I've just charged my 12volt battery in rear of 2009 RX 450h . Disconnect the negative terminal as stated in the owners handbook before connecting the charger. When recharged reconnect the negative terminal and power up the hybrid system . Settings will be restored automatically. Initialise the rear door as in handbook. WARNING don't close the rear door as you will to crawl into the boot via the rear seat to manually release the catch. Just follow handbook, then no problem. Mike