How To Build a Battery Pack from A123 Cells - Page 4 - RC Groups
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Dec 22, 2006, 05:45 PM
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Jimbo45cn's Avatar
great thread Lucien. Thanks, Jim
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Dec 22, 2006, 10:36 PM
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BandDButton's Avatar
talk about a lot of fantastic information. I'm going to build two of the 7s2p packs like the ones shown in the thread using the origional pack profile. Thaks,
Dec 22, 2006, 11:20 PM
Vic and Quinn Walton
rc2xs's Avatar
thankyou for this thread lucien, it was very helpful for me when I was building my pack.
Dec 23, 2006, 02:12 AM
Use the Force!
LBMiller5's Avatar

You are Welcome Everyone!

Thanks for the kind words about my build thread. I am glad that the information presented here has been useful to so many of you!

Dec 23, 2006, 09:02 AM
FPV for Me
TaSaJaRa's Avatar
Thanks for all the pics and work LBMiller5, It has been a great help to get me started.

I have made 2 packs from my 10s pack. One 4s and a 5s, 4s will fit in my RiteWing TL50 plane.
The flight time is a little shorter. But I still have good power.
The 4s replaced 2- 3s 2100's and came out an oz lighter.
With a much shorter charge time. I look to use the 5s in a Bigger Shrike I am building.

I use the Hyperion LBA10 Li-poly cell balancer and "Xtrema" 1-10 Cell Lithium Charger for all my A123 needs.
They work great together.

Here are my first 2 packs of many more to come.

Anyway thanks again for all the work.
Last edited by TaSaJaRa; Dec 24, 2006 at 09:57 AM. Reason: added weight pics
Dec 23, 2006, 11:27 AM
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BandDButton's Avatar
Hey guys,
What is the orangish looking tape that I see in these packs, and in the above pictures, and where can I get it?
Dec 23, 2006, 11:42 AM
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everydayflyer's Avatar

Do a Goggle or Yahoo Search
Dec 24, 2006, 09:56 AM
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TaSaJaRa's Avatar

The tape in question

Here is the best price I have found on the Kapton Tape (Polyimide tape)
Kapton Tape on eBay

Took a little over a week to get it.
Jan 04, 2007, 02:10 PM
Watt me worry?
Madmax1965's Avatar
I just finished building my first two 8 cell A123 packs. I used the Solderless Power Tubes from MEC and it was very easy to assemble.

I bought two Dewalt packs on Ebay for 90.00 each (shipping free),tore them apart, no problem at all. Well I did have one problem. When I was cutting the tabs apart to seperate the cells , one of the welded tabs came loose from the cell and left little holes in the end of the cell. I am somewhat concerned about using this cell.....what do you think? I had four cells left over and didn't need to use the one cell with the holes but I would like to use it later.

Also I did not install balancing connectors because I'm not too sure how to do this. Do you solder the balancing wires to the cell tabs? I am trying to not solder anything....if you know what I mean. I have heard the A123 cells don't go out of balance this true?

At any rate I will use these packs on a fun fly plane and will try and figure out how to attach balancing tabs to an eight cell (end to end)pack later on. I am trying to figure out how to use my Hyperion LBA10 net 6s+ balancer to balance any packs over 6s ...and how in the world to wire the pack connectors. Been into electric for awhile now but this is my first step into building my own packs.
Jan 04, 2007, 03:14 PM
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Madmax.... here is how I added taps to my A123 4S packs without directly soldering to any cells.

Jan 04, 2007, 03:44 PM
Watt me worry?
Madmax1965's Avatar
Thanks bjpaul....figured someone on here knew the answers.
Couple more "ask you" types.

Would this work the same on my 8 cell pack and how would I balance the 8 cell pack using the Hyperion LBA10 net 6s+? I never had to balance more than 5 cells before and this whole "anything over 5 cells" is new to me.
Jan 04, 2007, 05:23 PM
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BandDButton's Avatar
With the equipment currently available, I think that any pack over 6 cells will require that you have two balancing taps . I'm thinking of adding taps to my 7s2p packs that I built for my Top Flite giant P-51. I'm still waiting to see who ends up with the best balancer for these cells. What I did with my packs was to check the voltage on each cell before I assembled them and made sure that they were all within .01volt. I then assembled the packs, and checked the voltages again. Finally I charged the packs to top them off, and they were ready to go.
Good Luck,
Jan 04, 2007, 06:10 PM
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I use 8S packs... but I connect two 4S packs with a "Y" connector to do it. It is very easy to balance the 4S packs individually with my Hiperion LBA10.

To balance 8S you would need two LBA10's and the necessary cables to interconnect them. I guess you would need a 6S tap and a 2S tap wired correctly on that pack. It would be simpler to just wire two 4S taps to the correct cells (one 4S on the left stick and ons 4S on the right stick) and balance individually.

Jan 04, 2007, 06:14 PM
Watt me worry?
Madmax1965's Avatar
Every cell in my two packs were @ 3.3 volts.
You are right B&D I would need two of the Hyperion LBA10 6s balancers. I just bought the unit and am reading the instructions just now. DANG!....I thought this balancer would solve my balancing problems as I understood it would do up to 12s.

Bjpaul if I can figure out how to use your balance tap setup to my 8 cell packs I think I know how to install them without tearing the packs apart. Simply make entry holes to install the tap to each cell. I would run the wire to the bottom bar on the outside of my pack. Once everything is in place then use another piece of shrink to cover the changes. Can you give me a layout for hooking up the taps as per your plan, but for 8 cells? I would guess I would need two taps, maybe two 4 cell types. This is very new to me and I don't want to make a mistake. I do understand how you did the 4 cell pack.
Last edited by Madmax1965; Jan 04, 2007 at 06:37 PM.
Jan 04, 2007, 07:33 PM
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Remember the "button" on A123 cells is Neg (-) and the can is Pos (+).

Assume two 4S taps with 1 red and 4 black wires

Tap 1:
Wire 1 (red) Main pack Pos (+) terminal
Wire 2 (black) can of cell 2
Wire 3 (black) can of cell 3
Wire 4 (black) can of cell 4
Wire 5 (black) battery bar

Tap 2:
Wire 1 (red) can of cell 5
Wire 2 (black) can of cell 6
Wire 3 (black) can of cell 7
Wire 4 (black) can of cell 8
Wire 5 (black) Main pack Neg (-) terminal

Confirm with a DVM.


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