Hello. I have a 2011 Corolla S. Last winter the battery was dead one day. I opened up the hood and there was corrosion on the battery terminals. I pulled the battery out cleaned up the terminals charge the battery and put it back in the car. A day later it was dead again. I started the car after a boost and checked with the voltmeter. I got a reading of 14 V. I assumed it was a battery issue so I replaced the battery with a new one. The problem returned this winter about 12 months later. The car was dead. I pop the hood and noticed that there was a little bit of corrosion. I got the car boosted and after running for 20 minutes it would not start again. The battery was dead. I pulled the battery and charge that and cleaned up the posts and cables again. I put the battery back in the car and for a couple days of the car started no problem. Today the battery was dead again. When I start the car I got 14 V at the battery with the car running. Any ideas what could be causing the battery to discharge?