My '51 Chevy is 12 volt, with Petronix. Went to start it tonight, turned the key "on", hit the starter button, but the battery was dead. My 12 volt Battery Tender has stopped working ..... I connected my large charger to the car, only at 2 amps., then went into the house. After 5 to 10 minutes in the house, I realized I did not turn the key off, before connecting the charger. Key was still "on" for that short time. Did I mess up the Petronix, by leaving the key on, with the charger running? Battery is still charging, haven't tried to start it up yet.