Remote Control Battery Life

sheri1 · March 3, 2020

I seem to be having to change the batteries on my remote far too frequently. In the past in each of my previous cars, I would expect to have to change the batteries around once every couple of years or so. My NX remote needs new batteries approximately every 2 months!

I am doing nothing different with this car than any other I have owned.

Any suggestions?

steve2006 · March 3, 2020

I wonder if the key fob and car “talk” to each other constantly when in range of each other hence the Battery drain. Perhaps move the key further away from the car or buy one of those anti theft pouches which block the signals for the key fob.

I take it the batteries are a decent make?

malcolmw · March 3, 2020

I think you definitely have a problem. All my Lexus cars have had key batteries which last typically 2 years. However, of recent times I have had them changed at each annual service to avoid any issues. The cost is trivial.

Steve Oliver · March 3, 2020

This is not my experience so far. Both my key fobs are still fine, 6 months in. I do keep them both in RFID safe pouches though.

08ISF · March 3, 2020

You could try turning the key fob off when you're not going to use the car for a period of time, say overnight. Try this :

To disable the key, hold the lock button down while you double-press the unlock button. The red light on the key will flash four times to confirm the wireless transmission is turned off. You can also check this has worked by attempting to open the car by holding a door handle. The doors won't open when the key is turned off. To turn back on press the unlock button. Works on my RX.

The other thing is make sure you are using decent batteries. Poundshop ones where you get about 8 for a pound are a bit variable in quality. You don't need to swell Lexus' coffers but a couple of quid should get you a decent Battery. I've used GP, Varta, Panasonic in the past all OK

Do you keep the key fob with the spare key or next to a mobile phone or other electrical fitting? I've been told that this can cause the fob to keep seeking its partner i.e the car, and empty the Battery prematurely. Does the spare fob run down as quickly?

Hope this helps.

Eggie · March 3, 2020

The batteries in my NX fobs are over 2yrs old now and are still fine. However I do switch the fob off Overnight as described above.

Texas · March 3, 2020

The Battery in the remote key fob is on the Lexus service schedule to be changed annually ( but unless you take any additional keys you have then it will only be the one in the car on the day that gets changed. And yes the key is transmitting continually ( but not constantly) and the car is trying to detect it continually! ( but after about 10-14 days with no success then the car will 'give up' and if you approach after this time then you will have to press a fob button to 'wake up' the car.

NemesisUK · March 3, 2020

From the Lexus-tech.eu doc for the Entry and Start System Control. It seems the key fob is constantly listening, rather than transmitting?

"i. Battery Saving Function of Electrical Key Transmitter Sub-assembly
i. This function cancels the signal reception waiting state of the electrical key transmitter subassembly,
reducing the consumption of current from its Battery.
ii. The electrical key transmitter sub-assembly can be placed into and taken out of Battery
saving mode. When the electrical key transmitter sub-assembly is in Battery saving mode, the
entry and start system will not be able to detect the transmitter, as the transmitter will not
respond to signals from the vehicle. The function of the entry and start system will not
operate if the electrical key transmitter sub-assembly is in Battery saving mode.
iii. Pressing the unlock switch of the electrical key transmitter sub-assembly twice while pressing
the lock switch (the indicator light of the electrical key transmitter sub-assembly blinks 4
times) selects Battery saving mode for the electrical key transmitter sub-assembly.
iv. Battery saving mode can be canceled by pressing any switch on the electrical key transmitter
sub-assembly."

ENTRY AND START SYSTEM CONTROL ENTRY AND START CONTROL.pdf

sheri1 · March 4, 2020

Thanks everybody for the replies. Just to be clear, I only ever use Duracell or equivalent batteries and my Lexus dealer fitted new ones to both remotes during the last week in January and already the system is telling me the Battery level is low.

I have never experienced this with any other car including all four Lexus models I have owned, and have never had to 'turn off the remote' at the end of each day. My car is and has always been parked in the garage, so I have not changed anything other than my car!

Seems like I will need to follow your lead and get in the habit of switching off at night 😞

malcolmw · March 4, 2020

As mentioned above, I think this must actually be a fault which you should get fixed under warranty by Lexus. Two to three months Battery life is much too short.

DanD · March 6, 2020

I agree.

Also...

- Keeping the key in a RFID pouch has no bearance on the longevity of the Battery. You are just blocking the signal, not stopping it;

- Even if the Battery seems flat, there will always be enough 'juice' to allow the car to start. You have have to unlock the car manually using the key built into the key fob, but you will be able to start the car by placing the keyfob against the start button whilst pressing it. NOTE that the alarm may go off as you manually unlock the car, but will be disabled as soon as you start the car as indicated above.

mosaddique · May 4, 2020

Battery saving mode. Is this required to be done on both keys? Or is sufficient to do one one key/

Texas · May 4, 2020

Each and every key you want to turn off, as it is the Battery in that key that you are turning off when you do the button press & hold. Pressing any button on the fob after will 'wake' it up again.

Note, after about 2 weeks of no use the car will not detect the key fob automatically when approached and you will have to press a button on the fob.

cruisermark · May 5, 2020

There must be a fault here

The keyless entry on my 04 LS430 is perfect and Battery lasts around 2 years

DanD · May 6, 2020

On 5/4/2020 at 11:07 PM, Texas said:

Note, after about 2 weeks of no use the car will not detect the key fob automatically when approached and you will have to press a button on the fob.

If you turn the key off, the car will no longer detect it. The 2 weeks are irrelevant: I turn the key off each night, and in the morning the key is not recognised until I reactivate it by pressing a button on the fob.