Noob questions about hobby charger & cell balancing

[andrewnewman]

Greetings:

As the new year approaches I am considering buying a hobby charger and building a battery tray to charge loose (primarily Li-Ion chemistry) cells. I read the thread with great interest where folks with more experience (in both battery charging and woodworking!!) built impressive looking cell trays that are designed to work with a balancing charger.

If I understand correctly, to use one of these chargers you tell it the chemistry, capacity and # of cells in the battery (or tray in this case) and connect up (in addition to the primary charge leads) a series of balancing leads to taps on the (+) terminal of each cell. So my questions are two:

1. Since the cells are connected in series, I am assuming that the balancing leads need to "know" which cell position they are balancing for (cell's 1 through "n"). Are those little balancing connectors on the side of the charger keyed?
   
2. (This may be charger specific). Most hobby chargers I have seen have connectors for balancing leads for different numbers of cells (2, 3, 4 etc...). If I "tell" my charger that I have 2 cells but I have the balancing leads connected to the connector for the max # of cells supported will things work or do I have to make a separate balancing harness for each of the connector jacks depending upon how many cells I want to charge at any given time?

/Andy

 

[rmteo]

1. Yes.
2. Yes.

Or since you are charging loose cells (as opposed to a series connected battery pack), you can charge them in parallel without doing the balancing thing.

 

[eyrich74]

1. Yes
2. No (at least on the iCharger 1010B+) - If you make a series charging tray you make a harness that is for the max number of cells you can charge at once. Then you figure out if your charger starts counting balance cells from the negative side or the positive side.

The 1010B+ starts on the negative side.

Here is the pic:
http://www.flickr.com/photos/25375747@N02/4218865043/

If doing 4 cells I just connect the main leads and the balance harness.

If charging less then 4 I fill in cell holders from the negative side and then instead of connecting the main positive lead to the charger I use a wire with an alligator clip to the + side of the furthest holder filled.