Why did my ESC catch on fire? HELP!

[10gauge]

I could really use the forum's advice on why my Hydra 120 ESC caught on fire after 10 minutes of light use. It was the last run of the year and I was trying out my new LiPo batteries so I never went over 80% full throttle. In the beginning of the run, the Fall leaves got caught on the prop, so I slowed down several times and went in reverse slowly and it freed up the prop. So, it was a noncontinuous run ranging from very slow, with reverse operation, and to about 40mph towards the end of the run until the ESC went "Poof" and was charred beyond recognition. Just before the ESC went, the boat had slowed down. After retrieving the boat, I saw that the prop and the prop nut were missing and must have just come off just before the ESC caught on fire. (Not sure if I tightened prop well). But, the motor seems fine. Water cooling was also running smoothly.

Here's my set up:

30-inch Cat Hull
Feigao 8XL (2084kv) - New motor, seems fine.
X445 Prop
Hydra 120Amp ESC - used only 2 times.
Hextronic 4S2P LiPo 15-25C 4100mAh (8200mAh total) = 123 Amps
All Speedmaster HW, direct drive.

I know I was running at 123Amps, that's why I ran it cautiously and didn't go over 80% throttle. If anything, I thought the motor would go since it's rated at 83Amps. Also silly, not sure if I tightened the prop after switching it?

I am trying to figure out why the ESC burned up? Because of the prop coming off? -OR- Because I run a high Amp Lipo under partial throttle conditions?
How should I run a boat under partial throttle conditions, should I have used the Hydra 240 instead?

Believe me, I don't want to make this costly mistake again. With my friend manning the lake, I had to go back home to get my raft, which was still in the box. By the time I got back to the pond, it was totally dark by 6pm, temperature was 43 F, and the boat was barely visible the middle of the pond 500ft away.

Thanks guys!

[Mich. Maniac]

holy cluster, sorry to hear all that man. boat gods were angry today, actually sounds like you did a couple things wrong. full throttle is a must with these systems. if you cant run wot, change motor or prop. Wow. what a bumber, way to wrap up the season

[wickedgmc]

I agree with mich, full throttle is the way these things want to run

I lost a prop once and did not realize it until it was too late nad i had charred a hydra 120, so I would guess thats what happened to you.

Be glad you have a castle esc as there warranty while slow is one of the best in the business.

[Fluid]

It was the last run of the year and I was trying out my new LiPo batteries so I never went over 80% full throttle.

It is usually not a good idea to run at partial throttle for extended periods of time. This builds up heat in the ESC and could damage it.

In the beginning of the run, the Fall leaves got caught on the prop, so I slowed down several times and went in reverse slowly and it freed up the prop.

Leaves in the prop can give very high amp draws and can cook and ESC quickly.

Just before the ESC went, the boat had slowed down. After retrieving the boat, I saw that the prop and the prop nut were missing and must have just come off just before the ESC caught on fire. (Not sure if I tightened prop well). But, the motor seems fine. Water cooling was also running smoothly.

Watercooling does little to cool an ESC. If you ran the boat at full throttle without a prop that could also damage an ESC and a motor....

I know I was running at 123Amps, that's why I ran it cautiously and didn't go over 80% throttle.

How do you know you were running at 123 amps??? The only way to know would be with a datalogger. To reduce amp draw, run a smaller prop and drop the timing to low.

I am trying to figure out why the ESC burned up?...How should I run a boat under partial throttle conditions, should I have used the Hydra 240 instead?

Your setup is okay if it is running freely. That is impossible to tell from here.

It is always possible that the ESC was faulty, it does happen. ESC damage is often cummulative - if the ESC had been over-amped in the past or if it had ever been hooked up with reversed polarity, these could cause it to fail later. Running high timing advance also increases heat and ESC failure.


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[10gauge]

Thanks for the quick response guys! You mean Castle could warranty the ESC? It's literally charred with capacitors, PC boards, and soldered connections all melted off. I mean this thing exploded! It was like the Bismark firing off a salvo!

[10gauge]

Oh, the Timing Advance was set to NORMAL. And the Starting Power was set to LOW.

[Mich. Maniac]

As fluid stated, there were many things that could have happened and could have been avoided. wrapping leaves in prop could have spun drive dog, loosening prop nut just enough to loose prop, these things vibrate like crazy unloaded. Anytime this happens just stop. they are not like real boats in that sense that you can not put 80lbs torgue on prop nut. Yes also just cause batterys could put out that amperage doesnt mean you were drawing it. Think of it like a water pipe. you can put 60lbs pressure on 3" or 1/2" lines. this would be voltage. you will get way more flow from 3" line. this would be your amperage.

[NorthernBoater]

It is usually not a good idea to run at partial throttle for extended periods of time. This builds up heat in the ESC and could damage it.
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Explain this to me. My understanding with brushless motors is that the motors are not as efficient at partial throttle, not the ESC. A lower throttle would mean lower amps in the ESC. A well built ESC should have the same efficiency at any throttle level. However you are going to have less water flow to cool it.

[Mich. Maniac]

right, motor is the prob. causes more resistance to esc. causing heat to build in esc.

[Fast Guy]

The Hydra 120's have had a bad batch of fets. This can cause controller to loose one or more of its fazes and overheat big time. Sent it back to Castle. Follow the instructions on their site.

Here is an explanation on part throttle from Castles site.
"A speed controller controls power to the motor by turning full throttle current on and off really fast, 11 to 13 thousand times per second (Pulse Width Modulation or PWM). The percentage of each on/off pulse that is off compared to the part that is on determines how much power the motor sees. I.E. With a pulse that is 50% off and 50% on the motor will see 50% power*. Because each on pulse is 100% of full throttle current, a system set to pull 20 amps at full throttle through a Phoenix 10 will not last if you are throttled back to the point where you only see 10 amps on a wattmeter. The ESC in this case is still switching 20 amps, which it can’t do for long. Actually it is worse than the simple example above. Because an electric motor will always to try to pull as much power as is available to get to its rpm (volts times Kv), when you are running the motor below its Kv speed by switching power on an off, each on pulse will actually be way over the full throttle amp draw. That is why ESCs work harder at partial throttle than full throttle and why we underrate our ESCs. We underrate not so they can handle more current than their rating at full throttle, but so they can handle extended partial throttle operation with no problems."

[Steven Vaccaro]

Thats for posting that info. It clears a bunch of things up for me.

But where did you hear about the Hydras having a bad batch?

[SJFE]

That was great information thanks. I wonder if this is how all controllers operate???

[Fluid]

That is how most all BL controllers operate, and is why part throttle is not a good thing - for too long. The motor/prop combo is a determining factor, a mild setup will operate longer at part throttle than a hot setup will.

Water cooling is not too effective on most ESCs because of the poor heat flow path from the FETs to the water. The plates actually work by adding thermal mass, taking longer for the ESC to reach excessive temperatures. Milder setups run for long periods can benefit from water cooling to varying degrees.


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[SJFE]

That is a fact I have only recently come to understand. To be quite honest I think air cooling is a much better method of heat managment. The problem with that in our boats is obvious. I am however working on a solution. Affording it is the biggest part of the problem for me.

[ray schrauwen]

The plates actually work by adding thermal mass, taking longer for the ESC to reach excessive temperatures.

BINGO!


That is why I think I can push the heck out of my HEX 120, because I have WAY MORE thermal mass to dissipate the heat at any throttle setting. That combined with the fact that it is a smoother controller (airplane type with many more steps than some boat controllers) where I think ??? that it produces less spikes??

Are the Castle Hydra controllers really smooth like an airplane controller or are they similar to Hackers that have obvious fewer steps???

Looking for more insight please, thanks.