Dawnice System: Integrated Off‑Grid Power, Sized for Real Loads

The Dawnice System combines battery storage, inverter/charger, MPPT solar, DC‑DC alternator charging, distribution, and monitoring so the whole power setup behaves like one product. Build it around your actual energy use to get reliable, quiet power for vans and RVs, cabins, boats, and home backup.

Who This Is For

• Use if you want a permanent, serviceable system that can run appliances (refrigerator, laptops, tools, induction, pumps) without babysitting settings.
• Use if you need multiple charging sources (solar, alternator, shore/generator) that coordinate automatically.
• Not ideal if you only need a short‑term, plug‑and‑play power station or if a fuel generator is your primary plan for heavy, continuous loads.

Plan and Size in 6 Steps

1. List your daily loads

   Write each device, watts, and hours used. Example: 12V fridge (40W avg × 24h ≈ 960 Wh), laptop (60W × 6h = 360 Wh), lights and fans (40W × 4h = 160 Wh). Daily total ≈ 1,480 Wh.

2. Size the battery bank

   For LiFePO4, plan ~80% usable to extend life. Formula (12V): Bank_Ah = (Daily_Wh × Days_of_Autonomy) ÷ (12V × 0.8). Example: 1,480 Wh × 1.5 days ÷ (12 × 0.8) ≈ 231 Ah → select ~200–300 Ah.

3. Pick the inverter

   Match the largest single AC load plus surge. Add 20–30% headroom. If your biggest load is a 1,500W kettle, choose a 2,000–3,000W pure‑sine inverter.

4. Choose charging sources

   • Solar: Daily_Wh ≈ Array_Watts × Peak_Sun_Hours × 0.65–0.8. Example: 400W × 5 PSH × 0.75 ≈ 1.5 kWh/day.
   • DC‑DC (alternator): Charge_W ≈ Charge_A × 13.8V. Example: 40A ≈ 550W; 2 hours driving ≈ 1.1 kWh.
   • AC/shore or generator: A 50A DC charge setting ≈ ~700W; 100A ≈ ~1.3 kW (actual depends on equipment).

5. Distribution and protection

   Use busbars for clean parallels, main battery fuse/breaker sized to cable and device limits, and labeled DC/AC circuits. Target DC voltage drop: ≤3% critical, ≤10% non‑critical.

6. Monitoring and control

   Use SoC via shunt, history, and alarms. Helpful automations: quiet hours, shore‑current limit, low‑SoC load shedding.

Example Builds with Quick Estimates

Weekend Van / Compact RV

• Battery: 12V 200Ah LiFePO4 (≈ 2.56 kWh gross; ~2.0 kWh usable at 80% DoD)
• Inverter: 1,500–2,000W
• Charging: 200–400W solar + 30–40A DC‑DC
• Use case: Fridge, lights, laptops, small blender. 2 hours driving can recover ~0.7–1.1 kWh.

Off‑Grid Cabin

• Battery: 24V 200Ah LiFePO4 (≈ 4.8 kWh gross; ~3.8 kWh usable)
• Inverter/charger: 3,000W with transfer to generator
• Charging: 1.0–1.6 kW solar array
• Use case: Fridge, lights, work devices, occasional power tools; 1–2 cloudy days autonomy.

Live‑Work Van / Studio Rig

• Battery: 12V 300–400Ah LiFePO4 (≈ 3.8–5.1 kWh usable)
• Inverter: 2,000–3,000W
• Charging: 600–800W solar + 60–90A DC‑DC
• Use case: Laptops, A/V gear, induction (15 min at 1,200W ≈ 0.3 kWh), fridge. Drive 2–3 hours to add ~1.1–2.0 kWh.

Wiring and Protection Essentials

• Main battery fuse/breaker as close to the positive post as practical; interrupt rating must meet fault current.
• Use appropriately sized, fine‑strand copper cable. Aim for ≤3% voltage drop on critical DC circuits.
• Parallel batteries at busbars (not stud‑to‑stud) for even current sharing.
• Provide airflow and clearance around inverters/chargers; avoid engine bays and heat sources.
• Bond grounds to a common bus. Use GFCI/AFCI where codes require. Follow manufacturer torque specs on lugs.

Charging and Battery Care

• Follow your battery’s charge profile. Typical LiFePO4 (12V): Absorption 14.2–14.6V, Float 13.4–13.6V if used; some users disable float for cyclic use.
• Avoid charging LiFePO4 below 32°F (0°C) unless the battery is heated; many BMS will block cold charging.
• For longevity, daily charge to ~90–100% as needed and avoid extended storage at 100% SoC.

Compatibility and Alternatives

• Works with 12V or 24V systems; choose 24V for higher inverters or long wire runs to reduce current.
• Integrates with shore power or a generator via an inverter/charger with transfer switch.
• If you only need occasional AC power, a small portable power station may be simpler. For long heavy loads (e.g., large AC for many hours), a generator may be more practical.

Pros and Trade‑offs

• Pros: Coordinated charging, accurate SoC, safer distribution, easier troubleshooting, scalable capacity.
• Trade‑offs: Higher upfront planning effort, installation time, and need to observe electrical codes.

Installation Time and Skills

• Typical timeline: 1–2 days for a compact van system; 2–4 days for cabin with solar array and distribution panel.
• DIY‑friendly for mechanically inclined users; hire a qualified installer for AC wiring, generator transfer, or code‑inspected work.

FAQ

Bottom Line

Start with your daily watt‑hours, size the battery and inverter with margin, then add solar and alternator charging that fit your routine. The Dawnice System gives you a coordinated, serviceable power hub that’s quiet, efficient, and ready for real‑world use.