IS IT SAFE TO CHAIN TWO BATTERIES TOGETHER FOR A 1974 115 MERC. AS I UNDERSTAND IT I WOULD CONNECT THE POS OF ONE BATTERY TO THE NEG OF ANOTHER AND THEN CONNECT THE MOTORS CABLES TO THE THE TWO (POS/NEG) POSTS REMAINING ON EACH BATTERY.<br />IS THERE A DISADVANTAGE TO DOING THIS?<br />THANKS FOR...