F3A Pack(s) (Full Version)

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gene webber -> F3A Pack(s) (7/28/2007 3:22:31 AM)

Hi Guys,

Can I ask you A123 guru's a couple questions?

If a guy wanted to build an A123 pack suitable for an F3A Pattern plane what would it take?

Here's the parameters:

1. Capacity: 5000ma

2. Voltage: Aprrox 18v

3. Configuration: Example, 6 parallel, 4 series (I'm not real savy on how you get the necessary voltage and capacity.)

Cell weight is approx 70gms each, so what would it weigh?

Thanks



DLS II -> RE: F3A Pack(s) (7/28/2007 3:26:24 PM)

I'm no guru, but the config would be 6S2P- 19.8 volts, 4600 mah. It would weigh approx. 840 grams. Don



Tex Gehman -> RE: F3A Pack(s) (7/29/2007 12:31:44 AM)

I'm using 6S2P pulling 70A static in my Venus 40. It will do all I ask in the Aresti style of flying. A larger plane would like to have more. A 2M pattern machine would need a lot more. Tex.



gene webber -> RE: F3A Pack(s) (7/29/2007 1:03:25 AM)

OK, how much more? Would I need 2-6s2p packs? I will be using an AXI 5330/18 for power.

Just trying to see if A123 batteries are a reasonable alternative for LiPo batteries. They sure sound good to me if weight doesn't overcome their advantages.

Thanks Gene



Tex Gehman -> RE: F3A Pack(s) (7/29/2007 1:31:29 AM)

How many watts do you figure yu need? Tex.



gene webber -> RE: F3A Pack(s) (7/30/2007 5:40:08 PM)

Hi Tex,

Thanks for responding to my feeble questions. Most of the guys running lipo's are kicking out about 36v and watts vary, but seem to run about 2,000 watts. I could be wrong on the wattage number. The Axi website says 1850watts or there abouts running at 29v.

I'm looking for a 7-8 minute flight, I don't fly FAI which is the most demanding, they require more power and duration. I just like the idea and benifits of the A123 cell, besides its a bunch cheaper. If I can reconcile the weight and adequate run time issue I,m going to be a A123 kinda guy......

So mucho gracias for all your info and effort.


Gene



Tex Gehman -> RE: F3A Pack(s) (7/30/2007 7:17:56 PM)

So, if my 6s2p gives me about 19-20v under load of 60-70A you could extrapolate from there. Seems like about 11s would get you in the voltage ballpark, and 2p would give lots of duration. I just do 5-6 mins of aggressive aresti style flying with lots of tall vertical pulling (est) 60A and usually burn less than 3000 MAh from the 4600 pack. Tex.



bobferguson -> RE: F3A Pack(s) (8/7/2007 11:24:49 PM)

Could supply more information on your Venus 40? What motor? How are the batteries mounted. Can you change the batteries without takiing the wing off? Did you have to modify the firewall to mount your motor? What do you use to charge your batteries at the field? I would think a 6s2p would kill a deep cycle battery petty fast. Pictures would be great.
I have a electric Pulse XT that I use 4s2p packs and am looking for another 40 sized plane to use A123 packs.

Thanks Bob
quote:

ORIGINAL: Tex Gehman

I'm using 6S2P pulling 70A static in my Venus 40. It will do all I ask in the Aresti style of flying. A larger plane would like to have more. A 2M pattern machine would need a lot more. Tex.




Tex Gehman -> RE: F3A Pack(s) (8/8/2007 1:44:15 AM)

Bob: I have a cradle to hold the plane inverted and an electric screwdriver. The wing removal takes no time. The batteries are in SPTs and I have them taped together so they make a square pack of four columns of three cells. They're held in with a Velcro strap. I use a MaxCim 'D'wind and 4:1 GB/with either 12x8 or 12x10 APCe. The mounting is easy with the firewall mount made for the motor. I have a true deep cycle RV battery which allows me to do three charges on each of my packs for a total of up to eight flights in a morning. I also have a Honda 1000 for charging and using my power supply when I'm away for longer periods. Tex.



dick Hanson -> RE: F3A Pack(s) (8/8/2007 1:55:39 AM)

Lipos can only be hit so hard - then they die an expen$ive death
I went to A123 and am glad I did -I fly till the motor poops out on lo ESC setting -using 2amps from the "2300" to refill. the boys who love to blow the muney on LiPos will sing their praises but if yo u build a light pattern plane -the A123 will give you a faar better bang for the buck
I flew pattern -built pattern planes etc for many years - this is the best setup I have seen for just plain ol fun flying it so far I have just the two 4 cell powerd 3.4 lb pattern models - but they go like stink and will do all the tricks on the single packs



jrussell -> RE: F3A Pack(s) (8/8/2007 6:15:37 AM)

Dick,

are you saying you have two 3.4 lb planes powered by just 4 cells ea? or are you saying 3.4lb plane 2x4cell?

What size are the 3.4lb planes? I am wanting to go a bit bigger than my current planes and thinking A123, so trying to gather some info



gene webber -> RE: F3A Pack(s) (8/8/2007 8:48:54 PM)

Hi Dick & Libby,

Ya know Dick I'm trying to see if I can make the A123 batteries work for a 2m pattern plane. Tex in a previous post thought 11 cells would get me to the approx. voltage for an Axi 5330/18 11x3.3=36.3v puttin out about 2,000 watts.

So here's my questions:

1. Could I build a pack with 6s and 2p?

2. Would that give me 19.8v and 6900ma?

3. Could I combine 2 of these packs in series for 39.6v and 13,800ma? Or is my electrical knowledge and calcs faulty?

I think I read somewhere on this or another site a dewalt brick of 10 cells weighs approx. 1.5lbs, so that would put 16 cells at 70gms at approx.2.5lbs, add some wire and packaging and I should be under 3lbs.auw.

Do you or anyone else think this would work on a 11lb pattern plane?


Thanks Gene



Tex Gehman -> RE: F3A Pack(s) (8/8/2007 10:10:51 PM)

Gene: 2P is only 4600 MAh. Did mean to say 3P? Tex.



gene webber -> RE: F3A Pack(s) (8/8/2007 11:05:30 PM)

Hi Tex,

Well, my reasoning goes like this: 6 cells in series makes 19.8v nominal, but I only get 2300ma, add 2 cells in parallel @2300ma each I get 4600ma.These 8 cells would make 1 pack. So if I add the 6s@2300ma and 2p@4600 I get 6900ma......right? I'm not really sure how to get where I need to go, but I'm tryin'. Then if I hook up 2 of these identical packs together in series I get my 40ish volts and enough run time because of the paralled cells and there is peace and happiness in my world, not to mention at half the price of LiPo's. Most of the guys running LiPo's around here are using 2-18.5v 3700 to 5300ma packs in series and getting 10 minutes or so of flight time.

I don't know if I can build a pack like this and have a charger do the cell count and all the other stuff so it will charge properly without creating an IED. Sure hope not!!!! But this A123 cell stuff sounds good to me if it doesn't get to heavy and I don't need a Three Mile Island battery charger to charge em up.

Thanks

Gene



gene webber -> RE: F3A Pack(s) (8/8/2007 11:07:08 PM)

Sorry, double post deleted.



Gene



Tex Gehman -> RE: F3A Pack(s) (8/9/2007 12:38:44 AM)

Eh, Gene, it is faulty reasoning. To get a 6s 6900 pack you need 18 cells. Three six cell packs in parallel. Sorry, Tex.



gene webber -> RE: F3A Pack(s) (8/9/2007 11:37:48 PM)

OK Tex,

I see the error of my way. After rereading your post about using 11s to get the voltage I need, I found out if you mate 2 packs together whether for voltage(series) or more milliamps(parallel) they must be of the same configuration. So, you are right, I need 22 cells to get a 36v pack and 4600ma (11s2p) for my pattern plane. That puts me in the 3.5lb weight area. That's a no go. Dang it!

Thanks for your time and help bro....

Gene



dick Hanson -> RE: F3A Pack(s) (8/10/2007 12:58:38 AM)

If you try to exactly duplicate the voltage /amperage advertised for LiPos - then you are lost from the get go
first: the 10 cell pack is actually a 33 volt volt (nominal voltage pack) and two packs is 50 ozs.
if thatis excessive - you are ool.
the BUT is - I don't know of anyone who has optomized a setup for F3a - I know about the upper voltage rule so the 3 lb pack seems the reasonable approach for the current rules (no pun).
If the right motor /prop is used (and I don't have any experience in sorting out this size motor ) it all should work as yo can beat the crap out of the cells
I run mine flat in the air -really - no harm
The present LiPo packs have to shut down early or you ruin em pretty quickly . I see it all the time
based on the LiPos I see - you have to quit at 60% -( sound right?) whereas the 123 can go till they quit.) it doesn't harm em
I have no urge at the present time to try a 2 meter as my smaller ones are just toooo much fun and zero cost to operate .
I may get sucked into tho -



Tex Gehman -> RE: F3A Pack(s) (8/10/2007 1:27:12 AM)

Dick: I like pattern too, but am not sponsored, so its only the smaller planes so far. My Venus 40 is blowing me away with fun! I'll probably go to the Venus II this winter, now that I have experience with the A123s. Certainly would not do it with LiPOs as I'm not a rich guy. [:(] Tex.



gene webber -> RE: F3A Pack(s) (8/10/2007 1:36:50 AM)

Hi Dick,

Yea, I know the voltages and amp capacity are different between the two cell types (A123 vs LiPo), not to mention weight for a given amount of power. But I sure like the advantages the A123 cells have. If I can build a plane at 7.5lbs or under-no problem, but there is the paradox. AUW is 5kilos or 11lbs. , going to be pretty difficult to do that.

Consider yourself sucked in....lol

Thanks for your input.

If I might make a suggestion, could we put Libby under the employ of Homeland Security or INS?

Gene



dick Hanson -> RE: F3A Pack(s) (8/10/2007 4:11:02 AM)

when I did my EMC2 - what over 10 years ago - allframed was 54 ounces then all equipped was 10 .25 lbs l. solid foam surfaces 1/16" sheeting - fibreglass fuselage aluminum gear YS1.4 etc-pipe and over 1100 squares 2x2
then I did my homely Petrol Petrel with ZDZ40 gasser at 1280 squares again sold foam surfaces etc.. 11 lbs
frankly I think the majority of the current pattern planes are overbuilt - for the task- and I am familiar with the all carbon stuf -which I really don't care for
at all-
not cost effective in my book.
the motor and batts in A123 will hit close to four lbs -so a balsa framework model is the way to go - that and again foam surfaces covered with light wood and film covered
no carbon fiber aside from the wing tubes is req'd I have my new plane about half built -doing it again for the new ZDZ40 but it could go either way gas or electric.



SMacafee -> RE: F3A Pack(s) (9/27/2007 3:37:35 AM)

Theres a thread on this subject here with some peoples experiences using A123's in 2M pattern planes.



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