I have a 2008 Lexus RX400H and if I park overnight, the battery goes flat.
Took it to an auto electrician and he could not find the problem after having it for over 3 weeks. Finally, he installed an isolator switch on the battery. That means that when I am done for the day, I have to open the bonnet, lock the car with the remote, and then isolate the battery. In the morning, I do the reverse.
Any help would be appreciated.
Almost guaranteed this is it. Was last changed 8 years ago. Current battery has 80CCA left in it…
When I tell customers they need a new battery is goes something like;
You need a new battery…
But it was already replaced, should it really need one?
Oh, ok, when was it replaced?
2009…
*facepalm*
Is that right, a typical car battery is good around 5 years and starts going down hill from there?
They start going down hill the moment you buy them and connect them to a car. Most have a warranty for about 2 or 3 years and that is about all I would expect from one. Anything longer than that is a bonus.
I would say average battery life depends on how badly it is treated. A car that is driven to work and back, 20~40km round trip on flat, even roads, should last a good while. Cars that use start/stop engines, a little less. Short range driving or frequent starting and charging cycles, less again. Vehicles used for off roading or that travel longer distances over corrugated/rough roads, less life again. 2 years is warranty, 5 to 8 years is about average, any more than that, and you are doing ok.
Is the head unit (stereo) staying on when the car is switched off? It happened to my parents Prius recently and the start battery died. It may be similar tech to what's in the Lexus.
when I am done for the day, I have to open the bonnet, lock the car with the remote, and then isolate the battery. In the morning, I do the reverse.
What a stupid idea.
Why didn't the Autolec put the switch in the cabin of the car instead?
Makes for a good antitheft device though.
Best part is when it gets messed up and OP locks the car, isolates the battery and slams the bonut back down… Can't get to the isolation switch to turn it on to open the doors to get to the bonut latch to get to the isolation switch…
Isolate battery: can’t lock doors.
When was the last time you replaced the battery?(I assume you’ve tried that).
Clearly something is draining it. Have you tried the basics eg turn cabin lights to off, turn headlights from auto to off, make sure the radio and satnav screen is turned off (i.e turn radio off when you park and manually turn screen off).
You're lucky you have a Lexus. When a German car has electronics issue, it's like a nightmare to find the problem and it's almost always some dumb malfunctioning sensor. For example, VW and Audi and Porsche can't seem to build electronics around a window that stops it from triggering for no bloody reason.
Why for the love of GOD would you need to buy a OEM battery? As long as the battery is the same size and CCA it will work fine.
The Toyota ones are rather long lasting. If the price was reasonable I'd get an OEM battery.
Something very wrong with your auto electrician.
My bet is a lamp stuck on in a glovebox/boot/visor, stuck adjustment switch (so the motor is always silently straining at the end of its run) for a seat or a mirror, or something equally innocuous.
maybe a 24/7 dashcam powered by the car battery.
can also be those OBDII speedometer and heads up display.
Google tells me that others are having similar issues (though usually not overnight - it either drains quickly on accessories or parked for over a week). I've seen words flying around like excess drain from a pre-amp or the security system.
12 years on battery, could mean battery needs to be replaced