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Solar powered switch-mode charger (CN3801), protector (HY2112) and 5V booster (MT3608) for LiFePO4 batteries. The charger provides maximum power point tracking (MPPT) and can easily be modified to work with LiPo batteries.
| ID | Name | Designator | Footprint | Quantity |
|---|---|---|---|---|
| 1 | Connector | VIN1,VOUT1,BAT1 | HDR-1X2/2.54 | 3 |
| 2 | CN3801 | U1 | SSOP-10_150MIL | 1 |
| 3 | KF301-2P | BAT2,VOUT2,VIN2 | KF301-2P | 3 |
| 4 | HY2112 | U2 | SOT-23-6 | 1 |
| 5 | 100n | C8,C1,C2,C9 | 0805 | 4 |
| 6 | 22uH | L2 | IND-SMD_L7.3-W6.8 | 1 |
| 7 | 47uH | L1 | IND-SMD_L7.3-W6.8 | 1 |
| 8 | 27k | R3 | 0805 | 1 |
| 9 | 3k | R4 | 0805 | 1 |
| 10 | 2k | R9,R7 | 0805 | 2 |
| 11 | 1k5 | R1 | 0805 | 1 |
| 12 | 15k | R8 | 0805 | 1 |
| 13 | 100R | R6 | 0805 | 1 |
| 14 | 120R | R2 | 0805 | 1 |
| 15 | 10u | C7,C6 | CAP-D5.0XH5.5 | 2 |
| 16 | FDS4435BZ | Q1 | SOIC-8_L5.0-W4.0-P1.27-LS6.0-BL | 1 |
| 17 | R050 | R5 | 2512 | 1 |
| 18 | MT3608 | U3 | SOT-23-6 | 1 |
| 19 | Slide Switch | PWR | SLIDE SWITCH DPDT 1P2T | 1 |
| 20 | FS8205 | Q2 | SOT-23-6 | 1 |
| 21 | CHRG | LED2 | LED-0805 | 1 |
| 22 | DONE | LED1 | LED-0805 | 1 |
| 23 | 220n | C4 | 0805 | 1 |
| 24 | 4u7 | C5,C3 | 0805 | 2 |
| 25 | 22u | C10,C11 | 1206 | 2 |
| 26 | SS34 | D1,D2,D3 | SMA(DO-214AC) | 3 |
Comments (2)
Hi Stefan,
Do you think this could be modified to perform a UPS function for a Raspberry Pi?
I am interested in designing one, but working from yours, I can see the following changes required:
- USB 5V input rather than Solar Panel
- Fuel Gauge chip to report voltage level to pi over IIC perhaps (primarily to allow for graceful shutdown)
- Programmable 5V output to boot rPi up after USB input is restored (plus a small micro controller to do so I guess)
- Optional OLED display to allow system information display on the same board
I'm interested in your thoughts as I'm not very proficient with Power electronics.
Cheers,
Dan
@danricho Hi, I think the "CN3058 LiFePO4 Charger Booster" will be a better starting point, as it already works with 5V input and it's much simpler. However you will need a boost converter which is capable of delivering at least 2A. For communicating with the Pi I think a single line to one GPIO pin which tells the Pi to shut down by going low or high would be enough (I think there are some scripts for the Pi out there which do the job). The rest can be done with a micro, if you do not use the oled (instead some indicator LEDs) then a simple and cheap ATtiny13 would be enough. Do you prefer LiPo or LiFePO4 batteries? And by the way, I'm not a professional either ;-)