9 replies to this topic

[crazyphysicsteacher]

Okay, need to send this out. Have been running brushless at the local track using Parma motors and M-A Remora boards.

 

Within the past three weeks there have been at least three boards that went bad. One was possibly a bad install but two of them were bad from the start. Has anyone else had issues with Remora boards as of late?

[MSwiss]

I noticed you liked my post in the FB Brushless forum on my new JK C95 CNC machined, brass chassis weight.

 

Why wouldn't you pose this question there, where there has to be more brushless racers?

[crazyphysicsteacher]

Because there seem to be more posts on fb of completed cars and not much about issues. The individuals seem to give the same answers with little help on I depth issues.
I always found that when I go to here I get better answers and have always seemed to more actual in depth discussions before the fan boys arrive.

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[dalek]

At P-1 Slot Car Raceway in Winter Garden, the Mid-America Remora with KC 3200Kv motor is raced every Tuesday and we've not seen an unusal number of the Remoras fail.

 

Based on some of the solder jobs I've seen, it's clear that a significant percentage of racers don't know techniques and have the finesse and don't use an appropriate soldering iron tip and temperature to avoid risking damage to the fairly delicate ESCs.

 

[jimht]

Your post is too vague.

 

Questions about problems to do with slot car stuff, whether brushed or brushless, need more detailed info about the cars, setup and track.

 

However, you are more likely to get relevant help on Facebook than here.

 

Aside from that, Roger at MA/Parma has had cars run thousands of laps on his tracks with brushless and would be a good place to start.

[crazyphysicsteacher]

Your post is too vague.
 
Questions about problems to do with slot car stuff, whether brushed or brushless, need more detailed info about the cars, setup and track.
 
However, you are more likely to get relevant help on Facebook than here.
 
Aside from that, Roger at MA/Parma has had cars run thousands of laps on his tracks with brushless and would be a good place to start.

Did not think I needed to identify specific parts of the boards for the question I had. Two boards popped a transistor while the other was bad for the start. And while I could reach out to Roger about parts, I wanted experience from individuals who operate the boards regularly with motors that are not home sets.

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[crazyphysicsteacher]

At P-1 Slot Car Raceway in Winter Garden, the Mid-America Remora with KC 3200Kv motor is raced every Tuesday and we've not seen an unusal number of the Remoras fail.
 
Based on some of the solder jobs I've seen, it's clear that a significant percentage of racers don't know techniques and have the finesse and don't use an appropriate soldering iron tip and temperature to avoid risking damage to the fairly delicate ESCs.
 

Define unusual? We are running everything from 3k to 11k motors. We find the boards work well and had few problems. But now we see issues just like the early kc westrock boards. I had an x89 board blow just like a guy had a remora board blow.
We thought one was a bad solder job, but the there was another. So I am wondering how many others have experienced popped transistors.

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[jimht]

My experience with 7 different brands, including MA Remora, is that ecom failure during use has more to do with heat than anything else.

 

The heat may be caused by voltage, gearing, friction, cogging, bad contact, faulty components or whatever...it doesn't take long and poof.

[Bill Seitz]

The slot car E-comms have very limited surface area with which to cool the FET's, so there's definitely a thermal limitation with them. This means anything that makes the motors draw more current could cause a thermal overload and blow the transistors. I believe there are issues with this in most brands. On a visit earlier this year to a raceway that advocates brushless and tried hard to induce me to buy a full brushless car, the owner admitted some of his guys playing with 11000KV wing cars were finding the E-comms they were using would blow if the gearing got too aggressive. I've observed that when the brushless motors were first introduced, the gearing being used was conservative compared to brushed motors. As the brushless motor gearing has become more aggressive following the trend of brushed motors, there's been an increase in reports of E-comm failures.

 

Surface mount transistors depend on square inches of copper foil on the PWB to dissipate their heat, although some small heat sinks are available but would have to be designed into the board with sufficient real estate. Adding heat dissipators contacting the plastic body isn't an effective way to remove heat from a transistor. I was recently surprised at the square inches of foil one semiconductor manufacturer said was required for their FET, though I believe the device had a higher power rating than those used in E-comms. Even at that, it seemed like the board for a slot car would need to take up most of the available chassis space to meet the manufacturer's  recommendation with 3 FET's.

[crazyphysicsteacher]

Yeah, two boards blew during direction checking, not even on the track. One blew while being run, but the gearing is lower than than what could be run for a 6500 motor.
Two boards failed to power up, the other two seem to have shorted internally and then blew one of the power transistors. The last even failed such that while I was trying to test it, it shorted the programmer wire while stuttering the motor from the failed transistor.
As to cooling, all boards were mounted in a small surface area 3d printed moun that allowed max cooling.
While three at the moment is not much, that was within 2-3 weeks during the summer while we are trying to start a weekly race. So I am trying to see if others are finding issues

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