[TerryT]

On engine shutdown I now get a Low Key Battery message on the dash for 4-5 secs showing a remote fob icon with a depleted battery. (See first photo). 

The battery for the remote fob is oem from when I bought the car new in March 2018.  I tried my other remote fob and got the same message.  Its battery was replaced by Hyundai at the car’s 4000km service in April 2019.  (Replacement not necessary as such, just me being a Virgo). 

So, car is about 2.25 years old and has only done a miserable 6800km…not much of a time/usage drain on the fob batteries.

Both fobs do not show the common signs of a low battery i.e. they don’t have to be ‘close’ to the car or require a couple of presses to work (they work first time/every time, and at least 30m away) and their chirp is loud.

I have a good quality TPMS tool that incorporates a fob tester (frequency and battery status) and it says both fob batteries are 100%?  (See photos).

So, what am I missing?  Is there a secret battery that I don’t know of?  I love automotive mysteries and puzzles…except when it’s on my car. 

[Dazzler]

Hi Terry,

Never heard of this before. Obviously the remotes are fine, so it has to be whatever in the car that produces that warning that is faulty. I've never had to replace a key fob battery although that might be partly explained by the fact I've never kept a car with remote opening much past 4 years. 

[The Gonz]

I've used the one fob since 2009 and no change of battery yet. They don't build'em like they used to.

[Dazzler]

BTW Terry, don't bother asking at the Dealer.. they'll only FOB you off... 

[TerryT]

BTW Terry, don't bother asking at the Dealer.. they'll only FOB you off... 

 

[TerryT]

I've used the one fob since 2009 and no change of battery yet. They don't build'em like they used to.

That's exceptional battery life, especially if the fob is in regular use.  I believe the average life is about 3-4 years.

[Dazzler]

I've used the one fob since 2009 and no change of battery yet. They don't build'em like they used to.

That's exceptional battery life, especially if the fob is in regular use.  I believe the average life is about 3-4 years.

  Sounds like I've dodged a bullet swapping my cars regularly then...

[TerryT]

UPDATE
Short story: Turns out my key fob problem was, in fact, b-a-t-t-e-r-y.

Long story: Following yesterday's "Low Key Battery" dash message on engine shutdown, this morning I got a "No Key Detected" message when trying to start the car...and I was holding the key fob. Tried my other key fob and the car started.

I had the dealer's service centre check my two fobs...and replace both batteries. Problem fixed, no dash messages on engine startup or shutdown.

At home I checked both old batteries with a dry cell tester that applies some load. One battery was at 10% (2.06V) capacity, the other battery was 70% (2.62V). Don't know why my fancy TPMS tool showed both batteries in their key fobs were 100%...but it's something I will later discuss (robustly) with the supplier.

Also a little surprised at the relatively low battery life (2.25 yrs) I got from the originally-supplied fob battery, but maybe it was aged stock when fitted.

Edit. Standard fob battery CR2032 is a nominal 3V.

[Dazzler]

Cheers Terry, interesting. I'm sure more like 5 years would be the norm.. 

[TerryT]

Cheers Terry, interesting. I'm sure more like 5 years would be the norm... 

Mate, I'd happily settle for 3-4 years given my small fob usage (2.25 yrs/6800 kms, to date).

But if fob batteries are going to be my worst worry this year, i'll take it. 

[Dazzler]

Cheers Terry, interesting. I'm sure more like 5 years would be the norm... 

Mate, I'd happily settle for 3-4 years given my small fob usage (2.25 yrs/6800 kms, to date).

But if fob batteries are going to be my worst worry this year, i'll take it. 

Yeah true 2020 has put a lot of other things into perspective. An amputation would just be considered a flesh wound this year (a bit like Monty Python) 

[TerryT]

ISSUE: If the battery goes flat in a i30 PD key fob fitted with a mechanical Smart key. it's a little bit related to my thread topic.

This is for i30 PD owners who find themselves locked out of their car due to a faulty FOB battery and don't know about this workaround.  (Other, more knowledgeable, PD owners can have a little smile to themselves. )

1.  Remove mechanical Smart Key from the fob and use it to enter the car via the driver's front door.
2.  Press the FOB body into the Engine START/ STOP button (presumably while pressing foot on brake pedal?).
3.  Vroom, vroom.
4.  Replace battery asap.

[Simonsdvd]

I am having the same problem with my I30 (New in May 2018, 40Km mileage).  The Hyundai dealer serviced the car this morning and reported that my car battery possibly needed replacement as its charge level was low and that this could explain the key fob problem!  I have changed the battery in my key about 2 weeks ago but same problem.  My wifes key is rarely used and gives the same problem.

The garage suggested that numerous short journeys could cause the low battery problem.  I have put the battery on charge this morning.  It was showing a voltage of 12.1V at before stating the charge.

I wait and see if there is any change.  If not then I will try changing the fob batteries with new ones.  I will try Duracell unless anybody has a better suggestion.  I live in France so the chouce is a little limited.

[TerryT]

@ Simonsdvd - Just to clarify that your problem is the same as mine, did you get a dash alert saying "Low Key Battery" and/or "No Key Detected" (even though the key was in my hand).  My car battery was in good shape and my engine would start even with those fob key alerts.

Your Hyundai dealer said your car battery possibly needed replacement as its charge level was low and that this could explain the key fob problem.  I must be missing something here because, based on what you've said in your post, I cannot see that being the problem.  Did the dealer explain how or why to you?

Was your car cranking over (normally?/slowly?) and starting when you pressed the Start button? 

I use Panasonic batteries in my key fobs based on being a brand name and price at the time I bought a quantity for my various items that use CR2032.  I've also used Duracell 2032 in the past, no problems.

Anyways, hope you are able to report back that all is now good.

 

[sundiz]

Just a commet about that first "100% 433MHz signal" picture. Most likely that just shows that the radio signal is good, and all packages were red. If the antenna, tune of the antenna or radio chip brakes down, it can affect to the signal strenght or signal to noise ratio. Battery usually does not affect so much to the performance of the radio, until it runs out.

[TerryT]

Just a comment about that first "100% 433MHz signal" picture. Most likely that just shows that the radio signal is good, and all packages were red. If the antenna, tune of the antenna or radio chip brakes down, it can affect to the signal strength or signal to noise ratio. Battery usually does not affect so much to the performance of the radio, until it runs out.

Thanks for the post.  The following is just my meandering thoughts after I read your comments.

I re-read the manual for my TPMS tool (ATEQ VT56) and I had misunderstood a little what the tool display was telling me.  I thought the KEYFOB STATUS: xx % was the % of the fob battery as a 1:1 relationship e.g. KeyFob Status 26% means fob battery 26%. Not so, maybe.

The manual says the tool shows the strength of the signal being transmitted by the key fob...so, it's not the % of the fob battery.  But the strength of the signal relates to the strength of the fob battery e.g. according to the tool manual, a 100% signal strength means the fob battery is GOOD while a 26% signal strength means the fob battery is LOW.

Just need to find out from the tool supplier what is the relationship between the signal strength % and the battery strength % and, more importantly, what is the minimum % when you should change the fob battery. 

Below are copies of two pics from the manual with their test results.  They only reinforce my concerns in my previous posts as to why the car dash alert icon was telling me the fob battery was very low but my TPMS tool was showing 100% signal strength...and it turned out that the key fob batteries were very low.
   


      PASS: KeyFob is working within its range to the device.





      FAIL: Low signal strength, indicates low battery, replace battery (recommended).

[Simonsdvd]

Hi

I get the same problem (intermittently) on my key fob, even with new battery in my fob and my wife's key fob with the original and which has had very little use.  My local Hyundai dealer is not very communicative and the receptionist speaks very quickly with a local, Normandy accent.  My French is not up to technical discussions, so I do not have any explanation from them.  I get the impression that is was a "Go away and don't be difficult" response.

I have no problem with starting the car, even this morning with a temperature of -5C.  The garage showed me test results from their battery tester whhich is the basis of their comment.  I do not remember what it said.  I have charged the battery overnight and the engine does not turn over any faster and the key fob problem remains.  The battery showed about 12.1 before charge .

My belief is that there is problem with the sensor in the car.

[The Gonz]

I'm revisiting this thread rather than beginning a new one on the same problem.

Mrs G's PD fob stopped working so she began using the second one with no problem (so we know it's nothing in the car).

I proceded to dismantle the fob and replace the CR2032 battery with the only replacement we had, a CR2025, .7mm thinner but compatible otherwise. I then added some layers of tape to thicken it to a 2032 height.

The next morning it still didn't work. It's a good thing I have little trust in quick fixes, keeping the original 32 just in case the problem is elsewhere in the fob.

This afternoon I used the multimeter and found the original 32 was still producing 2.89V while the fresh 25 was producing 3V.
I then suspected the plus contacts (the small metal piece embedded in the shell to contact the battery edge) and cleaned, reshaped and realigned it, with special attention to its contact with the rectangular pad on the circuit board, which was given a light scrub.

The original 32 is working again.

The car has been reporting low fob battery voltage, but it doesn't mean it's the battery, not always.

[Greyhound]

Other than the Owners Handbook, is there a guide how to get into a Hyundai key fob to replace the battery?
I mean the flip key type as I have on my PD.

Toyota key battery replacements are easy, but I cant see a obvious way in on Hyundai fob. I do not want to force it open and break it when the time comes.

[The Gonz]

Push a blade into the seam along the body of the fob, with the key blade removed.
I find the gap where the key blade was is the corner that separates first.

The blade won't go in very far. The shell half without the buttons wraps its edge over the edge of the button half, so once the blade is in just a little, you need to fidget to get them to separate.

Oh, wait, you wrote 'flip-key' but the PD key here in Australia is the keyless type with emergency key slid inside, sorry.
This is the one matching the PD here, although the internals are different:
Hyundai Kona & Palisade Key Fob Battery Replacement - DIY - YouTube

This one matches the flip key on my FD:
How To Open And Replace Shell Of Hyundai/KIA i30/i20/Elantra Car Key Case - YouTube

I just realised as I was reviewing vidoes on the topic that I have circlip pliers as used here.
I'll be using these in future, much safer than the blade:
Key Repair Hyundai Kia Flip Key New Style - YouTube

[TerryT]

Other than the Owners Handbook, is there a guide how to get into a Hyundai key fob to replace the battery?
I mean the flip key type as I have on my PD.

Toyota key battery replacements are easy, but I cant see a obvious way in on Hyundai fob. I do not want to force it open and break it when the time comes.

Just saw that the Gonz has just beaten me with a detailed reply.  Anyways, I'd already typed my post based on my PD fob key, so here goes...

1. Remove the Smart Key from the fob body.



2. Note the small slot at the top, as shown below.



3.  Use a wide, flat screwdriver to fill the slot.  Twist the screwdriver to prise open the top halves of the fob body.  Use a screwdriver (or fingers) to carefully move around and split the rest of the body.



4.  Fob is now open, exposing the battery.



5.  Use narrow, flat screwdriver to carefully prise the battery up and out.



6.  Fit a new battery.

7.  Carefully match the two case halves up and use fingers to press down on the halves until the halves click into place.


Sorry if this doesn't help you but it may help those with the same key fob as mine.   

[The Gonz]

Thanks, Terry, and for the PD, that little yellow rectangle in the step 4 image is what I scrubbed to make a good connection with the two spring contacts beside the battery on the other half shell.
And as a bonus I just learned of the slot for the wide screwdriver to begin the separation.

[Greyhound]

Yes not all PD's in UK have keyless entry. Infact it was my preference not to have it, seeing the number of vehicle thefts that have been attributed to it.
None of the fobs in the YouTube video's are identical to mine, but I get the idea. Maybe circlip pliers will be needed.
If I come across a YouTube video that matches my key fob, I will post a link here for reference.
Thanks guys.

[TerryT]

Yes not all PD's in UK have keyless entry...

@ Greyhound.  Any chance of some photos of your key fob?

[TerryT]

Thanks, Terry, and for the PD, that little yellow rectangle in the step 4 image is what I scrubbed to make a good connection with the two spring contacts beside the battery on the other half shell.

Gonz, handy to know about your 'hack' for any future fob battery problems.

And as a bonus I just learned of the slot for the wide screwdriver to begin the separation.

Gonz, yep, the slot and right screwdriver are soooo much easier than trying to crack a virgin fob case with say, a plastic "guitar pick".  I had tried the pick method first and filled a Swear Jar within minutes.  Discovered the slot & screwdriver method and it was like winning Lotto.

[wooly]

Glad I looked in on the site tonight.

Just today I got the low key fob battery warning on my 2018 i30.
Mine also uses the smart key fob.

I would have expected more than 3 years use from a lithium battery, I wonder if the factory were supplied with a duff batch of batteries to use in the fobs.
Anyway I picked a couple at Bunnings today so I'll replace it tomorrow and see if it plays up again.

[Greyhound]

@ Greyhound.  Any chance of some photos of your key fob?

Photo of my PD key fob. I assume it is common but new, so perhaps noone has yet had need to open one up and post a "How to.."on YouTube.

[TerryT]

@ Greyhound.  Any chance of some photos of your key fob?

Photo of my PD key fob. I assume it is common but new, so perhaps noone has yet had need to open one up and post a "How to.."on YouTube.

Greyhound, thanks for the picture.  Your fob looks similar to the one in the last video link posted by The Gonz above.  So, suitable size external circlip pliers look like they provide a quick, clean way to crack the case.

If you have the time, please let us know how you went.  Maybe a picture or two if the process is markedly different from the video?

[TerryT]

I found two articles on key fob batteries concerning their life and storing the fob away from the car.   (I have edited the content for ease of reading).

When does the key fob battery need replacing?
When does the key fob battery need replacing?

Inside [the key fob] is an electronic chip that works as a transmitter; it transmits the signal when you press the button to open the door.  The key fob battery...may last for 2-3 years in a smart key fob and for 4-6 years in a regular fob with the key.  The reason for this difference is that the smart key fob also has a receiver and has to communicate with the car more often when it's inside or near the car.


Simple steps to maintain car key fob technology to make it last longer
Deal Diva: Simple steps to maintain car key fob technology to make it last longer

…He calculates that the car computer signal can read the fob from between 2 to 3 metres approx. away, he recommends anything beyond that as a safe distance to store or hang up your keyless entry remote.

For most car key fobs, the battery life is three to four years with normal use.  He also says where you store your fob could affect the battery life [and] doesn’t recommend leaving the fob in the car overnight, or on a hook near the car.

[The key fob] does continually send a signal, so it is draining the battery in the key fob and its cause an excessive drainage on the automobile’s battery because a computer is recognizing that signal saying I’m ready to start...

[wooly]

%u2026He calculates that the car computer signal can read the fob from between 2 to 3 metres approx. away, he recommends anything beyond that as a safe distance to store or hang up your keyless entry remote.

I think you could be on to something here.
I've always left mine in the car because it's in a locked garage anyway and it's one less thing I have to hunt for when I go out.
Makes sense that it would always be talking to the car sitting there just waiting to start.

Right, I'll have to keep it in another part of the house from now on.