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Old May 12, 2004, 01:56 PM
My Bulldog is my copilot ..
TheLost's Avatar
Joined Feb 2004
2,263 Posts
'All LiPo, All the Time'.. I'm a little concerned (plus.. I'm an idiot)

I'd like to start switching over to All LiPo's, but im not sure what packs to start buying. The only LiPo's I use now are Etec 2s1p 700's in a Tiger Moth. My other Planes are all about the same weight (13-15oz), Use the same motors (300-350's), and use the same packs (8cell 2/3AA 650's nimh).

I've been quite happy with this setup... until now. I put my first brushless into a plane just finished (MM Switchback w/AXI 2212/34) and I can't help but think how sweet it would be with a nice LiPo.

soooo.. I'd like a nice set of packs that will work with everything. can this be done? I'm worried about mixing 2s packs with 3s packs. I would think its safer to pick one (2s or 3s) and stick with it. That way I don't have to worry about switching my charger over (oops.. forgot... *boom*).

3s packs would seem the best choice for power.. but do I need to worry about unbalanced cells more than 2s packs? will they eat my EPS300 motors?

Would I be happy if I just buy a bunch of 2s 2100, 1800 or 1200 packs? or would they have less 'oomph' then my 8cell NIMH packs..

What packs do you find you fly most (or is a 'Jack of all Trade' pack nonexistent)?
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Old May 12, 2004, 02:24 PM
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youngstown ohio
Joined Jul 2003
74 Posts
I have the exact same question, thanks for doing the typing.
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Old May 12, 2004, 05:08 PM
In need of a new name...
Clarkston, MI
Joined Dec 2002
429 Posts
[QUOTE=TheLost]
Would I be happy if I just buy a bunch of 2s 2100, 1800 or 1200 packs? or would they have less 'oomph' then my 8cell NIMH packs..
[QUOTE]

Not enough 'oomph'
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Old May 12, 2004, 05:22 PM
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East Anglia, UK
Joined Sep 2002
29,703 Posts
I am about 4 months ahead of you.


What I did and why I did it is hotsorical, but what I have ended up with is as follows.

I fly IPS planes, speed 400 planes, speed 480 planes and I want also a pack for speed 600 and an astro 05 I have.

I have a poor 2s1p kokam 560 pack that just about does an IPS justice. Not quite a mistake, but not something I would recommend.

Now I have a 3s1p Kokam 340 pack for IPS models. LOTS of power out of that if you prop right. About 40W max. But better around 25W (2.5A, 10v)

The next pack up is for geared 400 models, and that happens to be an e-tech 1200 3s1p pack. Its a perfect match. Its not sutable for DD tho unless you use a 7.2v motor. Buying today I'd get 3s1p Irate 1100. Similar size and weight but a bit punchier. does aboput 90W - 9A 10v roughly

The 480 pack is 3s2p Irate 1100. I got that cell because its similar width to a pair of 600AE side by side. That does me up to 200W .

For 400W I expect to be using 3s2p Irate 2200. 40A 10v.

The only class of motor not really covered is speed 300 - they WOULD run off 3s1p e-tech 1200 but need more gearing to be safe. For some reason I have never ever bought a 300 class motor

These packs are in general shared between at least two models each. With three packs and three models each capable of about 20 minutes flight per charge MINIMUM I simply don't need more packs. I have an hour of solid flying time per charge, and if I were to go to the field and take the charger, the first pack would be recharged by the time I have flown out the third anyway, so thats at least an hour and twenty minutes of solid flying.

In practice I fly round the house and at the local sports field, and its usually more 'grab a model and pack, and go fly for half an hour and back for coffee'



I think this is a rational approach. Standardise on a suite of packs - preferably 3s - and adjust the motors props and gears to suit them so all your models fly of teh same packs as near as possible.. That way you spend less on LIPOS but can still have loads of fun.
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Old May 12, 2004, 06:11 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,005 Posts
I'll talk about the brushless speed 300 class motors.. The MPJ, MiniAC1215/16, Himax 2015/3600 and 4100 all like the 3s1200 packs. I've got 2 2s packs that just don't get used. The motors are all geared and most flying is done at 1/2-2/3 throttle. You can always use the 3s packs at part throttle whereas an underpowered 2s is uesless.
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Old May 12, 2004, 06:28 PM
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Brisbane Australia
Joined Nov 2003
805 Posts
I will have to weigh in on the side of 3S as well (fly mainly brushless but some brushed 350 and 400 set-ups). With 2S you are looking at just shy of a 7 Cell Ni? pack in voltage which is limited in what you can do.

2S works well where you specifically plan for it. I have a T3D II CAP and a Shrike Ornithopter both of which were set up for 2S. The Shrike still uses 2S the T3D now is brushless and 3S - while it flew it needed over 9 Amps on a simple 2S pack perform.

3S of course adds other issues as you need to have a more complex charger and be able to set a higher LVC to protect the cells - value currently being debated in another thread.

What I have done is used different connectors on my 2S packs (mini deans polarised) from my 3S (Power Poles). I also use a dedicated 2S (self made) charger and a commercial (Triton) for 3S as I am also a bit thick at times and know I will get it wrong at some stage.

Of course 3S suits my flying requirements which are sport flying and 3D. Sport flying on 2S is a bit too sedate for my requirements.

Michael
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Old May 12, 2004, 10:29 PM
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usa
Joined Mar 2003
1,018 Posts
I have taken a similar approach to Vintage1. I own primarily 3S1P ETEC 1200 mah packs. I use the 1Ps for projects that are 9 amps and under:

Microjet 1615/5 APC 6x4
MM Dandy Sport Razor 300 GWS 9x7
VX-400 E-glider AXI 2212/26 Graupner Folding 9x5

I hook up the same packs in paralled with a Y connector for projects the reach 10-16 amps.

Recently, I have upgraded my li-po stable with some IRATE 1100 mahs. These will probably handle projects up to 12 amps. More than that, I will be hooking them up in parallel again. That way, my upper limit will be 20 amps.

My IPS stuff is limited to a single DD acrobipe. It happily lives on a single ETEC 250 2S1P. I'd upgrade to 340 HDs too but my interest is more focused on bigger planes, what with the new 2600 10C cells and those wonderful AXIs.

JT
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Old May 13, 2004, 08:24 AM
Rehab is for quitters
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West Middlesex, PA, US
Joined Jun 2001
4,853 Posts
I have a couple of 2S kokam HD 1500's I use on a mini wing powered by a j250 and 4x4 prop. Very good choice for this motor. I also use the 2S packs with a BN-2 Islander (dual EDP 100 motors). They fly the Islander very well but the packs are pretty warm upon use. Haven't tried 'em yet in my other GWS warbirds (300 and 350 geared motors).

Dave...
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Old May 13, 2004, 09:34 AM
My Bulldog is my copilot ..
TheLost's Avatar
Joined Feb 2004
2,263 Posts
Thanks guys! It looks like i won't be happy with the 2s packs.. Do you think its worth the price for something in the 2100mah range? or should i stick with the 1100,1200's? I think i can get most pack sizes into the SwitchBack..

As for the 3s packs eating the 300 motors.. I guess its a good excuse to add more brushless motors
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Old May 13, 2004, 10:08 AM
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Arnold , Maryland, United States
Joined Nov 2002
897 Posts
If you are going to have different size motors, you are going to need different size packs.

The 300-400 size motors like about 8 volts, but the brushless motors like 12 volts better.
So right off the bat you will want 2 series, and 3 series packs.
The 3 series packs may also need to provide more current.
So you are looking at 2S packs at 9a, and 3S packs at 14a.
To get 14a, you may even need to buy packs that are physically larger. Like irate 1800, or 2200.

So you are faced with a lot of options. Too bad one choice won't do it all......But wait, it will.
If you standardize with irate 1100mah cells, they can provide 8.8amps.
Put a connector on each cell, and use Y adaptors to join cells together, and you can make 2S or 3S packs from the same group of cells.

Make up 2- 3S packs, and have a 3S2P 2200mah pack for your 17 amp aplication.

I am doing something like that myself. And it works for same cells / different planes. The only problem I have had is that the Y adaptors, and wire bundle gets bulky as the cell count goes up.

The reason I say "something like that" is, I just bought some irate 2600s for my large plane. It would take too many 1100s to do the same job.
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Old May 13, 2004, 11:12 AM
FLYER spelled I-squared-R
fliir's Avatar
Grand Rapids, Michigan
Joined Sep 2001
1,623 Posts
For all of my larger (30amps and up) projects, I have standardized on Irate 2P 2200 (i.e. 4.4AH) packs. These are 35A continuous, 44A burst packs. I serial them together with external connectors to create 2S (for an Astro 035 Cobalt), 3S (Twin SP-480 in parallel), 5S (Astro 25 Cobalt) and 7S (Astro 40 Cobalt).

I just mount male DEANS connectors on a small piece of 1/16 ply, solder up the contacts and insulate with silicone seal. I can post a picture if anyone is interested.

David
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