blowing caps 180esc

[ezhitz]

Just a question about the caps on the esc and what causes them to blow?
Just put in a new Hobbywing 180amp after the second run a cap let go I think
the problem was caused by half throttle running as the boat is to unstable at WOT
its in a 1/10 hydro 7XL 4S 5000mah pack spinning a x437.The eagle tree showed a spike 150 amps

http://www.youtube.com/watch?v=OoypEAo1Kbg

[scoota]

i have asked the same question down at the club my self , i will try and explain the best i can , the half throttle will get the fets working over time which will cause the ESC to run hot but not blow the caps .

i was told if you back off from full throttle to a stop , the the caps will have a full charge in them still & as the boat slows down in the water ,the prop starts to turn the motor , causing it to turn into a generator & putting more charge into the caps causing them to blow.

so now insted of coming off full throttle to a stop i run my boat to a gradual stop for a half a lap before bring it back to shore . Since i have been doing this i have not blowen any caps ...

[Flying Scotsman]

Just a question about the caps on the esc and what causes them to blow?
Just put in a new Hobbywing 180amp after the second run a cap let go I think
the problem was caused by half throttle running as the boat is to unstable at WOT
its in a 1/10 hydro 7XL 4S 5000mah pack spinning a x437.The eagle tree showed a spike 150 amps


http://www.youtube.com/watch?v=OoypEAo1Kbg

First off you are from Ontario.. ..How long was the first run and temperatures, battery depletion etc ....rest time....and time duration etc. before boom on second run.....plus as you have stated your throttle position probably caused the problem....talk to Doby, one of the few bright sparks left in Ontario

Douggie

[ezhitz]

Hi Douggie,Yes Ontario the first run was just over 1 1/2 minutes with temps under 120f
was about ten minutes before went out again.

[Doby]

Whereabouts are you?

I just added an Etti cap board to my 180 Turnigy after the caps had discoloured a bit. Seem to be finenow.

[ezhitz]

Hi Doby I'm in Brampton I will add a couple of caps to try it on the weekend and order
a Etti cap board for it.

[785boats]

The problem is even worse if the brake setting is set to ON. Some ESCs apply the brake automaticaly for a few second when the throttle is released if it is switched on.

Insaniac.
The testing has been done by many people. Here's one finding.
Cheers.
Paul.

[scoota]

Running at half throttle places about 50% of the battery power into the ESC and the rest into the motor. The cap blew due to excessive pressure which was caused by excessive heat in the ESC at half throttle.
If however, the cap shorted (high voltage breakdown) rather than exploded, then it was an over voltage problem...interesting comment about the back EMF of the motor-to-generator theory causing the (over voltage) problem...someone should do some tests to verify that!

i guess my generator theory has a bit of fact behind it , thanks to Pauls info

All i can say before i changed the way i brought my my boats to a stop , i was blowing caps on my ESCs all the time , and now it does not happen anymore !!!

The people that i ask these sort of questions to, know there stuff & would not give me an answer unless there was some sort of testing to back there answer!

[detox]

Prop appeared to be cavitating. Hull should jump on plane quicker than that. Lower the strut deeper into water and set to neutral. Maybe over cavitation caused it?


...

[BakedMopar]

I have the caps on mine and they have been working pretty well. They have dropped my cap temp over 15 degrees.

What size hull is that?

[785boats]

ezhitz.
There are a few other things that can cause caps to blow.


High resistance connectors between batteries & ESC including faulty solder joints.
Cables too long between battery & ESC.
Cables too small between battery & ESC.
Batteries not big enough to be able to supply the load the motor demands. including peak loads.
Brake setting on
Hard startup mode programmed in the ESC. Select Soft start. Its easier on the ESC.
Too little or too much timing programmed into the ESC. That 7Xl likes between 7 & 15 degrees. I run all my 2 pole Xl motors at 15 degrees.

Any one or a combination of 2 or more of those things can pop caps.
Of course it could have just been a faulty cap.

I know there are more reasons but I can't think of them right now.

Cheers.
Paul.

[ezhitz]

Thanks guys for your answers I know not seeing things first hand can only lead to a educated guess thats what great about this forum and all the vast knowledge somebody else probably already experienced it.
The esc was set forward only and 11.25 degrees timing running 4S 5000mah turnigy with 5.5 bullet connector.

Thanks Jack

[properchopper]

Just a question about the caps on the esc and what causes them to blow?
Just put in a new Hobbywing 180amp after the second run a cap let go I think
the problem was caused by half throttle running as the boat is to unstable at WOT
its in a 1/10 hydro 7XL 4S 5000mah pack spinning a x437.The eagle tree showed a spike 150 amps


http://www.youtube.com/watch?v=OoypEAo1Kbg

I am the only one that's picking up on the fact that a 7XL in a 30" boat, even with that small prop, is a bad choice ? 7XL's are usually used for 4S SAW riggers & such. I would run a 9XL ; in fact I often ran one in the 31" H&M that George now has and it was fast & ran a long time on 4S2P.

Just re-did my Vegas with a 180, added an Etti cap bank, like most of my high perf rigs. Or you can get Rubicon caps [ 1500 uF, 25V] from Newark Electronics for $5.67 for ten. ( I just did).

[BakedMopar]

I was thinking the same thing Tony. Thats why I asked for the size of the hull. OTOH I have been running an 8xl with a 120 for now until my 9xl comes. I have been running it with a ABC 1.6/3 and a x442 and temps are around 120 ish. I just want longer run times and cooler temps. If I didn't get the deal I did on that 9xl I would of bought a 10xl.

[ezhitz]

Yea Tony I know the motor is the problem Its really my sons boat and I said the 9Xl would of been better but he didn't listen whats the old man know .He just ordered from offshore a leopard 4074 2000kv to try in it.