BMW Keys With Soldered Batteries | KR55WK49127 Replacement | APEX Locksmith Denver
- Nick A
- Nov 17
- 3 min read
BMW Keys With Soldered-On Batteries – What You Need to Know
APEX Locksmith Denver – BMW Key Experts
www.locksmithdenvermetro.com | Call 720-999-4355
Some BMW models were equipped with key fobs that use non-removable, soldered, rechargeable batteries—a design that makes DIY repair extremely risky. These keys, including the well-known diamond-shaped style and the KR55WK49127 key, cannot simply be opened and have a battery swapped like newer BMW keys.
When these keys begin to fail, owners often try to cut them open or solder a new battery themselves, but this commonly results in a damaged circuit board or a completely dead key.
APEX Locksmith Denver specializes in creating new BMW keys, especially for models with soldered batteries that are no longer functioning.
BMW Models With Soldered-On Battery Keys
1. Diamond-Shaped BMW Keys (1995–2005)
These classic keys contain a rechargeable VL2020 battery soldered to the circuit board. Models that commonly use them include:
BMW 3 Series (E46) – 1999–2005
BMW 5 Series (E39) – 1997–2003
BMW 7 Series (E38) – 1995–2001
BMW X5 (E53) – 2000–2006
BMW Z3 – 1996–2002
Early BMW Z4 models
These batteries recharge while the key is in the ignition.
2. KR55WK49127 BMW Key – Also Equipped With a Soldered Battery
One of the most common BMW remote keys with a soldered battery is the KR55WK49127.
This key type is used in many mid-2000s BMW models, including:
BMW 1 Series (E87)
BMW 3 Series (E90/E91/E92/E93)
BMW 5 Series (E60/E61)
BMW 6 Series (E63/E64)
BMW 7 Series (E65/E66)
BMW X5 (E70)
BMW X6 (E71)
BMW X3 (E83)
BMW Z4 (E85/E86)
Like the diamond key, the KR55WK49127 key uses a rechargeable, soldered battery.BMW intended these batteries to last the life of the vehicle—but in reality, after 10–15 years, they begin to fail.
Why BMW Used Soldered Rechargeable Batteries
BMW engineered these keys to:
Recharge automatically while driving
Eliminate routine battery changes
Provide long-term, continuous power for the transponder and remote
However, because the battery is physically soldered to the circuit board, any attempt to replace it requires specialized tools and skill.
Why DIY Battery Replacement Is Not Recommended
Although many online tutorials claim a simple fix, BMW keys with soldered batteries are extremely easy to damage.
1. Opening the Key Usually Permanently Damages the Casing
Once cracked open, most BMW key housings cannot be resealed properly.
2. Circuit Board Damage Is Very Common
The solder points are delicate. Excess heat often destroys:
Transponder chip
Charging coil
Remote signal components
3. A Damaged Chip Means the Car Won’t Start
Even if the remote works, a failed transponder renders the key useless.
4. Broken Keys Cannot Be Repaired Without Special BMW Tools
Improper soldering or board damage usually means the key cannot be saved.
For most BMW owners, attempting to replace the battery results in a key that does not work at all.
APEX Locksmith Denver offers professional solutions for BMW keys with soldered batteries, including the diamond-style BMW key and the KR55WK49127 key.
We cut and program brand-new BMW keys—no functioning original key required.
✔ On-Site Service Across the Denver Metro
We come to your home, office, or roadside location.
✔ Advanced BMW Diagnostic & Programming Tools
We work with CAS, EWS, and other BMW immobilizer systems safely and correctly.
✔ Affordable Alternative to the Dealership
You get dealership-quality service at a fraction of the cost.
Whether your BMW key has stopped charging, lost remote range, or no longer starts the vehicle, APEX Locksmith Denver can create a brand-new, perfectly functioning key.
Call APEX Locksmith Denver Today
For expert help with BMW keys that have soldered-on batteries—including KR55WK49127—call the professionals trusted throughout Denver.
📍 APEX Locksmith Denver🌐 www.locksmithdenvermetro.com📞 720-999-4355
