Motor spec understanding

[mikejbb]

May 10, 2008 3:56:52 GMT 1 mrmugen said:

That motor is simply not enough I am afraid. I doubt the battery is shot.

Kevin

OK, now we're getting somewhere. Here's the specs:
Model: 2409-18
Weight: 70g
Voltage: 10v (2~3 Cell lipo pack)
Idle Current: .9
Kv: 1000
Shaft: 3mm Diameter
Max efficient current: 15.5A
Max Load: 20A
Max Power Output:180W
Suggested Propeller: 8*.3.8 or 8*6 GWS Hyper Drive

Which of the specs need to be different?
higher/lower kv
higher/lower current/load/W
higher/lower volts

I assume the current/load/W are really all related. Since watts will change with volts, I put them in the same category.

I guess I didn't do enough reading, but others on this site have used this motor. But hey, I'd like to understand so I can make the call in the future. I'll bet there's an article somewhere I need to read.

Thanks
Mike

[flydiver]

The stock motor on a lipo is ~ 12Amps (depends on prop and battery).
That motor is theoretically better unless something is wrong with it.
KV is fine, Amp load is good on 3S.
It IS A CHEAP MOTOR, so being a problem right out of the box is possible.

Jeff at HeadsUpRC has a totally different take on the prop:
tinyurl.com/5bkkyf
You may be significantly under-propping it.
I see you have a wattmeter, use it. Prop it to get ~ 16A at full throttle.
One of the things you can see with a wattmeter is if the battery sags badly showing it is not up to snuff.
FWIW, some cheap ESC's can choke down the flow of amps to the motor too.

fly

[duck9191]

heads up is a good place for info, so far there specs have been spot on for the two motors i have bough from them.

[mikejbb]

Well my cheap 2400mah mystery battery was shot. I have to prop up to keep it in the air. Using an 11-7 prop worked ok and only drew 13.4 amps. But she was a very slugish and would only stay up for 6-7mins and I dared not fly in winds over 5mph. So I ordered another battery.

Before any flying I bench tested the new 2400mah mystery lipo.
11-4.7 wot-22amp too hot, 1/3t-12amp - ok hot
10-8 wot-20amp too hot, 1/2t-14amp - ok hot
10-6 wot-20amp too hot, 1/2t-12amp - ok hot
9-6 wot-15amp ok but not enough thrust - heavy nitro prop!

The hot I'm referring to is the motor. The battery and esc were not more than warm.

So I took her up with the 10-6 at 1/2t or a little less and she flew great again. Like I remember. But only for 12min. A great 12min. So I'm back flying near Chicago in the 10+ mph winds with confidence.

So the TowerPro2409-18 1000kv / 180W motor is perfect for the sc and the 18amp esc is also perfect and is not choking and with a properly working 3s lipo battery, you do have to prop down or burn up like fly said a long time ago.

fly, I have learned my Hong Kong lesson. You said I would. I ordered 2 batteries and one came dead and I'm resp for return shipping of $9 for a possible replacement. Not gonna happen and I don't expect any help from ebay or paypal either.

Mike

[flydiver]

Seems a good many of the lessons in this sport are learned the hard way.
Here's some info I gleaned out of another thread. Couldn't find the link:

[/li][li]

Those cheap parts sure are attractive. I've bought a good many. Don't entirely regret it, since I did learn things, but the learning experience is a bit painful. I am trying to save a few people some of that pain but unless they experience it themselves they won't know what they missed. Maybe I shouldn't bother.

If you happen to remember I'd like to know the life of that motor. My TP's have started breaking wired between the stator and the main leads just from 'normal' use-about 3-6 months. This, of course, hoses the motor but worse the broken wire seems to send a bad signal or something back to the ESC and it gets fried too.
One of these days I'm going to try to wind one.

fly

[mikejbb]

Well I put the tp2409-18 motor on 4/25/2008 and fly for about 40 mins a day about half to 2/3's of the days, sometimes even more. The motor is still fine I think. Though the esc fried when I landed in a pond yesterday. Worse than pilot error. I was coming around like I do when the wind is from the east to land on the street next to the park. I was way up there and a tree jumped between me and the sc. So I could hear it, but not see it. d**n leaves, I didn't have that problem a few weeks ago. I waited about 2-3 seconds and she didn't cross the trees into view so I ran to the other side of the tree. I could bearly hear, but not see her. I up'd the throttle to hear better, but no help. I was already down wind with 8mph winds on the ground (per anomemeter) and higher up it was even more I expect based on the sc getting thrown every now and then. So I cut the tx power and she did a spiral dive. I didn't see where so I went hunting. She was floating in the middle of a pond past the end of the park I fly in so I was lucky I found her. She was soaked on top so I guess the wind flipped her over after or during the crash. The wind brought her to shore pretty quickly and I tuned her off. After what I thought was complete drying out using a hair dryer on low, a couple of hours I turned it on and the esc did part of its song, but did not find the tx or rx so I couldn't test the motor. I tested the tx - rx pair and they are fine as well as all servos. Later I tried the esc again and this time I heard hissing and no song, so it fried. I went to headsuprc.com and ordered a 32amp esc and tp2409-18 motor combo just in case.

But I expect the motor to be fine, we'll see.

So I had to fly my slo-v last night in the calm before the storm. Not as fun as the sc, but still fun.

Mike

[flydiver]

For cheap motors I'm moving to Suppo. www.lightflightrc.com/ is a good source. Seem to be better built than TP. I've given up on cheap ESC's and am going to Castle TBirds. Tired of problems with the other ones and I've tried a bunch.

Too bad about the dunking. I did that a couple of time to my old aerobird. Both times I was sure it was fried but after a thorough drying it came back. I think it's critical that it be entirely dry before juice goes into it to avoid shorts.

fly