Aux Battery Problems

[Jerzy_In_VA]

I've had an RX400h for about 13 months, and it has 25K miles on it. Six months ago I had a problem where the 12 v Aux battery would lose power after anwhere from 3 to only 1 day of non-use (the last time the car was parked overnight in an airport parking garage). The dealer replaced the battery.

Now, about a month ago, my car is now losing battery power after about 2.5 days of non-use. The dealer started telling me about not running the radio without the engine on, etc., but the car was in my home's garage, all doors closed, even automatic sensors like the headlights and wipers turned off. The dealer now says that there's been a problem with cars not holding aux battery power "because of all of the sensors running in the car." Their only solution was to sell me a trickle charger, but that doesn't help me if I have to leave the car at an airport parking lot.

I tried disconnecting the battery when I was gone for an extended period of time, but then found out that so many systems needed to be reinitialized.

I've seen some passing comments about similar problems, but nothing posted recently. Any advice? Thanks.

[katzjamr]

Its hard to believe this dealer who is in effect saying Toyota designed a car that drains the battery in three days because of 'all the sensors running in the car'. Electrical problems are time consuming to trace, but its clear that something is draining your battery that should not be. I would call Lexus corporate and get some resolution, go to another dealer if you can because as i have said too many times, not all Lexus dealers are created equal, and when my trusted mechanic could not fix starting problems in a Ford truck, i took it to a shop that specialized in electrical problems and they fixed it in one hour.

[thesaintjim]

I went on a 2 week vacation and my 400h started right up when I came back...

[smalcom]

In May I went on an 18 day vacation, and when I returned home, my RX330 was dead (not even a groan from the starter). AAA jump started, and I was able to drive it to the Lexus dealer to pick up my newly purchased RX400h.

[RX400h]

Its hard to believe this dealer who is in effect saying Toyota designed a car that drains the battery in three days because of 'all the sensors running in the car'. Electrical problems are time consuming to trace, but its clear that something is draining your battery that should not be. I would call Lexus corporate and get some resolution, go to another dealer if you can because as i have said too many times, not all Lexus dealers are created equal, and when my trusted mechanic could not fix starting problems in a Ford truck, i took it to a shop that specialized in electrical problems and they fixed it in one hour.

I agree. Try another dealership.

[Rx330driver]

so far my car has been okay whether or not i start it...maybe once even two weeks or so. I would definately go to a different dealer and dont leave their until they solve the problem or give you a loaner car to drive. either that or carry a spare battery in your trunk. lol

[rvtravel]

I left my RX 400h at in the airport parking lot for 33 days and thought all batteries may be discharged. I opened the door, turned the key in the ignition and it started right up and the indicator showed the hybrid battery was fully charged.

MY thought: there is something else discharging the aux battery

[Jerzy_In_VA]

I left my RX 400h at in the airport parking lot for 33 days and thought all batteries may be discharged. I opened the door, turned the key in the ignition and it started right up and the indicator showed the hybrid battery was fully charged.

MY thought: there is something else discharging the aux battery

I was hoping the dealer could trace whether there's an unexpected demand on the battery, but either they couldn't or wouldn't test that, all they tested was the fitness of the battery, which they said was good. <_<

Any ideas how I can do my own test? Is that something I can do from the fuse box? Any risks when I put the voltage meter probes in there? Thanks in advance.

[Legacy400h]

It depends on your meter. I think you'd need to check for any amperes flowing through the positive battery cable while the car is off. May be a slight trickle or may be more. Some meters clamp around the cable, while others have to use probes. Check the booklet which came with your meter.

[retired00]

Ask the dealer if he can do a "load test". I once had a 1 year old car that developed a battery internal short that would only appear under load. The static readings were all fine, but it would not start. New battery under warranty cured it.