300A Lite severe cogging on startup.

[IRON-PAWW]

Hi All,

I have a brand new 300A Lite Swordfish ESC. What happens is when I connect it to any motor with any battery or radio I'm getting pretty severe cogging in the motor for a second or so before the motor runs smooth. However, many times the motor cogs badly and simply stops. The ESC has done this from new straight from the box. Pretty happy with my solder jobs and connectors but am in the process of redoing them nonetheless. Pulled the shrink wrap from the unit and couldn't see anything untoward. Connecting 6S through it only at the moment with an additional 35v 6000uf cap bank. Motors tried have been Nue's (1521, 1527) and Leopard 1600kv. All suffer the same thing. This is bench testing only I might add.

Can anyone shed any light on what might be going on here. Dead ESC????

[oscarel]

Maybe try setting the PWM setting to something different and setting timing to auto. Removing the shrink wrap may have voided your warranty.

[kfxguy]

It's usually a setting.

[srislash]

I have had ESC's do this action before after getting wet or 'possibly wet'(I know you did not get it wet). I let them dry a week and then recalibrate, reprogram fully and they just about always go.
You could try your travel or reversing on the Tx as well.

[IRON-PAWW]

Thanks for the reply's guys.

So yeah - removing the shrink wrapping has probably voided the warranty but being in RC boating I'm well used to that.

The Boat *did* get two runs of less than a minute each. Probably more like 30sec each as the running gear was all brand new. Hull stayed dry internally though.

The PWM rate was set to 8khz. I've set that to 12khz on the bench and the issue does seem reduced. I can't make the motor cog and stop on that setting. However it might just be the removal of the shrink wrap and spray with Corrosion X that has had an effect now. I get a split second jump when I pull the throttle now - but not what I had before. At least I've got smooth running back in any case - on the bench at least.

____________> I've heard setting the PWM rate higher than 8khz can be a bad idea, basically causing overheats. What is people's experience with this??


So I've re-shrink wrapped and re-sealed the ends with a heat tolerant silicone. I also re-did the pathetic water tubing these ESC's come with. Will re-install and run - perhaps on 8khz PWM again. Then switch to 12 if the problem happens again.

Will report back what I find.

[ray schrauwen]

What charge level are your batteries while bench testing. I've had this happen only when I bench tested a SF200 8s esc using a partially charged 4s pack, I may try it with a 6s pack. When on the water it does not do this.

[IRON-PAWW]

Ray, it first began out at the pond after my second run. I'd bought the boat in to check temps etc and was going to go out again with it for a little longer run, but the cogging issue surfaced. So that was 2 x 6500mah 3S batts in series with a minute or so's running on them. But yeah, back home on the bench I'm using batts around storage charge of 3.8v per cell. So definitely not near full charge.

What I note is that while the motor is spinning I don't get the cogging/rough running issue at all. It's only ever from a dead stop that the issue surfaces.

Will test the setup again and see. I suppose it's possible the dodgy water tube connections I had may have leaked a bit, but I didn't see any evidence of that.

Any wisdom out there on setting the PWM rate above 8khz and implications?