Runaway Crawler

Funny... I couldn't figure out what's wrong with my new rig this morning when it ran away.. then as I gave up the trails and headed back to the main road for a short roadside recovery, I plug all the electronics back on again and tested it. Climb up the first slope and everything was well.. so I thought maybe I could catch up with you guys.
Reached the 2nd uphill and then halfway the electronics went mad again.
I finally decided to stop in case it ran off and crashed badly because I have no other rigs infront to stop it ( hahaha.. sorry for all the bumper crushing today guys )..
Then I was back again to the roadside recovery location, at that moment as I held my rig in my hand, the electronics went berserk again. This time, I really noticed something.. my receiver LED light went OFF.. indicating no power ( or something like that ).
Funnily I headed home and a while ago I decided to wire up everything again, repositioning my receiver, ESC and light unit slightly apart.
NOthing Happens. .. as in everything is A-OK !
I ran the rig around, jam brake all the wheels and give it a half throttle to load the motor and ESC, etc.. ran full speed forward and backward.. damn... no failure at all.

Then I switched off my transmitter.. the motor did not went full speed. There was a fail safe built in. The motor just stopped.

Now the question which really puzzled me... what really could had happened?

A few of you guys suspected it was Lipo voltage too high, but I ran Tamiya ESC with the same brand receiver on all my other onroad car, drift car and Tundra... never had this problem.

Wah lao... headache..

Just buy one more new truck lah

haha dont think it the lipo making the problem it just that the truck is to shy to meet ppl must bring it out more

Dieselx wrote:
A few of you guys suspected it was Lipo voltage too high, but I ran Tamiya ESC with the same brand receiver on all my other onroad car, drift car and Tundra... never had this problem.

It is a pity that you couldn't join us yesterday due to the electronics troubles.

Tamiya ESC: there's your problem! The Tamlya ESCs (like the TEU-104BK) are designed for old analog 27 MHz receivers that tolerate high voltages. Your modern 2.4 GHz system (ACE RC if I remember correctly) can only operate until 6V max.
The Tamiya ESC outputs the full battery voltage unregulated to your receiver -- which is 7.4V and more with a 2S Lipo. Way out of the spec for your receiver!

You said "it was working fine in other cars". Well, that's the thing with running electronics out of spec: It works fine -- until it doesn't like yesterday!

To solve your issue you will either need to replace the ESC with one that has a regulated 5V/6V output for your receiver (and servo!), or buy what is called a UBEC -- a small regulator that regulates your Lipo battery down to the save 5V/6V for your receiver.

Something like this:
http://www.jethobby.com.sg/cgi-bin/ezsite/prod/manager.cgi?action=show&pid=730&cid=42&idx=1&gid=23
(you might be able to find it cheaper in on-line stores )

The replacement ESC will be easier to wire up, the UBEC will require splicing of the cable that comes from the Tamiya ESC to the receiver, and needs to be hooked up to the Lipo too.
Like shown on this site: http://www.wattflyer.com/forums/showpost.php?s=82d28efefcbb22aff3f7bd48add36d67&p=476733&postcount=2


hope it helps, Werner

Hi Werner, understand your explanation. Thanks.

But I am just curious why it was OK with my other cars leh.. cuz I had 3 of these same receiver sharing around with 6 RC cars. 5 of the 6 cars are using Tamiya and I anyhow swap batteries to run on those cars, from Nicad, NiMH to Lipos... never had this funny run away issue..

This Receiver was taken out from one of my onroad car... I mean, dont doubt the possiblities that the over voltage is not causing the problem.. but I think I probably should just try out with the UBEC then..

But I think Liew's solution wont work... whahahaha...

No work ?
I wait to see when u buy another trail truck
Buy buy buy

Yo Man

How about test it with other set of electronic??

Maybe something some where shorted?

like the wire surface was cut???

i think is the Tamiya ESC...

i have issues with the Tamiya ESC.... when ever my servo draws high current, the ESC will go full throttle like your wrangler...

i'm running a 5A BEC and this doesn't solve the problem, neither did powering the servo direct from a Y-jumper out from my lipo...

the ESC runs ok when i put it in my df03ra....

i would say the BEC is rather sensitive to voltage fluctuations... although i tried adding a stabilizing capacitor, it still doesn't solve the issue...

well, but coldman and slow runs a few tamiya ESCs without issues.... maybe i got a faulty one...

My RC is Ok to used Tamiya 104ESC,.. ..

yup mine on the Wrangler is tamiya 104..
anyway i did bought a UBEC and hook up my receiver from the UBEC's 6V supply now.
but.. so far.. really.. nothing screw up with or without UBEC..so I really dont know and will give it a try again next trail...
hopefully didnt wasted my trip and $18 for the UBEC..

Come come. Try it on the coming trail.