Gyuri

I have a 2010 RX450H and if I don't use it for more than a couple of days the battery which was installed 8 months ago by Lexus totally discharges. I have changed the 12V battery every year in the last 4 years and the Lexus dealer cannot find the problem. I don't drive much (have now about 65,000 miles) but still see no reason for this to happen. Anybody else with the same problem and any solutions?? Aside from that I never had a mechanical problem with the car.

salimshah

Is that couple of days a month?

I assume the charging system has been checked. The there is a issue with a load ... lights left on, accessory or after-market add-on. You may like to invest in a battery tender (keeper), specially if you dont drive often enough. Lastly the new battery can be defective too.

Salim

Gyuri

I meant if I don’t use the car for two consecutive days the battery totally discharges.

Lexus checked the hybrid battery and it’s good according to them. I make sure everything is turned off when I leave including removing my iPhone charger from the socket. I was hoping that I could survive without a trickle-charger, but that would be the last resort. Still it is down to either the charging system or there is some current leakage and Lexus cannot figure out what is the cause.

Gyuri

i will take the car to Lexus this week here in Vancouver, BC. I will ask for the battery to be replaced (still on warranty). What else should I ask? This going on for 4 years since I moved from the East and started with this garage. The car was always with me first hand.

riredale

Well, SOMETHING is draining the 12v battery big-time. It should go for months in an airport parking lot without problems.

My understanding is that Lexus can put an ammeter in the circuit to see just how much drainage is happening. Could be a stuck relay or some function coming on periodically. Perhaps the testing device can track over time.

Gyuri

This is very useful - I will talk to them to monitor the battery and I hope they have an amp meter as you mentioned
which I assume will monitor from the fuse box area (fuse by fuse) to see if there is a regular drain or something occurring irregularly.
I will leave the car with them for a couple of days if necessary.
Beyond that it should be the charging system not doing its job, which is what they checked in the past. Being the 4th battery I doubt that faulty battery is the problem.

I will get back after the dealership has dealt with these issues. Thank you for the help.

Gyuri

See my reply above to Salim, it was meant to you as well. Thank you for the good advice.

riredale

And, by the way, it probably makes sense to carry along a jump starter battery. The one I have is about the size of a big bar of soap and it uses lithium batteries inside. It's unbelievable in that it can crank a V8 if necessary, though with your hybrid there's no cranking required if the 12v battery should ever let you down again. They are about $50.

salimshah

Vehicle not starting is much more complex in the hybrid RX. [start -> ICE engine kicks in]. My 450H does not start well over 1 minute I enter the vehicle.
After 2 days of sitting.
Does your RX respond to the remote key?
Can you tell us exactly what you see when you open the door to the point that you press the start key.
Do the cabin lights come one when you open the door.
When you press the horn does it sound good.
Without pressing the brake if you press the start what do you see on the screen.
All the above deal with the 12V battery. A trickle charger or jump can help. If 12v battery is low then the display will show you the message.

Beyond that we are in different world

Once you start with the foot on the brake. the regen-high_voltage battery does the initial reverse [for me as I back out]. After half a minute to actual movement, the high_voltage_battery which is spinning the wheels, also spins the ICE to get it running.

Salim

Gyuri

I took the car to Lexus who apparently never thought of putting an amp meter to each fuse terminal. Apparently the Car amplifier draws .25 amp when car is shut down which apparently is 5 times the normal for the entire car. They recommend to change the amplifier for about Cdn $750. This is after 4 years of checking and 3 batteries later.
Does this makes sense?

salimshah

So it is the "load".
You have to trust the diagnosis or confirm by unhooking the amp and see if the battery does not discharge. I would suggest getting a salvaged unit for 1/2-1/3 the price. LKQ specializes in Lexus among other recyclers.

Salim

tus

If they're talking about the audio amp, I would have assumed that it shouldn't be getting power with the car off so that circuit should be completely dead.

To me this says whatever is supposed to be shutting it off is not working right and still feeding it power, i.e. if the spigot on your house is working right and shutting off the water, it shouldn't matter that your hoze nozzle is defective and leaks a little when the water is on, if not you'll have a puddle because of the spigot and nozzle both being bad.

Of course I am not an expert on the wiring of a Lexus, and have seen stranger things, so this may not be the case. Just something else to bring up, along with how they tested the thing, before throwing more money at the problem

Gyuri

Salim

I wish I thought of all these issues - thank you for all this guidance , I will get back to Lexus. I thought that something must keep the car audio memory going and that requires a very small amount of power but still draws something and it is not totally shut as you would indicate.

I will test that differently - I am just going away for a month and Lexus has just recharged the battery when I went for regular service so we are starting with a recharged relatively new battery. I will pass now pass by the garage and ask them to disconnect the amp (I assume that will mean just to remove a fuse). IF when I come back the car is still starting, it will be the amp problem and the diagnosis is correct. If not, it will mean that it is something else.

Again thanks for your help.

Sawwhet

This is very helpful! Thank you for posting your dx. Im having the draining problem now and am glad to know to ask about load testing. Its interesting that you mention the car amplifier - talking about the sound system, a few months ago i would start the car and the cd player would make an 'ejecting' sound... but i don't usually use the cd player or audio... so now from your experience I know that something you don't expect to be active could be draining.. and from advice you got in response now i know that if a system you don't use often is draining that it could be possible to disconnect the system rather than start down the rabbit hole to pay to dx and fix...

Now if i can get the courage up to try the load testing myself...

Tx to all. I learned a lot from this thread!

riredale

Since the OP mentioned putting in multiple 12v batteries, I wanted to add a note that while the Lexus battery is $350+, I've just discovered you can instead get a "Group 35" AGM battery for far less and it's a perfect fit. Just did the job myself today, very easy and clean, since the battery is in the back under the floor on the left side. $220 here at Autozone in Oregon, but any auto store should have something similar.

Consult the sticky at the top of these threads.