How to change the battery in a Holden Commodore car key
So I guess the first question is why does the seemingly simple task of changing a battery in the remote control for my car warrant the creation of a dedicated web page. Two reasons, first Holden decided to make the job into an arduous task that took me a while to figure out and second, because Holden charge $140 for a replacement key when the battery goes flat.
This really bugs me in a huge way. Why should I effectively pay $140 for a battery that you can buy in the shop for a few bucks? I don’t really care if the battery did last the best part of ten years and that the key is on its last legs. It still works so I thought I’d have a go at replacing it myself.
Before I get into the steps to change the battery, I’ll first go through a few points about the key itself.
The first point I want to make is that the battery is not rechargeable. It just lasts for so long because it is a long life lithium battery and the remote uses very little power when you push the buttons.
Continuing the battery myth theme, the battery is actually spot welded to the terminals, not soldered so you will not be able to separate it from the terminals with heat. Why does this matter? Well, batteries and prolonged heating are not a good combination. Attempting to use a soldering iron to remove the terminals could lead to the battery exploding.
Next, the two screws in the bottom of the key do not actually hold the case together. They merely hold the metal key stalk in place. One of them does double as an electrical connector that bridges the gap between the stalk and the circuit board but that’s it.
Why is this important? Because after you change the battery, you will need to find a way to secure the two halves of the shell together again, there’ll be more on this later.
Finally, removing the battery from the key wipes the code from its memory that allows it to work with your car. This means that the remote will not work after you have finished changing the battery until you put the key into the ignition and start the car with it.
Why is this important? If you change the battery with the car deadlocked (push the lock button twice) and don’t have a spare key, you simply won’t be able to open the car again and you’ll be stuck. If you just have it locked, you will be able to open the door using the key but the alarm (horn) will go off when you open the door and will only stop when you start the car with the key.
Equipment and Skills required
A cross headed screwdriver.
A flat bladed screwdriver.
A sharp knife.
A soldering iron and solder along with basic soldering skills.
A High Speed rotary tool with diamond grinding bit (I use a Dremmel).
Sticky tape or glue.
Directions
Use a screwdriver to remove the screws holding the key stalk in and gently pull it out. Set the stalk and screws aside somewhere safe.
Now take the flat bladed screwdriver and use it to prise apart the key shell. Be as gentle as you can to avoid too much damage but remember that the thing was never designed to be open so you will need to use a bit of force.
Once the case has been opened, you will find that the circuit board is loose but still attached to the bottom case by a rubber seal. You should be able to simply stretch the rubber to remove it from the circuit board without damaging it. You will also be able to see the battery and how it has been spot welded to the terminal.
Next, we need to get out the high speed rotary tool with a diamond ball grinding bit. Running the machine at high speed, start to grind down on top of the spot welds directly.
Your aim here is not to grind all the way through, rather to weaken the metal in the terminal surrounding the weld until it is thin enough to allow you to snap it when you prize up the terminal.
Once you have ground out all four welds on top of the battery, take a sharp knife blade and use it to, as gently as you can prize up the terminal arms. You are going to bend the arms in the process regardless of what you do but try to minimize it as much as possible.
Unfortunately, the bottom terminal is also welded on too. This means that in order to remove it you need to use a soldering iron to melt the solder connection to the circuit board and pull out the battery, terminal and all so you can continue the process.
Once the battery has been released from the circuit board, repeat the process to remove the second terminal before soldering it back onto the circuit board.
The battery with the bottom terminal attached can be seen here
Now all that remains to do is to secure the new battery in place and re assemble the key. There is nothing in the key itself to hold the battery in place so you will need to use some sticky tape here. I put a small piece of tape over the top terminal itself before adding a second layer that extends around the sides of the board to hold the battery firmly down against the bottom terminal.
This bit is extremely important. Remember that if the connection is lost, even for an instant the key will lose its coding and the remote won’t work to unlock your car. In other words, make sure that you tape down the battery in such a way to make sure it’s just not going to move.
To reassemble the key, refit the seal rubber around the two key contacts, reposition the circuit board into the plastic body and replace the other half of the plastic shell. As I mentioned earlier, once separated the two halves of the plastic shell will not just clip back together so you will need to use either tape or glue to finish the seal.
Once this is done you can then replace the key stalk and screw it in. To test the key remote, you need to first go and start you r car with it. After doing this, providing you’ve been successful the remote should work like new.
So, it’s not a simple process but the 20 minutes I spend doing it has meant that I don’t need to spend the $140 to replace the key. Despite Holden saying it shouldn’t or can’t be done, if you have the skills, equipment and a key with a dead battery, I really don’t see that there is anything to lose by giving it a go. It certainly worked for me.
