Nator

Hello All,
I am pretty new to the electric RCPlane game and am having some issues with my plane. I had just recharged my battery after a rather successful flight. When Itry and start my plane again, it sputters a bit, starts spinning the prop and then stops. If I take the throttle back to zero and start again, the prop spins a bit but then will stop. Iam wondering if it is an issue with my Battery - ESC - Motor issue. I'll put my setup below, if anyone has any insight that would be greatly appreciated. If there is any other information that would help please let me know.

Battery - 11.1v 1300mAh 25C LiPo
ESC - 30A w/BEC
Motor - 1400KV - 10A(15Aburst) 2-4cell

Thanks!

DMcQuinn

My Feedback: (13)

It could be that the battery did not get charged. Do you have the type of charger that tells you how much energy was put back into the battery? Or is it just a light that comes on? Do you have access to a voltmeter so you can measure the voltage of the battery? Voltmeters have really gotten cheap, by the way. You can get a decent one at Harbor Freight some times for $1.99 (plus shipping).

I'd try charging the battery again. How long did it take to charge after the flight? If it was less than 30 minutes, then it was probably not charged.

DMcQuinn

My Feedback: (13)

Oh and if one of the three wires between the ESC and the motor is disconnected or loose, the motor will do some funny things.

Nator

Hi, thanks for the quick response. I charged it with a charger with the light. I tried the battery in another plane with a motor rating of 3500kv (a jet) which worked fine, and is why I thought it was a problem with how I set things up. I am thinking of going back and re-soldering all of my connections on my esc and motor to see if that is the issue, but I figured I would get some professional insight before I put all of that work into it.

Thanks!

DMcQuinn

My Feedback: (13)

Well if the battery worked OK on another engine with a similar load, then it's probably OK. Is the 3500 kV (jet) motor a similar size (in watts or Amps) to the 1400 kV airplane motor? The kV of a motor does not really tell as much as the amps or watts used by the motor/prop combination.

If there are no obvious breaks in your solder job, then I would not redo it.

Nator

The motor I am using right now pulls 10A (15 Burst) with a 9x4.5 prop. As for the Jet, I am not 100% on that. Since I am new, I don't have all of the tools to measure capacities and usage, but if it helps, it is the F-35 from BananaHobby and the battery works fine on it( http://www.bananahobby.com/1719.html ). I'm sorry for not providing the best info. I am still fairly new and am not versed on what I should know. I have a weird feeling one of the solder joints came loose, because my last landing was kind of rough and my soldering wasn't what it is now, so I think I will give it a shot just to rule that out. If, from the scattered, poorly put together amount of info I provided, you happen to see something that may be the problem that would be great.

Thanks!

Hawaiian Hawker

I had the same trip and it was my connections. Resoldered and it works fine now,

jester_s1

It sounds like either bad connections or a bad ESC. A cheap multimeter comes in handy in lots of ways on planes, one of which is checking the ohms across your solder joints in a situation like this.

Nator

Hi All,
First off, thanks for all of the suggestions. They were a great help to this rookie. I think I have found the issue, and it was a combination of two things. The first issue was the soldering on the motor connections. The motor came with the connections attached so I didn't get to check it out. The soldering looked really sketchy. I re-soldered it and tried it out. The motor sputtered a bit the first two time but has been working like a charm. The second issue is my prop size. Without a prop the motor runs perfectly cool. When I put on my 9x4.5 prop, it gets really warm, but the air flow from flight should keep it cool enough, thus I should probably downgrade to a smaller prop, or upgrade to a larger motor... I prefer the latter lol.

Again, thanks for everyone's help. Its good to know there are very knowledgeable people out there, and hopefully when I get good enough I can contribute a bit to this site.

jester_s1

Glad you figured it out. You might consider buying one of those cheap multimeters. You can make a shunt to let you measure the high amp draw of these motors to make sure you aren't overdoing it. If it saves you one motor or ESC it'll have paid for itself.

Hawaiian Hawker

"The second issue is my prop size. Without a prop the motor runs perfectly cool"
Looks like you still have a poor connection somewhere.

Nator

"Quote:
Looks like you still have a poor connection somewhere."

I'm a little puzzled by this. It was my understanding that with a prop the motor draws more amps, because of the increase in resistance caused by the prop the motor must draw more amps to make it spin, thus creating more heat. Therefore without a prop a motor should be drawing minimal amps, thus creating minimal heat, allowing it to dissipate rather quickly, so that it feels cool no matter how long it has been flying.

I may be wrong about this, but if you could explain further it would definitely help me learn more about RC planes.

Thanks

Hawaiian Hawker

Motor should run cooler and better without the prop. Mine wouldn't run more than halve throttle and heated up with the prop. Resoldered and it runs good and cooler also.

opjose

That is correct.

He mispoke.

CGRetired

My Feedback: (1)

One minor point here. The reason there is heat is not because of the prop, well, not totally. Heat is a waste, a byproduct of the way a motor is made. Ideally, if the prop turned and there was no heat, then all of the energy would be going into the prop. It would be 100% efficient.

That's just not so.

Part goes to turn the prop, part goes into making the heat. Just like glow fuel engines. Part of the fuel goes to run the engine, part goes to cool it off, and part goes right out the exhaust unused.

CGr.

jester_s1

Unless you are over amping the motor or have it enclosed in a cowl that won't let air circulate around it, it should be able to run with the recommended prop without overheating. If it is, then something is wrong.

opjose

Careful.

Spec'd props WILL in most cases overheat a motor that is run at full throttle on the ground.

In the air the motor unloads pulling fewer amps than it does on the ground, and cooling is far better... so manufacturers spec their props and motors for the "sweet spots" where efficiency tends to be better.