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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> A123Racing Support >> F3A Pack(s)
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F3A Pack(s) - 7/28/2007 3:22:31 AM   
gene webber


 

Posts: 80
Joined: 7/30/2005
From: Sacramento, CA, USA
Status: offline 		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
       Post #: 1

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


 

Posts: 81
Joined: 11/28/2006
From: Rantoul, IL, USA
Status: offline 		I'm no guru, but the config would be 6S2P- 19.8 volts, 4600 mah. It would weigh approx. 840 grams. Don

(in reply to gene webber)
       Post #: 2

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


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline 		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.

(in reply to DLS II)
       Post #: 3

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


 

Posts: 80
Joined: 7/30/2005
From: Sacramento, CA, USA
Status: offline 		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

(in reply to Tex Gehman)
       Post #: 4

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


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline 		How many watts do you figure yu need? Tex.

(in reply to gene webber)
       Post #: 5

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


 

Posts: 80
Joined: 7/30/2005
From: Sacramento, CA, USA
Status: offline 		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

(in reply to Tex Gehman)
       Post #: 6

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


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline 		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.

(in reply to gene webber)
       Post #: 7

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



Posts: 248
Joined: 6/21/2003
From: Mission, BC, CANADA
Status: offline 		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.


(in reply to Tex Gehman)
       Post #: 8

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


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline 		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.

(in reply to bobferguson)
       Post #: 9

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



Posts: 9858
Joined: 12/12/2001
From: slc, UT, USA
Status: offline 		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

< Message edited by dick Hanson -- 8/8/2007 1:56:19 AM >

_____________________________

I am watching you
Libby

(in reply to Tex Gehman)
       Post #: 10

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


 

Posts: 1
Joined: 3/24/2006
From: Chandler, AZ, USA
Status: offline 		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

(in reply to dick Hanson)
       Post #: 11

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


 

Posts: 80
Joined: 7/30/2005
From: Sacramento, CA, USA
Status: offline 		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

(in reply to dick Hanson)
       Post #: 12

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


 

Posts: 46
Joined: 5/9/2007
From: Winnipeg, MB, CANADA
Status: offline 		Gene: 2P is only 4600 MAh. Did mean to say 3P? Tex.

(in reply to gene webber)
       Post #: 13

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


 

Posts: 80
Joined: 7/30/2005
From: Sacramento, CA, USA
Status: offline 		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

< Message edited by gene webber -- 8/8/2007 11:19:19 PM >

(in reply to Tex Gehman)
       Post #: 14

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