Abstract

A power adapter driving battery loads typically uses constant current then constant voltage. The current limit, crossover voltage and termination current of the power adapter must match cell capacity. Poor settings make the power adapter charge slowly or top up repeatedly.

1. Two-stage Constant Current and Constant Voltage

With battery loads the power adapter charges at a set current first, then switches to constant voltage once cell voltage reaches the crossover, with current tapering as the difference shrinks. Crossover voltage of the power adapter must equal the full-charge voltage: higher accelerates aging, lower leaves the cell short. Transition should be smooth, since oscillation at the crossover interrupts charging and shows up as blinking indicators or jumping state of charge.

2. Charging Current versus Capacity

Constant current of the power adapter is usually set as a fraction to one times cell capacity, depending on chemistry and thermal conditions. Excessive output current raises internal temperature and shortens cycle life, while too low a current makes charging slow. When paired with a terminal, the power adapter should confirm whether the device has its own charging controller, so two limiting stages do not stack and cut actual current far below design.

3. Termination and Cut-off Current

In constant voltage the power adapter ends charging when current falls below a threshold, typically tens of times below the constant current value. Too low a cut-off extends charging time in the power adapter, while too high a value leaves the cell persistently undercharged. The restart threshold after termination also matters: whether the power adapter tops up when voltage sags depends on the balance between cycle life and runtime.

4. Trickle Charging and Deeply Discharged Cells

A deeply discharged cell has very low voltage, and charging the power adapter at full constant current may damage it. The power adapter normally pre-charges at low current until voltage recovers, then enters normal constant current. Pre-charge current and duration follow cell maker recommendations, and cells discharged too long should be treated as failed rather than charged, requiring timeout protection in the power adapter.

5. Thermal Protection and Staged Charging

Cell temperature rises during charging, and continued high current at elevated temperature accelerates aging or creates safety risk. The power adapter can step down current with terminal temperature sensing, reducing current at low temperature to avoid lithium plating and pausing at high temperature. Over-temperature thresholds and recovery logic of the power adapter must coordinate with the terminal battery manager so protections do not fight and cause frequent restarts.

Conclusion

The charging curve of a power adapter is not a fixed setting; it follows capacity, chemistry and temperature. Simsukian tunes CV/CC parameters to terminal battery specifications. Overseas buyers are welcome to contact Simsukian to confirm charging schemes for the power adapter.

FAQ

Q1: Does Simsukian support OEM and ODM orders?

A1: Yes, Simsukian supports OEM & ODM customization, including logo, casing, parameter and packaging adjustment.

Q2: What certifications can Simsukian provide?

A2: Simsukian can provide CE, RCM, FCC, UL, CCC, KC/KCC, PSE, SAA certification certificates. The company holds ISO9001 and ISO14001 system certifications.

Q3: What is the sample lead time?

A3: Sample preparation takes 5 working days.

Q4: What trade terms can be accepted for cooperation?

A4: Simsukian supports FOB, and EXW can be discussed upon customer request.

Q5: What is the warranty period for the products?

A5: The product warranty period is 1 year.

References

1. Simsukian Official Website

2. USB Battery Charging Specification 1.2

3. IEC 62368-1 Audio/video, information and communication technology equipment – Safety requirements