I need some advise on an SV27

[fletch51]

My buddy 80 miles away got a new, but discontinued Auquacraft SV27 to have fun with at a retention pond behind his shop. He also just won an ebay bid on another used one for his employee so they can race around at lunch or after work. He also likes it so much he is gonna get two of the SV27R's as soon as he can get his hands on them. He is new to RC boats, yet has some experience in RC cars, And neither of us know very much about LIPO or brushless. So here goes.

Thru my LHS I got him a pair of SMC 8000mah 2S lipo's (with a decent C that i can't remember)and two chargers and put dean's connectors on all. The SV27 ESC wiring is in series so I believe that means it's nominal voltae is 14.8V . Immediately after charging each battery I metered the batteries and they were 8.4V a piece, so in series 16.8V. I then shipped them to him, and he has been amazed at the speed(this new boat had never been run until He got these LiPo's)... However Sunday, He ran it for a while, dunked it once, and continued running and the ESC finally smoked bad. it even melted the plastic radio box.

He is not at all upset about any of this, and is more than willing to get different equipment to make it reliable. The radio box did get completely soaked about 2 weeks ago and He thinks maybe water is why the ESC failed.

I guess I'm looking first for suggestions on an ESC that would be great for this battery setup, and the motor can be changed too if necessary.

Once He gets reliable electronics then we will start messing with handling and props(everything is stock now).

Thanks, Fletch

 

[Grimracer]

Fletch

Number one deal is, what direction is he turning the boat. As a rule of thumb we turn right and not left. Hainng said that you can turn left just not all the time with the cooling pickup on the right side of the rudder.. the SVR addresses that with the trasom mount pickup.

8000mah.. whew.. that’s A TON of mah.. at what point did the ESC cook.. I know on 5000s the boat will run around 6min.. all in all that’s OK but just be mindfull of the power this system makes.. its good when using new batts to bring her in after a few min and check temps on things untill you get an idea of how hot things are getting

What prop are you using? Is the pond clean? If the prop is to large (sure we all want to go fast) and or there are weeds on the water you are going to brun stuff up..

Let us know when you know more

Grim

 

[fletch51]

Thanks a lot for the help Grim,

I just talked to him, and it turns out I misunderstood and incorrectly described the scenario when it burnt up.

I sent him charged packs and he had run it a few short runs, because he was learning how not to spin out crossing his own wakes, and that he should have added flotation to his first cowl and so on. after getting a new cowl he finally had a long 5 minute or so successful run, however still on the same charge I sent him. He is also mindful of watching the coolant stream during any run. He also said he does turn right almost exclusively and if he has to turn left he said he does it very slowly.

The Prop is the stock composite one. The pond is free of weeds and he said he watches the coolant stream.

It turns out he had just charged the packs for the first time himself the day after that 5 minute run.

Then, He said he put it in the water again and started going and within 10 seconds it was smoking bad.

I thought I saw in other threads, that the ESC is designed to handle up to 18 volts.

the first charge that I did to them resulted with 16.85 volts, And he didn't run the packs until 2 or 3 days later because I shipped them to him.

Thanks again,

Fletch

 

[Grimracer]

if they are 7.4 packs (times two) you are fine.

IF' he is running the boat lower then say half power most of the time the ESC again can get very hot.. the extra energy from the packs has to go someplace.. it becomes heat and can nuke things

Grim

 

[fletch51]

OH, OK,

I have seen golf cart speed controls do that at slow speeds, both solenoid relay/resistor types and solid state(transistor)ESC types.

After searching and reading all over the internet, I'm gonna get him to try a UL-1 60amp aquacraft waterproof ESC with lipo cutoff for now.

I appreciate your help

 

[longballlumber]

Fletch,

In addition to the comments that Grim has made, I wouldn't recommend running any longer than 4-5 min (at the max)!!!! This is a much different scenario than the cars he is accustomed too. With these brushless boats the longer they run the more heat they continue to generate. The heat generation never really "levels off" over time due to constant load on the entire power system. Make Sense. I think Grim mentioned it, but it is always recommend that you run brushless boat WOT as much as possible. After a run, give the power system, (batteries, motor, and controller) time to cool down rather than just throwing the boat out for another run. Again, this is a different concept that nitro boats where we can refuel all day long.

Later,

Mike Ball