Big Rock Bigrock 3S need your analysis on a problem

[boybianchi]

Hi guys,

First post on this forum. Hoping you can help identify a problem.
Bought a second hand Big Rock 3S.
After using it two times (beach and grass), i identify the following behaviour:

First 5 minutes everything OK.
Then: suddenly stops. No throttle. Steering OK.
ESC blinking red. Turn off and on resolves the issue but it will come back every 2 or 3 minutes after that.

My driving style and terrain is variable. Concrete, grass, dirt, woods, beach. Both low and full throttle intermittently.

I ride with a full 3s battery and did the recalibration trick for a blinking red ESC led problem.
To me it seems like overheating, but i can't figure out how it overheats after just a few minutes of runtime.

Any suggestions? Thank you!

 

[Mikeeeeeeeeeeeeeeeal]

If it's overheating that quickly, and you're positive you have a nice fresh pack in it, likely culprits are:

Geared too tall.
Bad connection somewhere in your wiring (motor and/or power)
Bad motor bearings/motor is done.
Beat/bad ESC.

Before anything I'd try a different battery to rule that out.

Also FWIW, I stay the heck out of sand, it's just not worth the hassle for me. Good luck

 

[Neelis]

Stock ESC?

 

[Tex Koder]

Is the ESC fan working/spinning when you turn it on?

 

[Mikeeeeeeeeeeeeeeeal]

Oh yeah also check for drivetrain bind. You want a nice smooth roller, not likely if it's covered in sand......

 

[RobRun]

If it's not the battery, then I would recommend pulling the power module out and checking the drivetrain for binding, like Mikeeee recommended. Roll the truck by hand. It should move smoothly. If you have sand in the gear boxes, or bearings full of sand, then it will not move smoothly. Also spin the spur gear on the bottom of the power module with your thumb. The only resistance you should feel is from the magnets within the motor, if it feels gritty, then there is probably sand in the motor bearings.

 

[boybianchi]

Stock ESC?

Yes, stock

Is the ESC fan working/spinning when you turn it on?

Yes it is.

 

[Wojoman]

If it's not the battery, then I would recommend pulling the power module out and checking the drivetrain for binding, like Mikeeee recommended. Roll the truck by hand. It should move smoothly. If you have sand in the gear boxes, or bearings full of sand, then it will not move smoothly. Also spin the spur gear on the bottom of the power module with your thumb. The only resistance you should feel is from the magnets within the motor, if it feels gritty, then there is probably sand in the motor bearings.

This. I was very surprised on the amount of bind and resistance my 3s had after a couple packs in a loose dirt/sand course! A good clean brought back to normal. Pay attention to the power module mention by Rob

When i had everything apart I cut a small hole in the chassis, like may do, right under the spur

 

[Tex Koder]

Take some pics of the power module (preferably remove from the chassis & opened up) and your ESC so we can better diagnose /help you.

 

[boybianchi]

If it's not the battery, then I would recommend pulling the power module out and checking the drivetrain for binding, like Mikeeee recommended. Roll the truck by hand. It should move smoothly. If you have sand in the gear boxes, or bearings full of sand, then it will not move smoothly. Also spin the spur gear on the bottom of the power module with your thumb. The only resistance you should feel is from the magnets within the motor, if it feels gritty, then there is probably sand in the motor bearings.

Thank you Rob, i'll do a proper check tonight and report back

Take some pics of the power module (preferably remove from the chassis & opened up) and your ESC so we can better diagnose /help you.

Will do tonight!

 

[Bustedaw11]

Sounds like lvc to me. Could be set too low.
Punch the throttle and temporally drops under the set value and throws the error. I've heard of them being set too low from the factory.
Just something to think about also

 

[boybianchi]

Sounds like lvc to me. Could be set too low.
Punch the throttle and temporally drops under the set value and throws the error. I've heard of them being set too low from the factory.
Just something to think about also

This actually makes a lot of sense, because just before it comes to a complete stop, i am able to drive at very low (but consistent!) speed. And once i turn the ESC off and on, it's back at it's original speed. How would i go about adressing this problem? I don't mind searching the forum, but what should i look for?

 

[Tex Koder]

This actually makes a lot of sense, because just before it comes to a complete stop, i am able to drive at very low (but consistent!) speed. And once i turn the ESC off and on, it's back at it's original speed. How would i go about adressing this problem? I don't mind searching the forum, but what should i look for?

ESC programmer

 

[Bustedaw11]

This actually makes a lot of sense, because just before it comes to a complete stop, i am able to drive at very low (but consistent!) speed. And once i turn the ESC off and on, it's back at it's original speed. How would i go about adressing this problem? I don't mind searching the forum, but what should i look for?

Unfortunately I don't think that value can be set on the stock esc. That low speed mode before it shuts down sounds exactly like lvc to me.
Try a reset and be sure that it is in lipo mode but I think thats all you could try.
If that isn't the issue you might be looking at a new esc and if thats the case look at jennys-rc. They'll be the best deal probably if your in the states.

Good luck man

 

[boybianchi]

Unfortunately I don't think that value can be set on the stock esc. That low speed mode before it shuts down sounds exactly like lvc to me.
Try a reset and be sure that it is in lipo mode but I think thats all you could try.
If that isn't the issue you might be looking at a new esc and if thats the case look at jennys-rc. They'll be the best deal probably if your in the states.

View attachment 333851

Good luck man

Thank you!
Yeah i already checked the settings on the ESC and they are correct.
Could buy a voltage alarm and go nimh mode but then again i bought the truck from someone and there is no way of knowing how many times he charged the 3S pack that it came with. If the battery is worn, does that increase the risk of triggering LVC? I got a new 3S Lipo on the way, i'm hoping this can buy me some more runtime. Otherwise it might be ESC swapping time.

 

[Mikeeeeeeeeeeeeeeeal]

Aight coo I'ma head out

 

[Neelis]

It seems your lipo is toast. Do you have a charger that can measure internal resistance? Those number can give a indication of the status of the battery.

For a new ESC, great options from Hobbywing are:
Ezrun max10
Quicrun WP10bl120
Quicrun 10bl120 (not waterproof)

 

[Bustedaw11]

Aight coo I'ma head out

Don't go, I hear @Bustedaw11 has no idea what he's talking about

It seems your lipo is toast. Do you have a charger that can measure internal resistance? Those number can give a indication of the status of the battery.

For a new ESC, great options from Hobbywing are:
Ezrun max10
Quicrun WP10bl120
Quicrun 10bl120 (not waterproof)

What he said

 

[Wojoman]

Yup, sounds like lvc to me too. I have a couple HW 10bl120 g2 coming in soon. But don't have first hand usage yet.

 

[Bustedaw11]

Yup, sounds like lvc to me too. I have a couple HW 10bl120 g2 coming in soon. But don't have first hand usage yet.

Thats the esc ill be getting a couple of next month also.