Depends what your charger can discharge at,it will have a limit.I wouldnt discharge a full pack at over 5 amps though or by the time their done they will be very,very hot. AS for a cutoff voltage standard is 0.9v per cell or 5.4v per pack. I am assuming since you said 7.2v pack you have nimh or nicd batts.In case you ment 7.4v as in lipo dont discharge below 3.2V per cell or 6.4 per pack to be safe.