If the ciggy lighter is permanent live(?) just put in power here for engough time to operate the CL, it does have DEFEAT mechanisms on the boot bonnet.
GET A NEW BATTERY!!
I had similar probs on mine(cos) in that the CL would not work when batt got flat, it is then I discovered that a previous owner had taken the rods off the locks to the key part so key did not unlock it, had to power up through boot light for 10 minutes to operate CL.
tabetha