Charging your BMW key fob can be a hassle, especially if you’re in an apartment without a garage. BMW suggests leaving the key in the car in position 1 for wireless charging, but that’s not always practical. For those seeking a convenient home solution, exploring a dedicated Key Fob Charger becomes essential. Low battery in your key fob can reduce its operating range, making remote functions less reliable. Many users have faced this diminished range after periods of infrequent driving and are looking for effective ways to maintain a fully charged key fob. While some have reported success with toothbrush chargers, a more focused approach to a key fob charger can be beneficial.
To investigate a DIY key fob charger, an Adafruit Induction charging set was used for experimentation. The idea is that the key fob, acting as the receiver, manages voltage regulation and protection. Stronger inductive coupling should lead to increased current draw and quicker charging. Testing revealed that the highest current draw (around 75mA above idle) occurred when the key was placed with the BMW roundel facing the inductive charging loop. This observation raises questions about the coil positioning within factory in-car wireless key fob charger systems. Examining a disassembled in-car charger could offer valuable insights into optimizing a DIY key fob charger setup. Perhaps acquiring an old unit for closer inspection would satisfy this curiosity and inform further key fob charger development.
The battery inside these BMW key fobs, a Panasonic VL-2020, has a 20mAh capacity and a standard charge current of just 1.5mA. This means a full charge should be achievable in significantly less than 20 hours, highlighting the feasibility of creating an efficient and effective key fob charger at home.
