Bad ESC?

[Cro Magnon]

Hi!

I've got a Rocket 26" which i ran a TP3630 2100kv on 4s with a Swordfish 120A controller and a X642 prop. No matter how loose it ran, it drained a 5000mAh battery in about 4 minutes. Thinking the motor was a little bit too small, i replaced it with a TP4040 2200kv, then the ESC burned. In my quest for a new ESC i came across a Castle Hydra ICE200 HV with a 75% discount. I know they a discontinued, and a bit overkill for a rocket 26, but i went for it.

Now, with the hydra, I'm getting 8 min 45 sec runtime with the same drive line and batteries! I was just testing so i did not run full throttle all the time, but still, it is a really big difference. Only thing i changed was swapping the teflon liner with a brass tube.

I know there is a few variables here, but, could it be possible the Swordfish 120 was faulty? I've been told that a worn teflon liner can cause quite a bit resistance, but can it cause a 50% lift in average amp draw?

And a last question: How does the ESC rating work? The hydra is rated with 50V and 200A, is that another way of saying it has got a 10000W rating, or is it 200A no matter how many volts you are feeding it?

Thanks,
Oddbjørn

[focused]

Did you try x442 ? For me i dont see the need to use 1.6 props in a mono or cat but more riggers/hydro`s but he thats me. For bigger boats we even use 1.2 props but larger ø runs are longer less amp draw.

[Cro Magnon]

Did you try x442 ? For me i dont see the need to use 1.6 props in a mono or cat but more riggers/hydro`s but he thats me. For bigger boats we even use 1.2 props but larger ø runs are longer less amp draw.

As i am a FE rookie, i'm still lost in the jungle of prop suggestions:) I bought the X642 i while ago, but after lurking around this forum, i have a few props on my "try list": the X537/3, X440/3 and the one you suggested, X442. Still, i don't think the prop is the explanation to why the amp draw was reduced 50% by changing the ESC and the teflon liner.

[focused]

Thats true , the prop inst but it can be a part of wat happened to the esc. What we do is testing sets of simple K props first instead of buying a lot of metall props .
I also think the motor wasnt that small for a 26" boat, i run a 4050 in a lizard 41/2 kg boat t180 esc and 52mm k prop nothing to worry it gets warm a bit thats it.
And yes maybe the esc wasnt that good at all but you never know with boats esc and peak ampdraws.

[siberianhusky]

Well you did go up in KV by 100 so that's almost 1500 rpm more. If the boat wasn't set up very well the added rpm could have pushed you into the red zone with the first esc.
That still doesn't explain the extra running time, to be honest I have no idea how you got almost a 9 minute run, 4 minutes is about right that would be about a 60 amp draw leaving you with about 1000mah or 20% capacity remaining. To get to 9 minutes you would have been running under 30 amps.
The only way this could happen is lots of part throttle running which is very hard on the esc and could be why the first one failed.
The numbers just don't add up or there is something about the way you are running that you aren't telling us.
Good move getting rid of the teflon. Waste of time to replace and only adds drag to the driveline and adds another failure point. The shaft only touches the brass in a couple spots when it's under load, ever noticed how a flex shaft tries to assume an S bend when you twist it in you hands? Does the same thing inside the stuffing tube when it's under load and only has a couple contact points. One of the reasons I also prefer an S bend in my stuffing tubes as opposed to a single gentle bend. You are letting the shaft do what physics wants it to do anyway.

[Fella1340]

Partial throttle runs will kill an esc. Brushless motors are designed to be basically run full throttle all the time. Any esc will heat up and burn running slow. If you really got those kind of run times the esc's must have been on the edge of smoking itself! If you want to run a slower boat, prop down, choose a lower kv motor/ less voltage. I can't explain what you said happened but 8 minute runtime is extremely long, you are very lucky your new esc didn't burn up to. You need to be running mostly full throttle so things will run efficient and not heat up. If your looking for a slow cruiser with long runtime brushless may not be the best way to go. Perhaps somebody could offer a combination to allow slow speed running. Keep the throttle wide open or mostly wide open and you'll keep your current set up from failing to!

[oscarel]

Any esc will heat up and burn running slow.

Most of the higher end escs do allow partial throttle without issues.

[flraptor07]

Your original set up with the SF120 was marginal at best with the 642 prop then when you went to the bigger motor you pushed it over the edge and let the magic smoke out. You're right the Hydra is over kill, that's why you're seeing such a big improvement in performance.

[Cro Magnon]

So the most probable cause for the SF120 burn was a god ol' overload. There were no partial throttle involved. Full speed all the way. As i stated above i was easy on the throttle when testing the hydra. Water was wavy and i wasnt in the mood for a swim:) flat out in the straights and long slow turns. Not too much hard acceleration. Esc, battery and motor was body temperature when finnished.

[flraptor07]

So the most probable cause for the SF120 burn was a god ol' overload. There were no partial throttle involved. Full speed all the way. As i stated above i was easy on the throttle when testing the hydra. Water was wavy and i wasnt in the mood for a swim:) flat out in the straights and long slow turns. Not too much hard acceleration. Esc, battery and motor was body temperature when finnished.

That would be my best guess from the info given

[martin]

Yep a 120a is to low for that motor & set up, the original 36 series motor you had is an ideal size for a Rocket 26. The 40 series is overkill in that hull.