My battery died after my 2007 RX400h sat in the garage for 17 days. Nothing happened at all when I turned the key. After a jump, the engine stopped in about a minute. The hybrid battery worked as I backed it out of the garage. Driving for 15 minutes all seemed normal. Now after sitting for a few hours the battery is completely dead again.

Will the 12 volt battery continue to charge if the engine is not running? How long do I need to drive after a jump?

 

I have a 2006 400h and the 12 volt died in the cold (I go to school in upstate NY), it required a jump and then I went ahead and had the 12 volt replaced. Everything works fine now.

If you're not willing to replace the 12 volt (which it seems you may have to), in order to recharge the battery a bit I would recommend putting the drive in B and driving for about a half hour or more.

EDIT:
Also, the battery will not charge if the engine is not running.

 

I've now had a second jump, this time by someone from the Lexus dealer. After the first jump I only drove about 5 miles, which was not enough.

The Lexus mechanic told me a couple of things:
* the 12 v battery continues to charge even when the gas engine is not running. There is a small alternator driven by the hybrid battery.
* it takes at least 30 minutes to give the 12 v battery a minimum charge.

 

Ah okay, I had not heard that the hybrid battery will charge the 12V, that's good to know.

 

I just returned from vacation. After 8 days no problem and my Auto lights were not turned to Off. I was told if I were going to leave it for 3 weeks or more I should disconnect the battery.

 

I went on vacation for over a month, did not disconnect my battery my 400h start right back up, I did make a quick 40 miles round trip to charge the battery a bit just to be safe.

 

Putting it in B isn't going to do anything except give you worse gas mileage.

The 12 volt battery is charged by the traction battery. There is no alternator. The engine does not have to be running to charge the 12 volt (but the vehicle does have to be in READY mode).

 

I apologize, that was just what my rep said to do after the battery was jumped haha

 

I find that a lot of the Lexus sales reps know less about the car than the people who actually own them.

Where did you mount the sub in your RX? I find the Mark Levinson system is definitely lacking in bass.

 

It's a 10" self-contained unit. The amp is built into the box itself. The wires run under the seat and (will have, after this weekend) a quick connect/disconnect built into them so that I can take it out by just unclipping the wires.