Here is a finalised design based on your requirements:
LOCAL / SOURCE END
48V DC Power Supply
Mean Well GST160A48-R7B
48V / 160W
│
│ 48V DC
▼
Tycon POE-INJ-1000-WT
Passive Gigabit PoE Injector
│
│ CAT6 cable
│ (Data + 48V power)
▼
REMOTE END
Tycon POE-INJ-1000-WT
Passive PoE Splitter
│
│ 48V DC
▼
Mean Well DDR-120C-12
48V → 13.8V DC Converter
120W / ~8.7A
│
│ 13.8V DC BUS
│
┌───────────┼────────────┐
│ │ │
│ │ │
▼ ▼ ▼
LiFePO4 12V LVD/UPS 12V loads
8Ah battery Controller
│
│ switched output
│
┌──────────┴───────────┐
│ │
▼ ▼
Waveshare CM4 NAS LINOVISION PoE Switch
+ NVMe 12V input
+ 4G modem 4 × 802.3af/at PoE
│ │
│ │
▼ ▼
Clean shutdown Amcrest IP5M-T1179EW
via GPIO/network PoE cameras ×4
| Device | Power |
|---|---|
| 4 × Amcrest IP5M-T1179EW | ~30–40 W |
| LINOVISION switch losses | ~3–5 W |
| CM4 + NVMe NAS | ~8–12 W |
| 4G modem | ~5–10 W |
| Total system | ~50–65 W |
The Tycon limit:
48V × 2.25A ≈ 108W
So normal operation has a good margin.
Use a 12 V LiFePO₄ low-voltage disconnect / UPS controller between the DDR output and the loads.
Recommended thresholds:
Battery < 12.2V
↓
Send shutdown command to CM4
↓
Wait 30–60 seconds
↓
Disconnect CM4 + PoE switch
↓
Battery protected
48V returns
↓
DDR outputs 13.8V
↓
Battery charges first
↓
Battery reaches ~13.1V
↓
Reconnect CM4 + PoE switch
↓
System boots
This prevents the cameras and computer from competing with the battery charger immediately after a blackout.
Recommended:
sudo shutdown -h now
or:
systemctl poweroff
Then remove power after shutdown.
This protects:
Do not rely on the DDR alone as a LiFePO₄ charger.
Keep the DDR at:
13.8V
but add:
A 3 A limit is a good match:
13.8V × 3A ≈ 41W
Leaving:
108W Tycon capacity
- 65W system load
- 41W battery charge
≈ 2W margin
A 2 A charge limit would give even more margin.
✅ Mean Well GST160A48-R7B
✅ Tycon POE-INJ-1000-WTS pair
✅ DDR-120C-12
✅ LINOVISION PoE switch
✅ 12 V LiFePO₄ battery
✅ CM4 graceful shutdown
Suggested fuses:
This design should be reliable for a remote camera/NVR installation and avoids the main weakness of the original design: a depleted battery pulling too much current through the Tycon during recovery.
| Item | Model / Specification | Qty | Purpose |
|---|---|---|---|
| DC Power Supply | Mean Well GST160A48-R7B — 48 V DC, 160 W | 1 | Main 48 V power source |
| AC input protection | MCB/fuse + surge protection (as required) | 1 | Protect power supply |
| DC output fuse | 3–5 A @ 48 V | 1 | Protect 48 V distribution |
| Item | Model / Specification | Qty | Purpose |
|---|---|---|---|
| Passive PoE Injector/Splitter | Tycon POE-INJ-1000-WTs GigE 4Pr Pasv PoE Inj/Splitter, Pins 1236V+,5-58VDC Input, 130W Output, Shielded RJ45, Removable Terminal | 2 | Send and recover 48 V DC over CAT6 |
| Outdoor Ethernet cable | CAT6/CAT6A UV-rated shielded cable (if external run) | 1 | Data + DC power link |
| Ethernet protection | Outdoor surge protector (recommended) | 1–2 | Lightning/surge protection |
| Item | Model / Specification | Qty | Purpose |
|---|---|---|---|
| DC-DC Converter | Mean Well DDR-120C-12 | 1 | Convert 48 V input to 13.8 V DC |
| Output adjustment | Set to 13.8 V | — | Maintain 12 V system/battery bus |
| DC output fuse block | Automotive blade fuse distribution | 1 | Individual circuit protection |
| Item | Specification | Qty | Purpose |
|---|---|---|---|
| Battery | LiFePO₄ 12 V 8 Ah | 1 | Backup power |
| Battery BMS | Built into battery (verify rating) | 1 | Cell protection |
| Battery fuse | 10 A inline fuse | 1 | Battery protection |
| Battery disconnect switch | 10–20 A DC rated | 1 | Maintenance isolation |
| Item | Specification | Qty | Purpose |
|---|---|---|---|
| Low Voltage Disconnect (LVD) / UPS controller | 12 V LiFePO₄ compatible | 1 | Disconnect loads on low battery |
| Adjustable voltage thresholds | Approx. 12.2 V OFF / 13.1 V ON | — | Hysteresis control |
| Load switching device | DC MOSFET switch or relay, ≥15 A | 1 | Disconnect CM4 + PoE switch |
| Supervisor controller (optional) | ESP32 / RP2040 / similar | 1 | Smart shutdown logic |
| Item | Model / Specification | Qty | Purpose |
|---|---|---|---|
| PoE Switch | DC PoE Switch 802.3af/at , Industrial, 5-Port LINOVISION Industrial 5-Port Solar PoE Switch |
1 | 12 V input, 4 × IEEE 802.3af/at PoE outputs |
| PoE Budget | 4 × 30 W ports, 120 W total | — | Camera power |
| Ethernet patch cables | CAT5e/CAT6 | As required | Camera connections |
| Item | Model | Qty | Purpose |
|---|---|---|---|
| PoE Camera | Amcrest IP5M-T1179EW 5MP Turret PoE Camera | 4 | Surveillance |
| MicroSD cards (optional) | Up to 256 GB supported | 4 | Camera local backup |
| Item | Model / Specification | Qty | Purpose |
|---|---|---|---|
| Compute module | Raspberry Pi Compute Module 4 | 1 | NVR controller |
| NAS carrier board | Waveshare CM4 NAS board | 1 | Expansion/storage platform |
| Storage | NVMe SSD | 1 | Video storage |
| Cooling | CM4 heatsink/fan | 1 | Thermal management |
| 4G modem | USB/M.2/mini PCIe modem (as applicable) | 1 | Remote connectivity |
| SIM card | Data SIM | 1 | Cellular backhaul |
| Item | Specification | Qty | Purpose |
|---|---|---|---|
| GPIO shutdown input | CM4 GPIO | 1 | Receive low battery shutdown signal |
| Supervisor software | Linux service | 1 | Executes clean shutdown |
| Power switch control | MOSFET/relay module | 1 | Removes power after shutdown |
| Item | Specification | Qty | Purpose |
|---|---|---|---|
| Weatherproof enclosure | IP65/IP66 rated | 1 | Remote equipment housing |
| DIN rail | Standard 35 mm | 1 | Mounting PSU/DC equipment |
| Cable glands | IP67 rated | As required | Cable entry |
| Terminal blocks | DC rated | As required | Power distribution |
| Earth/ground bar | DIN mount | 1 | Grounding |
| Ventilation | Filtered vent/fan (if required) | 1 | Thermal control |
| Item | Specification | Qty | Purpose |
|---|---|---|---|
| Power Bus | Fused 12V positive bus and 12V negative bus | 1 | Remote equipment housing |
| Fuse | 5A Blade | 1 | CM4 Branch |
| Fuse | 10A Blade | 2 | POE Switch Bramch Battery |
This list represents the production-ready version of the design rather than just the proof-of-concept wiring.