Key Battery Low Warning

[AlanDL]

A couple of weeks ago I couldn't get into my car.  I only had my key card with me, no fob.  I was outside a supermarket, had to call a taxi to get me home to get a fob, and then it started.  However, it was clearly the key Battery, which I have replaced.  Today, my fob has run out of juice.  The point is, I got no warning that the key Battery was low, for either devices.  On the previous NX I would get a "Key Battery Low" warning, which gave plenty of time to get new batteries.  No warning this time at all.  I thought maybe the key card low Battery wouldn't warn me (although has in the past), but now a fob has failed, clearly this warning notice is not available or working.  Anyone else know about this.  Warning to everyone: if there is no warning, make sure you have a spare Battery in the car (at least you can get into it with the metal key).

[Scotlex]

You would like to think that there was a low Battery warning.

If the batteries don't last very long they should perhaps be replaced at the yearly service.

[Ken R]

I got a warning on mine. Didn't react to it at first and the reminder message didn't appear again for a few weeks. Have since changed the Battery and all good. 

[Bounce75]

If I remember correctly on the IS300h service schedule it says replace fob Battery every service, whether they do or not who knows?

[Illogan]

The Lexus dealership I use replaces the batteries in both keys on every service.

And as these batteries only cost pence, then one can always replace them oneself every six months  (if one wishes) just for peace of mind.

Think of it as 'preventive maintenance!'

[AlanDL]

3 hours ago, Ken R said:

I got a warning on mine. Didn't react to it at first and the reminder message didn't appear again for a few weeks. Have since changed the battery and all good. 

What type of warning was it.  I found in the manual this: "If the Battery becomes low, an alarm will sound in the cabin when the hybrid system stops."  That's not that useful given the amount of noises when opening the door etc.  I used to have a visible warning on the dash on entry to the vehicle.  Also, I have changed the battery: a bit of a nightmare as the whole inside unit popped out, motherboard and all!  I managed to get it all back in one piece, but took a while.  Definitely not as easy as previous key, due to contouring (at least for me).

[Ken R]

It was a short chime and a message on the dash appeared saying "key Battery low".

[ArneT]

On 3/11/2024 at 10:51 AM, AlanDL said:

A couple of weeks ago I couldn't get into my car.  I only had my key card with me, no fob.  I was outside a supermarket, had to call a taxi to get me home to get a fob, and then it started.  However, it was clearly the key battery, which I have replaced.  Today, my fob has run out of juice.  The point is, I got no warning that the key battery was low, for either devices.  On the previous NX I would get a "Key Battery Low" warning, which gave plenty of time to get new batteries.  No warning this time at all.  I thought maybe the key card low battery wouldn't warn me (although has in the past), but now a fob has failed, clearly this warning notice is not available or working.  Anyone else know about this.  Warning to everyone: if there is no warning, make sure you have a spare battery in the car (at least you can get into it with the metal key).

Hmm odd, but not a complete surprise. The Battery on my keyfob for my NX300h seem to run down far too quickly, with the "Key Battery Low" warning coming up far too often (this happens on our UX300e too). I have disabled the keyless entry to make the Battery last longer and to prevent the risk of a relay attack. It is worth the minor inconvenience to press the button to unlock the car and disable keyless entry again each time I enter/leave the vehicle. Compared with not being able to unlock the car, or worse the car is no longer there to open!

[Sadz]

Interesting! My card key of the 2018 premier model lasts quite a long. I got the warning few times about 2 years ago and it was replaced during the service and it's still running fine.

[Barry14UK]

Some batteries are much better than others.  I fitted a cheapo once and it needed replacing with another after 3 months.

I wouldn't say Chinese batteries are bad because even some leading makes do Chinese made batteries but there is a better chance of longer Battery life if you get one with a reputable name on it such as but not limited to Panasonic, Sony, Renata, .Energizer  etc.

[ColinBarber]

3 hours ago, Barry14UK said:

there is a better chance of longer battery life if you get one with a reputable name on it such as but not limited to Panasonic, Sony, Renata, .Energizer  etc.

and it is brought from a reputable seller as there are a lot of fakes. E.g. purchase from amazon themselves not an unknown seller on amazon.