sox45

I own a ECX Circuit truck that I use to get my dog to chase it. I use it off road and I have had a local RC shop upgrade my motor and speed control to brushless. Now I am having an issue and they have worked on it a ton trying to fix it. This is what happens. I charge up the battery NiMH 4200 and take the car out. It starts off super fast and while it's driving it stops and I have to pump the throttle to get it to start again, sometimes it's full speed, sometimes less than that. The reverse rarely works and when it does you need to try over and over again. The guy who has been working on it at the shop said it works fine for them but once I get it home it is exactly the same. I get about 10-15 minutes or run time, but I can never keep it running as it just stops often. They said they do not believe it is the speed controller or the controller itself. They seem to think it is the battery and it works when they charge it with there charger. They sold me a new charger which I needed anyway but that has not helped. Any idea what is wrong with it? I am starting to get some attitude from the guy from the shop and all I want is the car to run and not change it's own speed or stop running all the time. Thanks for reading.

Steel_Rain

iTrader: (6)

2WD or 4WD? The Circuit has been updated over the years and I remember my 4wd had "jumpers" on the ESC (speed control) that tell it if your using Lipo or NiMh batteries. Verify the jumpers are set correctly. If you have the older style or 2WD, this may not apply.

Secondly, try a lipo pack (something about 3200mah or higher with a 20c or higher discharge rate) and see if the problem continues. To be frank, it sounds like either a battery/ESC issue (these ESC's have issues btw) or the gearing is to high for the terrain your running on and it's overheating/hitting thermal shutdown.

I've only had bad experiences with these ESC's so if the lipo battery change doesn't fix the issue and its not overheating, chances are its that. The intermittent reverse seems to support that theory.

sox45

Thanks for the reply, the speed control and brushless motor are a package and brand new. The speed control has a fan that is working and nothing seems hot. My circuit is the 2 wheel drive model. I will look into if it is overheating. Odd thing is they told me they have driven the car non-stop for the battery life and it does not stop or change speeds, but every single time I do it stops and needs the trigger pumped before starting up again around 20 times in a 10-15 min period of time and I can tell when it is running full speed as it is super fast but then maybe 60% of that other times. I wish I knew what to fix or replace as I want this car to work and I have already put some more money into it.

greener74

iTrader: (12)

I agree, try a lipo, and I would suggest something at least 5000mah and over 40c Lipo and Nimh have a different discharge curve and when you load a NiMh the voltage will drop faster when it gets weak compared to a lipo. Then it will slowly start to come back up. 10-15 min on a 4200 nimh is pretty darn good. Sounds to me like the ESC is detecting a low voltage situation and when the battery recovers it starts to work again. If you plan on running NiMh only, you can turn off the low voltage protection. But make sure to turn it back on if you switch to Lipo, because that will kill a Lipo.

slick2500

iTrader: (1)

What esc?
What motor?
What gearing are you running?
Stock tires still?

sox45

I am running a brushless Kinexsis 1/10 4-pole 4000Kv motor/ESC Combo by Horizon which was just installed just before this problem started. The gearing is stock.

slick2500

iTrader: (1)

I found this review of that motor esc on the Horizon website. Seems to be having the same issues as you.

"Bought this set up first time was great. We got our money's worth but then the speed controller started doing odd things like revving up and slowing down regardless of where we held the trigger. I figured for the abuse we put it through it was normal.
then I bought the same set up a second time and right out of the box the reverse is an issue, you have the hit the reverse trigger 5, 10 sometimes more times to get it into reverse. We have many cars that get used and by far this is not the set up I would go with. Motor seems pretty decent though."

Igottabeme

I have had this same problem with other rcs. Most of the time it was the battery so just try a different battery. There were other times it was a problem with the esc transmitter throttle calibration. You need to calibrate your transmitter to the esc. This sounds like your problem. Somes escs do this automatically others you have to calibrate it yourself manually for proper operation. It sounds to me like others have said its hitting lipo cutoff. I would verify that lipo cutoff is set to non protection if using nimh. This should be in your instruction manual on how to do this. Verify throttle calibration and lipo cutoff has been done because these two things sound like your problem. Also go for a 7.4v lipo more consistent power and make sure to set lipo cutoff (I set it to at least 3.2v per cell).

WdotDynamite

iTrader: (14)

I would definitely try a lipo battery and see if that helps. It sounds like your lhs is willing to help they have to have a lipo around you could test with