Is 'Balance Charging' multiple Li-Ion Cells from different states of charge OK?

JP Labs

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I currently have 6 TF Protected 18650 cells in use in various lights, and I'm looking for a full-featured hobby charger which can charge them all at once, even from significantly different states of discharge. Say, 3.5 to 4.0 volts in different cells. Parallel charging clearly won't work, since connecting any two cells at different voltages in parallel would pull too much current.



So, I've been searching and reading here, and learned a bit about series charging with a 'balance charge capable' charger like the Turnigy Accucel 6. BUT....I'm not clear on how much deviation in state-of-charge, or cell voltage, can be accommodated by such a charger. I read the manual, but I don't understand the specification, which states:



Current drain for balancing LiPo: 200 mAh/cell



Since mAh is a measure of capacity, not charge current, I don't get it:thinking:. Is this a typo, and the charger can actually adjust the current for each cell by up to 200 mA? Or, does this only apply in balance discharge mode, and there is no limitation in balance charging mode? If they truly mean it can only accommodate a 200 mAh difference in charge level, then the specification does not seem to take charge duration into account, as the device capability would actually be limited by current capacity of each balance channel, I think.



More specifically, can I use such a charger to 'balance charge' cells of significantly different charge levels, as long as the cells themselves are matched, or is balancing only acceptable for cells used in a single device, so their charge levels will never be too far apart?



Any help understanding this will be appreciated, as I'm trying to learn all the applicable operating procedures BEFORE moving beyond my simple, 2-bay, dual channel charger. I'd expect a pack charger to be able to safely handle such a situation in case of a failing cell, but I don't want to make any assumptions about charger capabilities that could result in an overcharge, or a wasted purchase.
 
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