Most new cars these days have a security system that requires an original key because, as has been explained to me, the key has a chip embedded in the head. Which is I guess why they have to make them so fat. I have one for my '99 Toyota and am starting to wonder why it doesn’t have a battery that needs replacing.
What kind of a chip can do anything, much less send an RF signal, with no power source?
The same is true with RFID chips in everything from cloths to dogs. The power comes by radio from the device reading the chip, in the same way that crystal radios were ‘powered’ by the very radio waves they were picking up and converting to sound.
Many (if not all) of these chips don’t “transmit” anything. They modulate a tuned circuit to load and unload the signal. That decrease in antenna voltage can be detected by the RFID reader. This is very similar to a Grid Dip Meter.
Some older versions were passive. The key was burned with a resistance value that had to be within a specified range. Duplicates without this range wouldn’t work.
This is a different thing from the radio-transmitter unlock, right? Because remote locking keyfobs certainly have batteries in them which run down. (And, according to the manual for my VW, have to be replaced by a dealer!)
Yes, it’s different. Keys themselves have built-in security features. You can’t just copy a car key at a typical key making booth and expect it to start your car; there are now, for the most part, built-in security features to the key itself.
ETA: Which is why it can cost ~$100 to replace a lost key.
Our Dodge Caravan had such fobs that had to have new keys a couple of times, but we never had to take those to the dealer.
What about newer car keys that have the remote unlock built right into the key itself? I understand the passive RFID thing in the key, but it would seem like the remote portion would need batteries now and then. Maybe it gets recharged when it’s used?? Our Honda has the remote in the key itself, and after 6 years we’ve never needed to do anything.
Been there, done that.
Mama Zappa: The active remote (press to unlock, set off panic, start) does need batteries but the OEM battery can last a long while. The device that merely detects whether it’s the right key or it is inside the car doesn’t.
Not talking about the RFID chip here, as that has already been covered, but the part of the key that locks/unlocks your doors. I know at least one car that recharges the battery inside the key whenever the key is in the ignition and the car is running. I’m assuming others have copied this idea.
Never thought about this before, but the remote keyfob receiver and now the RFID reader have to be on all the time. How long before they drain a car battery?