Kronos ESC Random Resets

[Stormwind]

So I've just got back from a very frustrating bash session due to a misbehaving ESC which has been occurring now for the last 2 sessions.

Essentially the Torox keeps resetting itself.
This mostly happens if I stop completely, no inputs on the transmitter at all.
I then pump all the controls and eventually it'll do it's cell count beeps and (possibly) I can continue.
There are times where it is literally sat there for minutes stuck in a reset loop whilst I desperately trying to get it moving with no success.
Sometimes it fails completely and I have to do a hard reset by pulling the battery and replugging it to get it to shift.

Whilst it mostly occurs whilst stationery, it has also happened once or twice whilst the car is moving. The ESC has cut out so I lose drive completely but I still have full control over the servo.

This happens right off the bat and all the way through the entire session so I know for a fact that it's not thermal cut-off; since it happens very regularly, I cannot run long enough continuously to get the motor/ESC hot at all.....
I'm fairly sure it's not battery related since I have tried multiple batteries and they all exhibit the same behaviour.

I've tried diagnosing this issue with the body off to watch the status LEDs on the ESC. When this behaviour occurs, the red light comes on followed by the green flashes counting the cells in the lipo.
I dunno if it is related or not but my power button also doesn't seem to work for the most part. I have to rely on pulling the plug to stop the ESC.
I have also checked over the cables and everything looks as it should. I was potentially thinking that it was a radio issue and the ESC was going into fail-safe? However, I am never far enough away to trigger a range issue and the aerial is correctly positioned and looks fine along with it's cables. I thought that potentially water may have gotten into the radio box. I have just had that off and there is a tiny amount of water as suspected but only a micro puddle in the bottom of the tray, nothing around the terminals so I doubt that is the issue.

I'm a bit stumped as to what to try next? Perhaps a factory reset on the ESC and go through the re-binding procedure to ensure that all the endpoints are correct perhaps?

 

[Jeffwazz]

Sounds like a duff power switch if it's also a problem to turn it off.
Do you have a spare switch from anything else to try?

 

[Stormwind]

Sounds like a duff power switch if it's also a problem to turn it off.
Do you have a spare switch from anything else to try?

I've got nothing to rob a power switch from unfortunately.
Is that something that can be replaced easily? When I had my Torox off last I thought that the power switch was soldered in to ESC itself? I can't seem to find just a replacement switch after a quick search so in theory it would be a case of snip the switch off an old ESC (if I had one) and then do the same with the Torox and solder on the new one?


I did just come across this old thread and it seems to match my symptoms. The suggestion of the ESC being wet may hold some truth here since I think the ground was very wet when it first starting showing this symptom and the next session was only the next day after it had been power washed and stuck back in the shed (I know that I should dry it properly....).
I have moved it inside next to the radiator at the minute to ensure that any leftover water is all dried up.
I'll be asking for a pet or car dryer for Christmas I think.

 

[Jeffwazz]

Some switches are easy - just unplug and swap.
Others have the switch wires under the epoxy potting, so simply cut and solder a new switch mid way down the wires.
This video

suggests a way to eliminate the switch completely.

Off course, if it has got water inside, a good squirt with GT85 or WD40 might just sort it out, and isn't as drastic as cutting wires!

 

[Klappars]

It sounds to me like the power switch is at fault, especially since you mentioned it doesn't work properly. It may be intermittently contacting the program button, making thee ESC enter programming mode, in which case the car wouldn't run.

I would also take the receiver out of the box and thoroughly dry it with an air blower, or hair dryer if you haven't got one.

The switch is a Hobbywing MAX8 part, which is soldered onto the ESC but could be replaced if you were able to cut the wires and solder a new switch onto the original switch wires coming from the ESC.

 

[Stormwind]

I have had my rig sat inside for the past week next to the radiator so am confident that everything is all dry.
I have tried plugging in again and found that the issue is still there, the ESC is booting straight away without usage of the power button which confirms to me that the power button is the issue.
I believe that this is a direct replacement part?

 

[Klappars]

I have had my rig sat inside for the past week next to the radiator so am confident that everything is all dry.
I have tried plugging in again and found that the issue is still there, the ESC is booting straight away without usage of the power button which confirms to me that the power button is the issue.
I believe that this is a direct replacement part?

That’s the correct part.

 

[Stormwind]

I have just replaced the switch with the part above and managed to get that all hooked up and working. During a quick shake-down in the front garden, I was able to switch the rig on and off with no issues without having to resort to touching the battery.
However, during that short test, I still experienced the issue mentioned above, the motor not receiving any drive at various times until the ESC decides to reset itself.

Again, this mostly occurred during braking or under no-throttle scenarios whilst attempting to turn around under coast. This issue happened around 4-5 times during a 5 minute (light) session in the front garden so cannot be thermal cut-out as the ESC was still cool to the touch.

I have factory reset the ESC and reset the endpoints in case either of those might be the cause. The only thing I can really think of is this might have started happening not long after I installed a new servo (an AGF 40KG). Could it be that the servo is drawing too much power and affecting motor output? That seems unlikely but I'm running out of things to think of here.

Perhaps it's looking like the ESC is on it's way out? The rig was gifted to me for Christmas 2022 so is less than a year old. Perhaps I should chat with Corally support about it?

 

[Jeffwazz]

Do you know the current requirements of the servo vs. the ESC BEC delivery maximum?
Back in the day™ Speccy stuff suffered from 'brown-outs' under high current draws, and a solution was to add a cap pack to smooth the current requirements.
Not Spectrum, but I had a duff steering servo (probable short, got hot when turning one way only), which would cause the ESC to reset (bleeps when back to neutral etc), and the fan would also slow down down noticably.

 

[Stormwind]

Hmm, can't seem to find anything related to the current draw of the servo (this is the exact one).
I'm fairly sure that the ESC fan is not slowing down in any way during this period.

Whilst attempting to test this theory of the servo causing this, I changed the ESC setting to bump up the BEC voltage from 6v to the high setting of 7.4v. No difference there either.

Unfortunately I don't have a spare servo to swap in temporarily to test that theory either.

 

[Jeffwazz]

Hmmmm, definitely worth a chat with TC support to see what they recommend.

The servo spec sheet suggests 4,6A peak draw.

The ESC bec will have to supply that along with the fan and the Rx.

 

[Stormwind]

Out of interest, how did you find that spec table?
I'd be interested to compare that to the current draw of the stock servo.

I've also just realised that I'm now slightly reluctant to talk to Corally since I have now technically modified the ESC by replacing the switch

 

[Jeffwazz]

Just on Google https://www.agf-rc.com/agfrc-a80bhmw-high-torque-programmable-servo-p2171404.html

Hopefully that's pasted in ok.
As it's a brushless servo motor, it might have a high inrush current, which might just drop the bec voltage.
I'd still talk to corally though, if nothing else you'll get a professional appraisal of your soldering skills

 

[Stormwind]

Just on Google https://www.agf-rc.com/agfrc-a80bhmw-high-torque-programmable-servo-p2171404.html

Hopefully that's pasted in ok.
As it's a brushless servo motor, it might have a high inrush current, which might just drop the bec voltage.
I'd still talk to corally though, if nothing else you'll get a professional appraisal of your soldering skills

Haha, I don't need a professional telling me they are crap. I know that myself
The only thing I have soldered on this rig is the new switch. Otherwise, it'd probably have many more issues than it currently has like my drone

 

[Klappars]

I have just replaced the switch with the part above and managed to get that all hooked up and working. During a quick shake-down in the front garden, I was able to switch the rig on and off with no issues without having to resort to touching the battery.
However, during that short test, I still experienced the issue mentioned above, the motor not receiving any drive at various times until the ESC decides to reset itself.

Again, this mostly occurred during braking or under no-throttle scenarios whilst attempting to turn around under coast. This issue happened around 4-5 times during a 5 minute (light) session in the front garden so cannot be thermal cut-out as the ESC was still cool to the touch.

I have factory reset the ESC and reset the endpoints in case either of those might be the cause. The only thing I can really think of is this might have started happening not long after I installed a new servo (an AGF 40KG). Could it be that the servo is drawing too much power and affecting motor output? That seems unlikely but I'm running out of things to think of here.

Perhaps it's looking like the ESC is on it's way out? The rig was gifted to me for Christmas 2022 so is less than a year old. Perhaps I should chat with Corally support about it?

It could be the current draw of the servo, if its this model:
https://www.agf-rc.com/servo-a80bhm-p2474391.html

The current peak at 7.4v is 4.3 amps, which is quite a lot. Do you have any other accessories running on the car like a cooling fan?

 

[Stormwind]

It could be the current draw of the servo, if its this model:
https://www.agf-rc.com/servo-a80bhm-p2474391.html

The current peak at 7.4v is 4.3 amps, which is quite a lot. Do you have any other accessories running on the car like a cooling fan?

I think it's the waterproof version of that model so likely to be exactly the same current draw.
I've got no further electronics running on the circuit and the stock motor, ESC and receiver.
When I was choosing a new servo I didn't even look at current draw

What is the best way to move forward here? Buy a cheap servo with low current draw (I could buy yet another stock servo but I've already killed two of those within 9-10 months) to see if the issue goes away? Is there some other way of bypassing the BEC on another circuit or something? I'd hate to feel like spending £90 on a decent servo was a complete waste

EDIT: Looks like this would do the trick actually for not a lot of money.
If I understand the description correctly, I can plug the servo into that and then power it off a separate 2S Lipo.
I mean it's a bit of a pain having two batteries but it certainly beats throwing £150+ on a replacement ESC or kicking the damn thing from frustration due to it crapping out on me.

 

[Klappars]

I think it's the waterproof version of that model so likely to be exactly the same current draw.
I've got no further electronics running on the circuit and the stock motor, ESC and receiver.
When I was choosing a new servo I didn't even look at current draw

What is the best way to move forward here? Buy a cheap servo with low current draw (I could buy yet another stock servo but I've already killed two of those within 9-10 months) to see if the issue goes away? Is there some other way of bypassing the BEC on another circuit or something? I'd hate to feel like spending £90 on a decent servo was a complete waste

EDIT: Looks like this would do the trick actually for not a lot of money.
If I understand the description correctly, I can plug the servo into that and then power it off a separate 2S Lipo.
I mean it's a bit of a pain having two batteries but it certainly beats throwing £150+ on a replacement ESC or kicking the damn thing from frustration due to it crapping out on me.

That cable would allow you to run the servo off a 2S Lipo or an external BEC like the one that Castle offer.

My suggestion here would be to buy a cheap servo, even a used one with lower specs than your AGF one, you don't need 40kg of torque!

You could then run that servo in the truck and see if it fixes your issue, if it does, then sell the AGF servo and buy another good servo but don't go any higher than about 28-30kg of torque to keep the power draw reasonable.

 

[Jeffwazz]

An external SBEC could be a solution. Something like this https://hobbyking.com/en_us/yep-20a-hv-2-12s-sbec-w-selectable-voltage-output.html?___store=en_us
to plug into the Rx would power the servo easily, straight from the main lipo.
The +ve power feed from the ESC back to the Rx will need to be cut/removed from the plug, leaving just the -ve and signal.
The SBECs tend to be quite electrically noisy, so stick it as far from the Rx as possible.
Or try a "brown out" cap pack to plug into a spare Rx port to provide a bit of a voltage buffer for the ESCs built-in BEC. As you're handy with a soldering iron, easy to make from scavenged bits.

Something like this - picture shamelessly stolen from eBay

 

[Horatio]

My concern is that the servo isn't the problem. I run a AGFRC 810BHMW on my Torox ESC, with dual fans, no worries.

Perhaps run the servo at a lower voltage and give that a go.

Is there a cap pack on your battery connection into the ESC?

If the ESC keeps on resetting, send it away for service - and buy a new one.

When it comes back fixed - you have an excuse to get a new rig to put it in!

 

[Stormwind]

My concern is that the servo isn't the problem. I run a AGFRC 810BHMW on my Torox ESC, with dual fans, no worries.

Perhaps run the servo at a lower voltage and give that a go.

Is there a cap pack on your battery connection into the ESC?

If the ESC keeps on resetting, send it away for service - and buy a new one.

When it comes back fixed - you have an excuse to get a new rig to put it in!

I was running the servo at 6v to start with when I first noticed this issue and then reprogrammed the ESC to output 7.4v to see if it made a difference which it didn't see too. I can't get any lower than that without some form of extra resistance in the circuit.

As for a cap pack on the battery, I have nothing external but I believe there is a big one built-in on the RTR models? It certainly looks like one.

I also found yesterday that the Torox's built-in BEC is rated up to 6A which I'd have thought would be more than enough to handle the 4.3A peak current draw from the servo.

I think it's likely that I'll email Corally to see what they say although I will have voided the warranty by replacing the switch
In the meantime, I might just source one of those externally battery cables for a couple of quid and then try it with a small 2S that I have kicking around.