Why does my battery die in the cold? Which battery is it? I drive a 2009 prius. Since winter has started my car is dying when it gets super cold outside. Is this due to the 12 v battery or the hybrid? I’ve jumped my car and driven it back and forth to a store about 40 minutes total and it seemed just fine. but this morning it was dead again. I’ve read that a prius will still drive with out the hybrid battery working so does that mean replacing the 12 v would fix my problem? I’ve never had the hybrid battery light come on either. This car is my only means to work and i’m broke as hell, please help out.