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Old Jun 29, 2003, 07:36 PM
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Melbourne Australia
Joined May 2003
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How far can you push an ETEC 1200 2S1P Pack

hello all.

I have a Etec 1200 2S1P pack and am curious how far you can effectively push them before you do long term damage.

The web sites indicate about 6amps normally and pushed to about 8amps in short bursts. I have also however read that these figures are "conservative" and was wondering if anyone out there has had some experience re this.

I ask this question as I have just bought a brushless combo and one of the gear options I am looking at peaks at about 11Amps. This would allow me to vertically (1.5 to 1 thrust ratio) easily and I would only be doing this in very short bursts....but more importantly I don't want to harm my packs. I have a safer gear option which will give me about a 1.1 to 1 thrust ratio at a maximum of 8.1Amps...which should be much safer.

Thanks, Michael
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Old Jun 29, 2003, 10:07 PM
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Alberta, Canada
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After about 5 - 5.5 amps continuous the cells get a little too warmish-hot for my tastes. I fly 2s1p in my mustang with the gws C gear drive and 10x8 prop. Flies pretty good but this is what I would consider the limit.
My A-10 that seems to draw 6+ amps made the batteries too hot and I've since moced to a 2s2p configuration. I'd peg the "conservative limit at somewhere around 4-4.5 C for the etec 1200 cells.
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Old Jun 29, 2003, 11:34 PM
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Melbourne Australia
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Thanks Mikey. I'm running the exact same config as you on the mustang (GWS I presume). Strangely enough, at first I was unhappy with the performance...no loops, messy rolls...etc. But on the weekend it was performing great, big loops, nice rolls..etc. Not sure why this was..I did a few things like change CG, grease the motor, reduce throws and of course the motor is more worn in..but whatever it was worked a treat. (in hindsight I wouldn't have bought the brushless).

The 10x8 is supposed to draw about 7.8A...but my own "dodgy" testing (sticking an mulimeter between the bat and the motor)showed about 5.5A. Have you done any testing in this area ?

How did you find you mustang when you first tried it on the ETecs?
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Old Jun 30, 2003, 12:49 AM
luc
I plant balsa sticks too
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France
Joined Feb 2000
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8A is no problem....some have even flown with 10A peak (at the expense of duration and cell life, I guess).
At those amps, drop in voltage is noticeable.
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Old Jun 30, 2003, 11:11 AM
Alphabandaid
Marshfield, Wisconsin, United States
Joined May 2003
1,259 Posts
P51 and Lip's

IF you retime th estock motor it pulls almost 10 amps, and makes the 2s pack pretty hot. If you stick with stock and no retime, then it pulls anywhere from around six to 7 amps in my epxperience(with 10x8 prop) and comes out warm . Methinks if pack is hot vs warm, then you'd better go 2s2p or change props.
Alphabandaid
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Old Jun 30, 2003, 03:46 PM
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Alberta, Canada
Joined Sep 2001
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I was first flying my mustang on 7x270 Nicad cells and the power was great for the first 60 seconds then started to fade pretty quickly. The cells also came out hot. Since switching to the 2s etec 1200's the initial power is a little lower but it lasts a lot longer! I generally land after 8-10 minutes. My mustang still loops funny (mushy) but will roll great. I did measure the current and came up with ~5.5 amps with a full charge static (Stock c gearbox , stock motor, and 10x8 prop).
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Old Jun 30, 2003, 05:14 PM
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Dallas,TX
Joined Jul 2001
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Not much to offer here since I've only started testing my 2 cell etec 1200 pack but i flew a direct drive motor over the weekend that was pulling about 6amps static (measured with cheapie 10 amp meter). After about a 10 minute flight, the pack was very warm but not hot (could be held in my bare hand). My cells had not been cycled so don't know if that is a factor. One observation I made is the voltage seems to hold up better than nimh cells. Meaning I don't get one minute of strong flight and 4 or 5 of mediocre flight. I get about the same performance all the way through my li-poly pack.
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Old Jun 30, 2003, 06:09 PM
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Melbourne Australia
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I have found the same with my ETECS...solid performance for the duration of the flight. Nice big loops (into the wind) and nice rolls. Mikey..how much does yours weigh ?...that might be the difference. Mine weighs a tad over 14oz, no rudder, no gear. I had to put two coins (about 1 oz) of weight :-( in then nose just to get it to balance.
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Old Jul 03, 2003, 02:07 AM
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Alberta, Canada
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Definitely more but I'm not sure how much as I've lost my scale (don't ask). It is setup for a/e/r with gear.
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Old Jul 05, 2003, 06:34 AM
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Darwin Australia
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My E-Tech 1200 2S1P pack flying in my GWS Zero has 221 minutes flying on it using a 9 X 7 GWS propeller. In this configuration it will get 14+ minutes of full throttle flying. This equates to about 5.1 Amps at flying speed.

I made two flights totalling 21 minutes of full power using a GWS 10 X 8 prop. This equates to about 6.85 Amps at flying speed.

The pack now resides in my E-Starter Floatplane and, because of higher weight and drag, is running at a higher amp draw. After only 3 flights I have not been yet able to get Amp figures as I have been to busy sorting out the water handling of the E-Starter.

With my charger I can measure the Amps while charging. The amount of Amps my charger puts out at the start of charge gives me a very good idea of the discharge level of the pack.

Hope that this gives some idea of the capability of the E-Tech 1200 cells.

Ken
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