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All Forums >> Radios, Batteries, Clubhouse and more >> Batteries & Chargers >> A123Racing Support >> First Post Asking For Info
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First Post Asking For Info - 7/31/2007 6:01:58 PM   
royc


 

Posts: 2
Joined: 7/31/2007
From: , FL, USA
Status: offline 		Hi all.

First post here, and a newbie where electric flying in concerned. But not new to R/C flying, first airplane I flew was a rudder only with a carrier only 27 mhz system, with a tube reciever and a tube transmitter. Yea I know, I'm showing my age...lol

I found this forum from the 123 site, I was interested in this new and marvelous new battery technology, and ordered a developer kit so I can do some testing. I did a lot of reading in here about the proper charging of these new batteries, and read the specs on it. But there is one thing I need to understand and that is the balancing. I noticed the balancing wires to some of the R/C packs, and if I understand they are connected between the cells. Would someone please explain what those wires exactly do, are the cells charged individualy, or is it a monitor system of some sort.

If there is an explanation somewhere I would apreciate pointing me to it.

Thanks

Roy
       Post #: 1

RE: First Post Asking For Info - 8/1/2007 3:49:20 PM   
A123 Racing


 

Posts: 102
Joined: 8/25/2006
From: Hopkinton, MA, USA
Status: offline 		Hello Roy,

The balancing taps used on most Lithium technology packs are wires that go to the nodes of the batteries. Lithium Polymer batteries typically have one more wire then there are cells (Ie. 4S pack = 5 wires). Each wire goes to a node on a pack so that a charger or a balancer can read the individual voltage of every cell. Some chargers charge through the balance connector because the charge rates are low. In our battery the balance connector has one less wire than the number of cells (3S pack = 2 wires). This is because we utilize the output wires for balancing also. A 3S pack has 2 balance wires and 2 output wires (total 4). The idea is the same we can measure across each cell to get the voltage. In our charger we supply 10A through the output cables. The charger monitors the voltage as it charges, if the cells charge properly then it does the balancing near the end of charge.

I hope this answers some of your questions.

Power . Safety . Life

Brian



(in reply to royc)
       Post #: 2

RE: First Post Asking For Info - 8/1/2007 5:24:50 PM   
royc


 

Posts: 2
Joined: 7/31/2007
From: , FL, USA
Status: offline 		Thanks for the info Brian, and yes I now know that the packs have wires connected to each individual node, after doing some extensive reading on this forum. I noticed in one of the post a schematic of exactly what your talking about. What got me started on this quest was from problems I was having with my batterie packs for my Bosch tools, and looking for something better.

I have another question on the balancing procedures. I noticed on a schematic in here, as you said in your reply, the charger is hooked up across the pack and then a wire is connected to each node for the balancing procedure. Does the charger charge the pack to the reccomended 3.6 volts per cell, and then after charger is off, balance the cells by using the battery voltage to direct the voltage to cells out of balance, to equalize all to the same amount within the balance range reccomended ?

Also once a battery pack has been balanced, does it need a balance each time its charged, or can it be charged a few times without the worry of an out of balance condition ? The question would be then, how often can the cells go out of balance if charged properly, and is it highly reccomended to balance each time.

I orderd two developer kits which are 6 cells each, so the ideal charge setup would be a charger and 6 cell balancer if I'm correct. I'm looking forward to getting those kits and for what I have read in here, you have a winner .

Thanks for your time.

Roy

(in reply to A123 Racing)
       Post #: 3

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