Originally Posted by shrowell
Can you explain this "non-active balancing" a little further (or point me to somewhere on the forum where it has already been discussed)? How does keeping the car on the charger achieve this balancing? I assume the current drawn is minimal once the batteries reach full charge. What will keeping the charger active for a week (or so) actually achieve?
Given this advice is coming from you, PowerSource, I guess this is more than just theorizing.
A123 uses a very primitive way of balancing the pack, basically they are using a bleed resistor to limit current to "balanced" cells this strategy attempts to bring the out of balance cells to the same level. Essentially the pack is limited by the voltage of the weakest "paralleled" cell.
Issue here is it takes a very long time to balance the pack and this balance technique wastes a lot of energy in heat (which also requires extra energy for thermal management). There are many smarter ways to balance the pack. The one on the A123 pack is probably the cheapest way though.