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Thread: Hot wires, get your hot wires....

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Old 04-21-2019, 08:14 AM   #1
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Default Hot wires, get your hot wires....

Sorta complex wiring below, please stick with me. If you are familiar with BECs and receiver by-pass wiring, I could use your help. I don't really want to have to explain the by-pass wiring if I don't have to - it's all hooked up as it should be and works.

The problem - A SMOKIN HOT WIRE!

Immediately before I switched to the HW 1080 and Holmes motor below, this exact setup was performing 100% flawlessly with a mamba micro X and Castle 1406 2850kV combo. All I switched was the ESC motor combo.

The setup:
- HobbyWing Quickrun 1080 ESC -- new
- Holmes Crawl Master Pro 540 13t
- Castle 10A BEC
- Holmes RX bypass adapter - this https://holmeshobbies.com/electronic...s-adapter.html
- Protek servo
- Spektrum SRS6000 RX
- two Dimension Engineering PicoSwitch relays - https://www.dimensionengineering.com...cts/picoswitch

The relays and BEC get power and ground from an adapter that inserts between the battery and ESC plug. One relay controls an axial light controller, the other a light bar and two 5mm LED rock lights. They are switched on and off with the transmitter. It's kind of cool.

So I switched to the HW 1080 and Holmes motor, motor on the bench, not even connected to the trans, plugged everything in to check it, the motor kind of spontaneously, erratically ran on it's own for a second or few, and there was a tiny puff of smoke from around where the ESC RX wires go in. It was tiny and quick, I didn't see exactly where it came from. Noticed a bit later that the insulation on the ground wire of the 3 wires from the ESC to the RX was pretty significantly melted.

After all this, I put it all back to the Castle setup and the rig again runs flawlessly.

I then connected up the HW 1080 to a new Spektrum SR515 RX, a Savox servo, very little use, same battery, same CrawlMaster Pro motor and, at least on a bench, it works flawlessly. So hopefully the smoke was the wire and there is no internal damage on the HW1080 ESC. Still questioning if I risk it in a rig. Maybe a rig with no body.....and a fire extinguisher near by.....

So I figure the issue is somehow with the BEC and RX bypass, or possibly the relays, since that is really all that's different, but I can't figure out how it's an issue with the HW1080/CrawlMaster motor combo, but not with the Castle brushless combo. The HW 1080 is not happy with something about the wiring, is my guess.

Any ideas?
Thx.
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Old 04-21-2019, 08:18 AM   #2
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Default Re: Hot wires, get your hot wires....

I would suspect a sticking relay.


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Old 04-21-2019, 10:46 PM   #3
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Default Re: Hot wires, get your hot wires....

pico swich:
Max relay voltage: 60VDC, 125VAC
Max relay current: 1A @ 24VDC, 0.5A @ 125VAC (60W lightbulb)
Relay resistance: 100 mΩ max
3.5V to 5.5V operating voltage (on servo pigtail)
30mA typical draw from receiver

5.5V? 30mA max, you're probably exceeding that since they are some low requirements, but I don't know why the issue would be at the ESC if this was the cause, and changing the esc, probably wouldn't have fixed it.
Is it possible a bit of solder or a stray wire shorted out a terminal and burned off?

Edit: perhaps the problem is because of the low voltage requirements, the switch does something strange because you use higher voltage to control it. The bec in the 1080 might not have been able to cope with the strangeness, but the mamba x bec may handle it better. are both of these esc's switching bec's? So the problem may still be there, only now its being managed better, could only be a matter of time and it could happen again or be putting extra strain on the esc now. Completely guessing.

Last edited by Voodoobrew; 04-22-2019 at 12:49 AM. Reason: Grammer
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Old 04-22-2019, 08:17 AM   #4
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Default Re: Hot wires, get your hot wires....

Quote:
Originally Posted by Voodoobrew View Post
pico swich:
Max relay voltage: 60VDC, 125VAC
Max relay current: 1A @ 24VDC, 0.5A @ 125VAC (60W lightbulb)
Relay resistance: 100 mΩ max
3.5V to 5.5V operating voltage (on servo pigtail)
30mA typical draw from receiver

5.5V? 30mA max, you're probably exceeding that since they are some low requirements, but I don't know why the issue would be at the ESC if this was the cause, and changing the esc, probably wouldn't have fixed it.
Is it possible a bit of solder or a stray wire shorted out a terminal and burned off?

Edit: perhaps the problem is because of the low voltage requirements, the switch does something strange because you use higher voltage to control it. The bec in the 1080 might not have been able to cope with the strangeness, but the mamba x bec may handle it better. are both of these esc's switching bec's? So the problem may still be there, only now its being managed better, could only be a matter of time and it could happen again or be putting extra strain on the esc now. Completely guessing.
I do not know if either or both are switching BECs. I looked carefully for any signs of a short, didn't see any.

I don't know if the relays have anything to do with it but maybe. The switching side of the relays gets power from the receiver. Id' have to check what the ESC voltage is set at, but if my receiver is getting 6V from the ESC, then maybe the switch side of the relays is getting more voltage than they are designed for (3.5v to 5.5V operating voltage). The load side of the relays powering the LEDs, at 60VDC max, is way under what it would ever see on 3S. And none of that 3S voltage gets through the relays back to the receiver, separate circuits.

But maybe there is some sort of feed back to the ESC if it's trying to give 6V to relays that don't want that much and causes an issue with the HW ESC but not the Mamba ESC??? Possibly maybe? Otherwise, I can't figure out why it seems to be 100% fine with the Castle setup and not the HW setup. I'm afraid to hook the HW stuff back up because it melted the bejesus out of the insulation of the ground wire on the ESC to RX wiring. I put heat shrink tubing on it.

But I better check the voltage the ESC is giving to my receiver....that is def worth doing in light of the "3.5V to 5.5V operating voltage" for those relays.
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Old 04-22-2019, 09:43 AM   #5
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Default Re: Hot wires, get your hot wires....

We have this sort of issue sometimes, but normally it is on helicopters, planes, and larger cars with multi-battery setups. It is normally caused by something not having a direct ground connection to the battery and the ground for that is being sent through the ground wire on the RX cable. Not sure why changing an ESC would cause this issue.

The Mamba Micro X has a linear BEC, the Hobbywing 1080 has a switching BEC. So there might be something there, but that really shouldn't cause that much issue.
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Old 04-22-2019, 11:56 AM   #6
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Default Re: Hot wires, get your hot wires....

Robert - thanks very much for chiming in on my thread. Really appreciate it. The 1406 2850kV/Micro X combo on my SCX10 II is really quite great. Wanted to tinker around with something different and have always wanted to try a Holmes 5-slot motor.

And your comments gave me a big "light bulb" moment. I think it may be a tiny ground wire from two 5mm LEDs that at one point I had soldered to the negative terminal on the Micro X ESC. I can't recall if I switched that back to a connector or not, but if it's still connected to the Micro X, that would be it because it would have been still connected to the micro X after I had everything switched over to the HW 1080 combo. I left the micro X in the rig, and was basically bench testing the hobbywing/Holmes motor combo, so the micro X was untouched in the rig. I bet that's it. It's usually something tiny that gets overlooked...... As soon as I can, I'll look. TY!
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