This is an embarrassing newbie question. I left my ignition on and the battery died. I bought 12 v battery charger, .75 amp. But the charger is flashing red. Red means, "the battery charger has AC power available and that the microprocessor is functioning properly. If the red light continues to flash, then either the battery voltage is too low (less than 3 V) or the output alligator clips or accessory ring terminals are not connected correctly. " It's connected the same way I successfully connected my battery maintainer all winter. What does the other mean?