Cirtix Stock Club Race - burnt out, pics

[losiracer]

Hi,
I have investigated a problem with my ESC (Cirtix Stock Club Race), whereby it drives the motor only if it initially turned by hand I found two burn chips:


https://plus.google.com/photos/10451...LSH5Yi53IfjnwE

It was driving a 9.5T Ultra Sportsman V2 with 2 Polys supplying power. I believe this is all in spec. Looking at the fails I'm imagining that the 3 power wires each run through two chips. ie the mid two burnt ones run the B wire. As such one of three is down and explains the capacity to run on when hand spun.

My question - so why has this happened. Is there a cause I need to avoid in future.

Cheers, Ian

[Robby]

I don't know, but is that "Stock Club Race" ESC designed to handle down to 9.5T motors?

And if it can, does it really seem wise to push the limit?

[losiracer]

Spec from Speed Passion website:
Burst Current 90A
Resistance 0.005 ohm
Battery(note 5)
4-9 Cell Ni-xx (NiMh or NiCd) or
2 Cell Li-Po / 2 to 3 Cell Li-Fe
• For 4-6 Cell Ni-xx or 2s Lipo: Use the
standard fan supplied with the ESC;
For 7-9 Cell Ni-xx: You must change the fan
because it cannot work with such a high voltage,
so please choose a high voltage fan or supply
the fan from the receiver (+5V); (note 4)
BEC Output 6.0V/BEC 2A
ESC type Sensored
Motor Type Sensorless or sensored brushless motor
Dimension 32mm (L) x 28mm (W) x 18mm ( H)
w/o cooling fan
BL Motor
Limited
Max >9.5T
Support USB
Software
upgrade
No

[imull]

What will have happened (probably) is that one of the FETs blew short and then when the other one was turned on then both of them effectivly shorted out the battery and blew the other FET.

There's not a lot you can do to prevent it, these things happen and sometimes it ends up a lot worse that a couple of blown FETs

[imull]

Looking at the spec for the FETs, they're only good for 25A continuous which is not out of the reach of a 9.5t. Were you running timing? Did you crash? Motors don't like being stalled!

Ian

[losiracer]

Hi Ian, thanks for confirming my thoughts. My son and I are fairly new to all this so no, no timing set that I'm aware of. As for a crash, well I cant rule it out.

We raced two heats at Telford Hot trax on wednesday, towards end of second car was making ti ti ti ti... noise, sounded like a tooth slipping, however nothing found upon inspection. This may have been running on 2 windings rather than 3. Upon third heat, it failed to start.

Ive ordered I new revention ESC, which goes down to 5.5T to allow more head room in future.

My last thought, given problem is so clear is it possible to source the chips and pass to a mate whos good with circuit boards to replace?

Ian