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 When a step down transformer is rectified to dc then used to charge a battery doesnt the flow of current still end up grounded back into the secondary of the transformer? Is anything being imparted to the battery other then the action of a flow from here to there but not actually into (consumed by) the battery? If it did put something into the battery would it not gain weight? Or lose weight as it drained?
  So if a isolation transformer is also a step down with a second set of lessor winds wrapped over the other side of the isolation secondary would half the cycle be consumed in charging the battery or would it simply make use of half the cycle to impart electron flow or movement through the rectifier into the battery and back to the transformer to complete the cycle which is in use by a full cycle dependent device being run off the isolated section of the transformer? It does not seem practical to believe it all turns to heat as it passes through the battery any more then all electron flow is turned to heat when it runs through a motor.
  Is this a right or wrong mental image?
  Also is the conversion to heat the only real loss to over come as a unwanted form of waste?