It is not advisable to charge any Nixx based group of cells in parallel unless you want to ruin them. Due to the nature of how the voltage changes as they near full charge, the ones needing the charge most will not get it and the current into the already charged cell(s) will increase instead of decrease. In short, DO NOT CHARGE IN PARALLEL if using NiCad or NiMh. Parallel charging works fine with LiPo's or Pb cells though.