My vehicle has a bad battery at 7500 miles. Could be a fluke. But the tow truck guy said that leaving the key FOB in the car drains the battery. I do leave it in overnight in my integral garage. Any truth to this? My 2009 LS had a similar setup and the original battery lasted 6 years with the key in, overnight, the whole time.

 

I would say that it could have some drain on your battery but kill it in 7500 miles? Not a chance.

Lexus will change out the battery under warranty.

 

Yup, they are doing so right now

 

I have heard that it can shorten the battery life on the fob. The Lexus service people change my fob battery at service.

 

Key FOB battery maybe, no way it caused your RX's battery to fail @ 7,500 miles..

 

Leaving the key fob in the car shortens the key fob battery but not the car battery. There are some bad car batteries. Mine had a short with less than 2000 miles. Thank goodness for great dealers because the Lexus warranty on the replacement battery is different!