mayday

Hopefully this post will help someone else troubleshoot a problem that stumped me for weeks.

I have a mini edge 540 3d ARF. Running Park 400 brushless, 25A esc, 3 pack LIPOs.

The plane directions said to run a 12 x 6 prop. I put this prop on and the performance was horrible. Not NEARLY enough power to run it. No WAY it would do any type of 3-d. In fact, it kept over-amping my ESC, which would cause it to shut down. So... I kept reducing the prop size until I was about half what I was supposed to have. Finally, it quit shutting down my 25A ESC (which is what was recommended in the plane directions), but now had no decent climb rate. I could not figure out why I had so little power, and why others were able to 3-d with a similar setup.

I **believe** the problem was my amature wiring of a switch. I wanted an on-off switch so I didn't have to unplug my battery. I built one myself out of an old park-flier setup that had an itty-bitty wire, and an itty-bitty switch. I placed this between the battery and the ESC, which mean all amps needed to run the motor had to pass through this. I realized my mistake when the switch finally got hot enough that it melted internally in place and would no longer switch off.

Wiring a small switch in like this is probably a commonly known no-no for you experienced modelers, but I'm guessing I'm not the only one (I hope) to do something this silly.

When I removed the switch, and wired everything together properly, my power increased SIGNIFICANTLY.

So, my question to you smart electrical guys out there, are these small wires really like using small water hoses... can they really restrict power supply, or do you think it was my switch? I always though too-small wiring would either work, or fail and burn-out completely, but not simply restrict.

Thanks for any input,

Mayday

DrDeath

My Feedback: (3)

Mayday,

Can't answer the wiring question, but something seems to be terribly wrong with your setup. I have the same motor, eflite 400 4200kv with a Phoenix 35 controller. I can turn the motor on high hold the plane straight out from my body and she will shoot straight up like a rocket ship with the stock prop. If I am not mistaken, the only problem with using smaller gauge wire is over heating.

Don't think this helps, but good luck

blueline

My Feedback: (6)

^

mayday

Dr. Death - Thanks for the feedback. Very encouraging to think this plane may fly after all. Can I ask what gear ratio and prop you have? I want a rocket too! :-)

DrDeath

My Feedback: (3)

Standard e-flite gear box at 6.6 to 1. The standard slow fly prop. Runs like a champ.

TManiaci

My Feedback: (6)

Mayday,

Yes, the small wire resembles a restricted hose, absolutley. You probably were significantly overheating the wires and swith contacts every time you ran the motor. It's all about resistance in the wire and/or contact.

[link=http://www.powerstream.com/Wire_Size.htm]HERE[/link] is a chart that shows wire-size vs. current carrying capcity (power transmission). As you can see, they recommend AWG 8 Gauge wire for 24 amps. The numbers are conservative here, but give you the idea. Most of our electronics are using 12-14 gauge wire on similar 25 amp design systems. The switch you used, by your description, probably had 18-20 gauge wire, maybe less.

BTW: Higher Gauge Number in thinner wire.

stangevil29

My Feedback: (1)

Ditto with Tmaniac, think of it like shotguns, the smaller the gauge more power. This is just my way of remebering it.
I work with high V and current everyday. You can very easily turn small wires into pasta noodles by applying to much current. just my .02
Stangevil29

ggcrandall1

Mayday,

If you want a switch you should wire it into the three wire cable that runs from the ESC to the receiver. Cut only the RED wire in the cable and install the switch in that line. This is the wire that supplies power to the receiver. Now the switch only needs to switch the power used by the receiver and servos which is a relatively small current. You will not be turning off the power to the ESC and it will still draw some current. However with the switch in the off position the receiver will not get any power and will not be able to sent a motor on signal to the ESC.

So remember this, do not rely on the switch to keep the battery from discharging between flying sessions. Always remove the battery at the end of the day.

Hope this helps.

Glen

rbushman3

hey guys, what about charging, i'm using 16 ga wire with an x-20 hacker esc for discharging. but for charging, the wire i got with the charger is much smaller. (like a Tx charger wire) not sure of size, maybe 22 or 24 ga. I didn't think it mattered as much as charging is much slower than discharging.

elevation

"Now the switch only needs to switch the power used by the receiver and servos which is a relatively small current. You will not be turning off the power to the ESC and it will still draw some current. However with the switch in the off position the receiver will not get any power and will not be able to sent a motor on signal to the ESC. "

Be aware that as pointed out above there is still some current draw on your ESC. If you plan to store the plane away, disconnect the battery from the ESC. Otherwise you risk draining your Li-Poly below the 3.0/cell limit. This will not happen over night but over a few days or more your Li-poly will be damaged.