[airfly]

Hi there guys,

I'm kinda new to the RC and I am still learning about them each day.
Anyways i have a Trex 450 with a stock Align 2800kv motor with a 45amp ESC on it. Recently I changed it to a Emax 3800kv motor.
I use as a battery 3 cell 3000mah 30c battery and latetly with the new motor I fried 2 batteries already they expanded and almost blew up on me. I went to the usual hoby shop i go to and they told me to replace the ESC with a better and change my tooth pinion, so i did both and replaced them.
But when I flew it this afternoon again the same problem, when I put idle up the battery gets really hot and it expand, it doesn't happen when i just hover but I don't know why when I put idle up the battery get really hot.
Also sometimes when i try to start and add power the motor makes some weird noise and it won't start.
Do you guys think is the motor that is bad because the old one never did.
Please help thanks.

[marcham]

1. How many amps are you drawing?
2. What is your headspeed?
   
3. What was the pinion with the original motor and what is the pinion with the new motor? Anywhere in the 10 to 11T range should be ok.
   
4. How many mah do you put back in the battery after flying, is it more than 80% of its capacity? Do you constantly fly down to voltage cut-off?
   
5. What brand ESC? Can you tell us exactly how you programmed it?
   
6. What is your throttle curve in idle up (you don't really want to fly below 95% throttle as it will cause your ESC to work harder).
   
7. As for the weird noises it could be the mounting screws that touch the windings or incorrect timing for that motor.
   
8. How tight is your gear mesh? Can you fit a piece of paper between the main gear and the pinion (you should just be able to see a crack of light between the two)?
   
9. How freely does the head spin? You should be able to make it spin 2-3 turns without too much of a push.
   
10. 3000mah 30C may be a little heavy for this helicopter, most people fly a 2200mah 25 or 30C. Is your helicopter properly balanced with that heavy pack? (set the blades front to back, place a finger under each side of the flybar and pick up the heli, the main blades should remain parallel to the

ground)

[Cougar429]

Your pack and 45A should be enough capability for a 450 unless you are doing some very serious 3D work. The fact you don't state this situation existed with the original motor leads me to believe that's where the problem lies. I would strongly suspect your motor timing is incorrectly matched in the ESC and/or you are running too large a pinion and dragging down the motor.

These brushless do not like to run below their optimum RPM or their efficiency falls off. That means your current draw will increase as well. You don't state if your motor and ESC are getting hot as well, but I suspect so.

[tatestate1]

Interesting fact! If you test you Lipo by touching the leeds together to see a spark, BAD! In 5 min or less you battery will swell up and boom!

Never Never short your Lipo!!! Not even for a milli sec.

If your motor stalls and locks up, that is a dead short. Dead shorts will kill Lipo's

[airfly]

Hi guys,

thanks a lot for your answers.

marchman: the stock pinion from the old motor was a 15T and yeah people told me it was the wrong one and maybe that was the problem, so i changed it to a 12T but still the same problem.
About putting back mAh on the battery i'm not really sure about it as im not thats advance on it yet.
The ESC brand is a SKY MASTER input 5.2v-26v and is a 40amp but i never programed it because i don't know how to do it.
My idle up is at 100-90-100
The battery yeah maybe they are a bit too much for it but i also have a Lipo that is 2200mAh 25C to 40C but the samething happened to that battery.

Courgar429: Im not really sure what the head speed as i dont have any tools to check it.
Also if you guys can tell me how do you check and change the timing of the ESC and motor that would be great.


tatestate1: About the sparks i never recall doing that.

[marcham]

I'm going to guess that you are not a member of a club. Since you don't have the tools or experience to measure and diagnose your problems, I suggest you join MAAC and make your way and join the nearest RC club.

There you should find modelers with a wealth of experience that should be able to help you out.

Keep in mind that hobby shops are not in the business of fixing your toys, they are in the business of selling you more toys! However, if your LHS has a helicopter guy then they may be abe to charge you an hourly rate to troubleshoot and repair your heli.


1. Buy a watt meter, preferebly one you can fly with: http://www.eagletreesystems.com/MicroPower/micro.htm

2. Buy an magnetic or brushless RPM sensor for the logger, to know how fast your head is spinning. DO NOT use a hand help RPM sensor, that would be ridiculously dagerous.

3. 12T may be still to high for your motor, I suggest 10 or 11T

4. Most chargers ($40 and up) will thell you how much energy you put back in your packs. If you don't know how much you are discharging or recharging your packs then you may be overextending your equipment. Even the $40 Accucel-6 charger will tell you how much you are putting back in. Keep in mind that you should not discharge your pack more than 80% of its capacity.

5. I've never heard of a Sky Master ESC, nor could I find information about it. Your ESC MUST be programmed appropriately for the motor you are using, some ESC will not work well with high KV motoros (like yours).

I presume you purchased this helicopter used, I suggest you contact the previous owner or retailer for the manual.

6. Your throttle curve sounds ok, personally, I would use 100-95-100

7. ... did you check the length of the motor mounting screws?

8. did you check the gear mesh?

9. Did you check the head?


New Q: Was this helicopter used?

If so, the hodge podge of components may indicate several crashes, which could have damaged any of the dozen or so bearings. This would increase the Amps as the RPMs go from normal mode to idle up mode.

The only real solution to that problem would be to remove every single bearing, check for notches in the movement, relube the good ones and replace the bad ones.

FYI, do you know about helifreak.com? A great place for helicopters.

[Nev]

Firstly read about swollen battery disposal, charging and caring for lipos.
http://thunderpowerrc.com/html/downloads.html

If you want to come through to Toronto I will gladly help you check out whats going on with your set up and see if I can help you out.

JOIN a club and get your MAAC, let someone with experience help you straighten out the problem before you have fire on your hands or worse a serious injury.

Something does not add up for me :
1.
45AMP ESC should not be able to deliver much more than 45AMPS before it will overheat and fry. Could not find any info on this ESC though

2.
3000Mah 3 Cell Lipo 30C (even a no name brand @ 15C) should be capable of delivering constant 45AMPS and if in fact 30c then constant delivery of 90AMPS.

3. EMAX 3800KV Outrunner according to what I can tell is only rated to a current draw of 40AMPS under load. Although I did see its literature said Recommended prop without gearbox 6"-8 ! You could try running this size prop straight onto the motor eliminate the heli and see what happens.

Buy yourself an Eagletree data logger it will show you exactly what is going on In fact I have a lightly used V2 if you want to get a used one you can have it for $50Cad shipped to your door. Also get yourself a brand name ESC in the future it will save you a lot of headache and getting help to program it will be easier. Also the cost will be long forgotten after the enjoyment lasts. Think about the packs you have killed already.

FYI
http://www.eagletreesystems.com/MicroPower/micro.htm

Good luck

[airfly]

Wow so much info at once but thanks a lot guys i really appreciate it. I have a MAAC but yeah i haven't join a club yet. I will try to do so and maybe ppl can help me out.

I am thinking that myb i just need to put the old motor back in and throw this one in the garbage lol that what i get buying cheap stuff

[Nev]

Again - If you want to come through to Toronto I will gladly help you check out whats going on with your set up and see if I can help you out. I am not in this for business just know what it is like when you start out..so I am offering to help you find your way. I banged my head lots with many small Electric helis eventually landed up with a Trex 600e..love it. I learned a lot on the way .

[airfly]

Nev thanks a lot for your offer i really appreciate it maybe we can set up a day, my friend (also a starter) and I can come and see you fly and you can give us some tips. Btw which club do you usually go to?