Before calling Toyota I would like some feedback from you guys--while just 8 months old I started having problems with my 12 volt battery being dead once a month or so. Got advice here about locking, etc so as not to drain the battery. Despite that, it happened 4 more times, went to Toyota, they replaced what they said was a bad battery for free. Now it is happening again--new battery is a year old and the car has been dead 3 mornings this month. When we put the battery charger on it, it makes a clicking sound and lo! the battery comes up immediately into the green, drives fine, starts up again at my destination, etc. Is it possible that it has a bad relay or something? (it is < 2ys old, 12K on it--seems to go dead after sitting for more than one day) Thanks for any insights...
I wouldn't have tolerated this situation as long as you have. The replacement may still be covered under the original warranty, ask the dealer. If not, it had a 1 year unlimited mileage warranty. Trickle charge the battery. When you know it is fully charged get the voltage readings. If the battery isn't holding a charge it will need to be replaced. If something is discharging the battery then the dealer will have to diagnose the problem & fix it under warranty. If an aftermarket part or mod is the culprit then this will be on your dime. Good luck.
Since you say that the 12V battery won't accept a charge, yet it fails to start the car, then I would say that the 12V battery needs to be replaced again. It's possible that a relay is bad and is staying closed when it should be open. If you have a digital multimeter you could measure battery current when the car is IG-OFF (you'll have to lock the doors and keep the Smart fob well away from the car for an accurate measurement.) If the quiescent current draw is more than ~30 mA then I would suggest looking for an electrical problem. Also, it appears that you are not driving the car much with only 12K miles after 2 years - so you may want to use a battery tender or else hook up a battery charger 2x per month to keep the 12V battery in good shape.
