INJURED AND CO-WORKER WERE LIFTING 24 VOLT BATTERY FROM BED OF PICKUP TRUCK WHEN HE FELT A POP IN HIS LOWER BACK. HE CONTINUED CARRYING BATTERYAPPROX 6-8 FT BEFORE PLACING IT ON SHELF FOR STO RAGE IN BUILDING. HE DID NOT SEE COMPANY PHYSICIAN UNTIL 3-25-02, WAS PLACED ON LIGHT DUTY ON 4-1-02, THEN TAKEN OFF WORK 4-4-02 WHEN MRIREVEALED HERNIATED DISC AT L4-L5.