So a while back I go to leave for work and the car (I'm assuming battery) is dead, won't start. This has happened before and I think I left my map light on overnight. So I didn't think anything of it when about 6 weeks ago, I go to leave for work and it is dead again. Figured I didn't shut the door all the way and the dome light was on all night. Then it happened again a month later, Jumped it and it was fine until this evening. Left work to head home and dead again so I jump it. Make it home (about 2 miles of stop and go traffic) to where I let it run, wedging the gas down because the engine will kick off if I just leave it there in park for a good 20 min (The car probably kicked on an off a 1/2 dozen times trying to successfully wedge the gas). Then I head to the grocery store and make a pit stop at the liquor store literally across the street. Just before leaving, I'm in the car sending a few text messages and it goes dead again and won't start. So I jump it and head directly to Autozone, about 2 miles away. I ask the guy to test the battery, as I suspect the battery is on its way out. The tester indicates a full and good battery so he suggests starting the car to see the charging output voltage, which says 13.6v and tells me normally an alternator puts out 14.6v (but tells me it could be an alternator that can change it output voltage or something like that so 1 volt less than normal charging might be normal). I see that this car doesn't have an alternator and the internal battery via the electric motor charges the battery.
I buy a battery anyway, Just in case. But because it was $160 plus tax and wouldn't start literally just before the 5 minute drive to Autozone (which isn't much time to charge), I'm wondering if it's something else is starting to go bad, maybe something related to the hybrid system? Jumping seems to do the trick so maybe the battery IS starting to go bad and because it's a hybrid the constant starting is causing it the battery to be weak? I don't know anything about the hybrid systems really and looking for some advice. I'd like to avoid getting stranded AND eating a $160 battery unnecessarily.

2006 RX400h with 135K miles.

 

Do yourself a favor install the new battery. They are very small and basically control all of the computers on the car. The battery may have an intermittent cell. At least than you will eliminate the small 12volt battery. The hybrid battery actually charges the 12 volt battery. The hybrid battery actually starts the engine, not the 12 volt battery.

 

When I was in the car and it went dead. The dash lights and touch screen all started acting weird (almost like they were trying to come on but couldn't.) and all the idiot lights came on. I know there is a light that comes on to let you know there is a problem with the hybrid system specifically and I haven't seen that. So maybe it is just a bad/ intermittent battery and what you are saying about the 12v battery running the electronics, it would seem to point in that direction now?

 

Yup have seen it many times on this site and the other Lexus site.

 

Thanks, Thomas1. Appreciate the time and help.