Diamond Key Rechargeable Battery Replacement DIY

[cakM3]

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 :thumbsup

http://www.ebay.com/itm/131754815195?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT (http://www.ebay.com/itm/131754815195?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT)

https://farm2.staticflickr.com/1563/25998338823_558454767d_o.png

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...
https://farm2.staticflickr.com/1503/26508328032_80a33c2f8b_o.png

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

https://farm2.staticflickr.com/1519/26508327832_895a507146_o.png


I used my X-acto knife to cut open the packaging to free up one of the batteries.
https://farm2.staticflickr.com/1684/26508327662_a60140b0aa_o.png

Here's what the battery looks like... just what I will need to do the swap.
https://farm2.staticflickr.com/1540/26508327352_03c2fa1bd3_o.png

Now for the procedure:

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

https://farm2.staticflickr.com/1489/26508327202_5ed451e9db_o.png

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...
https://farm2.staticflickr.com/1476/26508327062_7e06c77ce4_o.png

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...
https://farm2.staticflickr.com/1508/26508326922_c5f1e1b67f_o.png

https://farm2.staticflickr.com/1617/26508326462_a86cf9174b_o.png

About the time I was rounding the key I slipped and true to my words of caution I stabbed myself...
https://farm2.staticflickr.com/1641/26508326322_e18d1622b0_o.png

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...
https://farm2.staticflickr.com/1579/26508326182_a3b62eb682_o.png

make sure you have some room where you're working at and put the key down like this...
https://farm2.staticflickr.com/1502/26508325992_ec329f006a_o.png

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)
https://farm2.staticflickr.com/1536/26508325852_ce56305717_o.png
https://farm2.staticflickr.com/1541/26508325642_ee6537d465_o.png

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
https://farm2.staticflickr.com/1526/26508325482_fa6b5be9aa_o.png

and the "business side" where the key fob buttons engage with the circuit board...
https://farm2.staticflickr.com/1592/26508325302_81ec8a2e86_o.png

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

At this point you're ready to slip the new battery in place and resolder it to the circuit board. :thumbsup
https://farm2.staticflickr.com/1681/26508325132_d68a282554_o.png

Here are a few shots with the new battery soldered onto the circuit board...
https://farm2.staticflickr.com/1529/26508324962_59fb8104c2_o.png

https://farm2.staticflickr.com/1633/26508324812_94665c4159_o.png


Putting back the key fob is very easy at this point... put the circuit board back into the key fob.
https://farm2.staticflickr.com/1502/26508325992_ec329f006a_o.png


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.
https://farm2.staticflickr.com/1579/26508326182_a3b62eb682_o.png


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 :thumbsup

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.

https://www.youtube.com/watch?v=3YcFN3Ns0yI

http://uploads.tapatalk-cdn.com/20160423/5e01238069f091c98119eba66749e619.jpg

Edit: Vas posted this update regarding pricing for a new diamond key fob :thumbsup $140. Part number 66126955750

[Dual]

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?

[Johnmadd]

Very nic3 diy Charlie. :thumbsup

[cakM3]

Presumably the JBWeld ends the cycle- no more openings after this?

You should be able to reopen the key should the need arise [emoji1360]

[BMWCurves]

Great stuff as always, Charlie!

[Ssparrow]

Nice! Thanks for this


Sent from my iPhone using Tapatalk

[ELCID86]

Nicely done (except for the blood! :) I think I'd probably need gloves or end up as bad if not worse.

[cakM3]

Thanks everyone!! :thumbsup I hope this DIY helps others :)


Sent from my iPhone6S using Tapatalk

[330i ZHP]

Very nice write up.

[330i ZHP]

Two batteries "ordered" I made an offer instead of paying the 5.99 each

[cakM3]

Thanks Stuart and nice!

[Johnmadd]

Lol @ Stuart

[Simmsled]

Oh badass!
This is great. Many thanks.

[cakM3]

Oh badass!
This is great. Many thanks.

:thumbsup

Great way to save yourself from having to spend $250 for a new key at the dealer...

[WOLFN8TR]

Nice DIY Charlie....

[cakM3]

Nice DIY Charlie....

Thanks Gary! :thumbsup

[johnrando]

Awesome info, thanks!

Sent from my SM-G935V using Tapatalk

[danewilson77]

Awesome info, thanks!

Sent from my SM-G935V using Tapatalk
+1

Sent from an S6 Edge

[Whammy]

Thanks for the write-up Charlie! Placed an order to get the batteries and will attempt this.

[Oli77]

Very cool, thanks for the DIY!

[Vas]

Great up for people that want to go with this option. I was going to do this but the buttons on my keys are worn and don't fully click.

However if you want a new key, they are now roughly $140. Part number 66126955750*

[cakM3]

Awesome info, thanks!


+1


Very cool, thanks for the DIY!

Thanks guys! :)



Thanks for the write-up Charlie! Placed an order to get the batteries and will attempt this.

Not a problem Jeff! You should be okay :thumbsup


Great up for people that want to go with this option. I was going to do this but the buttons on my keys are worn and don't fully click.

However if you want a new key, they are now roughly $140. Part number 66126955750*

That's good to know Vas, thanks for updating pricing for a new key! :thumbsup

[Whammy]

Great up for people that want to go with this option. I was going to do this but the buttons on my keys are worn and don't fully click.

However if you want a new key, they are now roughly $140. Part number 66126955750*

Good to know in case I F up.

[CarbonZHP]

Bought this battery immediately upon reading. My backup key hasnt worked for years. I payed $9 for the same battery shipping from the states, getting here in a few days

[cakM3]

Thoughts on this DIY...

I have been driving with my "repaired" diamond key for a few days now... Key has been charged up and everything operates as it should. I have decent range operating my key and will be restoring my other two dead keys over the weekend.

I will have my leather mechanic's glove so I don't stab myself though ;)

Very pleased with restoring my key fob! :thumbsup


Sent from my iPhone6S using Tapatalk


Edit: I tested the distance of my key and can say I'm close to the 30m distance BMW posted for their key fob with the new battery I recently installed :thumbsup

[cakM3]

The diagram I posted below outlines the projected distance you should be able to operate your key fob assuming you have a strong battery inside...

https://farm2.staticflickr.com/1666/26148431823_7860bf69ac_o.jpg

I can say after replacing and then recharging my new battery in my key fob, I'm very close to the projected distances as posted above. :thumbsup

[az3579]

The diagram I posted below outlines the projected distance you should be able to operate your key fob assuming you have a strong battery inside...

https://farm2.staticflickr.com/1666/26148431823_7860bf69ac_o.jpg

I can say after replacing and then recharging my new battery in my key fob, I'm very close to the projected distances as posted above. :thumbsup
You can always extend the distance by holding it up to your chin. My original key/battery can still unlock the car beyond the distances that picture shows. Imagine how far you can go with a fresh battery. :)

Sent from my LG V10 on Tapatalk

[ELCID86]

I didn't know that the distance was longer from behind (and in front of) the car. It is pretty week from the side. I've tried the below-chin method with mixed results. Found this explanation:

This is a really interesting question. It turns out that your body is reasonably conductive (think salt water, more on that in the answer to this question), and that it can couple to RF sources capacitively. Referring to the Wikipedia article on keyless entry systems; they typically operate at an RF frequency of 315 MHz
315
MHz
, the wavelength of which is about 1 m
1
m
. Effective antennas (ignoring fractal antennas) typically have a length of λ2=12m≈1.5 ft
λ
2
1
2
m
1.5
ft
.

So, the effect is probably caused by one or more of the cavities in your body (maybe your head or chest cavity) acting as a resonance chamber for the RF signal from your wireless remote. For another example of how a resonance chamber can amplify waves think about the hollow area below the strings of a guitar. Without the hollow cavity the sound from the guitar would be almost imperceptible.

Edit: As elucidated in the comments, a cavity doesn't necessarily need to be an empty space; just a bounded area which partially reflects electromagnetic waves at the boundaries. The area occupied by your brain satisfies these conditions.

Edit 2: As pointed out in the comments, a string instrument is significantly louder with just a sounding board behind the strings, so my analogy, though true, is a bit misleading.

Edit 3: As promised in the comments, I made some more careful measurements of the effect in question, using a number of different orientations of remote position and pointing. I've posted these as a separate answer to this question.

share improve this answer

[Johnmadd]

Touching the key to your chin works all the time for me :dunno

[az3579]

I didn't know that the distance was longer from behind (and in front of) the car. It is pretty week from the side. I've tried the below-chin method with mixed results. Found this explanation:

This is a really interesting question. It turns out that your body is reasonably conductive (think salt water, more on that in the answer to this question), and that it can couple to RF sources capacitively. Referring to the Wikipedia article on keyless entry systems; they typically operate at an RF frequency of 315 MHz
315
MHz
, the wavelength of which is about 1 m
1
m
. Effective antennas (ignoring fractal antennas) typically have a length of λ2=12m≈1.5 ft
λ
2
1
2
m
1.5
ft
.

So, the effect is probably caused by one or more of the cavities in your body (maybe your head or chest cavity) acting as a resonance chamber for the RF signal from your wireless remote. For another example of how a resonance chamber can amplify waves think about the hollow area below the strings of a guitar. Without the hollow cavity the sound from the guitar would be almost imperceptible.

Edit: As elucidated in the comments, a cavity doesn't necessarily need to be an empty space; just a bounded area which partially reflects electromagnetic waves at the boundaries. The area occupied by your brain satisfies these conditions.

Edit 2: As pointed out in the comments, a string instrument is significantly louder with just a sounding board behind the strings, so my analogy, though true, is a bit misleading.

Edit 3: As promised in the comments, I made some more careful measurements of the effect in question, using a number of different orientations of remote position and pointing. I've posted these as a separate answer to this question.

share improve this answer

You lost me a couple of sentences in... :shifty

[ELCID86]

Me too!