Rccd

RC Cuts out during High load

Hey I need help with my RC boat I would appreciate all help I can get.

Last summer my boat started behaving strange it started cutting out when I hit around 70% throttle but when the propeller was out of the water (not under load) it did not cut out and I could run it at full throttle (didn’t run it a long time because it’s water cooled) it runs off 2x 7.4V 4000mAh 35C LiPo batteries. It seems it can’t handle load for some reason. After it cuts out i have to drop the throttle to 0% and then i can accelerate again.

Boat- joysway bullet V3 (stock)

Batteries 2x - 7.4V 4000mAh 35C LiPo (included)

Charger- intelligent lithium 2s/3s balance charger J-BC3S01 (included)

Appreciate all helpful answers

Hydro Junkie

And now is where the fun starts.
I can think of three things that would do that:

1. Too much power for the ESC to handle so it's "thermalling"
2. Too much drag in the system. Have you greased the drive shaft or strut?
3. Too much prop

Everything you said came back to load and those are the three that are normally the "guilty culprits"

Rccd

Yeah I’ve greased prop shaft with traxxas rc marine grease or something maybe at the start of last years season haven’t really ran the boat since then bcs I started getting these problems mid last summer ig it could be 1 I of the batteries I’ve tried changing contacts on 1 battery bcs it had melted for some reason ig it might have damaged the battery ? I don’t think it has too do with the ESC bcs it is stock and so are batteries.
I don’t know what u mean with the third one ?

Hydro Junkie

Okay, you just filled in a few blanks for us.

1. The drive shaft needs to be greased either before or after a day of running. This is especially important to grease the shaft BEFORE RUNNING if the boat hasn't been run in a long time. Grease left for long periods can and will get hard and increase the load on the motor and ESC
2. If the battery connector melted, that means it was either not installed correctly, causing serious resistance(resistance = heat) or your motor was drawing too much power, possibly due to drag from the drive shaft.

The third one from my previous post, too much prop, means just that. Either the prop is too large, has too much pitch or both. Are you running the stock prop that came with the boat? If so, that takes that one out of the equation.

I took my scale boat out yesterday, first time in a year(gee sound familiar?) and, first thing I did was grease the drive shaft. Last time prior, that being last summer, I hadn't greased it and it let me know very quickly. My drive shaft runs inside a brass tube and the metal-to-metal contact had it literally screaming. A quick remove/grease/reinstall took care it that issue and it was actually running decently, that is until the boat in front of me died and I had no time to react. The resulting collision took my boat out for the rest of the day and, by the time I got it fixed(work schedule killed a lot of time so the repairs took several weeks), I was forced to call it a season.

Rccd

yea the prop is stock I think the melted contact could be bcs I once accidentally connected the batteries with each other which caused a spark but just for like 1 ms bcs I noticed the spark and didn’t even have time to connect them properly.
il try greasing the prop shaft again

Rccd

thank u for the help. Please share any of ur thoughts and tips it all helps 🙏

Hydro Junkie

What most don't think about, and I should have mentioned, is that the load put on the motor/ESC/battery pack, when the boat is on the stand, is only a fraction of what it has when the boat is running in the water. Since the boat runs fine until you get up toward full power, that pretty much leaves loading as the only variable. Now with that said, one other thing that "could" be happening is that the drive shaft is pushing against the motor and causing it to have more drag. I doubt that is what's going on in this case but, then again, you never know when it comes to boats

Rccd

yea the load is much higher in water. I should also mention that the amount of throttle I could give before it cut out could get improved by changing the throttle trim on the controller but it got worse by time probably bcs the batteries lost more and more power because I was driving