Smart key info...

[Midnightsun]

What a brilliantly simple idea (that I wasn't smart enough to think of)! Pure Genius.
Tomorrow I'll be getting a set of spare batteries for both my Genesis and my wife's Lexus. According to the date stamps on the packages, they are are good for about a decade. Small price to pay for insurance.
Thanks for sharing the idea!

If you have the fob you can use the key to get into the car. Even if the battery is completely dead as in even if it fell out of the fob, you can still start and drive the car no problem. No point whatsoever having a spare battery in the glove box. See post #8 and 9 on page 1 of this thread.

 

[Gunkk]

I dont think I have ever had to replace the battery in a keyfob. But then I never had a car longer than 3 years, lol.

In 4 years with two gen-1s, I've gotten on average about 1 year of use out of my key fob batteries between replacements.

 

[kn5owa]

But if you lose your fob, you also can't get into the car either, so starting is your second priority in that case. I suppose if you get a locksmith to get you in, then having a spare fob to start the car is beneficial. However, if you remote start once inside and with the car locked, do you need the fob to put it into gear and drive off? I don't think so - so that might be an option too? I'll have to see if that actually works as it could be useful in a pinch.

If you lose your fob - you can get into the car - use the metal key that came with your spare backup fob - put it in a magnetic key box somewhere on the outside of the car - like back in the old days when we had real keys.

 

[prpctech04]

OK, I have the now OLD 2012 and if the key fob battery goes dead then you can insert the fob into a special port. On '12 the port is located just below the DVD on the left side and it is hidden behind small flap. If the fob is there then the car will start just fine. The key fob is like transponder so it will respond to proximity of your car as long as it is in that port. Look it up on '15 for the location of this port in your manual I imagin it must be some thing close to '12. My dealer told me it was a charging port for the fob, Ha Ha NOT. It is for emergency start if your battery goes dead. '11 Sonata got one in the in the arm rest box.

 

[Mark_888]

Actually, Midnightsun proved that a fob without the battery will still start the car - so this whole "issue" is really a non- issue. No need to do any of the above if you're fearful of a dead battery - your dead fob will still start the car!

I wonder if there is a capacitor inside the keyfob that holds a weak charge that allows the car to start without a battery (or a completely dead battery)? If that is true, then even the capacitor charge will eventually dissipate if the battery has been out too long.

How about removing the battery on a spare keyfob and leaving it out for a few months, and then see if you can start the car without a keyfob battery.

 

[Nikgen]

I wonder if there is a capacitor inside the keyfob that holds a weak charge that allows the car to start without a battery (or a completely dead battery)? If that is true, then even the capacitor charge will eventually dissipate if the battery has been out too long.

How about removing the battery on a spare keyfob and leaving it out for a few months, and then see if you can start the car without a keyfob battery.

Good point - but, if your fob battery "dies", and you need to hold it up to the start button to start the car, you hopefully won't wait a few months to replace it? If you do, you deserve to get stranded!

 

[TheKingInYellow]

I wonder if there is a capacitor inside the keyfob that holds a weak charge that allows the car to start without a battery (or a completely dead battery)? If that is true, then even the capacitor charge will eventually dissipate if the battery has been out too long.

How about removing the battery on a spare keyfob and leaving it out for a few months, and then see if you can start the car without a keyfob battery.

It will be a transponder. A magnetically coupled transponder requires no internal current, and to generates current when it is extremely close to a powered source. So, they've put a transmitter right in the start button, and you power the transponder by bringing it close. That gives enough current for the challenge/response system in the smart key to work.

 

[Mark_888]

Good point - but, if your fob battery "dies", and you need to hold it up to the start button to start the car, you hopefully won't wait a few months to replace it? If you do, you deserve to get stranded!

I agree. I replace my batteries at least every 3 years just to make sure I can lock the car from a decent distance.

The really paranoid can keep an extra battery in their car. You can get a 2032 battery at any discount store (Walmart, Target, etc) and probably most grocery stores.

 

[Mark_888]

It will be a transponder. A magnetically coupled transponder requires no internal current, and to generates current when it is extremely close to a powered source. So, they've put a transmitter right in the start button, and you power the transponder by bringing it close. That gives enough current for the challenge/response system in the smart key to work.

Years ago I had a Camry with that technology. It had (what looked like) a normal key (with a slightly larger than normal plastic piece covering the key handle), and there was no battery. But there was a security code stored in the key that could be retrieved by the car using transponder technology.

I am not 100% sure if this is how smart keys work. Here is one explanation I saw on the web:

"Now, at some point there may not be enough energy in the battery to power the transceiver. That's ok! A battery is not necessary! Since the RFID can be determined passively, you do not need power. All you have to do is place the key fob in close proximity to the car's reader. There RFID reader's location is marked on the steering wheel for your convenience [not applicable to Genesis]. Just hold the key fob next to the reader [start button for Genesis] and depress the start button. The RFID value is read and compared in a similar manner as an actual transmission. However, it may lack some level of full encryption used in a transmitting environment."​

 

[Michelf99]

How to change the Smartkey battery

Hello.
I lost my user manual and my Smartkey is getting weak. How do I change the battery inside? If I remove the metal key, I see two flaps with DH1 and DH 48. I presume they are removable...

Any help and direction will be greatly appreciated.

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[Aquineas]

Check out page 3-9 in the digital owner's manual.

 

[Forty01]

I believe you can program 3 fobs. Reason I say so is the Canadian V8 model comes with a smart key card and 2 fobs so 3 in total. I keep one in the car hidden in foil, use the credit card fob and still have a spare at home.

I have an American Genesis 2015 V8 Ultimate and purchased the Smart Key Card to add to my 2 FOB's, so having 3 is possible

 

[thane11]

I have an American Genesis 2015 V8 Ultimate and purchased the Smart Key Card to add to my 2 FOB's, so having 3 is possible

Yes, it's possible I have a smart key card and two regular key fobs active. Just remember to bring in the other two key fobs when they program the smart key so they can update all three to work with the car. The first time I went in I left one of the key fobs at home so it didn't work after they reprogrammed the car to work with the smart key.