Another option for solving my system energy lost (due to heat), in a complicated electrical infrastructure, is to produce portable battery packs. when the user show/swipe the membership card he/she receives the battery pack, which plugs into the bicycles and only then the bikes can be removed from the rack!!!
the user uses the bicycle, load the battery, brings the bicycle back to the rack, once again (but reverse) only when the bikes are plugged to the rack - the battery pack comes out!!
The user brings the battery pack back and the battery pack either serves more users before being discharged or taken to be discharge in the main power plant (according to battery load level).
This is a more sophisticated system for the user, but it allows direct discharging from small portable battery to main static battery (that distribute electricity to the park). this system prevent energy lost due to heat (in electricity "flow in the grid") and also the method prevents theft of mechanisms and vandalism to the system.