Starting several years ago SPC Racing was the very first RC battery company to test every Nimh battery pack sold and we were the first RC battery company to test each and every LiPo pack sold and we continue to do so even today. All SPC Racing LiPo.s are tested just prior to shipping using an ESR meter.  If the individual cell voltages and IR's do not meet our specifications, the pack does not ship.  That is our promise!