potential problem - anyone with similar experience?

[kookie_guy]

ok, so running the boat on the weekend before it gets too cold. Ran strong, then I threw in my brother in laws pack, and had a potential problem.

My packs are 7 cell, 3800mah with zero problems. Brother in laws are 7 cell, 4500mah, no problems in his BJ26. After running for about 10 minutes, I brought the boat back in, and when I popped the hatch, it was smoking. I've noticed it was coming from the ESC, and it looks like one of the capacitors on the unit has a bit of a bulge on the top of it.

Everything is still fully operational. Anyone with something similar? Any idea if it would be warrantied? It was only 7 cells, so not even close to the rated voltage of the ESC.

thanks.

[egneg]

What is the voltage rating on the caps?

[obrien]

If you ran it for 10 minutes it was probably just too long.

[kookie_guy]

What is the voltage rating on the caps?

I will check. But I would imagine at least the same as the limit for the ESC which I believe is 20 volts.

[kookie_guy]

If you ran it for 10 minutes it was probably just too long.

10 mins is too long?? what happens when I go lipos in parallel to get 16,000mah? will it melt?

[Fluid]

That depends on your setup, the ESC might burst into flames before you dump packs with a 16,000 mAh capacity. You will have to do something to reduce the heat buildup. Water cooling, smaller prop, smoother driveline all can help. But in reality 10 minutes is a long time for a fast electric boat due to heat buildup. Best to bring it in after 5-8 minutes, let it cool a bit then go out again. As a point of reference, race boats seldom run for more than 2 minutes, usually less. This goes for electric, gas or nitro....


/

[kookie_guy]

That depends on your setup, the ESC might burst into flames before you dump packs with a 16,000 mAh capacity. You will have to do something to reduce the heat buildup. Water cooling, smaller prop, smoother driveline all can help. But in reality 10 minutes is a long time for a fast electric boat due to heat buildup. Best to bring it in after 5-8 minutes, let it cool a bit then go out again. As a point of reference, race boats seldom run for more than 2 minutes, usually less. This goes for electric, gas or nitro....


/

well that's not good. I didn't realize there was a time limit on how long you can run. That probably did it then, as I was coming in, swapping packs, and running again. Did that for about 30 minutes total. But still, time limit, that's not cool.

[andym]

16,000mah wow, I would at least run a CC 120 with the cut off set at 3.2volts and still bring in after 5 Min. None of my boats are made to run longer than 3 min and my DF 33 comes in after 2.5 min wether the cut off has been hit or not, that has somthing to do with the 1527 though! You will find with Lipo,s of that size that the power avalible will exceed the watts the esc is capable of.

[kookie_guy]

well, the 16,000mah was the plan. Run 2 4s, 8000mah lipos in parallel so I can get the long run time. Guess now that I know about the 5 minute thing, I'm gonna have to rethink my plan, and just go with 2s lipos and bring the boat in every 5 minutes.

My water cooling is working like a charm. Even at low speed passes (really low speed) the water is still coming out the side, so I know it's working.

Anyhoo, hopefully the ESC is gonna last now that the cap bubbled.

[azjc]

2 4s 8000 packs will be pretty heavy, IMO you are better off with a set of high quality 5000 packs

[andym]

Thats cool , this forum is about learning how to run fast boats without the expense of torching everything inside!! At least until you think you know what you are doing and start pushing the bounderies hard!! I have know doubt you could get a boat to run at 45mph plus for 10 min but you will need to run large capacity esc and a quality motor with a relitivly low average amps. Or as they say( and as I have done way to often) you will let the smoke out. Because as a very wise man once said electricity is just smoke. Read this

http://www.peizhang.com/forfun/forfun_writings_smoke.htm

[Meniscus]

Nice article Andy, I like that! LOL