Question about E83 keys

[AceEngineer]

Goes anyone know the correct number of the rechargeable battery that is in the OEM diamond shaped keys? Mine is dying and I want to order the battery before I saw my key apart to replace it. I know it is a LiR (lithum ion rechargeable) and probable a 2020 or a 2025 or even a 2032, but I don't know which one and their leads differ. My E53 X5 uses the same diamond key and its batteries are dying too so the problem is compounded.

AceEngineer

[jamrobin]

It's actually a 2025...

https://www.amazon.com/dp/B07YQN8Z5D/ref=dp_cerb_1

I did mine a year ago and just make sure to keep switching keys so it never has the chance to fully discharge. Still works exactly as far away as the brand new key I also bought.

[X3456]

Here's what I purchased last...
https://www.ebay.com/itm/283445211530

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[AceEngineer]

Thanks for the info, but you guys gave me two different answers, a 2020 and a 2025. Turns out they are almost identical except for the height. I subsequently found this on the internet----

"For some reason, CR2020 batteries are not the most common batteries on the market and some users have difficulties finding them.
Their closest battery equivalents by size are CR2016 and CR2025 batteries, which are rather common.
But, problems are dimensions - all three batteries are 20 millimeters in diameter, but the height is different: CR2016 height is 1.6 mm, CR2020 height is 2.0 mm and CR2025 height is 2.5 mm.
If you are replacing CR2020 with CR2016 expect issues with shorter operating life (~90 mAh vs ~120 mAh), but also with contacts due to the 0.4 mm difference in height. It is possible to add thin aluminum foil between CR2016 battery and the contacts, but this is NOT recommended (just a possibility!).
If you are replacing CR2020 with CR2025 expect a longer operating life due to the larger capacity (~120 mAh vs ~160 mAh), if the CR2025 battery can fit the CR2020 battery compartment since the CR2025 battery is 0.5 mm thicker."

So my question now goes to X3456, Did you have any problem at all fitting the 2025 battery in the fob? The 2025 is slightly thicker than the 2020, but it has a larger capacity so it would be preferable.

AceEngineer

[White94RX]

Are you guys splitting the keys open to replace the battery? Then what to put it back together? Super glue?

[AceEngineer]

In my case I don't bother trying to salvage the fob, only the circuit card and the transponder chip. I have a key cutter and new empty blanks are about a buck from China, I have a dozen blank cases on hand. Salvaging the circuit card and the transponder means I don't have to mess with any programming. I bought the key cutter and all the programming stuff when I first got my E53 so I could make spare keys. I also make some BMW keys on the side for my indy wrench. You can buy the blanks empty or with both the circuit card and a transponder chip from China which is what I do when making new or extra keys. You have to be careful though when you buy the loaded blanks from China, some do not have the recharging circuit.

AceEngineer

[X3456]

Thanks for the info, but you guys gave me two different answers, a 2020 and a 2025. Turns out they are almost identical except for the height. I subsequently found this on the internet----

"For some reason, CR2020 batteries are not the most common batteries on the market and some users have difficulties finding them.
Their closest battery equivalents by size are CR2016 and CR2025 batteries, which are rather common.
But, problems are dimensions - all three batteries are 20 millimeters in diameter, but the height is different: CR2016 height is 1.6 mm, CR2020 height is 2.0 mm and CR2025 height is 2.5 mm.
If you are replacing CR2020 with CR2016 expect issues with shorter operating life (~90 mAh vs ~120 mAh), but also with contacts due to the 0.4 mm difference in height. It is possible to add thin aluminum foil between CR2016 battery and the contacts, but this is NOT recommended (just a possibility!).
If you are replacing CR2020 with CR2025 expect a longer operating life due to the larger capacity (~120 mAh vs ~160 mAh), if the CR2025 battery can fit the CR2020 battery compartment since the CR2025 battery is 0.5 mm thicker."

So my question now goes to X3456, Did you have any problem at all fitting the 2025 battery in the fob? The 2025 is slightly thicker than the 2020, but it has a larger capacity so it would be preferable.

AceEngineer

No problems...that is more the fit.

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[richardodn]

There's a video near the bottom of this page that covers the old diamond fob. https://fobbattery.com/vehicles/bmw/x3/
They of course sell the battery on Amazon. They do provide the correct PN VL2020 with the attached leads.

[jamrobin]

Are you guys splitting the keys open to replace the battery? Then what to put it back together? Super glue?

Box cutter and yes (well actually contact cement)... I also got a bobo on my finger. Be careful with the cutting! (LOL I was afraid to use my dremel with a cutoff wheel because there were so many warnings about damaging the board.)

The end result isn't beautiful so I put a cheap e-bay silicone cover on it. Hides the glue seam and bloodstains perfectly LOL.