound good either.

Make sure your batteries are not shorting out on the chassis. I did this on a 7020 and swoll the caps up.

The only thing I happened to notice from the pictures is that the controller has the black BEC jumper intact, which suggests that you are using the controllers BEC. It is in fact rated for 12 cells, but the xl motors can "ask" for a lot of power, which in conjunction with the "heat" generated by the bec could be heating things up pretty badly. Despite the 12 cell rating, it is usually best to run a receiver pack or UBEC when using 8 or more cells, due to the heat generated by the excessive voltage (bec is trying to "get rid of" the extra 8 or so volts). The gearing shouldn't be too far off at all, actually. I would try a receiver pack as the first step.
As for the steam....well I don't know. If the caps vented, that could be considered very bad. If they didn't vent, then steam suggests moisture, which is also considered bad! Try a receiver pack(and remove the controller's bec jumper) and report back.

I tried a reciever pack before the "steam". Cogging and heat were about the same. I took it off replaced the jumper and video taped last night without it. What should I do next?

Look for a short somewhere? was the motor hot, or just the controller?

Just the controller. Should I hook it back up and see if vents again?

I could use a third set of batteries protected from chassis.

do any of the caps seem to be disconnected? If anything, you are undergeared, not overgeared, so the controller shouldn't be working very hard at all. Got any pictures of the controller mounted in the truck?

Yes - Here

http://www.rustyonline.net/assets/images/IMG_0319.JPG

lol, join the club of broken escs...

nothing looks bad but i cant see anything that is under all that electrical tape

Is that a bad thing? I am just trying to protect it.

i dont think that is a bad thing as long as you take the tape off every once an a while to check on the wires i actually cover some wires myself with electrical tape and so far it hasnt had any ill effects

Electrical tape gets really gummy and messy, especially when it gets hot. Unfortunately, I can't think of anything else to use that would be easily removeable short of encasing the whole thing in a box and sealing the wire entry points while providing cooling for the heatsink.

I need to get shrink wrap in a variety of sizes and practice!

Thanks again for the reply

Thanks a lot. LOL

Was yours new when it died? At least you got to crash it first. I have only done a few speed runs on pavement.

:012:

Caps seem to be connected.

I don't know if this make a difference, but I just hooked up the stock titans and esc and it ran like a champ. Motors and controllers were barely warm after a solid 15 minute session.

The good news is that the new chassis and shock position work extremely well!!!:027:

Hey bigabike is this the same problem we talking about on the other thread.

Yeah it was at the end of last month before I got the 12020. I had a lot of bind when I damaged the 9920. No bind with 12020.