Star Key battery replacement e46, e39

[Bruski 35]

I've had a bit of a saga with the battery on my BMW star key recently.  It all starts during the export from the UK to NZ back in 2018.  The shipping firm lost my original e36 style key so as I was en route to NZ via Singapore when they told me so I could not get them the spare key, they had to pack the car in the container using those rollers they use for expensive motors. Fancy.

Anyhoo, the key the shippers lost is the e36 style that is really easy to replace the battery on, as shown here:

The shipping company contacted BMW UK who issued a replacement key, programmed it to the car and did all the donkey work.  All good I thought.  What I did not know of course, was they had replaced the e36 key with the newer star key, or e46 / e39 key.  Not to worry I thought, it is a bit flasher after all, and it works, who cares.

Issue is of course, the key has recently stopped reliably opening the car.  I was not using the car very much so I figured the key battery was being discharged and not charging enough while driving.  After driving for a ways, I would have to be very close to the car, hold the key to my head and hope for the best.  Still worked on start up and for driving though.

But I thought this is not sustainable so I asked the internet.  First I tried this geezer in a shell suit.  He was on the money:

 

 

It actually worked...........for a week.

So then I tried this German chap:
https://youtu.be/0kjGAUTb3Wg?si=twnlMTVnDmhvBHe9

This worked too, for a night.

Oh dear I thought, what about recharging it using a tooth brush charger:

 

 

That sort of worked, then didn't, at all.  Battery was burnt out I think.  But I thought, well I can cut it open and replace the rechargable battery or I can go the local stealers and buy a new key.

I was all set for sourcing the new rechargable battery when I stumbled across this guy in the US:

 

 

Note how the battery is just regular long life.

Hmmmmmmm I thought.  What are the chances.  Sure enough, after a bit of a go around on the key with a blade and a hacksaw, I opened the key to find a non rechargeable.  Thanks BMW.

So $2 worth of battery later, I have a functioning key, no need to program again.  Bonus.  They key looks ok super glued back together, not quite so flash as before I attacked it with a hacksaw, but beats a trip to the stealers for a new key IMHO.

Anyway, thought it might be useful to post for others who experience battery problems with the star key.

Thinking about it, whoever at BMW in the late 90s or early 2000s who thought it would be good to go from a screw release unit to a sealed unit, well danke, dummkopfs.