Weird issue, likely to be overheating?

[AC199]

The issue is as follows:

While racing, for the first few laps, the car runs normal, its fast, responsive and does its thing fine. Towards the end of the race though (5 min races) the car just stalls out (its a B44 so, not literal stalling) then will go again, and will run fine for a lap, then always goes mad, the steering works, but the motor is at full throttle and thus uncontrollable.

I've been saying for a while that I need a new Tx/Rx but I'm beginning to think it could be the esc.

Spec of the car is as follows

B44
540 Saturn (20t)
Ansmann 17t limit esc
Ansmann 3.1 Tx, and the R3.1 2.4ghz receiver.
Orion Carbon 90c 5600mah saddles.
Brand new batteries in the Tx

I suppose what I'm asking is, is this likely to be an overheating issue, or do I have a duff receiver or a duff speedo?

Thanks for any input

AC

[(off)roadrunner]

could be an overheating issue, the 90c orions are very powerful compared to the brushed motor/esc. so could be causing the problem,

i used to run the ansmann 3.1 tx/rx never had a problem with it, does sound more likely to be an esc related issue since you mentioned having steering but no response from the throttle controls.

best thing is try borrowing a different tx/rx from someone and try it that way you know which bit is at fault

[imull]

Running brushed motors with lipo can be tricky as the lipo keeps a much higher voltage for much longer. Are you experiencing a lot of comm wear? Are you rebuilding the motor every race or meeting?

I would guess that either the speedo is thermalling, although they normally shut down completely or that the motor is starting to overheat. Does the motor 'smell hot/burnt' at the end of the race?

[imull]

DOH, just looked the motor up and it's sealed :blush:

The smell bit still applies as does the overheating, you just won't be able to tell how much the comm is burning up. Does the motor arc/spark a lot? If you flush it with motor cleaner does a lot of crud come out?

[sosidge]

If the motor smells hot and is hot to the touch (unable to hold a finger for more than a couple of seconds, or more scientifically in excess of 75-80C), then you are working it too hard and likely need to gear down (smaller pinion or larger spur).

That would be my first step in resolving your problem.

4wd buggies put a lot of load on the motors, a load that may be beyond what a Saturn 20 can deal with. They are great motors in the right application, I use them all the time in my Tamiya Mini, but that is a front wheel drive car that weight 1300gm and never (intentionally) jumps!

[AC199]

I havent noticed a smell at the end of a race, will flush and check tonight.

Weird thing is, only difference between mine and a friends car, is the speedo and receiver. He's running a MRT, and a spektrum radio/receiver.

I think I'm going to replace the tx and rx this week, and if that doesnt cure the issue, I'll bang a QC3 in and see how that goes.

Only had the issue since I replaced the servo from an old futaba to a new savox, so the thinking is that something is either overheating, or overloading.

AC

[AC199]

If the motor smells hot and is hot to the touch (unable to hold a finger for more than a couple of seconds, or more scientifically in excess of 75-80C), then you are working it too hard and likely need to gear down (smaller pinion or larger spur).

That would be my first step in resolving your problem.

4wd buggies put a lot of load on the motors, a load that may be beyond what a Saturn 20 can deal with. They are great motors in the right application, I use them all the time in my Tamiya Mini, but that is a front wheel drive car that weight 1300gm and never (intentionally) jumps!

Sorry fella, you posted while I was eating, so didnt reply in my post above.

I understand what you're saying, but this is the motor that all of the guys use, it doesnt get that hot, certainly not over 60 degrees and at YORCC the 540 class has been running for ages, I doubt I'm putting the motor under more load than the rest of the guys.

Will have a check and see though, thanks for your input.

AC

[DCM]

I would replace your speed controller, the Ansmann units are made by mTroniks, and the budget ones aren't the best out there to be fare.... see if you can borrow a speed controller to run with your motor, radio and battery to see if it still happens.

[AC199]

Thanks for the input DCM, I think I'm just going to say balls to it, and replace the whole shebang. New Speedo, New TX and RX and just take it from there.

The ansmann one was what came in my mad rat, I had a QC2 which blew up on me, so just bunged this in, in the hope that It'd do the job, which it would appear that it isnt.

I'll replace the lot and take it from there.

AC

[sosidge]

Thanks for the input DCM, I think I'm just going to say balls to it, and replace the whole shebang. New Speedo, New TX and RX and just take it from there.

The ansmann one was what came in my mad rat, I had a QC2 which blew up on me, so just bunged this in, in the hope that It'd do the job, which it would appear that it isnt.

I'll replace the lot and take it from there.

AC

DCM is right - Mtroniks-manufactured ESCs are pure junk.

Start by running that QC3 you have, your other electrics may well be fine.

[imull]

Interesting that you say that the problems have arisen since changing the servo, I wonder if the BEC is getting overworked by the new servo drawing more current and the BEC is overheating by the end of the race?

Which Savox servo is it, one of the metal geared coreless ones?

As Sosidge says, use the QC3. The BEC on that will cope with the new servo.

[AC199]

Its the digital gearless 10kg torque one. Nice servo, but having read a little on the net, I think you're right and the ESC cant handle the draw.

QC3 ordered, be here tomorrow. Testing this weekend.

Thanks for your input everyone, thats why Opple is awesome!

AC

[imull]

Cool, update the thread after testing and let us know how you got on!

Excellent avatar BTW :thumbsup:

[AC199]

Cool, update the thread after testing and let us know how you got on!

Excellent avatar BTW :thumbsup:

Will do, if i can help anyone avoid this, I will.

(Half) Kiwi and proud old son, GO BLACK!

[CrashBangWallop]

What's happening is - your new servo is draining too much current from the receiver ( its a modern high power servo ) and dropping out the speed controller ( the BEC circuit will be typically only be able to supply 1 amp ) and resetting it while you are under load from the motor and steering at the same time which is why its having spasms.
Simple and cheap solution ( less than 3 quid ), install a power capacitor in the spare plug slot on your receiver if you have one. Maplins do a 16Volt 4700 microfarad electrolytic capacitor that will do the job and you need a spare servo lead and 10 mins of time to sort it out.
This will help to stop the servo draining too much current through the receiver and dropping your gear out.

Try this first before replacing all your gear - its cheap and might just work.

[mpg200]

Only just read this, may be a bit late

Have a look at this

http://www.oople.com/forums/showthread.php?t=85656

I do go off on a bit of a techy rant but hopfully it makes sense, anyway I have a power cap you could try on saturday, but i suspect it is just a rubbish speedo. Still cant hurt to try

come see me saturday and we'll se what we can do

[AC199]

My QC3 is here and am currently installing it, we'll see how that works. Thanks for the offer old bean, I'll keep it in mind.

AC

[AC199]

OKay, update after running/testing.

QC3 install went okay, I mean, it looks like its been soldered by a blind welder, but it does the trick..

First heat, went out, raced hard and just as I was parking up, the car did its stalling thing. Not impressed, had a bit of a paddy, threaten to kill the car, thought seriously about stamping on the thing, then went to see Mr Mpg200. Unfortunatley, he was just off out for his heat, so second heat basically went through the motions, drove round a little, put in 1 very fast lap, and then parked it for 2 laps to let everything chill.

After Mr Mpg had done his next heat, got the cap off him and installed it. Had a conversation with someone about how electronics might as well be a foreign language to me, and then charged me lipos and got ready for the next heat. Pushed hard in that heat, right up to the finsh, no issues at all. FINALLY! Seems that a lot of things are contributing to this issue, but I think the 2 major ones are the servo max travel being set just a smidge too long, the receiver being of the budget end of things, and the fact that I'm a twitcher on the steering.

Bottom line, power cap seems to have cured the issue finally, not entirely convinced the ESC was required in the end, but its better than what I had, and leaves me with a spare esc which with the power cap would work peachy I'm sure.

Huge massive mega thanks to Matt for loaning me the cap, you sir are a scholar and a gentleman, and lets hope this bring massive amounts of trouble free racing from now on...

AC