In case you are interested in what water will do to the bearings of your brushless motor, here's an example: The grease in the bearing looked more like rusty sludge than a lubricant. The bearing was also rusted in place, so it was destroyed when I tried to remove it. I had to grind out the outer race with a diamond tool. This particular motor was used on a pump and this was the bottom bearing. The top bearing was also rough, but at least I was able to get it out easily. I replaced both ball bearings with sleeve bearings and will test it in battle today. In addition, I added a coat of lacquer to the stator, since I noticed that the iron plates tend to rust.
I used to use aeroplate oil to dip the whole motor in to protect it (periodic dippin). I am out now and can not find more. One other option I have tried is the teflon bike chain lubes on the non-bearing components of brushless motors. worst case stainless bearings are available.
This inquiring mind wants to know how it went! I had considered getting tiny double-shielded ball bearings for my motors in Malaya... They're about $7 each though. Sleeve bearings would probably be cheaper.
at 7$ you can get stainless steel bearings. one other thing I worry about on the pump in particular is having bearings operating at high speed filled with water under load can cause balls to skip and shorten the bearing life.
Aye, what I'd like to know is how much would it shorten bearing life by? If I could get a solid year out of a set, that'd be fine.
The plain bearings worked fine. In fact, I had to bring the ship close to shore to check if my pump was running, as opposed to the last battle where I could hear it from across the pond. My pump is probably only turning between 2000-3000 rpm, so I'm not too worried about life on the bearings. Greg- where can you find SS bearings for $7?
Has there been a determination of the root cause of the brushless problems at MWC nats? And a possible solution?
Problem was the copper sulphate added to the water and the use of the first generation HK car controllers. A few others that were using the second generation wasn't having any issues. I've since tested my ESCs and they work fine now. Houston was the first time I have had any major issue with the ESCs other than the voltage cutoff thing earlier in this thread. The ESCs were ultra reliable up until Houston, Of course, anyone with exposed servo leads was having issues. At least two other captains had to replace receivers.
I haven't lost a bearing yet through two nationals ( 10 days runtime ). I did lose a hobbyking 100 amp speed control at 8 days runtime looks like possible water infiltration through a pinhole in the epoxy. The copper inside one of the fets looked discolored slightly, like heat or moisture caused it to begin oxidizing. I have only had one complete immersion on my motors and controls so far ( ring of death last year ) and no copper sulphate in the water. I think the bearings on the larger motors last longer, I have not done nightly maintenance on them, just end of event oiling. Brushless pump paid for itself this year, I lost 4 brushed motors in 5 days before I switched over ( cost $70) and I have been running the same brushless motor and controller on the pump ( also $70 ) for 10 days now. Plus I get a little more out of the pump than I used to. Ron Hunt
Hi all. I am contemplating going brushless on my current build and the next one. Right now I am building an MWC class 3 cruiser. I was originally going to go with a pair of silver can 540 brushed motors, but brushless is getting much cheaper than it used to be. Anyway, I am not sure what kv to go with. I am planning on using 1.25 inch 25 pitch props (BC) and 6v SLA batteries. What would you all recommend for motor and ESC?
Too tired right now (it is just after midnight). I'll make some recommendations tomorrow ... er later today after I wake up.
I've been using motors between 1800 and 2500 kV with 6V batteries. For a cruiser, probably between 2250 and 2500.
Ok. Well rested, fortified, and ready to toss out a few ideas. Two 540 size motors in a light cruiser is way overkill. Heh. Perhaps 28mm or 380 size motors would be better. They can handle those props, take up less space, and lighter than 540s in a boat that might need to watch the weight on. Going with a 6v, a 2.5:1 gear ratio, and a prop rpm of around 3000 (which should be more than enough for a two shaft cruiser), it looks like a 1300'ish kv (rpm per volt) motor might be a good starting point.
Sounds like it, but Scharnie (admittedly one prop) is running at about 85% throttle with a 2.5:1, 7.4V battery, and a 2100kV motor on a 1.25" four-blade prop, getting to 26 seconds.
