|Jan 08, 2003, 09:17 AM|
AF 010 and Kokams, don't leave 'em plugged in!
OK, so many of you have seen my reports about my geared Astroflight 010 tests on Kokams. The 010 has an on/off switch like most brushless ESC setups. Last weekend I was flying and spun the pinion off my motor (this was one of my mod jobs, not the one from Aeromicro). In my "excitement", I turned the motor off after a hasty landing (have you ever landed a plane with a free-wheeling prop? Talk about slow motion!) and neglected to remove the pack. Now I would not have thought this would matter, because I DID turn the switch off. But normally I remove the packs right away, I just forgot this time. The next day I pulled the plane down to work on it and noticed the pack was still on it. I removed the pack and took it to the charger to top it off (I had only flown it a minute or 2 when the pinion flew off). I always check voltage before and after charging, it's part of the routine. Imagine my surprise when the voltage showed 1.6 volts!!!! The FMA literature says never to allow a Kokam pack to drop below 2.5v per cell, and here I am with a 3 cell pack at 1.6, or 0.53 v/cell!! I thought it was toast. I put it on my 3 cell charger and the light would not even come on. So I popped it on my 2 cell charger and much to my surprise it started charging. It charged up to 8.25v (as high as that charger goes), so I moved it to the 3 cell charger. It then came up to full charge! I've flown that pack 4 times since then and it appears to give the same power and duration as before. Time will tell if there is any life-cycle damage, but I count myself lucky to get any more flights out of it at all.
So, don't leave a pack plugged in to an AF 010. Even if the switch is off, it's still drawing energy.
Also, if you crater those Kokams you might be able to bring them back! I still think it's a good idea to keep them over 2.5v per cell, but clearly they can go well below that and still be saved!
|Jan 08, 2003, 12:46 PM|
Joined Jun 2002
I just finished my Tiny-X.
AUW is 6.7 ounces with a wrapped C/F tail stick.
I use Qualcomms for now.
Well, i'm thinking about installing a Astro 010 on it.
I have some questions for you, please:
1) The 1020's are good up to 3.5C or something like that.
Isn't it pushing them a little bit hard with the 010 ?
2) I was thinking that a 5.33:1 gearbox with a 10x8
prop would give better thrust and pull less amps.
But you seem to get pretty good results (lots of vertical)
with the 4.43:1 and 9x7 prop. I'm puzzled.
Thanks in advance!
|Jan 08, 2003, 12:59 PM|
This is not unique to the AF 010 - many, if not all, speed controls have active circuitry whenever the drive battery is connected, whether or not a provided switch is on or off. That switch generally only controls whether or not the BEC regulator's output is getting to the Rx or not and has nothing to do with the motor power side of the controller or the microprocessor on board.
|Jan 08, 2003, 01:10 PM|
==1) The 1020's are good up to 3.5C or something like that.
Isn't it pushing them a little bit hard with the 010 ? ==
I've got 2 14t setups I'm running. On a 4.43 gearbox with 9x7, it pulls 4.2 amps at WOT. I rarely use WOT, 2/3 throttle gives me all the power I need for aerobatics. I only punch it when I want to watch it go vertical! It's not pushing the 1020's at all, based on the 15-20 minute run times they seem quite happy with the setup. 1020's are capable of up to 5 amps, but I suspect they can handle more in a 3 cell setup like I'm using.
The 5.33 gearbox is also running a 9x7 and nets consistent 20 minute run times. Vertical is much shorter than the 4.43 setup, but power is very good throughout.
==I was thinking that a 5.33:1 gearbox with a 10x8
prop would give better thrust and pull less amps.==
5.33/10x8- 4.2 amps, 45 watts
4.43/9x7- 4.2 amps, 47 watts
You can see all the Whattmeter tests I conducted here:
New geared AF 010 Whattmeter data
Like you, I expected the 5.33/10x8 to be a much more thrust oriented setup. I flight tested it and it does indeed have more thrust, but speed was down quite a bit. I tested 5 props and ended up sticking with the 9x7, it gave the best all around performance on my old Tiny.
|Jan 08, 2003, 01:20 PM|
Joined Jun 2002
Thanks Tres !
Now i need a second Tiny-X, more carbon rods and tubes,
a Mighty 010 and a GWS gearbox from AeroMicro.
All your fault !
Don't be surprised if you get a phone call from my wife soon...
Seriously, if i can cut enough weight from my next Tiny-X,
i might try a 3S pack of 1575's (when they are available).
Flight times of 10 to 15 minutes is OK, but not way cool.
Keep us posted on the new 450's...
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