Smart card does not require a battery? Revealing the "invisible charging technique" of contactless cards!​

Have you ever been curious - when swiping the access control card or bus card, the card obviously has no battery, so why can you instantly "live" when you get close to the card reader, complete swiping the card to open the door or deduct the fee? Could it really "get electricity out of thin air"? Today we will uncover the secret of this "black technology": How does contactless smart cards obtain electricity?

1. What is a contactless smart card?

The bus cards, access control cards, and campus cards we often call (no card insertion required, just close to the card reader to use), are all contactless smart cards (also called RFID cards or induction cards). At its core is a PVC card embedded with chips and antennas. It does not have a traditional battery, but can be activated instantly when approaching the card reader. It relies on a set of exquisite "wireless power withdrawal" technology!

2. Revealing: Where does the power of contactless cards come from?

The "energy" of contactless cards is actually "transmitted" by the card reader! The entire workflow is like "wireless charging":

1️⃣ Card reader transmits radio waves: When you bring the card close to the card reader (usually within 3-10 cm), the card reader will emit radio waves of a specific frequency (such as 13.56MHz) through the built-in coil, which carry energy and instructions. 

2️⃣ Card antenna receives energy: There is a small coil antenna hidden inside the contactless card (connected to the chip). When the radio waves of the card reader "sweep" the card, the coil antenna is like a "mini receiver", converting the electromagnetic energy in the radio waves into a weak current (the principle is similar to a transformer).

3️⃣ Current activation chip operation: Although the converted current is small (usually only a few milliwatts), it is enough to "charge and activate" the chip in the card. After the chip is started, the card reader's instructions are received through the antenna (such as "reading the card number" and "verifying the balance"), and then the stored data (such as identity information, consumption records) is trans.

Simply put: the radio waves emitted by the card reader are both "signal commands" and "energy source" - the card is "self-sufficient" by capturing these radio waves without requiring an additional battery!

3. Why do you sometimes fail to respond when swiping your card? Not enough energy!

Although this "wireless power withdrawal" technology is clever, it also has conditions and limitations - the radio wave intensity of the card reader, the distance between the card reader, and the sensitivity of the card antenna will all affect the energy reception effect.

❌ Common "failure" scenarios: 

• The card is too far away from the card reader (more than 10 cm) or too close to the card reader (close to the metal surface, the radio waves are blocked)

• The card reader is insufficient (the energy of the radio waves emitted by old equipment)

• The card antenna is damaged (such as the card bent, long-term high temperature causes the coil to break)

✅ Solution: When swiping the card, try to close the card to the sensing area of the card reader (usually with the "card swipe" mark), keeping a distance of 1-3 cm; avoiding the card from touching metal items; if it fails frequently, it may be that the card chip is aging and needs to be replaced~

4. Why choose a contactless smart card? 

• No battery required: maintenance-free, long service life (no problem for normal use for 3-5 years)

• Second response: read immediately when close, without plugging and unplugging, and the experience is super smooth

• Safety and flexible: supports encrypted communication (anti-copy), and can also integrate multiple functions (access control + consumption + attendance)

5. Our services: Professionally customized contactless smart cards!

As a smart card source manufacturer, we provide full-type contactless card customization:

• Chip is optional: low frequency/high frequency/ultra-high frequency (select safety level and read and write distance as needed)

• various materials: standard PVC, waterproof and wear-resistant, matte/gloss-surface process, adapted to different scenarios

• Function integration: supports IC/CPU chips, can print LOGO, QR codes, and even embed NFC functions

Whether it is community access control, enterprise one-card, campus card or transportation card, we can help you customize smart cards with stable power, safe and reliable power!