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Old Jun 27, 2003, 10:20 AM
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E-Tec Vs Thunder Power

Hi!

When comparing E-Tec 1200 3S2P to Thunder Power 2100 1S3P
I' m having almost the same weight but 300 mA more with the E-Tecs... C-rating seems to be the same so.....
Am I right or?

Peter
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Old Jun 27, 2003, 12:04 PM
luc
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wrong
3S2P ET will give you close to 10V and 2400 mA
1S3P TP will give you close to 3.6V and 6300 mA
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Old Jun 27, 2003, 12:15 PM
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I think he meant 3s2p ETec 1200s vs the TP 3s1p 2100s...

The ETec pack would weigh closer to 5 ounces. The TP pack is 4.5 ounces. You do of course gain a tad more capacity with the ETecs, but at the expense of that near 1/2 ounce weight gain.

Based on current pricing, the ETec loose cells would cost you around $80 and you would spend a few hours assembling them. Or, you could buy premade packs and the price would be closer to $100. The Thunder Power packs come completely assembled for $79.95.

Something else to consider is the form factor/shape of the packs.

Under load, the TP packs will develop slightly higher voltage.

Jason
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Old Jun 27, 2003, 12:21 PM
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The TP pack would be my choice. I saw them fly at SEFF and they perform very well. WEight savings is about .5 oz and they are thinner, but longer. So if you fly with the 3s2p pack stacked 6 cells high ofr CG, the 2100' s will need some weight to make up for it.

Kirby
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Old Jun 27, 2003, 12:26 PM
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Hi Luc,

You're right because of my typo....
I meant TP 2100 3s1p: 4.7 oz: 140 gram 16/22 amp
and E-Tec 1200(2400mA) 3s2p: 150 gram 15/20 amp

So the difference is indeed not that much 300 mA and 10 to 15 grams more for the E-Tec and a little less C- rating...

My point is that I always confusingly thought that the Thunderpowers were giving a much better weight/ mA rating then the other LiPo's, now I think the choice is more:
Which cellsize fits my model best...

Peter

Edit: As LVRC Flyer says: the price difference is something to take into your decision too...shipping to Europe for the TP's is $6,50 more but the E-Tecs are indeed $89 if you solder them yourself...

Decision is made on formfactor I think...

This is what we Dutch call: "miereneukerij" (antfuc****)
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Old Jun 27, 2003, 01:20 PM
luc
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ok, so I still disagree on the amps: 3S1P TP is given for 5C, so around 10A, whereas 3S2P ET delivers the same kinda percentage delivery at 16 amps.
All depends on how many amps you need: till 10 amps, go to TP (cheaper, lighter).
10 to 18 amps go to ET.
One good advice: avoid soldering yourself the packs, it's not ez, even with alu solder... If the solder is not very good, you quickly have imbalance and ruin the packs (don't ask me how I know...)
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Old Jun 27, 2003, 02:36 PM
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Yeah, I was wondering why everyone was recommending the ThunderPower pack...

The Etec 3S2P will run at 16A continuous, or up to about 20A in bursts. On the other hand, the TP 3S1P only runs 10A continuous.
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Old Jun 27, 2003, 02:47 PM
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Hi Luc,

http://www.espritmodel.com/ sells Thunder Power and on their site it's stated they are 16/22 amps???

Peter
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Old Jun 27, 2003, 02:48 PM
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Quote:
Originally posted by mkirsch1
Yeah, I was wondering why everyone was recommending the ThunderPower pack...

The Etec 3S2P will run at 16A continuous, or up to about 20A in bursts. On the other hand, the TP 3S1P only runs 10A continuous.
Well I'm confused now because according to the data on the Esprit site, the 3s1p pack of TP cells can handle 16A continuous and 22A burst...is that incorrect?

http://espritmodel.com/accesories_batteries.html#LiPol

Drivie
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Old Jun 27, 2003, 03:02 PM
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Something everyone seems to forget is voltage under load...

The TP packs are good for over 90% capacity at 6C (12.6 amps). However, the ETecs may in fact deliver over 90% capacity at slightly higher current draws (about 16 amps continuous).

But again, lets talk voltage. Under load, the TPs deliver higher voltage. That means more power. This weekend at SEFF I flew 2 airplanes that had previously flown on ETec 3s2p 1200s and then back to back with the new TP 2100s. On the Whattmeter, the TPs deliver more watts and more voltage under the same 12 amps loads. In flight, this was readily noticeable as it took less throttle to hover the plane when it was powered by the TPs and the vertical climb was better. As another note - the TPs also delivered more voltage at 22 amps for short 15 second brusts than the 2p ETecs in another model.

Yes, you do gain more capacity with the ETecs at a slight weight penalty. However, the TPs deliver more voltage/power given the right amount of current draw.

I also witnessed the TP 2100s in a 2s1p form fly in a VIP pylon racer with a Hacker motor pulling near 20 amps continuous - the pack delivered excellent power for around 6 minutes of flight. Of course, at this 9C+ avergae draw capacity delivered was not quite 90%, but it proved just how durable the TP cells are (Though this is not recomended practice for a pack since it will significantly decrease cycle life). In this case, the ETecs would have swelled and lost capacity/performance even on the first flight. The TPs were only very hot and used again the next day after taking on a full charge.

How many amps will your motor be pulling?

Jason
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Old Jun 28, 2003, 04:36 AM
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argh. I was planning on a 3s3p etec 1200 pack to replace a 10-cell kan pack, would a thunderpower be better?

the tp's deliver higher voltage, but can't handle higher C, etecs are lower but will take higher current... there's a curve here, what's the crossover point?
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Old Jun 28, 2003, 09:36 AM
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Quote:
Originally posted by luc
One good advice: avoid soldering yourself the packs, it's not ez, even with alu solder... If the solder is not very good, you quickly have imbalance and ruin the packs (don't ask me how I know...) [/B]
Hello Luc,
I understand that it is very difficult to get Thunder Power Batteries right now, and there is no real flight test for you to compare.
You will see this change in the next few months.
I am also making an effect to make Thunder Power reaching France in the next few week for major summmer evens.

The success stories of Thunder Power will be cover by many magazines in the next few months.
My priorities as below:
1)Low AC IR (also low and consistance dynamic impedence)
2)High burst current
3)High voltage
4)High discharge
5)Form/sizes
6))Highest energy density(Our dynamic power series)

*As you can see, I have put 3 other criteries above high
discharge, those are very important factors for high performance flight.
*You can also push TP-2100 to 6 or 7C with some loss of capacity if operating with some air flow.(trade off is always voltage and cycle life)

Regards,
Charlie

Thanks, Jason
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Old Jun 28, 2003, 12:07 PM
luc
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Hi Charlie and Jason
The problem is the lack of standard: If we take as a standard to get 90% capacity, Charlie, who is honnest, says the TP deliver 5C, i.e. 10.5 amps. With the same percentage, 2P ET deliver 7C, i.e. 16A.
I am sure we can suck 16A(or even more) from a TP pack, and 20 from a 2P ET pack (I did even 22 amps for test and it works) but, as Charlie points out, trade off is always voltage and cycle life.
So my feeling is that what is written in the site as 16 to 22 amps for TP is overrated (at least gives below 90% delivery).
My conclusion would be:
If you want to keep a 90% delivery rate:
below 11 amps, 3S1P TP
from 11 to 16 amps, 3S2P ET


Out of that I like a lot the TP for their size as they are quite narrow, very good for my pylon racers. I would just wait to get the 10C at 90% on 2000+ mA cells , which has been announced for new ET by Dave (no release date, of course, for not damaging present sales, I guess).
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Old Jun 28, 2003, 12:15 PM
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I'll put my $.02 in here as well. I've been using E-Techs in a variety of helicopters, including a Hornet (3s1p...), a Corona (2s4p...) and a Logo 10 (5s6p), for quite some time now.

Lately, I've been doing quite a number of tests on the Logo, trying to find just how far these packs can be pushed. I originally was concerned about the instantaneous current capacities because I've had a few instances where the packs of shutdown, causing crashes. Using a Whattmeter I found that my original 4s6p configuration was pulling in excess of 60 amps for brief periods under extreme loads. This confused me at first because initially the current levels were lower, in a more "normal" range, but after a few minutes of moderate loads the current levels shot up, eventually causing a shutdown. The reason for this is because over time the voltage started dropping steadily, which means the current has to rise for the same levels of power.

What I've found is that by going to a higher series configuration, in order to get a higher pack voltage (i.e. -- 5s vs 4s...), the "worst case" current loads could be reduced from 60+ amps to about 40-45 amps, which is low enough for this application that the cells don't start shutting down.

Primarily for comparison purposes, I got a 5s4p Thunder Power pack (actually one 2s4p and one 3s4p...). When I ran it through the same series of tests I was very much amazed to learn that no matter how hard I pushed it, I couldn't get it over about 35 amps. I had videotaped the Whattmeter readout and when I went over the tape I discovered that I never saw the same kind of steady voltage drop that I saw with the E-Techs. I don't have a minute-by-minute comparison yet, but I hope to get that today.

Although Jason has been trying to get me to "cross-over" into the TP world (), I have resisted to this point because I have definitely seen some advantages in using E-Techs, mainly because they are more readily available but also from a form factor point-of-view (the E-Techs are narrower which makes it easier to get them to fit in some applications...). The availability problem will go away soon, as Charlie ramps up production, and he is also addressing the form factor issue which is more important for smaller applications I think.

Anyway, I'm definitely seeing that the TPs do in fact work better, especially in larger applications, due to their ability to hold the voltage up for a much longer period, reducing the current requirements. The TP packs I'm using are based on the "older" 1950 mAh cells and the new 2050 mAh ones promise to be even better. It will be interesting to re-visit these tests when the new E-Tech 2000 and 3000 mAh cells become available. For now, however, I am going to definitely be on the TP side of the tracks, at least for my Logo 10. I'll continue to also use the 5s6p E-Tech pack as well but I'll be a little more careful. I also have a 5s5p pack setup but I'll probably just reconfigure those into a pile of "extra" 3s1p packs for the Hornet. Let see, that should let me fly it continuously for about 4-5 hours! Actually, I rarely even make it through a whole pack with this nervous little insect! I ususally have to go lie down for awhile after ten minutes!

-- Gary
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Old Jun 28, 2003, 12:33 PM
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Luc --

One point I was "missing" before is that with the E-Techs you need to worry more about current because of the voltage drop. With the TPs, this is less of a concern because the voltage stays higher.

If you are only comparing current, a better comparison might be to measure the power (watts/amps/voltage) after 15 minutes or so. It has been my experience that at that point the TPs will "require" less current for the same number of watts.

-- Gary
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