32. USB trickle charger¶
Status: OK
Charging current: 50 mA
USB port power is max 500 mA -> 9 charger can be connected to one USB port
32.1. Power dissipation¶
- LED
- current = 15 mA
- power = 30 mW
- R4
- current = 35 mA
- power = 60 mW
- Transistor
- current = 50 mA
- power = 100 mW
32.2. Charge time¶
T = C * 1.5 / 50mA
| Capacity | current | time(h) | time(d) |
|---|---|---|---|
| 1000 mAh | C/20 | 30h | 1.25d |
| 2000 mAh | C/40 | 60h | 2.5d |
| 3000 mAh | C/60 | 90h | 3.75d |
32.3. Schematic¶
32.4. Sources¶
Based on this design: http://www.extremecircuits.net/2009/10/low-cost-universal-battery-charger.html