BMW E90/91/92/93 as well as many BMW key fobs from the early 2000's, Mini. (there are many guides on how to do this on the internet).
eBay
2/5PCS M12 12V Battery Plastic Case Box Parts (no battery cell) For Milwaukee 12V 48-11-2411 M12 Li-ion Battery Shell Housing
Aliexpress UK
Remote key Fob. For Ford Galaxy (CA1) 2010-2015. All of our products undergo rigorous testing. Key Shell Case. For Ford Grand C-Max (CB7) 2010-2015. Battery Capacity:50mAh. Battery Size Code:2020. Battery Technology: Lithium Vanadium Pentoxide.
eBay
18V Rechargeable Battery 22500mAh 15000mAh Lithium Ion Battery With Battery indicator For Makita Electric Power Tools Battery
Aliexpress UK
BMW E39 and E46 keys (Commonly Known as Diamond Keys). BMW E90/91/92/93 as well as many BMW key fobs from the early 2000's. (there are many guides on how to do this on the internet). BMW had a different shape pcb leg mount put on the there batteries (which you cant buy) but this just requires a little modification.
eBay
ONEVAN 18V Rechargeable 588VF Lithium Ion Battery 22900mah Li-lon Battery With Battery Indicator For Makita 18V Battery Pin
Aliexpress UK
Li-ion Rechargeable Panasonic Battery VL2020 Lithium Coin for Mini BMW M 3 5 Key. ● New | Rechargeable. ● Compatible: Mini BMW M 3 5. ★ Money-back guarantee · Over 10 years of experience.
eBay
12V Battery Relay Switch Dual Remote Car Battery Disconnect Relay Anti-Theft Battery Shut Off Switch Compact Battery Isolator
Aliexpress UK
For BMW 1 3 5 7 Series X5 X3 Z3 Z4 E46 E39 E60 E63 E53. For Ford Galaxy (CA1) 2010-2015. For BMW 1 Series 2004 - 2013. For BMW 3 Series 2005 - 2013. For BMW 5 Series 2003 - 2010. For BMW 6 Series 2004 - 2010.
eBay
Coin Battery Container Coin Battery Holder Button Cell Battery Box for CR2016, CR2025, CR2032, CR2320, CR2325, CR2330, CR2335
Aliexpress UK
For BMW Mini 2006 - 2013 (R56). Remote key. Remote Key Fob. For BMW Mini Cooper S. For BMW E90/91/92/93 as well as many BMW key fobs from the early 2000's. Degree: 180 Degree Leg. For BMW Mini Coupe 2011 - 2015 (R58).
eBay
1pc 3V Battery Box 3Modes CR2032 Button Coin Cell Battery Socket Holder Case Cover with On-Off Switch Without Battery
Aliexpress UK
BATTERY, RECH LITHIUM 2330. Battery Capacity:50mAh. Battery Size Code:2330. Battery Technology:Lithium Vanadium Pentoxide.
eBay
1S-24S Measurement Lithium Battery Pack Voltage Tester display meter battery Single Cell Measure Li-ion Lifepo4 batteries
Aliexpress UK
Panasonic Accumulator Battery. Compatible Models: Used in BMW key fobs and many other applications. Note the characteristics solder pins of this battery are oriented at 90 degrees to each other.
eBay
1/3//5PC M&12 12V Battery Plastic Case Box Parts (no battery cell) For Milwaukee 12V 48-11-2411 Li-ion Battery Shell Housing
Aliexpress UK