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Thread: Diamond Key Rechargeable Battery Replacement DIY

  1. #1

    Diamond Key Rechargeable Battery Replacement DIY

    I know that there was some interest from people wanting to know how to replace the internal battery in our $250 key fob. Since the Diamond Key fob is sealed it is not intended for the average person to replace the internal rechargeable battery so typically the owner is faced with shelling out the cash for a functional key fob from the dealer and then have the key reprogrammed for the car (which is very easy by the way)...

    Well... here is the procedure to replace the internal battery for those who want to tackle this job. By the way... I will state:

    I am in no way responsible if any of you try this diy and mess up your key. You're doing this at your own risk.

    Now that my disclaimer statement is out of the way.... let's get on to the procedure!

    Tools you will need:

    1. A thin chisel or screw driver.

    2. JB Quik Weld to seal the key and tape to keep the key together while the Quik Weld cures.

    3. Soldering Iron and some solder.

    4. Sharp knife to cut open the package the batteries arrive in.

    5. Optional:Cheaters - glasses (if your eyesight is bad then having a pair of reading glasses will help do the delicate work of desoldering/soldering the battery)

    The battery I ordered is the same exact battery that was in my key. Here is the link to the eBay auction I used to source my rechargeable battery me=STRK%3AMEBIDX%3AIT

    sure beats paying $250 for a new key fob!

    It will take about two weeks for the battery to arrive so be patient, it will come...

    The package will arrive like this when it does arrive...

    Packaging was excellent as the batteries were in perfect shape when I took one of them out to do my DIY

    I used my X-acto knife to cut open the packaging to free up one of the batteries.

    Here's what the battery looks like... just what I will need to do the swap.

    Now for the procedure:

    1. Take one of your dead keys to be opened. I used my ZHP key for this.

    2. Take a thin flat blade screw driver or chisel to pry open the key. Be very careful when doing this part and take your time or you will drive the chisel/screw driver into your hand...

    As you continue to put the screw driver/chisel into the key you will start to follow the seam of the key as shown below in the pic...

    About the time I was rounding the key I slipped and true to my words of caution I stabbed myself...

    no big deal... I cleaned the wound and bandaged it and continued with my procedure. Just be careful when you're prying the key apart...

    As you slowly pry the key you will get to a point where you will be able to open the key up like in the pic below...

    make sure you have some room where you're working at and put the key down like this...

    Leaving it together somewhat will make putting it back together much easier but it's no big deal if you have both halves completely taken apart.

    Using a soldering iron, melt the solder at these two points as shown in the following two pictures below (circled in red)

    I made it a little bit easier to identify with the red circles and screw driver pointing to the solder joint

    Once you have desoldered those two points, the old battery will just slip off the circuit board. It was just that easy! Here is how the board will look with the desoldered joints... The back of the circuit board where the battery mounts

    and the "business side" where the key fob buttons engage with the circuit board...

    In both cases you can easily see the joints as I put red circles around them

    At this point you're ready to slip the new battery in place and resolder it to the circuit board.

    Here are a few shots with the new battery soldered onto the circuit board...

    Putting back the key fob is very easy at this point... put the circuit board back into the key fob.

    Where the seams are you apply the JB Quik Weld and then put the key together and tape it so the Quik Weld has time to cure.

    That's pretty much it! Keep in mind the battery will most likely need to be charged up so plan to take your car out for a nice drive then you can program the key to the car for remote operations. That's what I had to do and everything works perfectly now...hope this helps others who would rather have an option to reuse their worn key fobs

    Here's a video on how to reprogram the key although you don't necessarily need to put your key into position 1 5 times as shown in the video...the BMW procedure actually tells you to put the key into position 1 once then back to off and take the key out of the ignition and hold the unlock top button and press the lock (center button) three times and then let go of the unlock button. Remember to press and hold down the unlock top button the whole time you're pressing the lock center button three times.

    Edit: Vas posted this update regarding pricing for a new diamond key fob $140. Part number 66126955750
    Last edited by cakM3; 04-24-2016 at 05:28 PM.

  2. #2
    Join Date
    Feb 2016
    Portland, Maine, USA area
    Super cool! Thanks for this: I've been worrying about how to deal with these batteries...

    Presumably the JBWeld ends the cycle- no more openings after this?
    2006 6MT Coupe, Alpine White Premium, Cold Weather and Xenon packages
    MFactory 3.38 LSD 27mm M3 bar ECS strut brace Koni FSD's

    Other tweaks: see my profile

  3. #3
    Very nic3 diy Charlie.

  4. #4
    Quote Originally Posted by Dual View Post
    Presumably the JBWeld ends the cycle- no more openings after this?
    You should be able to reopen the key should the need arise

  5. #5
    Join Date
    Nov 2014
    Portland, OR
    Great stuff as always, Charlie!

  6. #6
    Join Date
    Feb 2015
    Nice! Thanks for this

    Sent from my iPhone using Tapatalk
    Shawn, 801

  7. #7
    Join Date
    Jun 2011
    Nicely done (except for the blood! I think I'd probably need gloves or end up as bad if not worse.

  8. #8

  9. #9
    Join Date
    Mar 2011
    Washington, DC
    Very nice write up.
    - Stuart


  10. #10
    Join Date
    Mar 2011
    Washington, DC
    Two batteries "ordered" I made an offer instead of paying the 5.99 each
    - Stuart


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